EVALUATION OF ADAPTABILITY AND YIELD STABILITY OF SELECTED SWEET CORN VARIETIES GROWN IN RIFT VALLEY PROVINCE IN KENYA

Abstract

Food security has been of a major concern globally. In Kenya the national development Blueprint Vision 2030, envisages the eradication poverty and enhanced food security. Agricultural sector’s economic importance thus cannot be over emphasized. Most research studies have laid focus on the impact of different crop management techniques on crop performance. Sweet corn is an important vegetable and commercial crop in many tropical and sub-tropical countries. It is a relative short season and moderately drought-tolerant crop that is adapted to a wide range of climates and soil characteristics (Bray, 1997). However the study on the adaptation and yield stability of sweet corn varieties grown in selected production areas in Kenya is not evident. A study was carried out using four selected varieties grown in three locations in Kenya for two seasons to assess this. The varieties selected were Chieftain, Star 7717, Pacific Queen Hybrid and a landrace. These varieties were obtained from local seed distributing agents and the farming communities. Bomet, Koibatek FTC and University of Eldoret in the Rift valley province were the selected test sites. The experiment was laid in a Randomized Complete Block Design (RCBD) with three replications. Quantitative traits measured included: the number of days to emergence, flowering and maturity. Other traits were germination percentage, the number of leaves at flowering, the plant heights, the total biomass and the yield. Qualitative traits scored were seedling vigour, leaf colour intensity and pubescence, stand-ability, snapping ease, tolerance to stress, cobs fill, husk cover and sweetness based on IPBGR maize descriptor. ANOVA of quantitative traits showed a significant variation among the varieties, seasons and locations at p ≤ 0.05 level of confidence. It was also observed that qualitative traits varied significantly among varieties; but that variation was not evident with seasons and locations. Early seedling vigour and tolerance to stress varied significantly with both seasons and locations. Variation in both quantitative and qualitative traits indicates the influence of the environment on the performance of a of a variety (GXE). Adaptation and yield stability varied significantly among the varieties at p ≤0.05 level of confidence. The regression coefficients (β) of the tested varieties observed were 0.81, 1.29, 0.302 and 0.04 for the varieties Pacific Queen Hybrid, Landrace, Chieftain and Star 7717 respectively. Pacific Queen Hybrid had a wider adaptation, more stable and high yielding variety across the test locations. Chieftain, Landrace and Star 7717 had lower adaptation, less stable and realized high yields in specific environment (location). Qualitative grading of environment showed Chepkoilel as being superior over Bomet and Ravine. Pacific Queen Hybrid ranked best among the tested varieties in all the test location and thus suitable for production in all the three sites. Chieftain and Star 7717 realized better yields the best Ravine while landrace was in Bomet respectively, hence these varieties can be recommended for each specific location.