Drought is a major constraint in some rice-growing areas of the United States. Its impact is most severe at the reproductive stage resulting in low grain yield. Therefore, assessment of genetic and phenotypic variation for drought tolerance in US rice germplasm is necessary to accelerate the breeding effort. Evaluation of 205 US rice genotypes for drought tolerance at the reproductive stage revealed tolerant response in rice genotypes Bengal, Jupiter, Cypress, Jazzman, Caffey, and Trenasse. Harvest index and fresh shoot weight were identified as important traits to explain the majority of variability among the genotypes under drought tolerance. Genotyping with 80 SSR markers indicated a low level of genetic diversity in US germplasm. Population structure analysis grouped the genotypes into eight clusters. The genotypes from California, Louisiana, and Arkansas formed distinct subgroups. Texas genotypes were similar to those from Louisiana and Arkansas. Marker-trait association analysis showed significant association of RM570 and RM351 with grain yield, spikelet fertility, and harvest index whereas shoot dry weight showed association with RM302 and RM461. The drought-tolerant genotypes identified in this study and the SSR markers associated with drought tolerance attributes will be helpful for development of improved drought-tolerant rice varieties through marker assisted selection.

During periods of drought, the irrigation needs of current warm‐season turfgrass cultivars and frequent municipal water use restrictions present a major challenge to the turfgrass industry. Turfgrass breeding programs have responded by placing more emphasis on improved drought response. During 2012–2013, 560 genotypes of four warm‐season turfgrass species developed by five southern breeding programs were evaluated for drought response in replicated field trials at seven locations. Breeders selected 35 genotypes as drought‐tolerant selections (DTS) for further evaluation. The objectives of this study were to verify superior drought response among DTS under short‐term drought conditions and to assess the effectiveness of this approach as a viable breeding strategy to improve drought response in warm‐season turfgrasses. Forty‐seven genotypes including standard commercial cultivars of zoysiagrass (Zoysia spp. Willd.), bermudagrass [Cynodon spp. (L.) Pers.], St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and seashore paspalum (Paspalum vaginatum Swartz) were exposed to dry‐downs in three consecutive years by withholding irrigation and excluding rainfall. Significant differences in drought performance were seen across genotypes over the multiyear study. Statistical contrasts found that DTS of zoysiagrass, St. Augustinegrass, and seashore paspalum generally performed better than the standard cultivars. Top‐performing DTS zoysiagrass and St. Augustinegrass genotypes maintained >50% green cover longer than the average of the standard cultivars. Based on this research, multilocational screening for drought tolerance was effective in selection of new genotypes with superior performance to standard cultivars and continued screening of turfgrass germplasm to identify new drought‐tolerant genotypes is warranted.

High temperatures can significantly reduce tomato (Solanum lycopersicum L) yield. A 5 × 5 diallel cross was used under high temperatures in a greenhouse to estimate combining ability and understand the genetic basis of tomato genotypes under heat stress. Additive gene action was predominant in governing most heat-tolerant morphological traits; yield was governed by nonadditive gene action. A cross involving high × high general combining ability (gca) or high × low gca had better specific combining ability (sca) effects. The genetic components and proportions studies showed heat tolerance was governed by nonadditive gene action and is a dominant trait. The parental variance (Vr) and parent–offspring covariance (Wr) relationship (Wr–Vr) indicated that heat tolerance traits were governed by overdominance. Significant correlation occurred between yield and yield-attributing traits. Heterosis was high for yield and most yield-attributing traits. Heterosis breeding involving crosses with high gca parents ‘CLN1621E × Nagcarlan’ and ‘BL1176 × Nagcarlan’ could be used to improve tomato for yield during heat stress. Selection for heat tolerance traits should be in early generations followed by selection for yield.

Although both salinity and alkalinity result from accumulation of soluble salts in soil, high pH and ionic imbalance make alkaline stress more harmful to plants. This study aimed to provide molecular insights into the alkalinity tolerance using a recombinant inbred line (RIL) population developed from a cross between Cocodrie and Dular with contrasting response to alkalinity stress. Forty-six additive QTLs for nine morpho-physiological traits were mapped on to a linkage map of 4679 SNPs under alkalinity stress at the seedling stage and seven major-effect QTLs were for alkalinity tolerance scoring, Na⁺ and K⁺ concentrations and Na⁺:K⁺ ratio. The candidate genes were identified based on the comparison of the impacts of variants of genes present in five QTL intervals using the whole genome sequences of both parents. Differential expression of no apical meristem protein, cysteine protease precursor, retrotransposon protein, OsWAK28, MYB transcription factor, protein kinase, ubiquitin-carboxyl protein, and NAD binding protein genes in parents indicated their role in response to alkali stress. Our study suggests that the genetic basis of tolerance to alkalinity stress is most likely different from that of salinity stress. Introgression and validation of the QTLs and genes can be useful for improving alkalinity tolerance in rice at the seedling stage and advancing understanding of the molecular genetic basis of alkalinity stress adaptation.

Blackeye peas (Vigna unguiculata L. Walp.) are mainly used as a vegetable throughout the world, however they may contain significant concentrations of quercetin, myricetin, cyanidin, and delphinidin for potential use as a functional vegetable. Thirty-eight blackeye pea genotypes were selected from the core collection in the USDA, ARS, Plant Genetic Resources Conservation Unit’s cold storage at 4 °C during 2016. Information regarding concentrations of quercetin, myricetin, cyanidin, delphindin, and correlations among these as well as additional seed traits including seed coat color, seed pattern color, seed pattern, seed texture, and years in storage would add value to the blackeye pea genotypes for use as a functional vegetable. Using high performance liquid chromatography (HPLC), the red seeded accession originating from Mozambique, PI 367927 produced the highest quercetin (469.53 µg/g) and myricetin (212.23 µg/g) concentrations. The black seeded genotype, PI 353236, originating from India, produced the highest cyanidin (1,388.82 µg/g) concentration. However, PI 353236 and the brown seeded genotype, PI 353352 from India produced the highest concentrations of delphinidin (1,343.27 and 1,353.94 µg/g), respectively. Several correlations were observed and interestingly only delphinidin showed a significant negative correlation (r = −0.293*) with years in cold storage indicating that delphinidin declined in the seeds stored the longest (from 4-45 years) at 4 °C. Principal component analysis (PCA) explained how the flavonols, anthocyanidins, and the additional seed traits contributed to the variation of the blackeye pea genotypes. The cluster analysis showed six clusters representing low to high phytochemical concentrations. The genetic parameters including σ²g, σ²p, GCV, PCV, h²_h, and GG indicate that improvement in these phytochemical traits is possible through selection. The genotypic and phenotypic correlations showed that improving one phytochemical significantly improved the other except for cyanidin with delphinidin. These results can be used by scientists to develop blackeye pea cultivars with high flavonol and anthocyanidin concentrations.