Comprehensive screening of rice (Oryza sativa L. subsp. japonica Kato) germplasm resources with different nitrogen (N) efficiency levels is effective for improving N use efficiency (NUE) while reducing pollution and providing high quality, yield, and efficiency agriculture. We investigated 14 indices of 38 varieties under three N application levels to assess differences among genotypes. Rice varieties were classified for screening and identifying N efficient. Descriptive statistical analysis results indicated significant differences in relative yield, and also in NUE indices (agronomic utilization rate and partial productivity of N fertilizer). The genotype main effects and genotype–environment interaction effects (GGE) biplot analysis was used to evaluate suitable varieties, compare the stable and high yield capabilities of different varieties, find the ideal variety, and describe the correlation, discrimination and representativeness of the indices under different N application levels. Descriptive statistical, discrimitiveness and representativeness and factor analysis were used to select indices, in which the panicle number per plant and soil and plant analyzer development (SPAD) value were the key indices for evaluation and identification. Heatmap and hierarchical cluster analysis based on the average value of evaluation indices, and scatter plot based on the comprehensive value of N efficiency (P) according to formula showed that all varieties could be divided into five types under different N treatments. Our findings work toward developing N efficient rice varieties to improve NUE, reduce N fertilizer application and thus N waste, consequently mitigating the effects of rice production on the environment to ensure food security and sustainable agricultural development.

To identify appropriate genotypes for breeding varieties suitable for semi-arid areas, yield components, as well as morphophonological traits of 127 safflower genotypes, were assessed at the Seed and Plant Improvement Institute, Iran. Cluster analysis revealed four distinct groups. The largest group (third cluster) includes 48 genotypes with characteristics such as mostly yellow-coloured flowers, mostly thorny with few thistle genotypes, relatively early-flowering, relatively high number of heads and grains per plant, highest 1000-grain weight with the highest grain yields. In contrast, the smallest group (second cluster) contains 13 genotypes with characteristics such as yellow florets, semi-dwarf, thorny, moderately late-flowering, low number of heads per plant and number of grains per head, low 1000-grain weight, and low grain yield. Principal component analysis results showed that the three components accounted for 29.5, 15.9 and 11.1% of the total variation, respectively. Graphic representation of the biplots based on the first and second principal components showed that the experimental genotypes were classified into four groups. The results also indicated that stem diameter, the number of branches, heads per plant and grains per head had the highest correlation with the first component, and grain yield, flower colour, flowering initiation and plant height had the highest correlation with the second component. These traits can be considered as an appropriate index for the selection of elite safflower genotypes for breeding varieties suited to cultivation in semi-arid conditions.

Most of the modern-day improved watermelon varieties succumb to various biotic and abiotic stresses mainly because of their narrow genetic base. Insights into the genetic diversity and population structure are crucial for broadening the genetic base and improving the adaptive value. The present experiment was conducted to study the genetic diversity and population structure of a germplasm panel comprising 336 Citrullus sp. accessions. Another objective was to formulate a core collection of Indian Citrullus sp. accessions. Data from 23 highly polymorphic microsatellite markers were used for genetic diversity and population structure analysis while both molecular and phenotypic data from 17 traits were used to formulate the core set. The markers yielded a total of 69 alleles with an average of three alleles per locus. Initially, the accessions clustered into two populations and an admixture group. Intra-population analysis revealed three and two statistically distinct subpopulations in Pop I and Pop II, respectively. The exotic collections were predominant in Pop I-A, Pop II-A and Pop II-B while the Indian accessions were preponderant in Pop I-B and Pop I-C. Pop I-B recorded the maximum magnitude of gene diversity and the highest number of alleles. The well-adapted Indian landraces could be deployed in future watermelon improvement programmes. The formulated core collection (n = 46; 23.71% of the entire collection studied) would ease in maintenance of the diversity present among indigenous Citrullus sp. accessions; would ease trait search while exploring Indian diversity and can be pooled with other collection(s) to form a global core of watermelon.

Genetic resources are of paramount importance for developing improved crop varieties, particularly for biotic and abiotic stress tolerance. Spot blotch (SB) is a destructive foliar disease of wheat prevalent in warm and humid regions of the world, especially in the eastern parts of South Asia. For the management of this disease, the most effective measure is the development of resistant cultivars. Thus, the present investigation was carried out to confirm SB resistance in 200 germplasm accessions based on phenotypic observations and molecular characterization. These elite breeding lines obtained from the International Centre for Maize and Wheat Improvement, Mexico, are developed deploying multiple parentages. These lines were screened for SB resistance in the field under artificially created epiphytotic conditions during 2014–15 and 2015–16 along with two susceptible checks (CIANO T79 and Sonalika) and two resistant checks (Chirya 3 and Francolin). Eighty-two out of 200 germplasm accessions were found resistant to SB and resistance in these lines was confirmed with a specific SSR marker Xgwm148. Three accessions, VORONA/CNO79, KAUZ*3//DOVE/BUC and JUP/BJY//URES/3/HD2206/HORK//BUC/BUL were observed possessing better resistance than the well-known SB-resistant genotype Chirya3. These newly identified resistant lines could be used by wheat breeders for developing SB-resistant wheat varieties.

Climate change realities such as high-temperature levels are among the causes of drought episodes affecting the productivity and yield stability of crops worldwide. Breeders, therefore, have a daunting challenge to overcome and a large gap to seal in the agricultural sector arising due to drought through the improvement of new tolerant germplasm. It is in this endeavour that the present study, which included nine winter wheat genotypes grown in the greenhouse, was conducted to evaluate their performance under well-watered and drought stress treatments for the traits: heading time, plant height, above-ground biomass, seed number/plant, grain yield/plant, harvest index, root length and root dry mass. A lower grain yield/plant was observed for each studied genotype under drought stress conditions than for those under well-watered conditions. Additionally, grain yield/plant depression varied from 69.64 to 81.73% depending on the genotype. Positive significant correlations between grain yield/plant and heading time, above-ground biomass, and seed number/plant under the drought stress treatment were obtained. Genotypes that recorded high root dry mass had both high above-ground biomass and seed number/plant under drought stress conditions. Positive correlations between grain yield/plant depression and plant height, seed number/plant, and harvest index depressions were also observed. Grain yield for each genotype under drought stress conditions was recorded, and the varieties ‘Plainsman V.’, ‘GK Berény’ and germplasm ‘PC61’, ‘PC110’ showed the best drought tolerance. These genotypes and germplasm will be used in different drought tolerance experiments and breeding programmes.

Short duration cotton (Gossypium hirsutum L.) cultivar may be more profitable for the growers, as it will have shortened critical growth window for drought, heat and insect pests. Therefore, in the present research work, two cotton advance lines IUB-71 and IUB-73 along with an approved cotton cultivar IUB-13 were tested under four different sowing dates i.e. S1 (25th April), S2 (10th May), S3 (25th May) and S4 (10th June) in 2017 and 2018 under field condition. Field layout was RCBD factorial with four sowing dates as one factor and three cotton genotypes as another factor with three replications. Data were recorded for plant height, total number of nodes, bolls per plant, seed cotton yield (SCY), above ground fresh biomass (AGFB) and harvest index (HI). An overall decreasing trend with increasing sowing dates was observed in all the traits except HI that relatively increased in all the three genotypes. Within each sowing date, a higher value for each trait was observed for genotype IUB-73 except for AGFB might be due to higher reproductive allocation. It is concluded that IUB-73 due to superior SCY and HI specifically under late planting is best fit for short cotton seasons with reduced critical window for cotton management.

Guinea grass (Megathyrsus maximus Jacq.) is an important forage species in vast rangelands/grasslands of India and several tropical countries owing to its high biomass yield, good nutritional quality and wide adaptation. Evaluation of the existing natural variation and selection of desirable genotypes is the most plausible breeding method for this apomictic and polyploid grass. Developing a core sub-set to narrow down the number of germplasm required for future genetic studies is also pertinent. The present study involved characterization of 152 diverse M. maximus germplasm representing collections from different agro-ecological zones of India as well as those procured from Africa and Brazil; and development of a core sub-set. Nineteen metric, seven non-metric and nine nutritive traits together established the presence of wide variability among the genotypes. Clustering of the genotypes resulted in eight distinct clusters. The largest cluster included genotypes from Ethiopia, north India, north-western India, south India and north-eastern hill region, thus represented the highest diversity. Eleven of the total 26 Ethiopian genotypes clustered together. Non-metric morphological traits effectively differentiated the genotypes, and were associated with nutritional quality also. Genotypes which flowered once in a year showed slightly better crude protein and digestibility. The clusters were further sub-clustered and representatives were selected to develop the core sub-set of 23 genotypes comprising 20 indigenous and three exotic accessions. Comparison of the range of diversity and mean value for traits as obtained in the core sub-set and that in the total germplasm indicated successful capturing of maximum diversity in the core sub-set.

In this study, maize landraces, previously collected from different regions of Turkey through a national maize breeding project, were screened for kernel oil content and oil quality. After a seed reproduction in 2017, the screening trial was conducted in 2018, using an Augmented Experimental Design with 192 local maize populations along with seven check hybrids. Data were collected on oil, oleic acid, linoleic acid, monounsaturated (MUFA), polyunsaturated and saturated fatty acids, total carotenoid and total tocopherol contents. The results showed that there was a considerable amount of genetic variation among the Turkish maize landraces for almost all the traits investigated in this study. Some of the evaluated landraces are available that could be considered as high oil variety or special genotypes in terms of certain oil quality traits. Landraces had significantly higher values than checks for oil content, oleic acid, MUFA and tocopherol contents. Genetic analyses suggest that the kernel quality traits could be successfully manipulated using the investigated plant material. Heritability values were found high for all the traits of interest, except for saturated fatty acid and total carotenoid content. The promising landraces detected in this study could be exploited in future breeding programmes upon further evaluations at the population level.

Mungbean yellow mosaic virus (MYMV) disease is one of the most devastating biotic constraints of mungbean production in India. Dependable knowledge on the number and mode of action of genes controlling resistance to MYMV disease is one of the keys to develop resistant cultivars. The F1s of four crosses derived from four MYMV resistant genotypes × one highly susceptible genotype, their parents, F2s and F3s along with a susceptible check were screened for responses to MYMV disease following the infector-row technique under natural infection conditions. A good fit of F2 population segregation to the hypothesized ratio of 15 susceptible:1 resistant and that of F3 population segregation to the expected ratio of 55 susceptible:9 resistant at 55 days after planting confirmed the involvement of two recessive genes in imparting resistance to MYMV disease.

In order to understand rice blast resistance gene patterns in rice landraces from Myanmar and Laos, we analysed the Pita, Pib, Pikh, Pi9 and Pi5 genes in 80 landraces through the use of functional molecular markers and functional fragment sequencing. These landraces were separated into four haplotypes (H1–H4) based upon three mutations identified in the Pita sequence. All four haplotypes were detected among landraces from Myanmar, whereas only the H1 and H2 haplotypes were detected among landraces from Laos. We additionally grouped landraces carrying 0–4 resistance genes into 18 genotypes based upon their resistance-susceptibility patterns and found that 16 of these genotypes were detected among Myanmar landraces at relative frequencies ranging from 2.50–12.50%, while 10 were detected among landraces from Laos at relative frequencies of 2.50–42.50%. The ‘Pib( + ) pikh(−) pi9(−) pi5(−) pita(−)’ genotype was found to be dominant, accounting for 12.5 and 42.5% of landraces from Myanmar and Laos, respectively. The Pib, Pikh, Pi5 and Pita genes were detected in 52.50, 32.50, 37.50 and 30.00% of landraces from Myanmar respectively, whereas they were detected in 52.50, 12.50, 30.00 and 17.50% of landraces from Laos, respectively. The Pi9 gene was rarely detected among analysed landraces and was particularly rare in those from Laos. These findings suggest that rice landraces from Myanmar are more genetically diverse than those from Laos, with clear differences in blast resistance gene patterns between landraces from these two countries.

Leaf morphology of crop plants has significant value in agronomy. Leaf rolling in rice plays a vital role to increase grain yield. However, collective information on the rolling leaf (RL) genes reported to date and different comparative bioinformatics studies of their sequences are still incomplete. This bioinformatics study was designed to investigate structures, functions and diversifications of the RL related genes reported till now through several studies. We performed different comparative and functional analyses of the selected 42 RL genes among 103 RL genes using different bioinformatics techniques including gene structure, conserved domain, phylogenetic, gene ontology (GO), transcription factor (TF), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein–protein network. Exon-intron organization and conserved domain analysis showed diversity in structures and conserved domains of RL genes. Phylogenetic analysis classified the proteins into five major groups. GO and TF analyses revealed that regulation-related genes were remarkably enriched in biological process and 10 different TF families were involved in rice leaf rolling. KEGG analysis demonstrated that 14 RL genes were involved in the KEGG pathways, among which 50% were involved in the metabolism pathways. Of the selected RL proteins, 55% proteins were non-interacting with other RL proteins and OsRL9 was the most interacting RL protein. These results provide important information regarding structures, conserved domains, phylogenetic revolution, protein–protein interactions and other genetic bases of RL genes which might be helpful to the researchers for functional analysis of new candidate RL genes to explore their characteristics and molecular mechanisms for high yield rice breeding.