Dynamics of chlorophyll and N concentration on e0 and e3 leaves of maize hybrids in winter in subtropical region
Authors: Adhikari Nav Raj , Ghimire Surya Kant , Sah Shrawan Kumar , Koirala Keshab Babu 
Published: January 2018

National maize productivity is very low in Nepal. To increase its productivity, hybrid maize breeding and their cultivation are indispensible. For it, fifteen newly bred single cross hybrids of yellow maize were examined to select superior high GYHs (grain yielding hybrids) from the standpoint grain yielding potentiality. In addition, dynamics of chl, N conc and red light absorbance-transmittance (RAT) have also examined from the standpoint of chl, N conc and RAT measure and their effects on grain yield (GY). For it, a trial of RCBD experiment was conducted in open field in winter in subtropical region in Nepal. Seeds were sown on October 3, 2012 plot in two row plot area of 1.4 x 3.0 m2. After anthesis, observations of chl and N conc implying RAT (red light absorbance-transmittance) SPAD (Soil Plant Analysis and Development) measures were taken from the topmost ear (e0 or E0) and third (e3 or E3) leaf above the e0 leaf in ten days interval during entire grain filling (GF). SPAD measures were transformed to total chl and N conc. E0 leaf has been found more grain yield determining than e3 leaf and terminal GF has been found more determining than early GF from the standpoint of correlation coefficients (r ) of GYs with chl, N conc and SPAD measure. From pooled variance analysis; SPAD and chl conc were not significant different in the two leaves and among the hybrids (Hybrids x Leaves x Ages). But, the SPAD and chl conc were significant different among the two leaves and ages (Leaves x Ages) irrespective of the hybrids. Different to the SPAD and chl conc, N conc was significant different in the leaves among the hybrids with respect to ages of the plants among the fifteen hybrids (Hybrids x Leaves x Ages). Thirteen top high GYHs 8, 12, 11, 13, 5, 6, 10, 1, 7, 14, 2, 9 and 15 were non-significant different from the standpoint of GY. The SPAD measures were in the non-significant range of 51-55 in e0 leaf in the duration from 95 to 125 d among the fifteen hybrids (FHs). Among the top four high GYHs 8, 12, 11 and 13; hybrid 11 lost chl and N from e0 leaf significantly on 135th d relative to the most of the hybrids. It means that the hybrid 11 could efficiently degrade N containing soluble protein and chl even on e0 leaf relatively. Top listed five high GYHs 8, 12, 11, 5 and 6 (except 13) constantly maintained chl and N conc implying SPAD on the e0 leaf up to the 135th d. In addition, it implies that these five hybrids sent newly up-taken N to kernels without degradation of the proteins and chl from the e0 leaf till the age of 135 d. High GYH 8 had degraded soluble proteins and enzymes and chl conc on e3 leaf and mobilized the degraded N to the kernels more efficiently from the e3 leaf. It is not necessary that maize hybrids must constantly maintain soluble proteins and chl conc during most of early to mid GF for high GY. Instead, diagnostic decline of the soluble protein and chl conc during early to mid GF also accelerate GF phenomena.