Soybean breeding strategy for Pakistan: Genotype x environment interaction and stability for soybean yield

The experimental material comprising of nine soybean cultivars were planted during two seasons (spring and autumn) at four locations for three years 1992–94. Cultural operations were done when needed. Variances due to genotypes, environments and genotypes x environment interaction were highly significant for days to flowering, days to maturity, plant height, first mature pod height, 100 seed weight, number of pods per plant, oil content and yield. Whereas analysis of variance for number of seeds per pod showed nonsignificant differences for genotypes, environment and their interaction, ‘NARC-III’, ‘NARC-IV’ and ‘Swat-84’ showed stability, in general, for days to flowering and ‘NARC-IV’ and ‘Swat-84’ showed stability in maturity. In plant height, ‘NARC-III’ and ‘NARC-IV’ performed better in good environmental conditions. ‘Harper’ showed stability for pod height, whereas ‘NARC-V’ was found stable for number of pods per plant while ‘Harper’, ‘Swat-84’ and ‘Williams-84 showed moderate stability for number of pods per plant. All genotypes showed differential response and stability for 100 seed weight. ‘NARC-III’ and ‘NARC-IV’ exhibited stability while ‘FS-85’ and ‘William-82’ showed stability for 100-seed weight. ‘Harper’ and ‘NARC-III’ had the highest oil content. ‘NARC-III’, ‘NARC-IV’ and ‘NARC-V’ were found stable and high yielding in low rainfall areas like Fatehjang and NARC. During spring, ‘NARC-III’ proved to be a better stable genotype for Gujranwala while ‘NARC-IV’ for Multan and ‘NARC-V’ for NARC are recommended due to their high yield potential. ‘NARC-V’ showed wider adaptability and hence it was identified as a stable genotype on overall basis. A plant breeding model has been described which will be very useful for the development of soybean cultivars as well as other commodities for different ecological zones in Pakistan.