DRY MATTER DISTRIBUTION IN POTATO GENOTYPES AS AFFECTED BY PHYSIOLOGICAL DEGREE DAYS

Abstract

Dry matter partitioning in six potato genotypes with diverse growth habit, duration and yield potential was estimated from the trials undertaken in two distinct sowing windows during three successive years at patna. Total dry weight was recorded at 10 days intervals starting from 30 days after planting (dap) up to 90 dap and empirical relations were developed between dry matter partitioning coefficient versus accumulated p-days. The dry matter partitioning coefficient is calculated as dry weight of plant part over total dry weight. The mean relationships over the different varieties revealed good correspondence between observed and estimated values of proportion of dry matter accumulation in the different plant parts with p-days. These were: y (Leaf) = - 0.0869 + 114.53X, r² = 0.87, n = 168; y (stem) = - 0.0142 + 57.05X, r² = 0.82, n = 168; y (Tuber) = 1.1243 - 198.19X, r² = 0.85, n = 168; where y is dry matter partitioning coefficient and X is inverse of accumulated p-days. p-days were calculated with minimum, optimum and maximum threshold of 7°c, 21°c and 30°c, respectively. These relations between p-days and dry matter partitioning were tested against recorded data of the third year and the results showed close fit between observed and estimated values indicating robustness of the equations.