Evaluation correlation between phenotypic traits in corn hybrids and their change trends under drought stress and non-stress conditions at flowering and grain filling stages
- Rahim mohammadian,Behnam tahmasebpour, Peyvand Samimifar,Habib Lotfi
To investigate the correlation of phenotypic traits in maize different hybrids, an experiment was conducted in split plot design with 3 replications under stress-free conditions and irrigation cutting treatments on flowering and grain filling stages in the experimental field of Tabriz agricultural management. Phenotypic correlation coefficients was assessed for all hybrids in drought free conditions and different levels of irrigation cutting treatments in flowering and grain filling stages, after data analysis and estimation of average characteristics of hybrids. In general, it is recommended to select hybrids likely to drought by grain row numbers and 1000 grain weight under non-stress conditions and 1000 grain weight is an appropriate criterion for above mentioned selection under irrigation cutting treatment.
Keyword: drought stress conditions, corn hybrids, phenotypic traits, grain filling stages.
Today a large part of breeding studies is devoted to studying plant responses to water scarcity and drought stress. In Iran, plant growth and production is influenced by drought stress more than any other factor(1). In general the best way to deal with drought stress is optimal use of water and plant’s modification to increase their drought resistance that is the plant ability to desired grow and produce under stress conditions(5). We can consider plant modification and their reinforced drought resistance as an important component of desired compositional method to cope with drought. The use of existing genetic diversity is the simplest measure of plant breeding for drought resistance and other environmental stresses. In this method, different genotypes were exposed to the related stress and those which handle this situation better are selected(9). It should be mentioned that water stress on plant growth stages does not work equally; some stages are very sensitive to increased drought stress, while others are less affected(2). It is noteworthy that the phenotype of a crop is the result of interaction between many genetic and environmental factors; moreover, these different environmental factors alter the rate of correlation between yields related traits(6). Singh and Singh (8) examined the phenotypic correlation of corn different traits. There is positive phenotypic correlation between grain yields with maize characteristics like the number of grain row, the number of grain per row and 1000 grain weight. Also we observed a negative phenotypic correlation between performances with maturity and evolution parameters such as the number of the days to 50% peak flowering, the number of the days to maize 50% drying and the number of the days to 50% physiological maturity. The plant height, maize and flower crown had positive phonological correlation with the performance. The maize related parameters and crop traits showed positive correlation(8).
Shiva and Jagarnat (7) were evaluated the relationship of different traits with the plant performance and the yield per area unit separately. There was positive and significant correlation between 1000 grain weights, the number of the grain per maize, the number of the maize per plant with total of plant’s dry weight and its percentage and the percentage of dry grain weight to bush(7). Bolanos and Edmeades(3) was determined the phenotypic correlation between grain performance with other traits under stress conditions. Edmeades etal (4) used the collected data to review the effects of drought stress and found a significant correlation between the grain performances with flowering period.
Methods and Materials
In this study, two groups of ten cultivars of early and medium maturity corn hybrids were investigated according to FAO maturity groups. This experiment was conducted split plot design with 3 replications and 3 treatments in the form of randomized blocks. The main factor was irrigation different levels and sub factor was ten cultivars from two group’s maturity. Along with the performance of the experiment in the field, characteristics were measured in the treatments related to early and middle maturity and in two stress groups.
Results and discussion
The coefficients of phenotypic correlation of studied traits under non-stress conditions showed that the correlation between plant performance with 1000 grain weight and the number of the grain rows was 1% positive and significant. The most correlation is related to the number of the grain rows. It means that under non-stress conditions the plant performance is influenced by 1000 grain weight that is so important. None of the traits had significant positive or negative correlation with 1000 grain weight. The correlation of the number of the grain row with the maize height, its length and the number of the leaf under maize was 5% positive and significant. So we found that under non-stress conditions, the performance is influenced by the number of the grain row and 1000 grain weight and those are appropriate traits for the maize performance.
Table1. The correlation coefficients of phenotypic traits in corn hybrids under non-stress conditions.
|3||Leave total number||0.164||0.701||1|
|4||Number of maize upper leave||-0.31||0.225||0.6||1|
|5||Number of maize under leave||0.397||0.73*||0.88*||0.158||1|
|6||Maize wood diameter||0.332||0.73*||0.454||0.315||0.387||1|
|7||Grain row number||0.106||0.541||0.193||0.132||0.142||0.324||1|
|9||1000 grain weight||-0.1||0.07||-0.3||-0.046||-0.354||0.153||0.683||0.41||1|
Phenotypic correlation coefficient of irrigation cutting treatments at flowering stage showed that none of these studied traits had significant and positive correlation with the maize performance. The correlation of 1000 grain weight with the number of grains per row was negative and 5% significant. It means that the reinforcement of grain row in irrigation cutting treatment has negative impact on 1000 grain weight and reduces its weight. The irrigation cutting treatment in the flowering stage makes pollen dried and reduces pollination and fertilization and increases hollow beads percentage so it has more drops influenced by the number of grain row increase and finally reduces 1000 grain weight.
Table2. The correlation coefficients of phenotypic traits in corn hybrids in flowering stage and irrigation cutting treatment.
|3||Leave total number||0.134||0.613||1|
|4||Number of maize upper leave||0.44||-0.179||0.214||1|
|5||Number of maize under leave||0.177||0.67*||0.75*||-0.483||1|
|6||Maize wood diameter||0.71*||0.332||0.36||0.166||0.211||1|
|7||Grain row number||0.069||0.044||0.001||0.008||-0.004||0.202||1|
|9||1000 grain weight||-0.122||-0.299||-0.338||0.213||-0.447||-0.583||-0.374||-0.581||1|
The under studied phenotypic traits correlation coefficients in grain filling stage and irrigation cutting treatment showed that the performance correlation of the maize with the traits like the maize wood diameter and 1000 grain weight was positive and significant and the most correlation is related to the maize wood diameter. It means that under irrigation cutting treatment, the performance is influenced by this trait and it is more important that 1000 grain weight. Also 1000 grain weight had significant positive or negative correlation with none of traits. So we can claim according there results that irrigation cutting treatment at the stage of grain filling impacts leaf photosynthesis and reduces the material transportation to the grain, so makes the performance reduced under stress free conditions. We conclude that it is possible to select 1000 grain weight resistance to drought according to the maize wood diameter under irrigation cutting treatment in grain filling stage.
Table3. The correlation coefficients of phenotypic traits in corn hybrids in irrigation cutting treatment, in flowering stage.
|3||Leave total number||0.67*||0.619||1|
|4||Number of maize upper leave||0.433||0.09||0.69*||1|
|5||Number of maize under leave||0.63*||0.76*||0.90**||0.308||1|
|6||Maize wood diameter||0.467||0.548||0.135||-0.074||0.22||1|
|7||Grain row number||0.524||0.332||0.054||0.074||0.03||0.38||1|
|9||1000 grain weight||-0.217||-0.113||-0.054||-0.275||0.08||0.35||-0.25||-0.07||1|
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