Abstract

The trinity of parental line superiority, climatic conditions during crop growth and effective cross-pollination is the decisive factor to reap best quality hybrid seed. In order to study the effect of environmental factors during sowing time on hybrid mustard seed quality, freshly harvested hybrid seeds from three plots sown on 21^st October (D1), 30^th October (D2) and 18^th November (D3), 2009-2010 were tested for quality traits before and after nine months of ambient storage. Percent germination had strong correlation with T_max at vegetative (r²=0.881) and seed filling stage (r²=0.88). Sunshine hours at vegetative and seed filling stage had significant correlation with percent germination (0.957 and -0.957 respectively), shoot length (0.898 and -0.870 respectively) and electrical conductivity of seed leachate after accelerated ageing (-0.880 and 0.856 respectively). No significant difference for germination and vigour indices was found between  1^st (D1) and 2^nd (D2) dates of sowing as the weather conditions during these two sowing periods was favourable and did not fluctuate much. Percent decrease in germination from D1 to D2 was 0.83/°C temperature decrease at vegetative stage and 1.33/°C temperature increase in seed filling stage. But percent decrease in germination from D2 to D3 was 2.31/°C temperature decrease at vegetative stage and 3.66/°C temperature increase in seed filling stage. A predictive model was developed as- Y= 234.545 - 1.688 × (±1.013) × RH_pf - 15.359 (±1.335) × SH_sf, where, Y= Percent germination, RH_pf = relative humidity at peak flowering stage and SH_sf= sunshine hours at seed filling stage. Seeds were subjected to accelerated ageing followed by electrical conductivity test after storage. D3 seeds had minimum germination percentage at 96 h ageing (5.1); significantly lower than that from D1 seeds (52.4). Grow out test result suggested standard isolation distance may be reconsidered to check out-crossing in optimum date of sowing. Seeds harvested from 21^st October sowing (optimum time of sowing) gave the best result regarding seed quality parameters than that in hybrid seeds from 30^th October and 18^th November sowings.

Key words: Indian mustard, hybrid seed quality, environmental factors, percent germination, predictive model, correlation coefficient.