Evaluation of days to silking and thermal time in enhanced-value (EVC) inbred maize lines (Zea mays L.) developed in Argentina

Abstract

The objective of this study was to identify special-use inbred lines with stable thermal time requirements for silking. Nine advanced inbred lines, generically designated as CIG, were planted across three locations between the 2000/01 and 2016/17 growing seasons. The stability of the evaluated physiological trait was measured using univariate methods: a. Parametric [coefficient of variation CV% (Francis and Kannenberg, 1978); regression coefficient bi (Finlay and Wilkinson, 1963); deviation from regression parameter S²di (Eberhart and Russell, 1966); ecovalence (Wricke, 1962), and coefficient of determination r² (Pinthus, 1973)]; b. Non-parametric [Si(3) and Si(6) (Huehn, 1990a and b)]. Genotype-by-environment interaction (GEI), response patterns, environmental classification, and genotypic stability were also studied through principal component analysis (PCA) using AMMI1 and SREG-GGE models. The inbred lines CIG4, CIG6, and CIG29, along with the check ZN6, were identified by nearly all parametric methods as stable materials regarding their thermal requirement to the silking stage, considering different types of stability. Principal component analysis identified line CIG29 and check ZN6 as the most stable genotypes; this result partially coincides with those obtained through the parametric approach. The AMMI1 biplot revealed that environments C1, C3, L3, L6, and V1, as well as lines CIG1, CIG6, CIG13, and CIG30, provided the greatest contribution to the genotype-environment interaction, as they showed extreme values within the IPCA1 variation range.