Limestone application on a Ferralsol soil and genotype by environment effects on yield and grain nutrient composition in common bean

Abstract

<p>Food and nutritional insecurity are prevalent in sub-Saharan Africa, where years of poor soil management have left most agricultural lands mineral deficient and low in organic matter. In Uganda, soil acidity is a major contributor to low agricultural productivity, hunger, malnutrition and the vicious cycle of poverty. To meet yield demands and nutritional needs in Uganda, publicly funded breeding programs released biofortified common bean varieties such as NAROBEAN 1 and 3, that are high yielding, drought resilient and high in commonly deficient nutrients such as iron and zinc. The main objective of this study was to determine the effect of limestone application as a soil amendment strategy on grain yield and grain iron (Fe) and zinc (Zn) concentration in NAROBEAN 1 and 3 grown on Ferralsol soils in central Uganda. Findings from the study showed that soil pH, CEC and soil concentration of extractable Ca and Na increased when more limestone was applied to the soil. On average the yield of NAROBEAN 1 was 30% and 48% greater than NABE 15 and NAROBEAN 3, respectively. Grain nutrients, Fe and Zn, were not affected by limestone application rates, however, their concentrations differed among bean varieties. We were also interested in how common bean varieties performed in different environments and how these interactions influence yield and nutritional value of the grain. We conducted another experiment in Colorado, Michigan, Iowa and Uganda using four common bean varieties (‘Montcalm’/dark red kidney, ‘Taurus’/great northern, ‘Eclipse’/black turtle and, ‘MY06326’/yellow Mayocoba). The objective of the study was to determine the effect of environment on total yield overall, yield components and grain nutritional composition. It was observed that yield and seed weight differed across locations and among varieties. Mineral concentration of bean seed P, K, and Mg and crude protein (CP) differed significantly among the varieties but were unaffected by environment. Although soil nutrients (such as Mehlich-3 extractable Fe, Zn, K, P), pH and organic matter to differed among the four experimental locations, we did not observe significant variety × elemental composition effects across environments.</p>