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Plastid terminal oxidase (PTOX) is a plastid-localized protein that acts as plastoquinol oxidase. The objective of this study was to determine the role of plastid terminal oxidase in response to drought stress and examine the differential response of PTOX pathway in both cultivated (Yousef and Morocco) and tolerant wild barley (spantaneum; HS) genotypes. Plants were subjected to different levels of soil water availability including control, mild and severe drought stress. Decrease in leaf relative water content as a result of progressive drought stressed led to decrease in stomatal conductance and increased enzymatic antioxidant machinery in all genotypes. Drought stress did not affect the PTOX transcript and protein level in cultivated genotypes Yousef and Morocco. However, PTOX gene expression and protein content significantly increased in HS genotype under severe drought. Assessment of PTOX activity via fast fluorescence induction curve in presence of PTOX specific inhibitor revealed that PTOX could efficiently oxidize plastoquinon pool and acts as alternative electron pathway in HS genotype. Results indicated that the role of PTOX in stress response was more significant in the wild barley than the cultivated barley varieties, where the emphasis has been on the desirable agronomic traits. [ABSTRACT FROM AUTHOR]

Under terminal drought conditions, due to the limitation of current photosynthesis, the impact of cereal stem carbohydrates reserves and their contribution to the grain yield preservation could be enhanced. The role of stem fructan remobilization on yield of barley was examined under drought conditions in the present study. The fructan accumulation and remobilization rate of the penultimate internode were studied in Morocco 9–75 and Yousef, as drought susceptible and tolerant barley (Hordeum vulgare L.) cultivars, respectively. Drought stress increased the fructan accumulation and remobilization in Yousef, supporting it from severe yield loss compared to Morocco cultivar. Under drought stress conditions, during grain filling of Yousef cultivar, the strong correlations were observed between the relative expression of the key genes involved in the fructan metabolism, that is 1‐SST and 6‐SFT (fructan biosynthesis genes) with the fructan content, as well as between the expression of 1‐FEH (fructan exohydrolase) and SUT1 (sucrose transporter) with fructan remobilization. Yousef cultivar contained considerable water‐soluble carbohydrate content of stem internodes, and a rise in osmolytes such as fructan may lead to the efficient osmotic adjustment, which in turn resulted in the maintenance of the water content and stomatal conductance. Based on the results, enhanced fructan accumulation and its induced remobilization under drought conditions can play an important role in yield stability of Yousef under stress. The barley genotypes with high potential for fructan production and remobilization under terminal drought stress could provide the appropriate materials for drought tolerance breeding and screening for these traits. Core Ideas: More fructan accumulation in the internodes of the drought‐tolerant barley cultivar was investigated.The induction of fructan remobilization under drought in the tolerant cultivar was examined.There is a higher expression level of the related genes in the drought‐tolerant cultivar.Grain yield is correlated with the expression of related genes under drought stress.Exploiting genotypic variation in stem reserves improves barley drought tolerance. [ABSTRACT FROM AUTHOR]

Salinity is a major problem affecting crop production in many regions in the world including Morocco. Agricultural practices such as fertilization could be useful to overcome this problem and improve crop productivity. The objective of our study was to evaluate the combined effect of phosphorus fertilization and irrigation water salinity on growth, yield, and stomatal conductance of forage corn (Zea mays L.) cv. "Sy sincerro". Field experiments were carried out for two years testing four levels of irrigation water salinity (ECw = 0.7; 2, 4, and 6 dS·m−1) and three rates of phosphorus (105, 126, and 150 kg P2O5·ha−1) fertilization conducted in a split-plot design with three replications. The obtained results show that irrigation water salinity had a negative effect on all monitored parameters. For instance, the dry matter yield reduced by an average of 19.3 and 25.1% compared to the control under saline irrigation with an EC value equal to 4 and 6 dS·m−1, respectively. The finding also showed that phosphorus applications tend to increase root weight, root length, stem length, leaf stomatal conductance, grain yield and dry matter yield under salinity conditions. For example, the addition of phosphorus with a rate of 126 and 150 kg P2O5·ha−1 respectively improved dry matter yield by an average of 4 and 9% under low salinity level (ECw = 2 dS·m−1), by 4 and 15% under medium salinity (4 dS·m−1), and by 6 and 8% under a high salinity level (6 dS·m−1). Our finding suggests that supplementary P application could be one of the best practices to reduce the adverse effects of high salinity on growth and development of forage corn. [ABSTRACT FROM AUTHOR]