مجید میرلطیفی

This research was performed to improve water productivity by changing a number of farmers' field practices such as tillage, dimensions of the irrigation borders, using newly released plants varieties, and improving fertilizer management in eight farms located in the Oskoo, Ajabshir, and Bonab cities, all parts of the eastern Uromieh Lake Basin, during 2015-2016 growing season. The adopted farm practices were applied in the treatment farms, while in the control farms, all the farming operations were implemented according to the local traditional practices. In all farms, the flow rates diverted to each farm, the soil moisture content in the root zone during the growing season, and indices related to the growth and yield of crops were measured. The indices of water productivity (WP), water use efficiency (WUE) and water economic productivity (WPe) were calculated. Water consumption was lower up to 9% while crops yields of the treatment farms were higher up to 34%, as compared with the control farms. According to the results, on average, implementation of applied technologies in the treatment farms increased WP, WUE, and WPe by 38%, 31%, and 56 %, respectively, as compared to the control farms.

Water scarcity across the world has led researchers to develop a new irrigation technique called pulsed drip irrigation in order to improve soil moisture distribution as well as to increase water productivity. Pulsed drip irrigation refers to irrigating for a short period then waiting for another short period and repeating this On-Off cycle until the entire irrigation depth is applied. In this study, the combined effects of pulsed drip irrigation and its On-Off time duration on yield, yield components and water productivity of silage maize under two growing seasons (spring and summer) were evaluated. The selected experimental design was split-plot in completely randomized block design with three replicates. The treatments were consisted of four pulsed drip irrigations (P1, P2, P3, P4) and two Off-Time duration, 1 and 3 times of On-Time duration in a pulse (T1, T2). Results indicated that the interaction of the studied treatments on yield, yield components and water productivity of silage maize is significant. The maximum dry yield and water productivity was 25.86 (ton/ha) and 5.95 (kg/m3) in (T2 P4) treatment (average of two growing seasons) which increased by about 17% compared to (T1 P1) treatment. Increasing the number of irrigation pulses to four times lead to 6% and 17% increase in the studied parameters, respectively, in T1 and T2 treatments. Consequently, based on the positive effect of increasing the Off-Time duration in applying pulsed drip irrigation with high flow rate, it is suggested that the ratio of Off-Time to On-Time duration should be increased.

An accurate estimation of reference evapotranspiration is crucial for optimal irrigation scheduling and management. Also, achieving accurate medium range forecasts of effective parameters in estimating reference evapotranspiration is a key component for dynamic irrigation scheduling. This study was aimed to investigate the effect of using Weather Research and Forecasting Model (WRF) regional forecasts to increase the accuracy of reference evapotranspiration estimation. Consequently, the precision and accuracy of the model, and the outcome of forecasts performance at 24, 48, 72, 96, and 120-hours were evaluated to estimate the reference evapotranspiration. For this purpose, the output of the model for four stations including Qazvin, Esmaeil-Abad, Karaj and Hashtgerd were extracted for a period of three months (May-July, 2018) with a 10-days average of the base period. The weather data of 2018 at these stations with the corresponding ones were compared afterwards. The results indicated that the 10-days reference evapotranspiration (average of all stations) in the study period, according to the base period were -20.9, -8.12 and 7.83 percent, respectively. These variations reflects the deviation of the reference evapotranspiration value in the study period in comparison with the base period, indicating the need for using medium-range forecasting in order to correct reference evapotranspiration estimates. The range of determination coefficient (R2) of model output was obtained to be between 0.813 and 0.921. Due to the statistics, the model output for all stations and the lead-time forecasting periods of 24, 48, 72, 96 and 120 hours can be evaluated with high accuracy and its application would enhance the accuracy of reference evapotranspiration estimates. According to the results, not only in terms of time coordination, but also in terms of quantity, there was a high similarity between the estimated values of evapotranspiration derived from its post-statistical output of the (WRF) with calculated values.

Aril color whitening or browning (AB) in pomegranate fruit is a physiological disorder that critically decrease fruit quality and market acceptability. To find the effects of cun screen, kaolin application, fruit thinning, supplementary irrigation and fertilizer on decreasing aril browning disorder of the pomegranate (Punica granatum L. cv. ‘Malase Torshe Saveh’), an experiment was carried out in Saveh using a complete randomized block design with three replications. Treatments were 1) 3% kaolin application at 40 days after full bloom (DAFB), 2) fruit thinning at 40 DAFB, 3) supplementary irrigation at 80 DAFB, 4) fruit thinning with kaolin application, 5) supplementary irrigation combination with fruit thinning and kaolin application, 6) control with conventional management, 7) Animal manure application with foliar spray of the potassium sulfate and Nitrate calcium, 8) sunscreen combination with kaolin application and supplementary irrigation. The experiment was carried out in 2014 and 2015 in a commercial pomegranate orchard, in Saveh, Iran. The physicochemical properties of the pomegranate fruits were measured. Results showed that the kaolin application had no significant effect on the aril browning disorder, but the sunscreen treatment combined with supplementary irrigation and kaolin application reduced the aril browning index (24%) and increased the abundance of non-affected fruit (%96), conversely the fruit thinning increased aril browning index (69%) and reduced the abundance of non-affected fruits. Moreover, the supplementary irrigation had positive effect toameliorate the aril browning disorder, but the aril browning was also influenced by high temperature, low relative humidity and water quality. Overhead sunscreen, increase soil organic matter, foliar application of potassium and calcium during the growing season and irrigation with fewer intervals can ameliorate the pomegranate aril browning disorder and improve the fruit quality.

Since more than 75% of the rice fields in Iran are located in the Northern provinces i.e. Mazandaran, Guilan, and Golestan; identifying the crop water requirement of rice fields is essential for water resources planning in the Northern provinces. The objective of this research was to ascertain the crop water requirement of two rice cultivars namely Hashemi and Khazar in Guilan province during 1389 growing season. Four iron barrels with diameter of 56 cm were used as lysimeters to grow the cultivars mentioned. According to a simple volume balance approach the crop water use of the four lysimeters were determined during the growing season. The elements of volume balance approach such as the depths of drainage, precipitation, and irrigation were recorded daily and the average of 5-day and 10-day periods were reported. The daily rice crop water use during the growing season was found to range from 2.4 to 6.3 mm/day with a seasonal crop water use ranging from 430 to 470 mm for Hashemi and Khazar cultivars, respectively. Daily reference evapotranspiration was computed by the FAO-Penman-Montith equation and accordingly rice crop coefficients were computed. The crop coefficient of Hashemi variety was found to be 1.1, 1.3, and 1.1 during the initial, mid, and end growth stages, respectively. In addition, the aforementioned parameters for Khazar variety were 1.2, 1.3, and 1.1.

An Application of new irrigation methods to increase water use efficiency is essential، due to global water shortages، and as well a consumption of more than 70% of fresh water in the agricultural sector. In this study، the effect of Full Irrigation (FI)، Partial Root-zone Drying (PRD) treatments at two levels (provision of 75% of ET (PRD75) and 55% of ET (PRD55)) vs. Deficit Irrigation treatments at the same levels (75% (DI75) and 55% (DI55)) on yield and yield components of maize under a complete randomized design and under open filed conditions has been investigated during two growing seasons (2010 and 2011). Results revealed that the differences (for some yield components)، between FI and PRD treatments were lower than those observed between FI and DI treatments. Results also indicated that the level of kernel yield، (in PRD75 treatment)، as the most economical constituent of yield trait، was not significantly different from that of FI treatment (the difference being less than 10% for each year). An assessment of soil water content revealed that in PRD75 treatment plant water uptake was more efficient. Therefore، it can be concluded that PRD75 treatment، which resulted in a non-significant decrease of yield and yield components and while resulting in a 25% decrease in water use during the treatment periods (increase in water use efficiency of 16% and 20% during years 2010 and 2011 respectively)، would be a promising water-saving method as in MazandaranProvince.

Effect of water quantity and quality on wheat grain yield and yield components were studied in northeast of Golestan province. The treatments included four water levels with 50(W1), 75(W2), 100(W3) and 125(W4) percent of crop water requirement and four water quality with salinity of 1.6 (S1), 7.9 (S2), 10.8 (S3) and 13.6 (S4) ds/m. The experiments were evaluated using a randomized complete block design with split-plot layout which considered water quantity as main plots and water quality as subplots, with three replications. The results revealed that water quantity and quality were significant on wheat yield. Different irrigation depths and salinity levels were not significant on spike number per m2 and were significant on 1000-grain weight and grain/spike. The seasonal water consumption by wheat increased when water quantity increased, while it decreased when irrigation water salinity increased. For example, in treatment W4, treatment S4 consumed 88% water as of S1 treatment. Seasonal distribution of water content and salinity in soil profile showed that water content increased when irrigation water salinity was increased. The highest salt concentration occurred in surface soil layer. In all treatments, using saline water accounts for the improvement of water use efficiency (WUE) when fresh water is considered, comparing to total applied water (fresh saline). So that, in W3S4 treatment, WUE for total water use was equal to 9.8 while for fresh water it was 20.9 kg.ha-1.mm-1.