Evaluating Heritability and Relationships among Phosphorus Efficiency Traits in Maize under Low P Soils of Western Kenya

Low available phosphorus (P) remains a major limitation to maize (Zea mays L.) productivity across the world. Selection for P efficiency is key as part of strategies to achieving agricultural sustainability. The objectives of this study were to: (i) determine the phenotypic and genetic relationships among P-efficiency traits in maize under low P soils and (ii) determine the heritability of some of these traits under similar conditions. A total of 32 experimental maize hybrids were evaluated for tolerance to low P in a replicated trial at four locations for one season. The experiment was laid out in a split plot arrangement in RCBD replicated 3 times across two P levels (36 kgP/ha and 6 KgP/ha). Grain yield had the highest correlation (r= 0.44-0.95) with most P- efficiency traits at both P conditions. It also exhibited high positive and significant correlations with plant height (rg = 0.72**) ear height (rg = 0.54*), cob Length (rg =0.81**) and stover yield (rg = 0.61**) while it was negatively correlated with days to anthesis and silking. The correlation between grain and shoot P concentration and grain P content with majority of the P efficiency indices (P acquisition &Utilization efficiencies &P efficiency) at both P levels was low & tended to be negative and non-significant indicating that seed P reserve, and stover P concentration, had minimal contribution to differential P efficiency. However, the relationship between shoot P content with P-efficiency traits was significant (r= 0.51-0.95), suggesting that shoot P content is a useful parameter in selecting for P efficiency in maize. Moderate to high heritability (0.50-0.95) was observed for the various traits showing that a large proportion of the observed variations were due to genetic differences among the hybrids. This study has determined genetic and phenotypic associations among P selection parameters that can help in flexing the selection methodologies to suite unique circumstances and environments.