GENETIC ANALYSIS OF GRAIN YIELD AND TURCICUM LEAF BLIGHT RESISTANCE IN MAIZE (Zea mays L.)
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Date
2023-12-07
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Acharya N G Ranga Agricultural University
Abstract
The present investigation entitled “Genetic analysis of grain yield and TLB resistance in maize (Zea mays L.)” was carried out during rabi 2021-22 at Agricultural College Farm, Bapatla, Andhra Pradesh, to study the combining ability of parents and crosses and also to estimate the magnitude of heterosis for kernel yield and its contributing traits apart from character association of different traits with kernel yield. The material involved was 11 lines that were crossed with 4 testers in line x tester mating design to produce 44 crosses. The parents along with 44 crosses and 5 checks were evaluated in simple lattice design with two replications.
The analysis of variance (ANOVA) revealed significant differences among the genotypes for all the characters indicating the presence of substantial amount of variability and intrinsic genetic variation in the genotypes studied.
Analysis of variance for combining ability revealed that the parents vs crosses exhibited significant difference for all the traits indicating the presence of variability in the genetic material. Among the parents, the line, VL18828 exhibited significant gca effect in desirable direction for days to 50% tasseling, days to 50% silking and ear girth; VL19705-8 for ear placement height and no. of kernels row-1; VL171488-2 for ear placement height and kernel rows ear-1; SNL19588-23 for plant height in desirable direction. Among the testers, LM13 recorded significant gca effect in desirable direction for traits like ear length and 100 kernel weight; BML7 for protein content; BML6 for 100 kernel weight and ear girth and LM14 for ear placement height. Out of 44 crosses, significant high sca effect in desirable direction was recorded by the cross VL19255 x BML7 for days to 50% tasseling, days to 50% silking; VL175869-14 x LM14 for ear length,
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ear girth and kernel yield plant-1; CAL1733-13 x BML6 for kernel rows ear-1; VL171488-2 x BML6 for ear placement height; SNL19588-23 x LM13 for protein content. The high sca effects for most of the crosses were resulted due to parental gca combinations with low x low, high x low and low x high. Therefore, we can infer that to attain high sca effect of a cross, one can include some low general combiners along with high general combiners in hybridization programmes.
Heterosis studies revealed that the crosses SNL19564-20 x BML7, VL18828 x BML7, VL18828 X BML7, VL171488-2 X BML7 and VL19255 x BML7 recorded significant positive mid parent heterosis and heterobeltiosis for kernel yield. Among the 44 crosses, based on mid parent, better parent, standard heterosis (DKC8171), sca effect and per se performance the cross, VL175869-14 x LM14, was identified as the best hybrid for kernel yield.
The ratio of GCA variance to SCA variance for most of the traits like days to 50% tasseling, days to 50% silking, plant height, ear placement height, ear girth, kernel yield plant-1 was less than unity indicating the predominace of non-additive gene action whereas it was more than unity for days to maturity, kernel rows ear-1, 100 kernel weight and protein content indicating the predominance of additive gene action in the inheritance of these traits.
Correlation and path analysis revealed that the kernel yield could be improved by improving the traits viz., plant height, ear length, ear girth, no. of kernels row-1 and kernel rows ear-1, as they showed positive significant association with kernel yield.
All the 64 genotypes were screened against turcicum leaf blight disease under artificial epiphytotic conditions to identify resistant/tolerant genotypes. Disease score was recorded at tasseling, 20 DAT and maturity stages by using 1-9 scale. At maturity stage 12 crosses, seven lines and one check showed resistant reaction (R) indicating the usefulness of these crosses in maize crop improvement programmes.
In the present study 26 SSR markers were used for assessment of molecular diversity in 15 parental inbred lines along with 5 checks. Out of these primers seven primers viz., bnlg1335, bnlg1666, bnlg2086, bnlg238, Phi054, umc1029 and umc2077 recorded PIC value more than 0.6; these primers could be effectively utilized for genotype differentiation and genetic diversity analysis suggesting their potentiality in future genetic diversity analysis. These markers, were reported to be associated with TLB resistance and the data indicated that lot of variation in the resistant genotypes for the reported associated markers indicating the polygenic inheritance of this trait and usefulness of these in developing novel maize hybrids having the desirable TLB resistance.