Selection Criteria for Grain Yield and Moisture in Maize Yield Trials

Abstract

Grain yield and moisture in maize (Zea mays L.) are positively correlated, and must be considered simultaneously. Typically, breeders desire to identify better‐yielding hybrids within each of several maturity groups. Data from 28 multiple‐location yields trials were used to (i) compare five indices for ability to identify hybrids that are high yielding for their maturity; (ii) investigate the validity of assumptions used in developing estimated indexes; and (iii) investigate possible relationships between effectiveness of indexes and violations of assumptions. Selection criteria evaluated included: BSE, a base index; S‐H, a Smith‐Hazel index; Y/M, the ratio of yield and moisture; REG, yield adjusted for the regression of yield onto moisture; and DSG, a desired gains index designed to hold moisture constant. Departures from normality for distribution of grain yield means and for moisture were detected in 18 and 32% of the experiments, respectively. The regression of yield onto moisture varied considerably across experiments, with a mean coefficient of 12.5 kg ha−1 yield per g kg−1 moisture. Selection differentials of REG, BSE, and DSG for yield were 92, 91, and 89% respectively of that resulting from direct selection for yield, but changes for moisture were considerably less than those for selection based on yield. The Y/M selection differential for yield was only 64% of that of yield, and had a large decrease in grain moisture. No association between the success of an index and nonnormality was observed. Both BSE or REG are recommended for identification of hybrids that are high yielding for their maturity. However, these or other indices employed should be carefully evaluated in the context of the breeder's circumstances and objectives.

Evaluation Maize Genotypes for Yield and Yield Components and Constructing Selection Index

“…All the indices tested excluded the yield had a relative efficiency more than the results in the same table indicate that all selection indices include the yield trail gave 100% efficiency equal to those when used the yield only, the increase in efficiency was very low and not important, while the selection index which was with no grain yield few relative efficiency as compared with efficiency index which include the yield, there for the better selection indices depend on the yield only to select the better genotypes and the indices was L1=09619(grain yield ). These results were in agreement with the result obtained by Eta-Ndu. andOpenshaw.…”

“…These results were in agreement with the result obtained by Eta-Ndu. andOpenshaw. 1992. andRabie et al .,2004.…”

“…Several types of selection indices have been developed, the first one formally introduced, and probably the most widely known is the so called Smith-Hazel index (Simith,1936 andHazel,1943), among others that followed are the base and weight-free indices. One of the requirements for using the Smith-Hazel index is estimation of phenotypic and genotypic variance and covariance (Lin,1978 andBaker 1974).Various studies have been carried out selection indices as an effective selection criterion in their programs on different crops (Hallauar et al,.1988); (Eta-Ndu and Openshaw, (1992); Rabiei etal (2004); Berrardo and YU, (2007);Muhammed and Syed, (2010) and Rafale et al, (2017). reported that selection index is procedure to provide a single criterion for selection among genotypes by including combination of several traits and also selection index is to find a linear combination of phenotypic value that maximizes the expected gain in aggregate genotype.…”

QTLs and candidate genes for desiccation and abscisic acid content in maize kernels

“…Maize ( Zea mays ) kernel moisture at harvest is an important trait in temperate regions because costly additional drying is needed to reach 15% water content, which is the level compatible with good seed preservation during storage. Although yield is correlated to maximum water content occurring approximately 40-60 days after pollination (DAP) [ 1 ] and to a lesser extent to kernel moisture at maturity [ 2 ], the yield/moisture ratio at maturity is variable enough to allow selection for both higher yield and lower moisture at harvest [ 3 , 4 ]. For example, recurrent selection has been successfully applied for reduction of kernel moisture by the introduction of tropical germplasm into temperate-adapted germplasm [ 5 ].…”

QTL Detection for Grain Water Relations and Genetic Correlations with Grain Matter Accumulation at Four Stages after Pollination in Maize

“…Improvement in grain yield should be obtained through increase in grain numbers per ear and per area. However, Capelle et al [28] considered that the yield/ moisture ratio at maturity was variable enough to allow selection for both high yield and low moisture at harvest [64][65][66] has successfully applied recurrent selection for reduction of kernel moisture by the introduction of tropical germplasm into temperate-a DAPted germplasm. So, correlation between grain yield and moisture at harvest might vary among different germplasms, high yield and low moisture might be realized through extensive selection.…”