The rising demand for popcorn necessitates improving the popping quality with higher yield of popcorn cultivars. Towards this direction several Quantitative Traits Loci (QTLs) for popping traits have been identified. However, identification of accurate and consistent QTLs across different genetic backgrounds and environments is necessary to effectively utilize the identified QTLs in marker-assisted breeding. In the current study, 99 QTLs related to popping traits reported in 8 different studies were assembled and projected on the reference map "Genetic 2005" using BioMercator v4.2 to identify metaQTLs with consistent QTLs. Total ten metaQTLs were identified on chromosome 1 (7 metaQTLs) and 6 (3 metaQTLs) with physical distance ranging between 0.43 and 12.75 Mb, respectively. Four identified metaQTLs, viz., mQTL1_1, mQTL1_5, mQTL1_7 and mQTL6_2 harboured 5–8 QTL clusters with moderately high R2 value. The clustered QTLs were from two or more experiments. Based on the expression pattern in endosperm and pericarp tissues, a total of 229 genes were selected. Nineteen of these genes are involved in carbohydrate metabolism. Of the 19 genes specifically involved in carbohydrate metabolism, 11 of them were in these regions, implying the importance of these clustered QTLs. MetaQTL1_1 at bin location 1.01 coincided with the reported QTLs related to various agronomic traits like stalk diameter, tassel length, leaf area and plant height. The identified metaQTLs can be further explored for fine mapping and candidate gene identification, which can be validated by loss or gain of function. Identified metaQTLs can be used for introgression of popping traits towards enhancing the popping ability.

Highlights Dry seeded rice (DSR) [drill and precision broadcast] was tested over beushening . Dry Drill-DSR resulted in US$ 166−550 ha −1 higher net benefit than beushening . Net benefit gain from precision broadcast-DSR was US$ 188−312 ha −1 over beushening . Effective integrated weed management options were identified for DSR. Other benefits of DSR were reduction in seed rate, labor and production cost.

No abstract

Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F 1 s and two F 2 s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F 2 populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F 1 s and normal distribution pattern in F 2 s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F 2 populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.

Drought stress is the most important production constraint in maize (Zea mays L.), especially in rainfed agriculture. To improve productivity of rainfed maize, the development of hybrids with tolerance to drought stress is an important objective in maize breeding programs. The present study was undertaken to identify maize hybrids that perform better under drought-stress and drought-free conditions by using various selection indices. These selection indices were calculated on the basis of yield (t ha–1) performance of hybrids measured under drought stress and optimum environments. A set of 38 cultivars was evaluated at 10 environments (representing five each of drought stress and optimum growing conditions). The average reduction in grain yield due to drought stress was 52%. Effects of genotype, environment and their interaction were significant sources of variation in determining grain yield, respectively explaining 5.0–7.4%, 55.0–60.2% and 12.0–15.0% of total variation in yield under drought-stress and drought-free conditions. Of eight selection indices considered for study, three indices such as harmonic mean, geometric mean, and stress tolerance index were identified as suitable for selection of genotypes capable of performing well both under drought-stress and drought-free environments. Drought response index and drought resistance index were found useful in identifying hybrids that performed better under drought stress. Stress susceptibility index was negatively correlated with yield measured under drought stress. Stress susceptibility index could be used as selection index but only in combination with yield performance data under water-deficit conditions in order to identify drought-tolerant hybrids with reasonable productivity. Test weight, shelling percentage, days to maturity, and ear girth were found to be useful traits for improving yield performance across diverse environments. Cultivation of identified drought-tolerant hybrids would be useful to enhance maize productivity in drought-stress environments.