Persistent hypoxia can cause pulmonary arterial hypertension that may be associated with significant remodeling of the pulmonary arteries, including smooth muscle cell proliferation and hypertrophy. We previously demonstrated that the NADPH oxidase homolog NOX4 mediates human pulmonary artery smooth muscle cell (HPASMC) proliferation by transforming growth factor-beta1 (TGF-beta1). We now show that hypoxia increases HPASMC proliferation in vitro, accompanied by increased reactive oxygen species generation and NOX4 gene expression, and is inhibited by antioxidants, the flavoenzyme inhibitor diphenyleneiodonium (DPI), and NOX4 gene silencing. HPASMC proliferation and NOX4 expression are also observed when media from hypoxic HPASMC are added to HPASMC grown in normoxic conditions, suggesting autocrine stimulation. TGF-beta1 and insulin-like growth factor binding protein-3 (IGFBP-3) are both increased in the media of hypoxic HPASMC, and increased IGFBP-3 gene expression is noted in hypoxic HPASMC. Treatment with anti-TGF-beta1 antibody attenuates NOX4 and IGFBP-3 gene expression, accumulation of IGFBP-3 protein in media, and proliferation. Inhibition of IGFBP-3 expression with small interfering RNA (siRNA) decreases NOX4 gene expression and hypoxic proliferation. Conversely, NOX4 silencing does not decrease hypoxic IGFBP-3 gene expression or secreted protein. Smad inhibition does not but the phosphatidylinositol 3-kinase (PI3K) signaling pathway inhibitor LY-294002 does inhibit NOX4 and IGFBP-3 gene expression, IGFBP-3 secretion, and cellular proliferation resulting from hypoxia. Immunoblots from hypoxic HPASMC reveal increased TGF-beta1-mediated phosphorylation of the serine/threonine kinase (Akt), consistent with hypoxia-induced activation of PI3K/Akt signaling pathways to promote proliferation. We conclude that hypoxic HPASMC produce TGF-beta1 that acts in an autocrine fashion to induce IGFBP-3 through PI3K/Akt. IGFBP-3 increases NOX4 gene expression, resulting in HPASMC proliferation. These observations add to our understanding hypoxic pulmonary vascular remodeling.

This study evaluates the potential for adaptability and tolerance of wheat genotypes (G) to an arid environment. We examined the influence of drought stress (DS) (100, 75, and 50% field capacity), planting times (PT) (16-November, 01-December, 16-December and 01-January), and G (Yocoro Rojo, FKAU-10, Faisalabad-08, and Galaxy L-7096) on phenological development, growth indices, grain yield, and water use efficiency of drip-irrigated wheat. Development measured at five phenological growth stages (GS) (tillering, jointing, booting, heading, and maturity) and growth indices 30, 45, 60, and 75 days after sowing (DAS) were also correlated with final grain yield. Tillering occurred earlier in DS plots, to a maximum of 31 days. Days to complete 50% heading and physiological crop maturity were the most susceptible GS that denoted 31–72% reduction in number of days to complete these GS at severe DS. Wheat G grown with severe DS had the shortest grain filling duration. Genotype Fsd-08 presented greater adaptability to studied arid climate and recorded 31, 35, and 38% longer grain filling period as compared with rest of the G at 100–50% field capacity respectively. December sowing mitigated the drought and delayed planting effects by producing superior growth and yield (2162 kg ha−1) at severe DS. Genotypes Fsd-08 and L-7096 attained the minimum plant height (36 cm) and the shortest growth cycle (76 days) for January planting with 50% field capacity. At severe DS leaf area index, dry matter accumulation, crop growth rate and net assimilation rate were decreased by 67, 57, 34, and 38% as compared to non-stressed plots. Genotypes Fsd-08 and F-10 were the superior ones and secured 14–17% higher grain yield than genotype YR for severely stressed plots. The correlation between crop growth indices and grain yield depicted the highest value (0.58–0.71) at 60–75 DAS. So the major contribution of these growth indices toward grain yield was at the start of reproductive phase. It's clear that booting and grain filling are the most sensitive GS that are severely affected by both drought and delay in planting.

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A field experiment studying the effect of water stress on alfalfa (Medicago sativa) productivity and water use efficiency was conducted at the Agricultural Experimental Station of King Abdelaziz University. The design of the experiment was randomized complete block design (RCBD) with four replicates. It consisted of three treatments, namely: field capacity treatment (FC) as a control, 85% FC and 70% FC as stress treatments. The irrigation water for all treatments was precisely supplied using recent technology known as the water electronics module (WEM).Results indicated that decreasing water supply decreased fresh and dry yield of alfalfa but increased irrigation water use efficiency (IWUE). As a result, 13 and 27% of irrigation water were saved from 85% FC and 70% FC treatments respectively in each cut compared with the FC treatment. The reduction of water supply resulted in a yield reduction of 12 and 21.7% for 85% FC and 70% FC, respectively. The results also proved that WEM is a practical tool to precisely supply irrigation water and can be used effectively to control deficit irrigation. RÉSUMÉUne expérience sur le terrain a été réalisée à la station expérimentale agricole de l'Université du Roi Abdelaziz pour étudier l'effet du stress hydrique sur la luzerne (Medicago sativa), sa productivité et son efficience d'utilisation de l'eau. La conception de l'expérience était en blocs aléatoires complets (CR) avec quatre répétitions. Elle se composait de trois traitements à savoir: le traitement en irrigation à la capacité au champ (FC) comme témoin, par comparaison aux traitements de stress à FC 85% et FC 70%, respectivement. L'eau d'irrigation pour tous les traitements a été ajustée précisément en utilisant la technologie récente connue sous le nom de 'water electronics module' (WEM).Les résultats indiquent que l'approvisionnement en eau diminue les rendements frais et sec de la luzerne, mais augmente l'efficacité d'utilisation d'eau d'irrigation (IWUE). En conséquence, 13 et 27% de l'eau d'irrigation ont été épargnés par les traitements FC 85% et 70% respectivement dans chaque coupe. La réduction de l'approvisionnement en eau a entraîné une baisse de rendement de 12 et de 21,7% pour les FC et le FC 85% à 70%, respectivement. Les résultats ont également montré que WEM est un outil pratique pour fournir l'eau d'irrigation précisément et peuvent être utilisés efficacement pour contrôler l'irrigation déficitaire.

An experiment was conducted in indoor lysimeters to study the effect of deficit irrigation on water use efficiency and bird pepper (Capsicum annuum L.) production under drip irrigation system. Sixweek-old seedlings of hot pepper were transplanted into the lysimeters. Four seedlings spaced 40 cm apart were grown in each lysimeter. Three irrigation treatments were investigated. The first treatment (W1) was 100% of the field capacity as a control. The second and third treatments (W2 and W3) were giving 85% and 70% of the field capacity, respectively, as deficit irrigation treatments. The deficit irrigation practice was applied after 15 days of the transplanting and continued for the whole growth season. The results indicated that the highest yield was obtained from W1 which grew under no stress. Deficit irrigation tends to increase water use efficiency and decrease the fresh fruit yield. Giving 85 % of the field capacity (W2) led to save 41% of the irrigation water and reduce the total yield by 28.9 %. Giving 70% of the field capacity (W3) resulted in 85 % of irrigation water saving but 40% of the total yield was lost. The study indicated that, bird pepper is very sensitive to water stress, however water deficit is a practical technique to save large amounts of irrigation water.

No abstract

A field experiment was conducted in the western part of Saudi Arabia to optimize irrigation water use (IWU), yields and quality of the 'Nabbut‐Saif' date palm grown in sandy loam soil under arid conditions. Four water regimes were investigated. The supplied amounts of irrigation water were 50, 65, 82 and 100% of date palm water requirements to the first (W1), second (W2), third (W3) and fourth (W4) water regimes, respectively. The daily water requirement was calculated using the Penman–Montieth equation for dry climates and applied to the trees three times a week through a drip irrigation system. Results indicated that giving 65% of total date palm water requirement maximized date yield by producing 46.1 kg per tree and resulted in the best IWU (0.8 m3 kg−1 per tree). Increasing the water regime to 82 and 100% of total water requirement produced only 45.5 and 46 kg per tree respectively and reduced IWU. Generally, fruit quality characteristics were insignificantly affected by the water regimes investigated. The results suggested that supplying 34 m3 yr−1 per tree for date palms grown under the conditions of the western part of Saudi Arabia is enough to maximize IWU, yield and quality of the 'Nabbut‐Saif' date palm cultivar. Copyright © 2014 John Wiley & Sons, Ltd.

This paper describes the simulation results for continuous and surge flow irrigation under short field conditions by the computer model SIRMOD III in order to evaluate the performance and applicability of the model for short furrows and to investigate the viability of the two-point method for calculating infiltration parameters under continuous and surge flow irrigation in short fields. These specific field conditions are found on farms smaller than 1 ha and with a furrow length of 70 m. To evaluate the model a series of experiments has been carried out in two locations in Egypt and in one site in the Netherlands. The experiments in Egypt were conducted on a field with clay soil situated at the Agriculture Experimental Station, Assiut University, and on a sandy soil field located at the Assiut University Experimental Station for Desert Land, El-Wadi El-Assuity, Assiut. The experiments in the Netherlands were carried out at the Tunnel Experimental Setting of the Irrigation and Water Engineering Group of Wageningen University. The tunnel was covered as a greenhouse to protect the investigations against the external weather conditions, especially rainfall. Two soil types were available inside the tunnel, namely sandy clay and sandy clay loam. All the experiments were carried out in furrows with a blocked end and their length and width were 70 and 0.70 m, respectively.Measured field data were used to evaluate the computer model SIRMOD III. The results of the evaluation indicated that the model can accurately simulate continuous and surge flow irrigation under short field conditions for the measured infiltration parameters. These field data are very important for a good simulation of the advance time and consequently the infiltration. The two-point method can be successfully used to obtain the infiltration parameters for continuous and surge flow irrigation under short field conditions and for different soil types.