Abdelhalim Elazab

Rice is a staple food grown worldwide. While white rice varieties have been extensively studied, there is limited information on the performance of pigmented rice genotypes and their tolerance to water deficit. This study evaluated nineteen black rice genotypes and one white cultivar over three years under contrasting water regimes: traditional flooding and non-flood irrigation (NFI). Genotype–environment interactions and their impact on agronomic, yield, and grain quality traits were assessed. Black genotypes under NFI showed reduced flowering and grain quality. The average yield was 31% lower than the white cultivar. Significant genetic correlations were found between grain yield and days to anthesis (DSA), grain weight (TGW), chalkiness (CHA), and translucency (TRAN), with high broad-sense heritability (H² > 0.9). Most traits exhibited high heritability (H² > 0.7), indicating strong genetic stability. Grain yield (GR) was highly and negatively correlated with percent sterility (PS) (r = −0.84) and had a heritability of 0.76. Environmental conditions significantly influenced yield, confirming the potential for selecting water stress–tolerant genotypes. These findings provide valuable insights into black rice breeding and optimizing water management practices to support sustainable production. To our knowledge, this study is the first to evaluate the performance of a diverse set of black rice genotypes across multiple seasons under contrasting water regimes in a Mediterranean environment.

Drought significantly constrains common bean (Phaseolus vulgaris L.) production worldwide, and as climate change intensifies, projections indicate a subsequent reduction in yield. This study aimed to identify drought-resilient genotypes among twenty common bean lines in Chile under two water regimes: regular irrigation and terminal drought stress. The research was conducted over two seasons in south-central Chile. Drought significantly reduced grain yield (22.7%), aboveground biomass (37%), harvest index (19.5%), the number of grains per pod (61.3%), and hundred-grain weight (10.1%). Genotypes 452, 473, and 483 exhibited minimal yield reductions (<11%) and maintained stable physiological performance, including higher quantum yield of photosystem II and efficient photoprotective mechanisms (increased ΦNPQ) under stress. In contrast, sensitive genotypes like Blanco Español showed marked yield loss (54%) and lower photosynthetic efficiency. Chlorophyll retention emerged as a key trait for identifying high-yielding, drought-tolerant genotypes. Drought also accelerated crop maturation in susceptible genotypes, compromising yield potential. These findings highlight the importance of integrating agronomic, phenological, and physiological traits in breeding programs to develop drought-adapted varieties. The tolerant genotypes offer valuable genetic traits to improve drought resilience and contribute to food security in the face of climate change.

Investigating the key traits associated with genetic gains in grain yield (GY) is essential for developing winter wheat (Triticum aestivum L.) breeding strategies. The study objectives were: (a) quantifying the photosynthetic contribution of flag leaf and ear to the grain filling; (b) analyzing if their contributions are associated with the genetic gains in GY; and (c) analyzing their relationship with other agronomical and physiological traits. Thus, six winter wheat genotypes of different release years were grown under optimal conditions in a greenhouse trial during 2019. Grain yield increased by 126 kg h^–1 yr^–1, with the harvest index's change being the key factor affecting these gains. Compared to the control treatment, ear shading decreased ear contribution to grain filling by 16.35%, while both flag leaf and awn removal increased contribution to grain filling by 4.46 and 5.90%, respectively. Ear photosynthetic contribution estimated by source manipulation treatments showed a significant increase with the release year (0.54% yr^–1). Whole ear gas exchange measures correlated positively with GY, and both dark respiration and gross photosynthesis showed positive correlations with the release year. The main findings of the study were: (a) GY gains in Chile were mainly due to the increased harvest index (HI), while the aerial biomass (AB) did not play a significant role in these gains; (b) the increased ear size besides the terminal heat stress during the study highlighted the ear role as the primary photosynthetic contributor to grain filling; and (c) using source manipulation techniques as an indirect selection trait for high ear photosynthesis appeared to be promising.