a o; m n; m m; d z
Abstract
Large areas of Iran are affected by salinity and drought. Due to the tolerance of almond (Prunus dulcis) to water stress, this tree is mainly grown in arid and semi-arid regions, where salinity is commonly another agricultural problem at such areas. Sensitivity of almond trees to salinity calls for special ...
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Large areas of Iran are affected by salinity and drought. Due to the tolerance of almond (Prunus dulcis) to water stress, this tree is mainly grown in arid and semi-arid regions, where salinity is commonly another agricultural problem at such areas. Sensitivity of almond trees to salinity calls for special attention to the integrated effect of salinity and water stress on its water relations. This study aimed to evaluate the combined effect of salinity and drought stress on almond water status. The trial was conducted during 2014 based on randomized complete block design with three replications on a loamy sand soil at horticultural station of the Agricultural Research Center of Azarbaijan province. Treatments comprised three irrigation salinity levels viz. 2 (T1), 4 (T2), and 5 (T3) dSm-1. Leaf (Tc) and air (Ta) temperatures, air relative humidity, leaf water potential (LWP) and integrated volumetric soil water content (SWC) at three depths (0˗20, 0˗40, and 0˗70) were measured at midday (12˗14) during the growing season. Results indicated that salinity had significant effect (p<0.0001) on stomatal conductance (gs), Tc, LWP and available water depletion (AWD). Seasonal averages of gs for treatment T1 to T3 were 0.86, 0.59 and 0.44 cm.s-1, respectively, and the corresponding LWP were ˗1.90, ˗1.93 and ˗2.16 MPa. Also, significant correlation was found between gs, LWP, Tc and AWD. Based on the regression equations, threshold value of gs for initiating stress was obtained to be 0.73 cm s-1. Corresponding LWP and AWD for this gs value were ˗1.85 MPa and 64%, respectively. Optimum Tcfor highest gs was determined to be 28.2 oC. Highly significant correlation between Tc and other water status indicators showed that midday canopy temperature may be a useful tool for assessment of water status and irrigation scheduling of almond orchards.
A O; A S
Abstract
Various tillage systems have different degrading and or beneficial effects on soil structure and aggregates of top layers and, thus, affect infiltration characteristic especially the infiltration rate and the slope of infiltration equation. The objective of this study was to evaluate the effect of tillage ...
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Various tillage systems have different degrading and or beneficial effects on soil structure and aggregates of top layers and, thus, affect infiltration characteristic especially the infiltration rate and the slope of infiltration equation. The objective of this study was to evaluate the effect of tillage method and depth on infiltration, penetration resistance, plant available water, and crop yield in Tabriz plain in a clayey textured soil. In this study, four treatments including A1 (chisel plowing at 20 cm depth), A2 (moldboard plowing at 20 cm depth), A3 (moldboard plowing at 30 cm depth) and A4 (no tillage) were compared in three replications using a randomized complete block design. Results indicated that there was significant difference between treatments in infiltration rate at different time increments (1, 2, 5, 10, 30, 60, 120 and 180 min). Based on the slope of infiltration equations, the infiltration rate in A1 decreased more rapidly than the other treatments. Initial infiltration rate in A3 (482.8 mm hr-1) was higher than the other treatments, but differences between the other treatments were not significant. This difference may be attributed to tillage depth. Infiltration rate in A3 was higher than the other treatments but its preference in comparison with A4 (no tillage) just extended until 60 min and then declined rapidly. This result shows that the layer below the tillage depth controls infiltration rate after about 1.5 hr. In all the four measured layers (0-10, 10-20, 20-30 and 30-40 cm), A3 and A4 had the minimum and maximum penetration resistance, respectively. Effect of tillage treatments on plant available water and crop yield was not significant.
azhdar onnabi milani; sedghali zamani
Abstract
Proper use of water resources in arid and semi-arid regions is important and vital. This study was conducted to evaluate the effect of irrigation scheduling by various methods on crop yield and water use efficiency (WUE) by wheat, and determining suitable irrigation-scheduling method for irrigation of ...
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Proper use of water resources in arid and semi-arid regions is important and vital. This study was conducted to evaluate the effect of irrigation scheduling by various methods on crop yield and water use efficiency (WUE) by wheat, and determining suitable irrigation-scheduling method for irrigation of wheat in Saeedabad, Tabriz. A field experiment was conducted with 10 irrigation treatments (I1 to I10) in randomized complete block design with 4 replications. The irrigation timing treatments comprised of two ratios of irrigation depth to evaporation from class A pan i.e. 0.8 (I1) and 1.0 (I2), two soil water potentials -40 (I3) and -60 (I4) kPa, two soil water contents i.e. 40% (I5) and 60% (I6) soil available water in root zone, two canopy temperatures i.e. stress degree days equal to 10 (I7) and 12 (I8), and irrigations at different physiological growth stages i.e. crown root initiation (CRI) + flowering (I9) and CRI + late tillering + boot + milk stages (I10). Results indicated that there was significant difference between treatments in biomass, grain yield, WUE, kernel weight, protein content and harvest index (HI). Among the treatments, I2 had the maximum biomass, grain yield and kernel weight. I9, I10 and I3 were the best treatments in WUE, seed protein content, and HI, respectively. Although the selection of the best irrigation scheduling method depends on water resources availability and existing facilities, in general, with due attention to irrigation frequencies and other consideration such as volume of applied water, grain yield, WUE, and simplicity of the method, we can recommend irrigation at –40 kPa soil water potential as a suitable method for timing of irrigation under this experimental condition.