Studies on genetic parameters and combining ability in maize for the production of hybrids with low phytic acid

Abstract

Phytic acid is a major constraint in affecting the nutritional concerns of the people feeding on maize. Being a strong negatively charged chelator, this compound binds all the positively charged minerals like iron and zinc. It also acts as a major storage compound of phosphorous. Thus monogastric animals lacking phytase, fails to absorb these minerals and is considered as a antinutritional factor. This experiment was conducted to identify the potential donors for low phytic acid to produce hybrids with moderate phytic acid content. With this objective a reference set for phytate (2-16 mg/g) formed from a base population was screened. A D2 analysis in the reference set was done and this classified the genotypes into eight clusters. The genotypes with low phytate were grouped in cluster 4. Highest significant variability was observed for all the traits including phytic acid. Cob weight followed by phytic acid had a highest heritability with high genetic advance as percent of mean indicating the effectiveness of selection for these traits due to the presence of additive gene action. Among the six low phytate lines observed, UMI-113 had lowest phytate content of 2.77 mg/g. These six low phytate genotypes classified in cluster 4 were then selected as testers and were crossed to four elite lines. Among the 24 hybrids produced, three hybrids., UMI 1200 x UMI 1099, UMI 1201 x UMI 1099 and UMI 1210 x UMI 1099 yielded higher than the standard check with medium levels of phytic acid ranging from 10.23-10.46 mg/g. The line UMI-1099 was found be a good general combiner for yield related traits with a negative combining ability for phytic acid. Hence this line could be successfully used in low phytate breeding programs and these identified hybrids could be further used in poultry testing trials for analyzing the bioavailability of nutrients.