Combining Ability for Yield and its Related Morpho-Physiological Traits in Maize (Zea mays L.)
Loading...
Date
2005
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
MPUAT, Udaipur
Abstract
The present investigation entitled “Combining Ability for Yield and its Related Morpho-Physiological Traits in Maize (Zea mays L.)” was under taken to study the magnitude of general and specific combining ability effects, heterosis, heterobeltiosis, economic heterosis, genotype x interactions and stability parameters for various characters under study. The experimental material comprising of 60 hybrids, 23 parents and 4 checks, a total of 87 genotypes were evaluated during kharif 2003 in randomized block design with 3 replications under four environments viz., E1- early sown and irrigated, E2- normal sown and irrigated, E3- late sown and irrigated and E4 late sown and terminal moisture stress. The data were recorded on 15 morpho-physiological traits. The drought susceptibility index was also calculated.
The analysis of variance revealed that mean square due to genotypes was significant for all the characters in all the four environments. Only two characters exhibited homogenous error over the environments. Pooled analysis of variance for these characters revealed significant difference among genotypes, environments and interaction between them.
The per se performance in general indicated that all the parents belonged to early maturity group and most of the parental inbreds were having acceptable yield levels which qualified them to be parents of single cross hybrids.
The parental line L20 (EI-527) was identified for highest mean grain yield per plant, 100-seed weight, ears per plant, harvest index, for days to 50 per cent silking and days to 50 per cent brown husk in one or the other environment. Parental line L18 and L19 exhibited minimum mean values for days to 50 per cent tasseling, days to 50 per cent silking, days to 50 per cent brown husk and ASI in E1 and E4 environments and for plant height, ear height, leaf rolling and tassel score in majority of the environments. The tester T3 (EI-472) exhibited maximum values for grain yield per plant, 100-seed weight and ears per plant in E1, E3 and E4 environments while T2 exhibited lowest mean values for maturity related traits in one or the other environment.
The hybrid L11 x T3 (EI-517 x EI-472) exhibited maximum mean values and maximum estimates of positive significant economic heterosis for grain yield per plant in all the four environments. The hybrids L11 x T1 (EI-517 x EI-460), L1 x T1 (EI-506 x EI-460), L2 x T1 (EI-507 x EI-460) and L9 x T2 (EI-515 x EI-499) exhibited minimum values for days to 50 per cent tasseling, days to 50 per cent silking, days to 50 per cent brown husk and ASI in at least one environment while hybrid L8 xT1 ( EI-514 x EI-460) exhibited significant negative heterosis for days to 50 per cent silking in E2 environment.
Out of the 60 hybrids, 34 hybrids exhibited significant positive heterobeltiosis for grain yield per plant in E1, 42 in E2, 35 in E3 and 27 in E4 environment. The maximum estimates of positive significant heterobeltiosis for grain yield per plant was exhibited by L17 x T2 (EI-532 x EI-499) in E1, L13 x T2 (EI-519 x EI-499) in E2, L11 x T3 (EI-517 x EI-472) in E3 and L9 x T2 (EI-515 x EI-499) in E4 environment. The hybrid L15 x T1 (EI-521 x EI-460) exhibited maximum estimates of significant heterobeltiosis in negative direction for days to 50 percent tasseling, days to 50 per cent silking and days to 50 per cent brown husk in atleast one of the environment while hybrid L17 x T2 (EI-532 x EI-499) showed highest estimates negative heterobeltiosis for leaf rolling and chlorophyll stability index along with significant heterobeltiosis in negative direction for desiccation tolerance in E4 environment.
Most of the hybrids exhibited positive relative heterosis for traits like plant height, ear height, tassel score, ears per plant, 100-seed weight, grain yield per plant and harvest index in most of the environments indicating that for these traits the genes with positive effects were dominant. On the other hand, for days to 50 per cent tasseling, days to 50 per cent silking, anthesis-silking interval, leaf senescence, leaf rolling, chlorophyll stability index and desiccation injury majority of the hybrids exhibited significant negative relative heterosis indicating that for these traits the genes with negative effects were dominant.
The analysis of variance for combining ability revealed that mean squares due to lines, testers and line x testers were significant for most of the characters which indicated that experimental material possessed considerable variability and that GCA and SCA were involved in the genetic expression of various traits.
The 2 SCA effects were greater that 2 GCA for almost all the characters in all the environments and across the environments. It thus indicated the preponderance of non-additive gene effects in the expression of the traits under study. The estimates of GCA effects revealed that in general, inbred lines L1, L2, L3, L4, L9, L11, and L20 were considered good general combiners for yield and majority of the yield contributing traits.
The best hybrids which exhibited positive significant SCA effects for grain yield were L13 x T2 (EI-519 x EI-499), L4 x T3 (EI-509 x EI-472), L11 x T3 (EI-517 x EI-472), L2 x T1 (EI-507 x EI-460) and L3 x T1 (EI-508 x EI-460). Highest estimates of negative significant SCA effects for chlorophyll stability index include L1 x T3 (EI-506 x EI-472) in E4 environment while for desiccation injury highest negative significant SCA effect was shown by hybrid L15 x T1 in E3 and by L10 x T2 (EI-516 x EI-499) in E4 environment. Hybrid L11 xT1 (EI-517 x EI-460) showed highest negative SCA effects for maturity related traits in one or the other environment. In general, close association between SCA effects, economic heterosis and per se performance for grain yield per plant was observed among the best hybrids identified on the basis of SCA effects.
The stability analysis revealed that mean squares due to genotype x environments was significant for all traits which indicated the influence of environmental conditions on the genotypes evaluated. The mean squares due to G x E (linear) were significant for all the traits indicating environments were quite variable for traits under study.
Hybrid L16 x T1 (EI-522 x EI-460) was found to be stable and suitable under different environment for grain yield per plant. Hybrids L10 x T2 and L16 x T2 were found to be stable and suitable for grain yield under unfavourable environments while hybrids L2 x T1, L12 x T1, L2 x T2, L3 x T2, L13 x T2, L15 x T2, L17 x T2, L18 x T2, L1 x T3, L4 x T3, L5 x T3, L7 x T3 and L19 x T3 were found stable and suitable in favourable environments.
An overall perusal of performance of hybrids for grain yield per plant revealed that hybrids L2 x T1 (EI-507 x EI-460), L13 x T2 (EI-519 x EI-499), L17 x T2 (EI-532 x EI-499), L4 x T3 (EI-509 x EI-472), and L11 x T3 (EI-517 x EI-472) which exhibited positive significant SCA effects and economic heterosis with mean higher than general mean and best check were also stable under favourable environments. These hybrids were also stable for most of the yield contributing traits.
Thus, the present study revealed that emphasis should be given to those genotypes which specifically possess drought adaptive traits under moisture stress condition to stabilize the production for year-to-year. Since drought tolerance is a complex trait governed by number of factors a combination of morphological, physiological and biochemical parameters should be considered. Identificaiton of genotypes with short ASI, reduced height, tassel size, low leaf senescence, leaf rolling, CSI, desiccation injury along with drought susceptibility index and higher prolificacy can help in the development of drought enduring stable genotypes.
Drought is encountered practically in all productive environments.Thus, breeding for drought tolerant lines are receiving emphasis, so as to optimize the use of water and nutrients and to maximize the economic product under low input environment. Thus, the lines that were selected on the basis various morpho-physiological traits can be used in future breeding to constitute germplasm population and to increase the level of resistance among desirable lines. Since hybrids were found to be better under stress from the present study, these can also be involved in the development of drought tolerant and productive single cross hybrids which can be directly used for general cultivation after confirming its potential through multilocational testing.
Description
Studies on the Combining Ability for Yield and its Related Morpho-Physiological Traits in Maize
(Zea mays L.)
Keywords
null
Citation
Lukose and Godawat, 2005