Inter-Relationships Between Yield And Yield Attributes Of Potato Grown Under Supra-Optimal Ambient Temperatures

Abstract

Forty eight potato genotypes were evaluated in Saminaka (Lat. 100 27’N and Long 40E, Mean Min. Temp 25oC, Mean Max Temp 31.5oC) during the rainy season of 1999 and 2000 to determine the inter-relationship between yield and some important agronomic traits in the potato grown under high ambient temperatures. The genotypes were laid out in a randomized complete block design with three replications. The genotypes exhibited highly significant variability (P<0.01) for all traits assessed. Tuber yield was positively associated with number of stems/plant (r = 0.246, P<0.05); plant height (r = 0.206, P<0.05); and number of leaves/plant (r = 0.237, P<0.05). Both the correlation and regression of yield on days to tuber initiation and days to maturity were negative and significant. This suggests that earliness in tuber initiation and maturity led to increased yield under supra optimal temperature probably due to
reduced period of exposure to heat stress. Number of tubers per plant (R2 = 0.383) and average tuber weight per plant (R2 = 0.125) had the highest coefficients of determination of yield and by far the highest direct effects on yield (87.5% and 66.9%respectively) when compared to other attributes suggesting that they were the major contributors to yield under supra-optimal temperature conditions and may be relied upon in selecting for improved yield under such conditions.