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Previous research results of Blue Panic (Panicum antidotale Retz) in arid conditions under different irrigation methods proved an increase in forage yield and water productivity (WP) under full and water stress conditions. However, a thorough search in the literature revealed that its water requirement has not yet been determined. Therefore the objective of this research was to measure evapotranspiration (ETc) and crop coefficient (Kc) for a Blue Panic crop under arid conditions. Four draining lysimeters constructed in Jeddah (21° 480 300 N, 39° 430 2500 E) were used to measure its ETc and Kc under a plentiful water supply. Results revealed that ETc varied from 141 mm in the first harvest to 292 mm in the sixth, with an average of 225 mm per harvest. The Kc value was different from one harvest to another. The average Kc over all harvests was 0.7, 1.2, 1.3 and 1.0 for the initial, development, midseason and late stages, respectively. Average fresh and dry forage yields per harvest were 30.5 and 12.6 t ha1, respectively. AverageWP was 55 kg ha1 mm1. The predicted ETc based on the measured crop coefficient value and ET0 show a good fit between measured and calculated ETc. Copyright © 2018 John Wiley & Sons, Ltd.

Field experiment was carried-out during 2015/16 and 2016/17 seasons at the Agriculture Experimental Station of King Abdulaziz University to investigate the effect of stress and fully irrigations with different plant densities on yield and yield attributes of sunflower and to determine water productivity under the investigated treatments. The design of the experiment was a split block with four replications. Main blokes contained fully and stress irrigation water regimes while the sub mains comprised six plant densities of sunflower cultivar (Helianthus annuus L). Results revealed that decreasing irrigation water regime to 65% of field capacity (FC) reduced daily and seasonal water supplies, yield, yield attributes and oil content of sunflower crop but increased water productivity. Increasing plant density reduced head diameter, seeds yield/plant and seed index. Combination of 50 cm row spacing with 15 cm inter row spacing under 100% FC and 60 cm row spacing with 15 cm inter row spacing under 65% FC produced the highest significant seeds yield and water productivity. In these combinations using full irrigation requirement increased seeds yield by about 10% compared with the stressed one. However, the stress combination increased water productivity by about 38% compared with fully irrigation combination.

This study was conducted during 2015–2017 seasons in the Agricultural Research Station, King Abdulaziz University at Hada Al-Sham region, Saudi Arabia. The aim was to investigate the effects of planting Al- Hassawi clover between sugar beet rows in two intercropping systems: 1 sugar beet row: 2 clover rows (1:2) and 1 sugar beet row: 3 clover rows (1:3) besides sugar beet monocrop and Al-Hassawi clover monocrop. Also, number of harvested cuts from clover during the sugar beet growing season (1, 2 and 3 cuts) on sugar beet yield, sucrose yield, clover yield, leaf area index and land equivalent ratio (LER) were investigated. No significant differences were found between sugar beet fresh root or sucrose yield/ha under the intercropping systems 1:2, 1:3 or sugar beet sole crop with one or two cuts from clover. Fresh forage yield/ha from clover significantly increased as number of cuts increased using the two intercropping systems. The highest clover forage yield/ha was produced from the clover sole with three cuts. The highest LER was produced under the 1:3 intercropping system with two cuts or one cut of clover.