Genetics of tolerance to low nitrogen in tropical maize (Zea mays L.) and construction of a selection index for simultaneous selection with associated traits
1998
Chen Zehui
Under low N condition, additive, dominance and epistasis controlled the inheritance of grain yield, number of green leaves below ear, ear leaf area, anthesis-silking interval, ear leaf chlorophyll content, plant height and shoot dry weight. There were significant additive genetic differences in the base population for grain yield, number of rows per ear, 100-kernel per row of ear, ear length, number of ears per plant, number of green leaves below ear, anthesis-silking interval, ear leaf area, and shoot dry weight, and highly significant additive differences for plant height. Grain yield was highly, significantly, and positively correlated with yield components, number of kernels per row of ear, number of ears per plant, ear length, and ear diameter and with agronomic traits anthesis - silking interval and ear leaf area and significantly correlated with number of green leaves below ear and shoot dry weight. Number of ears per plant, anthesis-silking interval, ear leaf area, number of green leaves below ear and grain yield were used as selection criteria for tolerance to low N. Expected genetic gain from selection index that included certain selection criteria surpassed that from direct selection for grain yield. For improving grain yield alone, the index that included anthesis-silking interval, number of green leaves below ear and number of ears per plant had a selection efficiency of 49 percent over that from grain yield direct selection. Results showed that multiple trait index selection can simultaneously improve grain yield and correlated traits efficiently
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