Effect of Temperature Regimes on Post- Anthesis Physiological Traits in Soybean (Glycine max (L.) Merrill)

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Date
2016-06
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University of Agricultural Science, Dharwad
Abstract
A field experiment was conducted during summer, 2016 to study the effect of temperature regimes on post-anthesis physiological traits in soybean (Glycine max L.) at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad. The experiment consisted of four dates of sowing viz., 01-01-2016 (D1 temperature regime), 15-01-2016 (D2 temperature regime), 01-02-2016 (D3 temperature regime) and 15-02-2016 (D4 temperature regimes) with three genotypes viz., JS-335, DSb-21 and KHSB-2. The morphological parameters viz., plant height, number of branches and number of nodes per plant were recorded significantly higher under D1 temperature regime (44.98 cm, 4.20 and 14.99, respectively) and lowest under D4 temperature regime (38.69 cm, 2.60 and 12.90). Similarly, the phenological parameters viz., days to flower initiation (44.00 days), 50 per cent flowering (46.00 days), pod initiation (51.20 days) and physiological maturity (85.56 days) and heat units like GDD, PTI and HUE were significantly higher in under D1 temperature regime. The SPAD values, membrane injury index, peroxidase activity chlorophyll content, photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency were also significantly higher under D1 temperature regime and lower under D4 temperature regime. Significantly higher flowers per plant (112.43) and flower to pod ratio (2.91) was recorded by KHSB-2 under D1 temperature regime. The genotype, JS-335 recorded relatively higher pollen fertility under all four temperature regimes. Yield and yield components viz., number of pods per plant (41.23), seeds per pod (2.62), test weight (13.08 g), harvest index (41.42 %), seed weight per plant (13.62 g) and seed yield (18.85 q ha-1) were significantly higher under D1 temperature regime and lower under D4 temperature regime. The genotype, JS-335 recorded higher pollen fertility and yield compared to DSb-21 and KHSB-2, substantiating that JS-335 is relatively heat tolerant.
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