Tropospheric ozone causes various negative effects on plants and affects the yield and quality of agricultural crops. Here, we report a genome-wide association study (GWAS) in rice (Oryza sativa L.) to determine candidate loci associated with ozone tolerance. A diversity panel consisting of 328 accessions representing all subgroups of O. sativa was exposed to ozone stress at 60 nl l^–1 for 7h every day throughout the growth season, or to control conditions. Averaged over all genotypes, ozone significantly affected biomass-related traits (plant height –1.0%, shoot dry weight –15.9%, tiller number –8.3%, grain weight –9.3%, total panicle weight –19.7%, single panicle weight –5.5%) and biochemical/physiological traits (symptom formation, SPAD value –4.4%, foliar lignin content +3.4%). A wide range of genotypic variance in response to ozone stress were observed in all phenotypes. Association mapping based on more than 30 000 single-nucleotide polymorphism (SNP) markers yielded 16 significant markers throughout the genome by applying a significance threshold of P<0.0001. Furthermore, by determining linkage disequilibrium blocks associated with significant SNPs, we gained a total of 195 candidate genes for these traits. The following sequence analysis revealed a number of novel polymorphisms in two candidate genes for the formation of visible leaf symptoms, a RING and an EREBP gene, both of which are involved in cell death and stress defence reactions. This study demonstrated substantial natural variation of responses to ozone in rice and the possibility of using GWAS in elucidating the genetic factors underlying ozone tolerance.

Intensification of staple food crops such as Yam (Dioscorea spp.) while sustaining the environment is imperative in providing food for the expected 9.6 billion global population by 2050. In West Africa, amid the threat posed by climate change on food security, yam production is associated with deforestation and land degradation. Integrated soil fertility management and improved staking options for intensification and sustainable yam production on continuously cropped fields hold the key to addressing this challenge. This review evaluates the last decade's yam production trends in West Africa and in three leading yam-producing countries, Nigeria, Ghana, and Côte d'Ivoire, using the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) data. A production increase of 1.72, 1.43, and 1.35 times resulted in an area harvest increase of 2.25, 1.23, and 1.59 times in Nigeria, Ghana, and Côte d'Ivoire, respectively. Nigeria and Côte d'Ivoire had the worst yam productivity across the decade by producing at an average yield 17.3 and 12.5%, respectively, of the estimated potential yam yield (50 t ha⁻¹). Even in Ghana, where the productivity increased across the decade, the average productivity was 33% of the estimated potential yield. Thus, it can be observed that the primary reason for the increase in yam production across the globe and in West Africa is mainly because of the increase in area under cultivation in the major yam-producing countries. The projected future erratic rainfall and elevated daily mean temperature as a result of climate change would cause declining tuber yields. Meanwhile, the importation of food such as rice as a strategy to improve food availability cannot be accessed by poor rural households due to the strong correlation between international food price hikes and prices of these foods. However, there is less relationship between international yam price hikes and yam prices in West Africa. Therefore, yam production and sustenance could be vital for food security for the increasing population of West Africa. This study reviews current research on soil fertility and staking options for sustaining yam production on continuously cropped fields. Promotion and adoption of these improved technologies would enhance food security and contribute to achieving Sustainable Development Goals 1 (No poverty), 2 (Zero hunger), 13 (Climate action), and 15 (Life on land).

The global temperature increase of 1.1°C over the past decade and human population growth are already escalating competition for water in locations where water is scarce, adversely affecting agriculture. Water-smart farming was developed to address challenges associated with the availability, access and use of agricultural water. It complements practices and goals related to agricultural water in climate-smart agriculture. It encompasses several climate-responsive food cropping systems, water-saving methods, tools, and technologies to grow food sustainably. Effective implementation of water-smart farming can ameliorate the pressing burden of agricultural water competition. Therefore, the conceptual framework of water-smart farming and its principal elements or ideology are introduced in this review. The major pillars of water-smart cropping, which include conditioning and improving the soil’s capacity to capture and hold moisture, basic infrastructure for water harvesting, storage and use as nature-based cropping solutions were elaborated. Further examples of technologies and best practices in water-smart crop farming, such as breeding for drought-tolerant crop varieties, promoting dryland cropping systems, alternate wetting and drying technology, water drainage and control structures, rainwater harvesting, utilization of irrigation reservoirs, cover cropping and intercropping for enhancing soil moisture conservation were presented. The review also briefly shows the contribution of some of these best practices and adaptive technologies of water-smart cropping toward promoting water-saving methods used for growing rice, maize, legumes, cassava and peri-urban vegetables.

A vigorous root system in barley promotes water uptake from the soil under water-limited conditions. We investigated three spring barley genotypes with varying water stress responses using rhizoboxes at the seedling stage. The genotypes comprised two elite German cultivars, Barke and Scarlett, and a near-isogenic line, NIL 143. The isogenic line harbors the wild allele pyrroline-5-carboxylate synthase1-P5cs1. Root growth in rhizoboxes under reduced water availability conditions caused a significant reduction in total root length, rooting depth, root maximum width, and root length density. On average, root growth was reduced by more than 20% due to water stress. Differences in organ proline concentrations were observed for all genotypes, with shoots grown under water stress exhibiting at least a 30% higher concentration than the roots. Drought induced higher leaf and root proline concentrations in NIL 143 compared with any of the other genotypes. Under reduced water availability conditions, NIL 143 showed less severe symptoms of drought, higher lateral root length, rooting depth, maximum root width, root length density, and convex hull area compared with Barke and Scarlett. Within the same comparison, under water stress, NIL 143 had a higher proportion of lateral roots (+30%), which were also placed at deeper substrate horizons. NIL 143 had a less negative plant water potential and higher relative leaf water content and stomatal conductance compared with the other genotypes under water stress. Under these conditions, this genotype also maintained an enhanced net photosynthetic rate and exhibited considerable fine root growth (diameter class 0.05–0.35 mm). These results show that water stress induces increased shoot and root proline accumulation in the NIL 143 barley genotype at the seedling stage and that this effect is associated with increased lateral root growth.

Water stress (WS) during spike development strongly affects final grain yield and grain quality in cereals. Proline, an osmoprotectant amino-acid, may contribute to alleviating the effects of cell and tissue dehydration. We studied five spring barley genotypes contrasting in their drought response, including two introgression lines,S42IL-143andS42IL-141, harboring aPyrroline-5-carboxylate synthase1- P5cs1allele originating from the wild barley accessionISR42-8. We tested the hypothesis that barley genotypes harboring a wild allele atP5cs1locus are comparatively more drought-tolerant at the reproductive stage by inducing proline accumulation in their immature spikes. At the booting stage, we subjected plants to well-watered and WS treatments until physiological maturity. Several morpho-physiological traits had significant genotype by treatment interaction and reduction under WS. Varying levels of genotypic proline accumulation and differences in WS tolerance were observed. Spike proline accumulation was higher than leaf proline accumulation for all genotypes under WS. Also, introgression lines carrying a wild allele atP5cs1locus had a markedly higher spike and leaf proline content compared with the other genotypes. These introgression lines showed milder drought symptoms compared with elite genotypes, remained photosynthetically active under WS, and maintained their intrinsic water use efficiency. These combined responses contributed to the achievement of higher final seed productivity. Magnetic resonance imaging (MRI) of whole spikes at the soft dough stage showed an increase in seed abortion among the elite genotypes compared with the introgression lines 15 days after WS treatment. Our results suggest that proline accumulation at the reproductive stage contributes to the maintenance of grain formation under water shortage.