Genetic analysis of maize (Zea mays L.) composite under stress and non-stress conditions

Abstract

Hybrids and composites of maize developed in India, at the research station under much better agronomic conditions did not show the expected superiority on the farmer's field, where conditions are commonly sub optimal due to erratic monsoon and low fertility in majority of the fields. Therefore, the choice of environment for selection has gained importance in maize breeding [1]. An improved population Mahikanchan was used as experimental material for the development of 256 full-sibs progenies following NCO-I. Mahikanchan is an early maturing yellow grained composite derived from CD-Yellow gene pool, developed at Centre of All India Coordinated Maize Improvement Project. These 256 full families (64 half-sib families) were developed during rabi 2001-02 at Rajasthan College of Agriculture, Udaipur. To develop full-sib and half-sib families, each sixty four randomly chosen male plants were crossed with 6 random female plants. After harvest out of six female plants, four successfully pollinated female plants that had sufficient seed for field evaluation were retained to constitute a male group (a group of four families involving the same male parent). The sixty-four male groups were assigned to sixteen sets with each set comprising 4 male groups. Each set of 4 male groups thus has sixteen families (full-sibs) in it. Various male groups were assigned to the sets at random. In each replication sets were randomized and in each set the sixteen full sib families were also randomized. These 256 full sib families were evaluated in incomplete block design (simple lattice design) with two replications in rainfed farming situations of Udaipur under two fertility levels of NPK viz., 120:60:00 kg per hectare (E1) and 60:60:00 kg per hectare (E2). Each family was sown in a single row plot of 3 meter length maintaining a crop geometry of 60 x 25 cm. Observations were recorded on eleven traits (Table 1) out of which, ASI was recorded on plot basis while rest of characters were recorded on 5 random plants. Data for individual characters were subjected to analysis as proposed by Comstock and Robinson [2, 3] NCO-I.