Drought was maintain ed in pot raised plants by

N2 - Insects and drought cause severe losses in the production of maize in many developing countries. Conventional breeding efforts to enhance the level of resistance to a number of insect pests and tolerance to drought have been successful, although only through large efforts of many breeders and over a large period of time. Continued improvements will only be possible through substantial investment of resources. Recently, success in identifying quantitative trait loci (QTL) in several plant species using various molecular marker systems offers alternative methods for accelerating conventional breeding programs. As the first step towards using molecular markers in CIMMYT's maize breeding program, restriction fragment length polymorphisms (RFLPs) have been used to understand the genetic basis of resistance to two corn borer species, southwestern corn borer and sugarcane borer, and to one major component of drought tolerance, anthesis-silking interval. A number of QTL with effects large enough to be regarded as significant in breeding were detected for each of these traits and many of them presented stable effects over environments. While variability in the number and location of QTL has been found when compared across populations, several loci were found to be quite consistent. Simple calculations can be made which estimate that the total genetic potential in maize for these traits is high. It is argued that to ultimately access and manipulate this potential, the use of linked molecular markers as indirect selectable markers is both feasible and necessary.

Secondary traits for maize grain yield under drought stress

Define anthesis silking interval Custom paper Academic Service

Anthesis to Silking Interval Usefulness in Developing Drought Maydica

Vargas M, van Eeuwijk FA, Crossa J, Ribaut JM, 2006. Mapping QTLs and QTL× environment interaction for CIMMYT maize drought stress program using factorial regression and partial least squares methods. Theor Appl Genet 112: 1009-1023.

PHENOTYPING FOR ABIOTIC STRESS TOLERANCE IN MAIZE DROUGHT STRESS

A short ASI has been identified as an easily measured.
The positions of the 68 mQTL for grain yield and anthesis silking interval.
Anthesis to Silking Interval Usefulness in Developing Drought Tolerant Maize.

Anthesis silking interval drought tolerance Integrated Crop Management Iowa State University
New in Plant Physiology Ovary Abortion Under Drought Stress Silk growth during pollination

Drought-induced changes in anthesis-silking interval are related ..

Some of the mQTL detected in this study explained up to 13% of the phenotypic variance for GY and ASI under stress and/or optimum conditions. Because each mapping populations had an average of 174 progenies, it is possible that some of the mQTL of large effect may showed upward biased estimation (Beavis effect) of the phenotypic effects [,]. MQTL with large physical intervals may also contain several linked genes influencing the same trait. This has been reported even in cases where QTL effects have been fine mapped to more than one specific gene []. As far as we are aware, this is the first study that reports extensive mQTL results using over 3100 individuals that were genotyped using the same SNP platform and phenotyped in the same way across a wide range of managed water stressed and well watered environments. Future investigations may involve fine mapping and/or verification of some of the mQTL regions detected across 4-6 populations using large population size and high marker density. The results from this study provide highly valuable information for researchers working on QTL mapping for possible use in marker assisted selection and/or QTL cloning.

PHENOTYPING FOR ABIOTIC STRESS TOLERANCE IN MAIZE DROUGHT STRESS Nature

yield under drought, anthesis-silking interval, ..

Drought is a severe threat to maize yield stability in Serbia and other temperate Southeast European countries occurring occasionally but with significant yield losses. The development of resilient genotypes that perform well under drought is one of the main focuses of maize breeding programmes. To test the tolerance of newly developed elite maize inbred lines to drought stress, field trials for grain yield performance and anthesis silk interval (ASI) were set in drought stressed environments in 2011 and 2012. Inbred lines performing well under drought, clustered into a group with short ASI and a smaller group with long ASI, were considered as a potential source for tolerance. The former contained inbreds from different heterotic groups and with a proportion of local germplasm. The latter consisted of genotypes with mixed exotic and Lancaster germplasm, which performed better in more drought-affected environments. Three inbreds were selected for their potential drought tolerance, showing an above-average yield and small ASI in all environments. Association analysis indicated significant correlations between ASI and grain yield and three microsatellites (bnlg1525, bnlg238 and umc1025). Eight alleles were selected for their favourable concurrent effect on yield increase and ASI decrease. The proportion of phenotypic variation explained by the markers varied across environments from 5.7% to 22.4% and from 4.6% to 8.1% for ASI and yield, respectively. The alleles with strongest effect on performance of particular genotypes and their interactions in specific environments were identified by the mean of partial least square interactions analysis indicating potential suitability of the makers for tolerant genotype selection.

Nitrogen fertilization impact on agronomic traits of maize hybrids Define anthesis silking interval

the presence of drought tolerance genetics ..

Meta-analyses reduced the number of QTL by 68% and narrowed the confidence intervals up to 12-fold. At least the 4 mQTL (mQTL2.2, mQTL6.1, mQTL7.5 and mQTL9.2) associated with GY under both water-stressed and well-watered environments and detected up to 6 populations may be considered for fine mapping and validation to confirm effects in different genetic backgrounds and pyramid them into new drought resistant breeding lines. This is the first extensive report on meta-analysis of data from over 3100 individuals genotyped using the same SNP platform and evaluated in the same conditions across a wide range of managed water-stressed and well-watered environments.