EFFICIENCY OF SELECTION CRITERIA TO IMPROVE MAIZE PERFORMANCE UNDER LOW AND HIGH NITROGEN. 2- Grain yield and components

Abstract

Four selection criteria ; grain /plant (GN) , anthesis-silking interval(ASI) ,yield efficiency (YE) and leaf area duration (LAD) ,were tested on selected plants of maize (Zea mays L.) cv.R-106. The experiment was applied for six consecutive seasons on the farm of the Dept.of Field Crops Sci./College of Agric./Univ.of Baghdad .Plants of high grain yield coincided with the desired criterion were taken , selfed, and harvested for three selection cycles under 200 and 400 kg N/ha . Seeds of third cycle of each selection criterion were planted for panmixia . The resulted seeds were grown in a yield trial for evaluation under 60 and 80 thousands plant/ha in spring and fall seasons .The results showed superiority of low nitrogen selected plants population that were selected for shorter ASI increased grain number/plant% 23.6 and% 34.4 , and ear number /plant by % 8.4 ,%19.4 over original population in spring and fall, respectively. Grain weight was increased by %10.8 ,%13 and,% 12.5 for GN,ASI and LAD in spring season. In fall season grain weight was increased by %9 and %17.6 for GN,ASI, respectively. This increase was reflected on grain yield increase for ASI over original population and all criteria, it gave 93.15 and 146.11 g/plant in spring and fall, respectively. Selection criteria under high N responded positively and gave grain yield higher than original population in both seasons. Selection under high and low of N levels led to improve individual plant performance for many genetic and phenotypic traits, and resulted in increasing the efficiency of plants that were selected under high and low levels of nitrogen. We recommend to using these criteria for selection and to develop inbreds tolerant to low nitrogen and high densities, particularly the selection for ASI, and evaluate their performance to be used in breeding programs for producing cultivars and hybrids suitable for environments of stress.