A field experiment was carried out at Agriculture Research Station of King Abdulaziz University, Jeddah, Saudi Arabia to study the effect of fine particles, tillage system, and polyacrylamide application rate on the soil penetration resistance during the two seasons (2015/16 – 2016/17). Experimental design was split-split plot with four replications. Main plot included two percent of fine particles, (A = 25.2 silt + clay) and (B = 38.5 silt + clay). Sub-main plots included three tillage systems; no-tillage (NT), moldboard plowing with rotor tiller (CT1), and chisel plowing with disk harrow (CT2). Sub-sub plots were three polyacrylamide (PAM) rates; 0, 10 and 20 kg ha-1. Both locations were cultivated by wheat crop for two consecutive seasons. Results revealed that tillage system affected soil penetration resistance. Penetration resistance results revealed the existence of compacted layer beneath the tilled depth in all treatments in both locations. However, its hardness in location A was higher than in location B. The CT1 treatment had the highest value of cone index; however, the penetration resistance of CT2 and NT treatments was similar. High rate of PAM application improved penetration resistance especially with CT2 tillage system.

A field experiment was carried out at the Agriculture Research Station of King Abdulaziz University to study the effects of fine soil particles, tillage system and polyacrylamide on wheat production and some soil chemical properties. The design of the experiment was a split-split plot with four replications. The main plot included two soils A and B, (A with 25.2 % silt+ clay while B with 38.5 % silt+ clay). Sub plot included three tillage systems namely: No-tillage (NT), Moldboard ploughing with rotor tiller (CT1) and Chisel ploughing with disk harrow (CT2). The sub-sub plot included three polyacrylamide (PAM) rates and were 0, 10 and 20 kg/ha. The obtained results indicated that soil of location B was better than the soil A because wheat production in location B was significantly higher than that of location A. CT2 produced the highest grain yield for wheat crop followed by NT and CT1 tillage systems respectively. Application of different rates of PAM (10 and 20 kg/ha) increased yield production compared with 0 kg/ha. Soil nutrients including N, P and K were significantly increased in the soil of location B compared to location A. The nutrients also increased by increasing PAM rates in both locations.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

This study was performed to evaluate the effect of both cow and chicken manures application on the immobilization of Ni and Zn in soils. Effect of cow and chicken manures on the bulk density, pH and the distribution of Ni and Zn in various chemical fractions of an alkaline, sandy loam soil was explored in a PVC columns study. Cow and chicken manures were mixed at rates of 10, 20 and 30 g/kg of soil. The soil-manure mixture was incubated for two months at room temperature. Sequential extraction procedure was performed on all samples from each column to determine Zn and Ni in different fractions (soluble-exchangeable, organic, carbonates and residual). Results obtained showed a decrease in soil bulk density with an increase of 0.3 units in soil pH as compared to the control. After 60 days of incubation, Ni concentrations were found to be 28 and 34% of inorganic fraction, while the residual reaction accounted for 58 and 53% for cow and chicken manure respectively as compared to the corresponding control. In case of Zn, soil organic matter fraction accounted for 53-57% of the total Zn. The soluble and exchangeable fraction which, although, slightly increased with time remained very low (2-4%) for the two metals. Therefore, the addition of the manures resulted in improved soil bulk density and showed a good potential in immobilizing both two metals in the studied soil.

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.

A field experiment was carried out at the Agriculture Experimental Station of King Abdulaziz University during the 2013 and 2014 seasons to study the effect of water regimes and palm coefficient on growth parameters, yield and irrigation water use (IWU) of tissue culture-derived ‘Barhee’ date palm cultivars in a newly established orchard. Four water regimes T1, T2, T3 and T4 representing 70, 85, 100 and 115% of water requirement were studied to select the best water regime that maximizes yield and IWU. Water requirement in 2013 was calculated based on the FAO palm coefficient (Kp) but based on measured Kp during 2014. Results revealed that using measured Kp reduces water requirements in the summer season and increases date yield. It saves about 12% of irrigation water compared to FAO Kp. Increasing the water regime increased yield per palm, where the highest yield was obtained from T4 (16.5 kg per tree), and the least from T1(12.4 kg per tree). IWU is increased by decreasing the water regime. However, the differences between T4 and T3 were not significant, indicating that giving the highest water regime produces the highest yield. It is concluded that increasing water supply maximizes yield production of young tissue culture-derived ‘Barhee’ date palms in a newly established orchard. Copyright © 2016 John Wiley & Sons, Ltd.

Screening of drought tolerant genotypes for arid land cultivation is the best approach to avoid yield losses as breeding and selection are time taking techniques. Current experiment was planned to evaluate late sown wheat cultivars potential for drought tolerance and adaptability in Jeddah region, KSA. Four wheat cultivars (Yocoro, Rojo, Faisalabad-2008, F-10 and L-7096) were tested against drought stress applied as (75% and 50%) of total crop water requirement. A 100% water requirement was also applied as control. Data regarding crop growth stages, growth, grain yield and yield contributors were tested by using MSTAT-C. Drought stress significantly decreased all growth and yield traits except harvest index and the effect of water stress was the most severe where 50% of the total water requirement was applied. Both studied crop growth stages (days to complete tillering and days to complete 50% heading) were also affected to applied water stress and effect was more pronounced for days to complete 50% heading. Studied cultivars responded variably for different growth and yield traits. Cultivar Yoco Rojo took minimum days to complete tillering and heading while L-7096 presented the highest plant height and dry biomass accumulation. Faisalabad-2008 reported maximum values for grain yield and yield contributors except spike length that was maximum in Yocoro Rojo. Based on the field evaluation, it’s concluded that Faisalabad-2008 produced significant results for growth and yield traits among studied cultivars and can be successfully grown in arid land conditions under limited water supplies.

A field experiment was carried out at the Agricultural Experimental Research Station of King Abdulaziz University to study the effect of irrigation level, row spacing and inter-row spacing on productivity and irrigation water productivity (IWP) of Canola. Two irrigation levels, IFull (100% of field capacity) and Imin (65% of IFull), were investigated. Three row spacing, S1, S2 and S3, represented by 20, 40 and 60 cm between rows were studied under each irrigation level. Three inter-row spacing, IRS1, IRS2 and IRS3, represented by 5, 10 and 20 cm between plants, were investigated for each row spacing. Results indicated that Imin reduced seed yield per plant, total seed yield and oil percentage but increased IWP. Decreasing row and inter-row spacing decreased seed yield per plant but increased total seed yield and IWP. The highest oil percentage (36.1%) was obtained from S2 during both growing seasons. The triple interaction optimized total seed yield, IWP and oil production. The best combination was IFull–S1–IRS2 with average production of 8430 kg ha
1 seed yield which is expected to produce 2990 kg of oil, followed by Imin–S1–IRS1 which produced 6750 kg ha
1seed yield with about 2270 kg ha
1of oil. Application of this combination saves 35% of water but reduces oil production by 24%. Copyright © 2016 John Wiley & Sons, Ltd.