Diversity in plant parasitic nematodes associated with pointed gourd.
Pointed gourd belongs to cucurbitaceae family and is extensively cultivated in eastern Uttar Pradesh (10000 Hectares), Bihar (14000 hectares), West Bengal, Assam, Orissa, Madhya Pradesh, Maharashtra and Gujrat. Its plants are perennial in nature and can survive for several years even if left uncared. This crop occupies large area of land in India. The system of cultivation varies from region to region such as trained on pandals or ardours especially during the rainy season in southern and western India. However, it is most susceptible to root-knot nematode, Meloidogyne incognita, the population level or density of root-knot nematodes were found in the range of 15–100 per cent of the root and soil samples. This nematode induces severe damage to pointed gourd on coarse-textured sandy soils, particularly during droughts stress. Crop failure is noticed at earlier stage of vines. In view of fact it is necessary to evolve the integrated strategies for management of root-knot nematode in this viny crop.
- Pointed Gourd
- Root-Knot Nematode
- Integrated management
Pointed gourd (
It is rich in fibre and promotes good digestive health by treating ailments in the digestive system.
It improves the immunity of the body and prevents you from catching regular flu, cold and sore throat.
According to Ayurveda, Pointed gourd is a natural blood purifier and filters out all the toxins and impurities.
Its seeds help in controlling blood sugar levels and protect you from the verge of becoming a diabetes patient
Pointed gourd (
It is most susceptible to many pest and diseases resulting heavy loss of fruit yield reducing the income of marginal farmers whose are mostly cultivated in India and elsewhere. Among these, nematodes cause severe losses to pointed gourd. The extent in production of crop fruit yield by phytoparasitic nematodes depends to a large extent on the farming system employed. In general nematodes may be less injurious to the plants under more extensive and varied growing systems i.e. multiple crop farming and shifting or staking cultivation in subsistence agriculture or in widely spaced rotations of commercial farming systems than in more intensive production where more cropping and narrow rotations are practiced .
Perennial cropping systems, promote nematode population build up with time. The extent of the increase depends on the nematodes initially present and on the percentage of susceptible plant per unit area. Intensity of damage usually increases slowly with time in the perennial cropping system, as compared to the rapid increase in damage encounter in large scale parwal production where near annual cropping is practiced (Figure 1).
1.1 Noxious threat to pointed gourd
Root-knot nematode caused by
In a fortified survey conducted by [6, 7, 8] of pointed gourd cultivated area of the farmer fields of eastern U.P. and another areas of the state showed that the population level of root-knot nematode (
Root-knot nematode (
1.2 Parasitic nematodes incidence
Important diversity presence among the polyphagous nematodes of various localities of eastern part of India including a part of U.P. Mostly pointed gourd has been recorded as a host during frequent survey made by many scientists for at least one of the most frequently occurring species of root-knot nematode,
|Nature of feeding||Common name||Scientific name||Symptom caused|
|Lance nematodes||Stunting the vines and foliage of crop|
|Dagger nematodes||Root tip swelling|
|Root-knot nematode||Galls on roots,twigs or vines creeped on grounds|
|Reniform nematodes||Yellowing of foliage|
Root-knot nematode, which increase to damaging levels within a few season in susceptible crop are so common in perennial crop production that frequently they are taken to represent “Hidden enemy “in general. The other nematodes also cause heavy losses alone or in synergistically associated with other disease causing pathogens like fungi, bacteria, viruses etc.
1.3 Crop losses
No authentic information on crop loss due to attack of root-knot nematode in available. Thus an experiment was conducted at farmer field where crop was treated with Carbofuran@2.0 kg a.i./ha to determine the avoidable yield loss by keeping untreated check. Observation revealed that Carbofuran @2 kg a.i./ha reduced root-knot infection by 43.80% and which helped to increase the fruit yield by 43.80% over untreated control [3, 8]. It has been recorded drastic decline in marketable fruit yield when initial population of J2 had 2–3 juveniles/gm. field soil which was above threshold level. The quantitative loss in fruit yield had 43.8 per cent (Table 2) where field was not protected with nematode but protected field crop had markedly higher fruit yield was observed through the fruit picking period with a seven day interval. In the non-protected plants, fruit yield is suppressed and difference was marked in months of July and August picking when fewer fruits have been picked but no such difference had noticed during March and April picking of crop season .
|Treatment||Fruit Yield (Q/ha)||Root-knot index(1–5)||Per cent loss in fruit yield|
|Carbofuran 2 kg a.i./ha||69.40|
2. Symptomatology of root-knot nematode,
The common symptoms of root-knot nematode on pointed gourd have been found out the general stunting which are not grown as much as plants grown in nematode free soil, low vigour, chlorosis, necrosis, defoliation and twig die back. Twig galls has also been observed along with root galls (Figure 2) . Infected plants are more susceptible to other diseases caused by fungi, bacteria  and tend to stop producing early. In pointed gourd the presence of galls on the root system and on propagated vines is the primary symptoms associated with Meloidogyne infection. During the warm days of July –August, the infected plants showed unhealthy growth and severe disease symptoms and a tendency to wilt. Stunting, non-emergence of sprouts, premature drying and shedding of leaves have been found in nematode infected fields where crop was being cultivated [2, 12].
2.2 Gall formation
In galls formed by the nematode swelling of the central cylinder, highly deformed vascular elements and the spherical part of the nematode surrounded by the cortical parenchyma can be easily observed at low magnification in stained roots. During warm period, gall formation on roots and twigs is more conspicuous than in colder climate. Infected plants show fewer small rootlets, reduction in aerial growth in first year, while in second year and onwards crop showed marked decline in its production with the increase in nematode population and number of gall, smaller root system to support plant growth (Figure 2). The stunted plants showed poor root system, sometimes with large and confluent galls on the main root and twigs. The size and form of the galls depends on the species involved, number of nematode in the tissue host and plant age. In parwal the roots forms large, fleshy galls whereas twigs and shoot-galls unlike the root galls are of woody consistency. The size of galls varies considerably with age of plant parasitized by root-knot nematode species. In such cases the examination under the microscope revealed that infected young roots are full of pearly white nematode females attached by their heads and their egg masses covered by gelatinous matrix adhering with soil particles. This nematode completed its life cycle on pointed gourd within 30–45 days (Table 3) during warm season . When plants are severely infected by
|Penetration and development stages(J2)||Number, days after inoculation|
|1||3||6||9||12||15||18||20||24||27||30||34||P = 0.05|
|Penetration of J2||145||118||182||140||—||—||—||—||—||—||—||—||3.72|
|Spiked tail stage||—||—||—||175||95||105||95||—||—||—||—||—||2.95|
|Moulting of J2||—||90||75||70||105||130||—||—||—||—||—||—||1.87|
|Deposition of gelatinous matrix||—||—||—||—||—||—||—||130||45||65||20||—||1.65|
|Emergence of J2||—||—||—||—||—||—||—||—||—||—||40||75||0.95|
3. Biological study of root-knot nematode on crop
3.1 Biology and life cycle of nematode
It is a perennial crop, vegetatively propagated through vine cuttings and root suckers. One of the most important limiting factors in its profitable cultivation is heavy infestation by root-knot nematode. Due to non-availability of information on biology of nematode on this crop it was ascertained and determined the biology and reported that penetration of J2 in roots continued up to 9 days with maximum numbers penetrating on 6th day. After penetration, the juveniles oriented themselves longitudinally near the vascular area behind the root tip and started moulting in 72 hrs. Young females appeared from 18th day after inoculation. Deposition of gelatinous matrix and egg-masses started from 20 to 24 days followed by emergence of J2. Majority of the eggs were retained in the egg masses. The number of eggs varied from 50 to 385 per egg mass. The larval penetration in roots resulted in the formation of necrosis and irregular shaped syncytia. The infection also caused the formation of confluent round to spindle shaped galls laterally on roots  (Table 3).
The root-knot nematode is primarily root parasites. The adult females are sedentary and remain inside the root while males are vermiform and are inhabitant of soil. Sexual dimorphism is pronounced.
Several workers have been studied to determine the biology of root –knot nematode,
The population density and damaging potential of root-knot nematode and other phytoparasitic nematode on pointed gourd vary considerably from field to field. During field survey conducted by [5, 7, 18] assayed the population density of each plant parasitic nematode and compared with growth parameter of pointed gourd. The strongest correlation between the population densities of root-knot nematode and growth responses recorded when soil assayed for nematodes were made on first, second and third year old crop. Root-knot nematode
There is a study on which has been worked out the damaging threshold of
4. Integrated management of root-knot nematode,
M.incognitain pointed gourd crop
Reduction in crop yield due to nematode can be greatly managed by using available management practices ). Crop rotation is one of the oldest and most economic methods of controlling nematodes. However, these management practices must be taken before planting or propagating the crops through its vine nature. Once the nematode are persisted inside the roots/twigs (Figure 2) effective and potential treatments are not available, therefore, control strategies needs to be preventive rather than curative in nature and aimed from the onset at preventing the build-up of high population densities. Many techniques used for managing root–knot
4.1 Cultural practices
Cultural practices may be minimised root-knot nematode damage. Practices such as removing the roots of each crop as soon as harvest is being completed, followed by tilling or summer deep ploughing of the soil two to three times is very effective in reducing nematode population .
4.1.1 Root-knot free field and propagating material
Nematode free planting material should be used for propagation. Field must be ensured free from root-knot, nematode in order to reduce dissemination. Chemical disinfection of propagating material is a common and effective measure in large areas where as other methods must be deployed for subsistence farming .
4.1.2 Crop rotation
Several workers [6, 11] have already been suggested rotation designed to reduce the impact of root-knot nematodes in tropical cropping system. A number of rotations exist in the pointed gourd growing areas which are predominantly composed of cruciferous crop, moderately resistant to tolerant against root-knot nematode. Usually farmers are grown pointed gourd perennially, it should be followed a mix cropping of inter-cropping system or companion cropping which can be reduced the susceptibility and promote tolerance of pointed gourd to root-knot nematode disease. Recommendations of a survey carried out by the various scientists [5, 18] helped to impede root-knot nematode invasion in pointed gourd by using the mustard crop in rotational cropping system.
4.1.3 Destruction of roots and vines
Practices such as removing the roots of each crop as soon as harvest is completed, followed by tilling the soil two to three times is every effective in reducing nematode levels. The tilling operations destroy the plant roots and prevent further reproduction of the nematode. It also exposes the nematodes to the drying action of the sun and wind, which reduces the level of nematode population. Maintaining optimum conditions for plant growth in terms of soil pH, fertility and soil moisture increases the tolerance of light to moderate nematode attack and makes plants less susceptible to other stresses as well. Galled roots and vines remaining in the field after harvest should be eliminated by uprooting and destruction. The spread of nematode can be retarded and the initial population density reduced because the nematode cannot survive and reproduce on the roots in the soil after harvest.
Practices such as removing the roots of each crop as soon as harvest is completed, followed by tilling the soil two to three times is very effective in reducing nematode levels. The tilling operations destroy the plant roots and prevent further reproduction of the nematode. It also exposes the nematodes to the drying action of the sun and wind, which reduces the level of nematode population. Maintaining optimum conditions for plant growth in terms of soil pH, fertility and soil moisture increases the tolerance of.
4.2 Organic amendments
In eastern U.P., India, growing areas of the crop wherein it was revealed the dreaded association of root-knot nematode,
|Soil amendments with||Emerged sprouts per plant pit||Infected plants/vines(%)||Length(cm) of vines||M.incognita population density in 200 cc soil||Galls/gm of root system||Females/gm of root system||Root-knot index|
|Press mud @25Q/ha||13.00||49.00||175.10||50.00||6.00||14.00||4.00|
|Neem leaves @25Q/ha||18.00||30.00||181.60||40.00||3.00||7.00||4.00|
|Carbofuran @ 5 kg a.i./ha||14.00||24.00||187.40||32.00||3.00||6.00||3.00|
4.3 Companion crops
Pointed gourd is an important profitable cash crop which is extensively cultivated in eastern part of Indian continent. This crop has been raised along with different marigold varieties as companion crops which have been shown lowed gall formation and egg mass development in roots. The highest toxic effect due secretion of metabolites and various root amino-acids on gall formation was exhibited by marigold varieties such as Saffron Spice variety of marigold allowed to lowest gall formation than that of Yellow Gate. Whereas, lowest reproduction factor has been recorded in root-knot nematode,
4.4 Resistance sources
Resistant varieties reduce the population of root-knot nematode and produce a good crop even in the presence of nematodes. The effectiveness is increased when combined with crop rotation. By alternating root-knot resistant and susceptible crop within a given site from one year to the next, the overall nematode problem can be reduced by preventing a build-up of high populations. This practice may reduce the risk of serious damage to the susceptible crop. There are many reports of root-knot, Meloidogyne sp. parasitizing plants which have been reported non-host, an important factor in developing rotation based control system . The effectiveness is increased when resistant host combined with crop rotation. By alternating resistant and susceptible crop within a given site from one year to the next, the overall nematode population can be reduced by minimising high population build-up. There is so any resistant material available in pointed gourd against root-knot nematode hitherto, Verma and Anwar, 1993 reported that except BP-2 all the germplasm of pointed gourd viz. BP-1,BP-3,BP-4,BP-5,BP-7 and BP-8 were highly susceptible to M.incognita. Variety BP-2 has some tolerance against root-knot nematode [5, 18].
4.5 Effect of potential Rhizospheric fungi
Various scientists have been revealed standard concentration of culture filtrate of saprophytes exhibited nematotoxic effect by inhibiting the hatching of root-knot nematode,
Chemical control is the most advocated and no doubt paracticable method of root-knot nematode control. However, for pointed gourd crop of high economic value it becomes a must. The pit application of Carbofuran, phorate @ 2 kg a.i./ha gave a satisfactory control. Application of carbofuran, oncol and hostothian @ 0.1% as vine dip treatment are also useful in increasing sprouts and suppressing nematode population. The plants vines get infected when buried in soil fields for cultivating the crop fetching remarkable fruit yields of the crop. Various chemicals including different dosages of basamid Gr have been reported as successful in controlling by significant reduction in gall formation stimulating the growth enhancements of the crop .
The crop fetches more prices in the market and its demand due to everyday consumption as vegetable and stupendous nutritive value. A preliminary survey of the crop in eastern U.P. India indicated the association of root knot nematode with unthrifty growth of plants in many areas. It is most susceptible to root-knot nematode resulting heavy loss of fruit yield reducing the income of marginal farmers whose are mostly cultivated in India and elsewhere. In case where nematode infection at sprouting time of pointed gourd has taken place, sprouting does not survive to grow new plants and its proper growth. The sprouts that survive to form new plants flowering and fruit production are highly reduced. As the season advances the nematode galls are often invaded by fungi and bacteria that induce rotting. Wherever nematode populations are very high, young sprouts may be killed over large areas even without a trace of gall formation appearing on roots. Reduction in crop yield due to nematode can be greatly managed by using available management practices. Crop rotation is one of the oldest and most economic methods of controlling nematodes. However, these management practices must be taken before planting or propagating the crops through its vine nature. Once the nematode are persisted inside the roots/twigs effective and potential treatments are not available, therefore, control strategies needs to be preventive rather than curative in nature and aimed from the onset at preventing the build-up of high population densities. Many techniques used for managing root–knot