Pod/seed maturity indices of
Malabar Bauhinia (Bauhinia malabarica) is a native ornamental species belonging to the family Fabaceae, distributed throughout India in semievergreen and moist deciduous forests and in gardens. Information regarding seed characteristics and seed handling of the species is meagre. This study describes seed characteristics, germination behaviour and pretreatment for enhancing seed germination of B. malabarica. Treating the seeds with concentrated sulphuric acid for 30 min reduced germination duration up to 6 days and increased germination rate up to 100% against 22 days of germination duration and 10% germination in seeds without treatment. The results of this study are helpful for conservation and nursery practices of B. malabarica.
- maturity index
- seed germination
- germination value
- sulphuric acid
Studies of the genus
A few investigations were done on
2. Materials and methods
Periodical observations were carried out on mother plants of
Seeds were subjected to different pre-sowing treatments to enhance seed germination and reduce the germination period. The following were the pretreatments applied for the study:
T1: control (no pre-sowing treatment).
T2: soaked in water for 24 h.
T3: soaked in water for 48 h.
T4: soaked in hot water for 2 min.
T5: soaked in hot water for 5 min.
T6: soaked in hot water for 2 min + soaked in water for 24 h.
T7: soaked in hot water for 5 min + soaked in water for 24 h.
T8: soaked in GA3 (500 ppm) for 2 h.
T9: soaked in GA3 (1000 ppm) for 2 h.
T10: acid treatment (conc. H2SO4) for 10 min.
T11: acid treatment (conc. H2SO4) for 20 min.
T12: acid treatment (conc. H2SO4) for 30 min.
Tap water (≈35°C) was used in T2 and T3 treatments, whereas in the treatments T4–T7, hot water (85°C) was used. Different concentrations of gibberellic acid (GA3)/gibberellin A3 (chemical formula: C19H22O6) were used in T8 and T9 treatments. Concentrated sulphuric acid (98%) was used in the treatments T10–T12.
Seeds (n = 100 in 4 replications) were sown in germination trays having a size of 25 × 20 × 5 cm filled with vermiculite and kept in germination room (30 ± 2°C and 90% RH) under laboratory condition. Randomised block design was adopted for the experiment. Data on seed germination were recorded starting from seed germination till culmination and computed germination-related parameters. Germination initial time (GIT), germination percentage (GP), germination duration (GD), mean germination time (MGT), mean daily germination (MDG), germination energy (GE), peak value (PV) and germination value (GV) were calculated [20, 21, 22, 23, 24].
Germination-related parameters were determined as follows:
where Dg = first germination day and Ds = seed sowing day.
where G = no. of germinated seeds and T = no. of seeds sown.
where Gf = final day of germination and Gi = initial day of germination.
where Gt = no. of germinated seeds at day-t, Dt = no. of days at ‘t’ from the day of sowing and G = total no. of germinated seeds.
where GP = germination percentage and Gd = no. of days to complete germination.
where Xn = no. of germinants on the nth counting date and Yn = no. of days from sowing to the nth count.
where PV = peak value and MDG = mean daily germination.
2.1 Statistical analysis
Each trait was analysed using mean values under the various pretreatments. The variation on mean values between these treatments were performed through analysis of variance (ANOVA) done by statistical software SPSS version 22.
3.1 Seed weight and moisture content
The study recorded 7092 ± 50 seeds per kilogram. Moisture content (MC %) of fresh seeds was 5.35%.
3.2 Maturity index
The optimum maturity indices for seed collection of
|Fruit||Colour||Yellowish-green turned to blackish-green|
|Water content||Very less|
3.3 Pod/seed characteristics
Colour, shape, size, type, weight, number of seeds per pod and per kg, type of germination, etc. are presented in Table 2.
|Colour (mature)||Blackish brown|
|Size (cm)||15.25 ± 4.75 × 2.15 ± 0.25|
|Wall type||Dry, semihard|
|Seed||No. of seeds/fruit||10 ± 2|
|Size (mm)||.02 ± 1.11 × 6.14 ± 0.88|
|Wall type||Dry, hard|
|Weight||7092 ± 50|
3.4 Seed germination
|Source||Sum of squares||Degrees of freedom (df)||Mean square||F-value||Sig.|
Germination-related parameters under different pretreatments such as germination initial time, germination percentage, germination duration, mean germination time, mean daily germination, germination energy, peak value and germination value are given in Table 4.
Maturity indices help to collect seeds with maximum viable seeds. The optimum maturity indices of
The present study indicated that the highest germination was recorded in acid treatments (acid scarification for 30, 20 and 10 min). All other treatments exhibited poor performance in germination. Germination initiation period was minimum in the treatments T4, T10, T11 and T12, whereas maximum was in T1, T2, T5, T8 and T9 treatments. The lowest germination initial time shows speedy initiation of germination among pretreatments.
Estimation of germination percentage is the best tool to explain seed viability of a particular lot. Seeds treated with concentrated sulphuric acid for 30 minutes (T12) resulted in very high germination rate (100%) than that of other treatments. The study also revealed that the hormonal treatment had no significant role on seed germination of
Germination duration (GD) is helpful to understand the duration required for completing the process of germination. Germination duration in the present study varied with treatments (06–26 days). The study showed that the seeds scarified with concentrated sulphuric acid for 30 min helped to reduce germination period into 6 days compared to 26 days in seeds soaked in water for 24 h. The lowest GD shows the minimum period required to complete germination among pretreatments. Mean germination time (MGT) is the indicative of emergence performance of seed lots. Mean germination time (MGT) was highest in seeds treated with concentrated sulphuric acid for 30 min (21.67) where the treatment gave 100% germination, whereas the least value was in seeds without any treatment (T1). Similarly, mean daily germination (MDG), germination energy (GE), peak value (PV) and germination values were also highest in the treatment T12.
Mean germination time and mean daily germination are used as a gauge of the rate and time spread of germination. High MGT and MDG values indicate high germinability of seed lots due to pretreatments. Peak value indicates the maximum germination rate in a particular day, and germination value is the expected seedlings in the field or nursery. Germination energy and germination value are the easier way to understand the rate of germination and period of germination. Highest GE and GV show the enhanced germination and reduced duration.
The study resulted in scarification of seeds by concentrated sulphuric acid for 30 min which was the best pre-sowing treatments for enhancing seed germination and reduce germination period in
The study gave update to seed characteristics and germination behaviour of
We are grateful to the Kerala Forest Research Institute for scientific support. We thank Ms. Lakshmikutty VA and Mr. Suresh MK, the support staffs of Kerala Forest Seed Centre, for providing help and cooperation during the experiment.
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