Analysis for Seed Yield and its Components in Moth-bean ( Vigna aconitifolia ) under Hot Arid Conditions

Ten varieties of moth bean { Vigna aconitifolia (Jacq.) Marechal} were evaluated for seed yield and its components under rainfed conditions during kharif 2006 and 2007. Significant differences were observed among genotypes for days to flowering, plant height, peduncle length, days to maturity and seed yield/plant. The variabilities recorded were highest in seed yield/plant and peduncle length, and high for plant height, and moderate for days to flowering and 100-seed weight. Days to flowering, peduncle length and plant height had high heritability coupled with high genetic advance. Pod length was the only character, which had significant positive association with seed yield/plant whereas petiole length and days to maturity had significant negative association with seed yield. Association analysis showed that for higher seed yield, longer pods, short leaf stalk and early maturity should be given emphasis in breeding programme of moth bean. Among all the varieties tested, RMO 257 was identified as the best seed yielder for arid environment.

, CAZRI Moth 1, CAZRI Moth 2 and CAZRI Moth 3 of moth bean were sown in a randomized block design with three replications in plot size of 4 m ´ 4 m with row spacing of 50 cm using 10 kg seed/ha.The experiment was under rain grown conditions and no fertilizer/manure was applied.Due to delayed rains, the experiment was sown on 11-8-2006 in first year and during second year the date of sowing was 26 th July.Data were recorded on days to 50% flowering, plant height at 50% flowering (cm), peduncle length at 50% flowering (cm), days to maturity, petiole length at maturity (cm), pod length (cm), 100-seed weight (g) and seed yield/plant (g).Data were analyzed using a statistical package Windostat Version 7.5.

Meteorological data
Numbers of rainy days were twenty in both the years, but the total rainfall was 270.4 mm during 2006 (first year) and 323.7 mm during 2007 (second year).July experienced more rains (73.4 mm) in 2007 than 2006 (27.7 mm).In 2007, there were 234.3 mm rains from July to September and it was 242.4 mm in 2006.Hence, rainfall of July to September was almost equal in both the years but the distribution of rains was uneven during first year as August received 185.5 mm rains, 76.5% of the total rainfall of the three months, while in second year the rains were uniform during the period.There were no rains during October in both the years.Highest mean maximum humidity was recorded in August and it was 86% in 2006 and 81% in 2007.Mean maximum temperature ranged from 32.6°C to 37.1°C in 2006 and 34.7°C to 36.4°C in 2007 from July to October.

Analysis of variance
The analysis of variance (Table 1) revealed significant differences among genotypes for days to flowering, plant height, peduncle length, days to maturity and seed yield/plant in both the years, and for pod length in first year and for petiole length and 100-seed weight in second year.

Variability and heritability
Mean, range, phenotypic and genotypic coefficients of variation (PCV and GCV), heritability and genetic advance expressed as percentage of mean are presented in Table 2. Range was wider for days to flowering in both the years, and for plant height, peduncle length, days to maturity and seed yield in second year.PCV values were higher than their respective GCV values for all the characters studied indicating the role of environmental variance in the total variance.The magnitude of PCV and GCV were mostly higher in the second year.Phenotypic coefficient of variation was maximum for seed yield/plant (32.2 and 62.0 in year 1 and 2) followed by peduncle length (25.4 and 31.0 in year 1 and 2).Value of PCV was also high for plant height.The difference in the extent of PCV and GCV was GA as %age of mean more for seed yield/plant in both the years, which revealed considerable influence of environment on expression of this trait.
Phenotype reflects genotype truly when the character is highly heritable hence heritability is important from the breeder's point of view for adopting suitable breeding methodology for improvement.Burton (1952) suggested that genotypic coefficient of variation, along with heritability estimates, would give better idea about the efficiency of selection.Days to flowering, days to maturity, peduncle length and plant height had high heritability.The estimates of heritability were moderate to low for 100-seed weight, seed yield plant -1 , pod length and petiole length.Sihag et al. (2004) reported low heritability for pod length.Among the characters studied, the broad sense heritability was maximum for days to maturity (99.8%) and minimum for petiole length (0.7%) during second year.Expected genetic advance was maximum for seed yield (65.5%) and peduncle length (58.9%) in second year.The genetic advance was high for peduncle length, seed yield, plant height and days to flowering, and it was low for days to maturity, petiole length, pod length and 100-seed weight during both the years.
Genetic advance depend on selection intensity, heritability and phenotypic standard deviation.Hence high heritability need not necessarily mean that the character will show high genetic advance but whenever this association occurs additive gene effects are probably important.In this study, such association was found for days to flowering, plant height and peduncle length.Simple selection may prove effective to improve these characters.On the other hand high heritability coupled with low genetic advance was estimated for days to maturity, whereas seed yield/plant had low heritability in first year and moderate in second year, and high genetic advance.Petiole length, pod length, and 100-seed weight had low to moderate heritabilty and low genetic advance.This indicated the effect of non-additive gene effects, such as epistatis, dominance type of interaction (Panse 1957).

Association analysis
The genotypic and phenotypic correlation coefficients between all the pairs of eight characters for two years are presented in Table 3.Most of the genotypic correlation coefficients were found to be higher than their corresponding phenotypic correlation coefficients because environmental effects were removed from these associations.Theoretically the value of correlation coefficient is not more than one, but it comes because it is an estimate.Similar to present study, Paul et al. (1996) also reported values of correlation coefficients more than one for many character pairs in pigeon pea.Seed yield/ plant, a complex character, had positive association with peduncle length and pod length in both the years, and 100-seed weight in first year.Pod length was the only trait, which had significant positive relationship with seed yield/plant in both the years, whereas 100-seed weight had significant positive relationship in first year.Seed yield/plant was negatively correlated with days to 50% flowering, plant height, days to maturity and petiole length in both the years and 100-seed weight in second year.Days to maturity and petiole length had significant negative relationship with seed yield.
Among the other characters, days to 50% flowering had significant positive association with plant height, days to maturity, petiole length, and 100-seed weight in both the years.Similarly, plant height had significant and positive association with days to maturity, petiole length, and 100-seed weight in both the years.Significant positive correlations were also observed between peduncle length and pod length, and days to maturity and petiole length in both the years.Pod length had significant negative correlations with days to flowering, plant height, days to maturity and petiole length in both the years.
The association of pod length and seed yield/ plant revealed that longer pods should be one of the important characters in seed yield improvement programme.Significant negative association of seed yield with maturity revealed that earliness had advantage over late maturity for increased seed yield under rainfed conditions in arid zone.Negative and significant correlation of seed yield with petiole length indicated that short leaf stalk should be preferred for the improvement of seed yield in moth bean but this character had low heritability, an appropriate method of recurrent selection may be used for breeding of short leaf stalk varieties.

Per se performance
The per se performance of seed yield and its components has been presented in Table 4. Days to flowering and days to maturity were less during first year because of shorter growing period.IPCMO 880 took longest time to flower and to mature in both the years and during second year it took 76 days to mature.Similarly, variety Maru Moth also matured in 76 days during second year.In a threeyear experiment, mean maturity period Maru Moth bean was 76 days (Bhansali et al. 2004).Values for plant height, peduncle length, petiole length and seed yield/plant were mostly more during second year for all the varieties.Plant growth was less during first year and minimum plant height recorded was 7.9 cm with RMO 225 and RMO 435, while Maru Moth attained maximum height (11.9 cm) closely followed by IPCMO 880 (11.4 cm) and CAZRI Moth 1 (11.2 cm).Less height during first year was due to shorter growing period.During first year, peduncle length was minimum with Maru Moth (1.9 cm) and maximum with RMO 225 (4.3 cm), while IPCMO 880 had longest peduncle (6.3 cm) during second year.
The length of petioles was mostly more than double during second year and the value was maximum with CAZRI Moth 1 (12.4 cm) followed by CAZRI Moth 3 (12.1 cm).All the varieties produced comparatively longer pods during first year, except variety Maru Moth in which the pod length was same in both the years.Similarly, 100-seed weight was more during first year with all the varieties, except CAZRI Moth 1.It means pod length and 100-seed weight are probably more important in breeding short duration varieties as rains were late and crop growth period was shorter during first year.Seed yield/plant ranged from 0.93 g (CAZRI Moth 3) to 2.37 g (RMO 257) in first year, while the range was wider during second year, where it was 1.87 (Maru Moth) to 9.75 (RMO 257).Mishra et al. (2008) reported a wide range (1.6-19.1 g) for seed yield/plant in moth bean.In our study, seed yield/plant was more during second year and variety RMO 257 was the best seed yielder.In an experiment of eight genotypes conducted for three years variety RMO 257 ranked second for seed yield (Bhansali et al. 2004).The variety flowered early (33 days) in both the years and also matured early (62 and 65 days).Thus, it had both earliness and high seed yield.Therefore, variety RMO 257 should be considered for improvement while developing high yielding short duration varieties.
The study thus, revealed that earliness, short leaf stalk and longer pods are important characters for breeding high yielding varieties of moth bean for arid zone conditions.Days to flowering had high heritability and high genetic advance could be improved through simple selection.Days to maturity, petiole length and pod length had limited scope for improving through simple selection.