Economic Importance and Yield Potential of Sugarcane in Pakistan

Abstract

Sugarcane is mainly cultivated in the tropical and subtropical regions of the world, and nearly 85% of sugar is used worldwide. The area, production, and yield of sugarcane has been increased worldwide as well as in Pakistan as compared to other crops. It is the second largest economically important crop after cotton. It is a high-value cash crop that has significance for sugar industries in Pakistan. It contributes about 0.6% to the GDP and 2.9% of the total value added in agriculture. It creates huge revenue for the government and is used as a source of energy/power. The climate of Pakistan is favorable for sugarcane production in Punjab and Sindh provinces. Different climatic factors, i.e., sunlight, temperature, germination, tillering, growth, humidity, dew, frost, hailstorm, windstorm, sunburn, and drought, significantly affect the production of sugarcane. Pakistan is a principal cane-growing country and stands at the fifth position in the area, sixth position in cane sugar production, and ninth largest sugar producer in the world. This chapter describes the economic importance, climate, and yield potential of sugarcane in Pakistan.

1. Introduction

Sugarcane is a globally significant crop as it provides nearly 85% of the sugar consumed worldwide. In recent years, the planting of sugarcane for the production of biofuels has expanded rapidly as cases of energy canes. The cultivation of sugarcane is one of the most important activities around the world due to their alimentary, environmental, social and economic implications, and potential productive diversification with coproducts and byproducts [1]. Sugarcane is a worldwide crop cultivated in more than 105 countries. From its very origin, in earlier times to its present-day production, sugarcane has played its role in improving the socioeconomic conditions of human society [2].

Previous trends have shown a tremendous increase in area under sugarcane production throughout the world. However, for 2019–2020, global sugar production is estimated to decline 3% to 1745 million tons while sugarcane was grown on 26.5 million ha. This diminution is attributed to the 5 million tons drop in India’s production, resulting from lower area and expected yields. However, Brazil and India are essentially tied as top sugar-producing countries, while Pakistan occupies the fifth place [3].

It is mostly used as a food crop for the production of raw and refined sugar, gur, and shakkar. Sugarcane improvement has traditionally focused on sucrose-yield traits. In the future, energy canes with higher yields of fermentable sugars and fiber (bagasse) for biofuel and electricity applications will be developed [4]. Sugarcane has gained importance for its dietary value and its industrial utilization for several products. Its products and byproducts have revolutionized a native and international trade, and the crop production trends have played a dominant role in altering the economic and fiscal position of countries.

Its juice is used for making white sugar, brown sugar (khand), and jaggery (gur) [5, 6]. The sugarcane bagasse, a byproduct, is nowadays valued by producers from the sugar sector since it is presented as the main feedstock source for bioenergy and biofuel production. In Pakistan, almost 3.50 million metric tons of bagasse is consumed with an average recovery rate of 30%. Bagasse is conventionally recycled as confined energy in sugar factories, i.e., boiler steam is required to generate and drive the prime movers [7].

Bagasse is used for the production of compressed fiberboard, paper, plastics, and furfural. Owing to the high silicon content on sugarcane, bagasse can be used to produce silica, a valued material for industry and health products. Molasses are used in distilleries to manufacture ethyl alcohol, butyl alcohol, citric acid, etc. Sugarcane filter cake (press mud) has good potential as organic fertilizer [8].

2. Importance of sugarcane

2.1 Dietary value

Sugar is used as a sweetener in many dishes of varying tastes, beverages, and pharmaceutical products. It is an important constituent of human diet, having a pleasant taste and a high calorific value of 387 per 100 grams [7]. Some fruits and vegetables also have some forms of sugar (Table 1), but it is not derived as a commercial product [10].

Fruits	Sugar (%)	Fruits	Sugar (%)
Mangoes	12.7	Oranges	8
Strawberries	4.1	Apricots	7.8
Pomegranates	11.6	Plums	8.4
Guavas	4.7	Pears	8.4
Papaya	5	Pineapple	8.4
Watermelon	5.3	Cherries	10.9
Grapefruit	5.9	Apples	8.8
Figs	13.8	Grapes	13.8
Peaches	7.1	Bananas	10.4

Table 1.

Sugar contents in different fruits.

Source: [9].

The trend of using low-calorie sweeteners (LCS) has now developed in some quarters. Among the low-energy sweeteners, saccharin is the oldest sweetener [11]. Sugarcane juice contains zero fat, cholesterol, fiber, and protein [11]. This is the healthiest and the most nutritious drink one can think of consuming [12]. The latest research showed that both sugar-sweetened beverages (SSBs) and LCS beverages were linked with an increased risk of developing type 2 diabetes. Sugar percent in different fruits has been presented in Table 1 [12]. Some forms of sugar are produced from palm trees, sugar maple, sweet sorghum, maize, sugar beet, and sugarcane (Table 2) [2].

Palm trees	9% sucrose on the weight of palm juice
Sugar maple	2% sugar maple sap
Sweet sorghum	9% sucrose (brix 19%, pol 15%).
Maize	2–4% glucose
Sugar beet	12–18% sucrose
Sugarcane	10–13% sucrose

Table 2.

Plants utilized for commercial sugar production.

Source: [13].

2.2 Grower’s prosperity

Sugarcane is a high-value cash crop that has significance for sugar and sugar-related industries in Pakistan. It contributes about 0.6% to the GDP and 2.9% of the total value added in agriculture and has brought prosperity to grower’s community [14]. In areas of cane concentration, healthy socioeconomic change is witnessed, which has improved the living standard of growers. The dilemma is that farmers normally do not receive a fair market price for their sugar crop [15].

General problems faced by almost every farmer regarding sugarcane production are lack of irrigation water, nonavailability of improved varieties of sugarcane, high cost of inputs for land preparation, diseases, insect pest, weeds, and marketing problems [16]. The adversities faced by sugarcane farmers have been unequivocally portrayed by the multitude of protests organized by sugarcane farmers. Given the failure of the governments to resolve these issues, it is apparent that a different course of action needs to be taken to address the fundamental problem. We need to look beyond our conventional strategies.

In developing countries, the sugar factories delay the timely payments of sugarcane farmers. In view of millions of sugarcane farmers, the governments need to swiftly resolve the most pivotal issue before it further retrogrades. In return, governments mainly have two options. First, one is to pay back the dues to the farmers from the state treasury or provide subsidies to sugar factories. Either way, the government will have to shift the monetary burden to the taxpayers [5]. In the short run, given the obstinate demand of sugarcane farmers to receive their payment and the incapability of sugar factories to make the payments, this seems to be a plausible option.

2.3 Sugar industry of Pakistan

A total of 89 sugar mills are operational [17]. Sugarcane cultivated on an area of 1.16 million ha during 2020–2021 [3]. On regional basis, Punjab’s share in the total sugarcane area of Pakistan was 65.7% followed by Sindh 26.8% and Khyber Pakhtunkhwa (KPK) was 7.5%. The yield of sugarcane was increased from last five in 2020–2021; the highest yield was recorded 69.55 t/ha, while the maximum share in yield was of Punjab at 59.5 tons (Table 3).

Province	Area (1000 ha)	Share in cropped area (%)	Prod. (1000 ton)	Provincial share in prod. %	Yield (t/ha)
Punjab	643.4	4.71	43,346.6	65.7	67.37
Sindh	286.0	9.95	17,233.8	26.8	60.24
KPK	109.4	6.31	5753.9	7.5	52.62
Pakistan	1038.9	5.37	66,334.4	100.0	63.85

Table 3.

Provincial distribution of sugarcane production in Pakistan in 2020.

Source: [3].

The area under sugarcane in Pakistan has increased from 960,000 has in 2001–2002 to 1,040,000 ha in 2019–2020 with an annual growth rate of 1.0% [18]. The total increase in area, production, and per hectare yield during this period is around 26.7, 73.1, and 27.5% during the period [3].

2.4 Labor and workforce

Sugarcane is a source of employment for millions of people both at the farm sector and in sugar industry [19]. For example, in Pakistan, all most 15,000–25,000 families are involved in the sugarcane zone of one factory. Almost 980,000 farmers were engaged with sugarcane cultivation in Pakistan, out of which 707,000 farmers worked in Punjab, 200,000 in Sindh, and 81,000 in KPK. On average, 1200 employees working in a sugar mill with workforce of 106,800 individuals in the production and processing departments. Overall, around 4 million employees are engaged directly or indirectly in sugar business in Pakistan [20].

Owing to the lack of mechanical sugarcane farming (planting and harvesting) in Pakistan, innumerable workers are deployed in cane harvesting, transport, and loading and unloading of cane. The huge involvement of technicians in farm machinery with the transport system of tractors, trolleys, and trucks depicts the quantum of business in various sectors [5].

2.5 Source of food fodder and fertilizer

Sugarcane is used as a source of food and fodder. The press mud and fly ash products of sugar industry are high-valued organic fertilizers. Filter cake is used as fertilizer and used in brick kilns [21] also used with distillery effluent and nitrogen-fixing bacteria. Some processors/factories have acquired certificates of halal and organic products like sugar/gur/shakkar [6]. The production of organic gur and shakkar is about 1000 tons having a business of around 300 million [6, 22].

2.6 Government revenues

In Pakistan, the revenue is derived in the form of general sale tax (GST) on the sale of sugar, which is 17% of the sugar price. A substantial amount is recovered as sugarcane Cess Fund @ Rs. 2.00 per maund of sugarcane, delivered to sugar mills. Land revenue and water rates, @ Rs. 400 per acre of cane, amount to billions of rupees per annum and is the direct source of income for the government. The excise duty on molasses and alcohol is also a big source of revenue for the government as well [23].

2.7 Source of energy/power

Molasses, the main byproduct of the sugar industry, is utilized for the production of alcohol, rum, and as feed for livestock. Ethanol has now gained high importance as an energy product [24]. Sugarcane is used as feedstock for ethanol production and as biofuel in vehicles. The use of high-pressure steam boilers and efficient use of energy in the sugar factories has given new vistas of cogeneration from bagasse and trash to export surplus electric power to the national grid system [25]. The production of biogas from spent wash/vinasse fermentation is also a source of cheaper energy in distilleries [24, 25].

2.8 Industrial utilization

Sugarcane occupies a prominent place for high biomass-fiber production and molasses. As a raw material, sugarcane has attained worldwide importance for dozens of industrial derivatives. The main byproducts of cane are molasses used for alcohol, bagasse utilized for energy production, cogeneration, the manufacture of particleboard, and filter press cake used as organic fertilizer [26].

In the present-day market economy, the profits derived from the manufacture of sugar are getting low, and more attention is paid to the manufacture of byproducts. Today, the focus is to adopt sugar production technology to yield energy-based coproducts, ethanol, and electricity. Cane acreage fluctuates depending upon market forces, socioeconomic conditions, and crop competitions [24].

3. Cane yields on the global level

On the global level, sugarcane is grown in 105 countries located in equatorial, tropical, and subtropical regions. Cane area, production, and yields of principal cane-growing countries are shown inTable 4. The world data show that during 2020, sugarcane was grown on an area of 25.98 million hectares with a cane yield of 70.9 tons per hectare (t/ha). Concerning area, Brazil occupies the leading position by growing cane in an area of 10.18 million hectares followed by India, China, Thailand, and Pakistan growing cane in an area of 4.39, 1.38, 1.37, and 1.22 million hectares, respectively [28].

Year	Punjab		Sindh		KPK		Pakistan
	Area (ha)	Yield (t/ha)	Area (ha)	Yield (t/ha)	Area (ha)	Yield (t/ha)	Area (ha)	Yield (t/ha)
1947–1950	170.0	37.7	8.10	34.1	41.30	28.40	201.9	33.47
1959–1960	286.6	27.09	20.20	41.70	65.20	30.40	396.6	26.80
1969–1970	454.9	43.3	83.40	40.9	81.70	39.7	620.00	42.50
1979–1980	501.4	38.7	129.90	35.90	87.10	39.20	718.50	38.3
1989–1990	501.0	37.30	250.7	49.30	102.10	43.40	854.3	41.5
1999–2000	672.1	40.3	230.6	51.27	108.3	46.3	1009.8	45.9
2009–2010	607.4	51.6	233.9	57.7	100.8	44.7	942.9	52.36
2016–2017	777.82	63.78	320.51	63.05	118.57	47.50	12.16.9	62.00
2017–2018	859.13	64.10	333.30	61.85	148.53	51.2	1340.9	62.11
2018–2019	710.61	63.19	279.50	59.72	110.10	48.8	1101.1	60.97
2019–2020	643.430	67.37	286.090	62.93	109.36	52.62	1038.9	63.85
2020–2021	776.98	73.36	279.69	65.56	107.44	52.38	1164.12	69.55

Table 4.

Growth in area and yields of cane in cane-growing provinces of Pakistan from 1947 to 1950 to 2020–2021.

Source: [27].

During the midst of the twentieth century world, the average yield was hardly 42.5 t/ha, which has now increased to 70.9 t/ha. During 1950–1953 period, principal cane-growing countries, Brazil, India, China, and Thailand, had the cane yields of 38.7, 32.1, 35.2, and 17.5 t/ha, respectively, much below the world average. During five decades of progressive development, Brazil, China, and Thailand improved their yields to a level of 74.5, 76.1, and 75.2 t/ha, respectively, which exceeds the world average of 70.9 t/ha. Still, there are countries with an average yield of 121.0 tons per hectare (Guatemala) and 112.7 tons per hectare (Egypt) as shown in Table 5 [30].

Country	Area (1000 ha)	Production (million/t)	Yield (t/ha)
World	25,976.94		70.89
Brazil	10,184.34	758.55	74.48
India	4389.00	306.07	69.74
China	1377.11	104.79	76.10
Thailand	1368.27	102.95	75.24
Pakistan	1216.89	73.40	60.31
Mexico	722.00	56.95	73.78
Australia	457.47	36.56	80.62
Philippines	439.47	29.29	66.94
Indonesia	430.11	21.21	49.32
Colombia	397.39	34.64	87.16
Cuba	387.70	16.07	47.45
Argentina	378.82	19.16	50.54
USA	365.88	30.15	82.41
Vietnam	281.15	18.36	65.29
Guatemala	278.97	33.76	121.01
South Africa	264.50	17.39	65.74
Burma	163.25	10.37	63.52
Bolivia	151.99	8.05	52.96
Cameroon	136.29	1.29	9.45
Egypt	135.40	15.26	112.70

Table 5.

Sugarcane area, production, and yields of top 20 cane-growing countries during 2017.

Source: [29].

Pakistan grasps an important position in cane area and production in the world and ranks on top fifth position, but with respect to cane yield (69.55 t/ha), it ranks much below the principal cane-growing countries [31]. Compared with other countries, it appears that Pakistan took a late start to meet yield gaps. Even India has touched 70 t/ha, while Pakistan has yet to travel a lot to reach this yield level.

The highest cane yield of 121.01 t/ha is reported in Guatemala, followed by 112.70 t/ha in Egypt. Among the top 20 cane-growing countries are Colombia (87.16 t/ha), the USA (82.41 t/ha), and Australia (80.62 t/ha), while China, Thailand, Brazil, and Mexico have exceeded 70 tons in yield [28]. Pakistan has just 60 tons against about 70 tons yield of India. Though Pakistan stands at the fifth position in cane area and production in the world it has to travel a lot in the compatible field of yields per hectare.

4. Effect of latitude

The data in Table 6 indicate that world’s largest cane area is located in South America (44.5%), closely followed by Asia (40.3%). The continents of North America, Africa, and Oceania grow cane in a small fraction of 8.85, 8.91, and 1.82% area, respectively. The maximum cane area (55%) falls in countries situated in latitude ranges of 10–20° N or S. The countries in latitude ranges of 0–10°, 20–25°, and 25–35° grow 10.5, 16.5, and 19.5% of the total world cane average, respectively. The continent of Asia has a relatively higher proportion of cane grown in 25–35° latitudes, South America in 10–20°, while cane area in North America and Oceania mostly fall in latitude ranges of 20–25°.

Continent	Latitude ranges—cane area and (cane yield)					% Share in area
	0–10	10–20’	20–25’	25–35’	Total
Asia
Area; Yield	691.861.1	3496.466.3	2421.466.5	3869.362.5	10,478.964.7	40.3
Africa
Area; Yield	523.534.5	400.952.6	138.942.7	468.382.8	1531.654.7	5.9
North America
Area; Yield	765.0	14.8	1162.0	365.9	2307.7	8.9
	89.2	59.7	62.9	82.4	74.7
South America
Area; Yield	733.0	10,336	118.0	385.4	11,572.7	44.5
	82.7	74.2	56.0	50.7	74.6
Europe
Area; Yield	—	—	—	0.08	0.08	0.00
				27.0	27.0
Oceania
Area; Yield	7.1	35.2	435.5	—	477.8	1.8
	28.7	42.3	80.6		73.4
Total world
Area; Yield	2720.4	14,283.6	4275.8	5088.9	25,976.9	100
	70.0	71.7	65.9	64.9	70.9
% Share in area	10.5	55.0	16.5	19.6	100

Table 6.

Cane area (thousand ha) and cane yield (t/ha) of various continents located in different latitude ranges, during 2017.

Source: [32].

The latitudes have a great impact on cane yields. The highest cane yields are observed in Latitude ranges of 0°–20° (70.0–71.7 t/ha) followed by 20°–25° (65.9 t/ha) and 25°–35° (64.9 t/ha). It indicates that as we go away from the equator, there is a gradual decline in cane yields. With respect to overall global cane yields, North America and South America have the highest yield of 74.7 t/ha and is closely followed by Oceania (73.4 t/ha), while the yields of Asia (64.7 t/ha), Africa (54.7 t/ha), and Europe (27.o t/ha) are considerably low. The latitude range of 10°–25° is considered the most favorable for cane production.

5. Correlation of latitude with cane yields and juice quality

5.1 Cane yield

On the global level, the effect of latitude on cane yields is well marked [33]. The yield level toward the equator is high, and as the cane growing is shifted away from the equator, yields show a gradual decline [34]. The survey of the global area indicates some very interesting climatic features of countries lying in favorable climatic zones but having very low yields [34] (Table 7).

District	Cane area (thousand ha)	Cane yield (t/ha)	District	Cane area (thousand ha)	Cane yield (t/ha)
Punjab
Punjab	859.3	64.10
Sargodha	65.96	57.18	Sheikhupura	2.02	59.30
Khushab	8.90	56.91	Nankana sb.	13.76	56.26
Mianwal	3.24	50.45	Lahore	0.40	50.17
Bhakkar	29.95	65.21	Kasur	30.76	51.37
Faisalabad	112.50	57.00	Multan	6.47	52.85
T. T. Singh	38.44	62.35	Lodhran	5.26	69.27
Jhang	55.04	59.30	Khanewal	6.88	63.36
Chiniot	43.71	55.43	Vehari	17.81	57.46
Gujrat	2.43	48.61	Muzaffargarh	61.11	68.44
M.Bahauddin	23.88	52.48	Layyah	18.21	65.58
Sialkot	1.21	35.05	D.G. Khan	10.12	69.36
Narowal	1.62	31.91	Rajanpur	32.37	82.09
Gujranwala	202	39.06	Bahawalpur	30.35	66.41
Hafizabad	6.47	48.42	R.Y. Khan	193.03	77.75
Okara	14.57	49.90	Bahawalnagar	13.76	58.11
Sahiwal	4.86	54.05
Pakpattan	2.02	53.95
Sindh
Sindh	327.29	62.96
Thatta	36.37	59.30	Nawabshah	35.71	69.19
Badin	42.60	46.45	Nawshehra Feroz	22.26	63.26
Hyderabad	6.39	57.33	Sanghar	17.34	67.21
T.M. Khan	18.88	64.14	Sukkar	7.86	66.22
T.Allahyar	20.45	45.47	Khairpur	22.76	62.27
Matiari	15.84	66.22	Ghotki	53.40	82.71
Jamshoro	0.58	44.48	Larkana	0.71	69.68
Dadu	4.50	53.37	Kambar	0.19	54.36
Mirpur Khas	18.90	55.37	Shikarpur	0.47	45.46
Tharparkar	0.28	60.29	Jaccobabad	0.15	40.52
40.52Umarkot	1.64	63.60
Khyber Pakhtunkhwa
Khyber Pakhtunkhwa	148.53	51.23
Bannu	0.43	39.74	Naushehra	2.04	50.77
Charsada	32.20	43.48	Peshawar	10.71	51.94
D. I. Khan	63.08	62.00	Swabi	2.21	38.75
Malakand	4.88	38.17	Tank	1.09	39.96
Mardan	30.39	42.48	Others	1.50	25.38

Table 7.

Sugarcane area and yields of various districts in Punjab, Sindh, and Khyber Pakhtunkhwa, during 2017–2018.

In present-day agriculture, the word “favorable climate” has been replaced by “favorable environment” [8, 34]. High yields of cane and sugar are obtained under such dry environments where satisfactory soil water balance can be achieved by irrigation water under optimum soil and crop management practices [12, 13]. The sugarcane varieties have been developed, which owing to their great adaptability can be cultivated under a wide range of climate and soil conditions [16]. The cultivation of sugarcane is, therefore, spread in tropical, subtropical, and temperate regions between latitude ranges of 0° and 37° N and S. World data indicate that the best cane-producing areas in Asia are situated in 25°–35° latitude [35]. On a global level as well, after 10°–20° latitude, 25°–35° latitude region produces the maximum cane in the world (Table 8).

Years	Sugar recovery percent cane
	Sindh	Punjab	KPK	Pakistan
1947–1950	—	7.23	7.08	7.16
1950–1955	—	7.73	7.43	7.58
1955–1960	—	7.54	8.08	7.81
1960–1965	7.97	7.91	8.03	7.97
1965–1970	8.85	8.41	8.62	8.63
1970–1975	8.88	8.67	7.68	8.41
1975–1980	9.24	8.42	8.01	8.56
1980–1985	9.10	8.28	8.39	8.59
1985–1990	9.09	8.23	8.85	8.72
1990–1995	9.35	8.23	8.59	8.72
1995–2000	9.55	7.93	8.02	8.50
2000–2005	9.35	8.61	8.10	8.69
2005–2010	9.49	8.78	8.12	8.80
2010–2015	10.10	9.75	9.20	9.68
2015–2016	9.94	10.65	9.44	10.16
2016–2017	9.77	10.16	9.43	9.87
2017–2018	9.79	10.55	9.52	10.02
2018–2019	10.31	10.79	10.41	10.47
2019–2020	9.71	10.21	10.30	9.89
2020–2021	9.43	10.02	9.86	9.61

Table 8.

Sugar recovery trends in sugar mills of Sindh, Punjab, and KPK during 1947–2020.

Source: [3].

5.2 Cane quality

Lower latitudes assure longer days with increased sunshine duration during the growth phases of the plant. As such, high sucrose contents in cane are noted at around 18°S and 18°N. Sugar contents drop rapidly from these latitudes toward the subtropics and less rapidly toward the equator.

High sugar recoveries demand relative temperature disparity (RTD) value around 14–16°C, low daily mean temperature 10–12°C, and low relative humidity (<50%), during ripening [36]. The wider range between a day (maximum) and night (minimum) temperature during ripening results in higher sucrose contents [37]. High altitudes of 1000 mm or more within equatorial climates and low altitudes of subtropics also produce good-quality cane [38, 39]. Tropical countries or regions with high average temperature (25–27°C) and high precipitation of more than 1500 mm produce more biomass of cane, but it is of low sugar contents. In tropical areas where the weathers are distinctly wet and dry, moisture status inside the cane is a dominating factor in the synthesis and translocation of sugars. Under such conditions, control on irrigation and fertilizer is exercised to hasten or delay the maturity [40]. In modern agriculture, high sucrose content is achieved irrespective of latitude, in regions of low precipitation of both tropics and subtropics, if optimum soil and crop water balance have been achieved by human control. The climatic features have distinct behavior on plant growth and maturity phases:

• The high yield of cane per hectare is the result of a large biomass production, which is caused by moderately high temperature, high precipitation, and longer growing season. These, however, do not favor high sucrose recovery in cane [33].

• High sucrose contents in cane are a function of relatively low temperature and low precipitation during the maturity phase, which, otherwise, depress growth [36].

6. Climatic factors with effects

The change in weather factors, such as sunlight, temperature, rainfall, humidity, and solar radiation, affects the different phases of growth, maturity, and ripening phases of the plant [41].

6.1 Sunlight

Sunlight is used as photoperiod to regulate various growth processes in vegetative phase and for flowering. The sugarcane yield is governed by:

1. the amount of sunlight exposure to the crop over its lifetime, during various phases of growth

2. ability to intercept and use light energy to produce carbohydrates, the main source of sugars.

For sugarcane, the desirable locations with respect to light availability are within 30°N or °S, and more so on tropical latitude ranges. Crops having high yield and great potential need longer time span with greater light. For the best yield, 18 months are preferred as compared to 12 months [41]. Tillering is badly affected in long hazy season. For good tillering, excessive light is required; if plants grow to close in, light is curtailed that causes tiller mortality.

6.2 Temperature

Sugarcane crop might be exposed to scorching heat with a maximum mean temperature of 40–42°C reaching to the highest maximum of 48–50°C in Pakistan, India, and other countries. A little deviation was observed in maximum and minimum temperature during summer and winter months in tropical and equatorial climates, except on mountain heights or regions under the influence of cold or hot sea currents.

6.3 Germination

Germination estimates revealed that in Pakistan, the optimum temperature range was 28–33°C [42]. Germination is accelerated in the temperature range of 26–33°C, is sensitive at 22°C, and is decreased at 18°C and below. The range 32–38°C is reported to be the optimum temperature for germination.

In Pakistan, September and March considered the ideal conditions for good germination. When the temperature is above 25°C, the maximum germination of almost 75% was obtained within 20–25 days of cane planting. In February and March, temperature is somewhat lower and takes 4 or 5 weeks for complete germination. Rains may extend the germination period [43].

6.4 Tillering

In sugarcane, tillering is noticeably correlated with temperature. Tillering gradually increases with increasing temperature until the maximum is reached somewhere around 30°C.

6.5 Growth

Temperature is considered the chief growth-monitoring factor. The range 26–27°C is the ideal temperature for optimum growth; growth is checked at 10°C and 27°C is optimum for both growth and nutrient absorption [40]. The critical temperature for cane growth is 8–20°C [11, 37] and below 12°C, growth ceases; if it is less than 5°C, the leaves become pink [11, 37]. Canopy development is governed by the prevalence of moderate temperature between 21°C and 38°C with a relative humidity of 50% [44]. At a temperature of 35°C, the decrease in growth rate is due to an increase in photorespiration [4]. Cane is found to thrive at temperatures as high as 45°C in Pakistan.

The lower leaves die and the upper leaves show a yellow-green appearance. 27°C is the optimum temperature for growth and nutrient absorption [45]. A seven-fold decrease in phosphorus uptake was noticed as the temperature decreased from 22.1°C to 16.7°C [45]. A drop in root temperature from 23–19°C cuts phosphorus intake to one-third and reduces nitrogen intake to about one-half [45].

6.6 Maturity and ripening

Large differences between day and night temperatures favor the process. The range 10–12°C is considered the minimum temperature for ripening [46]. However, the ripening process is accelerated with the drop in humidity in the environment and leaf moisture in the plant [1]. To hasten the ripening process, mild drought conditions may be created by withholding irrigation.

With respect to sugar contents in cane, this process needs further clarification. Low temperature and moderate water deficit associated with nitrogen deficit are the most important ripening agents [47]. Some authors propose that in addition to air temperature and soil moisture, the variables such as photoperiod and solar radiation must also be considered [28]. Cloudy days are limiting factors for sucrose accumulation in plants. Solar radiation is directly related to sugar ripening. The factors such as air temperature, precipitation, and cloud-free bright shining days increase the time period available for photosynthesis [48]. A temperature of 20–250°C during the day and 10–14°C during the night, associated with bright sunny days with low humidity, are ideal for sucrose synthesis and accumulation in leaves.

6.7 Humidity

The growth of cane crops depends upon atmospheric humidity and proper soil moisture. High humidity for a long duration may inhibit evapotranspiration and affect growth. High humidity causes infection of some viral and fungal diseases. Evapotranspiration rate increases with high temperature and low humidity to balance the water stability in the plant, thus hindering growth, and may also increase the sensitivity of sugarcane to some sap-sacking pests such as mites. A positive correlation has been found between the rate of cane elongation and rainfall. The distribution of rainfall is more important than total rainfall, and light showers are more beneficial than heavy rains. Water needs of plants shower influence cane growth through moisture absorption by leaves, raising atmospheric humidity and keeping the leaves’ surfaces clean for optimum transpiration and respiration. Moderate rainfall of 750–1000 mm supplemented by sufficient and timely irrigation is considered best for healthy crop growth. As already discussed, the ripening period demands moderate moisture stress.

6.8 Dew

Dew deposits on leaf surfaces help in foliar absorption of moisture. It also delays the rise in leaf temperature and, thus, reduces the rate of evapotranspiration. Dew deposit is estimated to be 0.25–0.40 mm per night with a total of 25–30 mm per annum. Thus, dew deposits help to mitigate the severity of water stress to a certain degree in moisture stress areas.

7. Sugarcane agro-climatic zones with yield and production potential in Pakistan

Pakistan with cane sugar production of 70 million tons during 2016–2017, ranked fifth in the world [49]. As influenced by climatic conditions and cane/sugar marketing trends, cane production varies from year to year.

The sugar industry has developed a daily cane-crushing capacity of 567,920 tons for 125-day crushing duration [19]. The Pakistan sugar industry attained a sugar recovery level of 10.47%, during 2018–2019. Considering further propagation of quality cane varieties, it is not far to achieve an average sugar recovery of 11.0% [10].

As for cane production, so far average yield is just 64.30 tons per hectare; nevertheless, some of the districts of Punjab and Sindh have achieved an average cane yield of 82 tons per hectare [14]. Improved production technology and inputs need to be further mobilized to enhance national yield to 70 tons per hectare and then to plan for 75 tons. However, sugarcane cultivation is confined in part of coastal areas and plains, and plains of river Indus and adjoining rivers in Sindh, Punjab and Khyber Pakhtunkhwa provinces [50].

It means with better inputs and management practices, average cane yields in Pakistan can be increased to 75 tons per hectare. In the present scenario, if the interest of millers prevails with somewhat more investment in cane yield maximization campaigns, 70 tons per hectare should be the national goal for Pakistan, and this would need extraordinary efforts.

7.1 Punjab

Punjab has very hot summer and very cold winter. Hot season starts by the month of April and continuous till August. The temperature is the highest (48–50°C) in extreme periods from May to July, with a mean maximum range of 37–42°C and a mean minimum range of 23–28°C for the corresponding period. During winter, the mean minimum range of 4–6°C is observed associated with occasional mild frost. Climate is more extreme in southwest regions in Multan and Khanpur zones. In monsoon season (Mid or late June), two-thirds of rainfall was received. The rainfall pattern of upper Punjab is higher and declines gradually toward central and southern Punjab [51]. Dera Ghazi Khan (D. G. Khan) is also situated in the dry region of the Northwest zone of Pakistan. Atmospheric humidity was low almost 33–40% during summer and 55–65% during winter due to low precipitation.

The cane area is concentrated in Faisalabad, Bahawalpur, Dera Ghazi, and Sargodha Divisions. The cane yields of Punjab have gradually increased to 64 t/h. However, within the province, average yields of 75 and 71 tons per hectare are obtained in Bahawalpur and D. G. Khan divisions, respectively. The average yield of Rajanpur District is reported to be 82 t/h, while the yield of R. Y. Khan is 77 t/h. The highest yield of 82.09 tons per hectare was obtained in Rajanpur district, followed by 77.75 tons per hectare recorded in R. Y. Khan district. The yield of districts located in Bahawalpur, D. G. Khan, and part of Faisalabad divisions are between 60 and 70 tons per hectare. In the rest of the districts, yields vary between 50 and 60 tons per hectare.

7.2 Sindh

Sindh is divided into two zones. The lower Sindh constitute Hyderabad and Mirpur Khas divisions, which are bordered by Arabian Sea coast. Compared with other regions, daily mean temperatures are relatively higher in winter and lower in summer, and the monthly mean shows lesser variability in maximum and minimum temperature. During May and June months, the mean maximum is higher (40–42°C), but the mean minimum (26–28°C) is favorable for growth and maturity phases.

In Badin and Thatta districts, temperature is relatively milder with cloudy weather during May–July. Coastal winds higher the humidity level as annual rainfall in Hyderabad (178 mm) and Badin (222 mm) districts is very low. Low relative humidity (46–66%) and mild mean minimum temperatures (8–16°C) free from frost during ripening are favorable for good sugar recoveries [16].

The upper Sindh, including Sukkur and Larkana divisions, is much away from the influence of coastal climate. The summer and winter months experience extreme weather with extremely low rainfall (88.2 mm). During summer, relative temperature is higher compared to lower Sindh, as such crops are subject to moisture stress. Stress conditions in Sukkur division are mitigated by better soil, crop, and water management practices. The yield of Sukkur division is the highest, around 75 t/ha, in Sindh followed by 67 t/ha in Benazir Abad. Larkana faces poor soils and more waterlogging; hence, yields of Larkana are much low. Climatically, the lower Sindh, including Bhanbore division, is close to the coast and should be more conducive to cane production than the central and upper Sindh areas. In fact, owing to higher cane and sugar yields, the cane fields of Thatta and Badin districts with part of Hyderabad and Mirpurkhas were declared the sugar land of Pakistan [16].

The highest yield of 82.7 tons per hectare was recorded in Ghotki district; Larkana and Nawabshah showed cane yields of around 69 tons per hectare. Eight districts showed a yield between 60 and 68 tons per hectare, while yields of the rest of the districts range between 40 and 60 tons per hectare. It may be noted with great concern that yields of districts Thatta and Badeen in the coastal area of lower Sindh have dropped down to 59.3 and 46.5 tons, respectively [16]. This is attributed to waterlogging with a large area under rice crop and fish farms.

7.3 Khyber Pakhtunkhwa

The province faces extreme climate during summer and winter months with mean maximum and minimum temperature ranges of 36–41°C and 4–5°C, respectively. Dera Ismail Khan (D. I. Khan) considered hot weather in summer with 271-mm rainfall annually, and Peshawar division considered cold weather in winter with 404-mm rainfall. Both the zones have a huge difference in rainfall patterns. This region has very low humidity and a higher RTD factor since there is no favorable effect on cane growth. The mean minimum temperature is low 4–5°C, and frosts are of common occurrence in the area [52].

Sugarcane is concentrated in Dera Ismail Khan, Peshawar, and Mardan divisions [52]. The cane yield of the province is hardly around 51 t/ha. However, Dera Ismail khan has attained a good position in cane yields (61.27 t/ha). D. I. Khan district is leading in cane yield with 62 t/ha. All of the remaining districts have yields lesser than 51 t/ha.

8. Cane area and production

Pakistan is a leading cane-growing country and ranks fifth in cane area and its production in the world. During the initial stage of the creation of Pakistan in 1947–1950, the cane was grown on an area of 201,900 hectares, and here, most of the cane was planted in Punjab (149,300 ha), a little in KPK (44,800 ha), and quite negligible in Sindh (7830 ha). There was one sugar factory in KPK and one very small factory in Punjab. Cane was mostly grown for cottage industry to produce gur, shakkar, and khand and only 2% of total cane production was utilized for white sugar production [6]. During the past seven decades, gradual expansion in sugar industry was associated with spontaneous expansion in the area under cane reaching to 1.039 million hectares, during 2020–2021 [29]. The decade-wise development in the area with cane yields during 1947–1950 to 2020–2021 period in cane-growing provinces of Pakistan is reproduced in Table 4.

Table 4 also indicates that in the initial periods of Pakistan existence (1950–1960), cane yields were around 26–33 tons per hectare. For the following 40 years (1960–1990), cane yields were oscillating just between 33 and 42 tons per hectare. Nevertheless, after 1990, cane yield started taking a boost with a gradual rise to 69.55 tons per hectare during 2020–2021. The Sindh province has even touched 65.56 tons per hectare during 2020–2021, while Punjab reached a level of 73.36 tons per hectare during 2020–2021. However, yields of KPK are still static, around 52.38 t/ha [52].

Medium and small farmers, those who own 2–10 acres of land, have a little flexibility to grow rice in addition to sugarcane. These farmers can purchase sugarcane inputs from private sources. Their primary concern is the timely availability of extension services from the public sector [1]. Increasing the share of sugarcane in these farmers’ crop portfolios is the main goal of sugar mills.

Fast expansion in the sugar industry created competition in cane procurement that persuaded millers to initiate development activities in mills zones. A number of sugar mills invested in seed propagation of new cane varieties, fertilizers, and plant protection measures with technical guidance to growers [15, 19].

9. Sugarcane industry

Initially, cane was grown just to meet “gur,” “shakkar,” and “khandsari” demands of the local market and household needs [5]. With the creation of Pakistan in 1947, only two sugar mills (one in Sindh and one in Punjab) were operational. Resultantly, after every 10 years’ period of span, we find a group of new sugar mills, scattered all around the cane-growing regions. At present, there are 89 sugar mills in operation, including 45 in Punjab, 38 in Sindh, and six in KPK.

In the initial period of industrial development, sugar mills installed crushing capacities were hardly around 1500–4000 tons’ cane daily, but now daily cane-crushing capacities of sugar mills range from 12,000 to more or less 24,000 tons. The magnitude of the sugar industry expansion may be realized from the fact that during 1947–1950, the sugar mills had a crushing capacity of just 2800 tons of cane daily, while the daily cane-crushing capacity of the present-day sugar industry is around 590,000 tons, for 120-day crushing duration. Pakistan sugar industry has passed through different phases of development [19]. In its initial stage, almost all the cane was crushed in a local crusher for “gur,” “shakkar,” and “khandsari” production [6]. Only 2% of total cane production was utilized for white sugar manufacture in two small factories. Gradually, the sugar industry expanded to the extent that 95% of Sindh, 67% of Punjab, and 67% of KPK cane production were crushed in sugar mills [19]. In KPK, there is more trend of “gur” usage, and two sugar mills have been closed due to the nonavailability of cane for sugar mills [6].

10. Cane-crushing duration

In the earlier period of industrial development, while the crushing capacities of sugar factories were around 1500–4000 TCD, sugar mills operated for 180–240 days a year even at 3.5–5% recoveries in summer months. Mills used to start sometimes in October and continued crushing till June. Now, we find that sugar mills with usual crushing capacities of 8000–12,000 TCD still have several factories with 18,000–24,000 TCD. These days, cane is sufficient enough to complete crushing in a period of 120–135 days. The objective is to complete the crushing of cane during the period of its peak maturity. Nevertheless, Cane Act allows a crushing period of 1st November to 15th March for 160 days. While finalizing the crushing duration and especially the start of the crushing season, sugar recovery is of prime consideration.

11. Sugar recoveries

Sugar contents in cane play a leading role in regulating the economic viability of a sugar mill; in usual terms, it is indicated by “sugar recovery.” It is the amount of sugar recovered per quintal (100 kg) of cane crushed in a sugar factory. It is affected by a number of factors in the environment, field, and factory [53, 54]. The matter has been discussed at length in the text; however, important ones are listed hereunder.

11.1 Factors affecting sugar recoveries

11.1.1 Cane varieties

Cane varieties have a dominant role in improving sugar mills recoveries. High-sugar-yielding varieties need to be grown, and preference should be given to early maturing varieties having high sugar contents.

11.1.2 Improving agronomic conditions

Improving agronomic conditions have a significant role in improving sugar mills recoveries. Following are some agronomic conditions that improve the sugar recovery of cane varieties.

• Good fertile salt-free land.

• Sweet water zone.

• Planting a time-longer growth period is preferred.

• Judicious use of balanced fertilizer, “K” application not to be ignored.

• Timely application of fertilizer, delayed application to be avoided and “N” contents in plant tissues should exhaust by maturity time.

• Judicious use of irrigation water, excess application to be avoided.

• Restrict irrigation before crop harvest.

• Measures to save the crop from lodging.

11.1.3 Natural calamities

Measures should be taken to save the crop from drought and frost.

11.1.4 Crop harvest strategies

Crop harvest schedule according to crop maturity and maturity period of cane varieties. Cane harvest according to the crushing capacity of sugar mills and milling operation to be regular and consistent. Cane stalks to be free of trash/extraneous matter; cane staling must be avoided.

11.1.5 Sugar factory milling and processing

All possible measures are to be taken to reduce sugar recovery losses during various milling and processing operations. The Pakistan sugar industry, during 65 years of development, has expanded from two small factories in 1947 to 89 sugar mills in 2016–2017. The first phase of 35–40 years is not much appreciable with respect to sugar recoveries attained in the factories. The sugar recoveries in Sindh province, due to its relatively favorable climate and somewhat better sugar varieties, have been observed at a little over 9%.

However, in Punjab, the major cane-producing area, the sugar recoveries have been oscillating between 8 and 8.5% up to the year 2000 [55]. The same is true for KPK province (Table 8).

The sugar industry has now a good number of quality varieties, including BL4, Thatta10, CP77-400, Nia 2004, NIA 2011, HS12, SPF234, CPF 237, CPF246, CPF 249, CPF 250, CPF 252, CPF 253, SG 676, Th 2109, and Th 326. These varieties have a sugar recovery range of 9.5–12.5%.

Resultantly, after the year 2010, the Pakistan sugar industry shows a progressive rise in its sugar recoveries, which have reached an average level of 9.61% during 2020–2021 (Table 8).

12. Conclusion

Sugarcane is the second most economically important crop of Pakistan after cotton. The data presented in this chapter showed that with the passage of time, the area, production, yield, and sugar recovery of sugarcane are increased greatly. However, in Pakistan, sugarcane is mostly used as multiple sources of food, fodder, and fertilizer as well as in many beverages as sweetener. A large number of people are involved with the sugar industry of Pakistan, thus creating human resource and work force for the country. The sugar industry of Pakistan earns huge revenue for the government. As for climatic conditions, Pakistan climate suits for its cultivation especially in Punjab, Sindh, and KPK provinces. In Punjab, Rajanpur and Rahim Yar Khan are the best suitable areas for sugarcane cultivation, while Sindh Ghotki and Thatta districts are the best suitable areas for sugarcane cultivation. In KPK, D. I. Khan and Murdan districts have the highest production. Sugar industry is gradually improving its status regarding its sugar recovery level. While checking the sugarcane varieties being grown and crushed in the factory, there appears a direct relationship between the cane varieties and the sugar recovery of the mills. The sugar mills having a large area under high sugar varieties would depict much better recoveries than the mills crushing a large percentage of low-quality cane. It is a matter of programming to harvest and crush cane according to its maturity, varietal combination matters much. The sugar industry of Pakistan needs a series of new varieties in the channel; for that matter, there should be a close liaison between the research institutes and the sugar industry for the betterment of sugarcane crop.