High Stem Count: A Negative Morphological Growth Parameter in Irish Potato (Solanum tuberosum l.) Production

Abstract

Indubitably, some morphological parameters contribute positively to Irish potato (Solanum tuberosum Lin.) yield in terms of their high values (numbers) but conversely, increase in stem count (number of stems stand-1) brings about decrease in potato yield. This phenomenon was investigated during a three-year study on potato production under alley cropping system in both rain-fed and irrigated cropping seasons. In carrying out this experiment, completely randomized block design comprising 5 treatments and 3 replicates for 5 cropping seasons was employed. Treatments included different levels of Albizia lebbeck green manure application with or without its hedge rows (commencing with 6 months’ old saplings) and the control. Results showed significant effect of stem count on yield (at P<0.05) sequel to smaller sizes of tubers from numerous stems stand-1 which led to low tuber weight/yield (potato being a stem tuber). Simple correlation matrix between stem count and yield was negative and significant (r=-0.891, P<0.05) at rain-fed cropping season, bivariate and multiple correlation / regression analyses of growth parameters versus yield indicated negative relationship of stem count with yield (r = -0.891, R2 = 0.794, P < 0.05) in rain-fed cropping seasons as opposed to irrigated cropping season which were not significantly different. Thus, the correlation between stem count and tuber count was positive but negative with yield (the higher the number of stems stand-1 the more the smaller potato tubers especially in treatments with low nutrient status) the lower the yield.