فهرست مطالب h. r. salemi

The stress caused by dryness can affect plant growth and physiology. Several coping mechanisms (recovery, avoidance, tolerance and drought escape) have been developed to mitigate the impact of drought stress, and  most strategies involve survival during stress condition. The aim of this study was to compare the morphological and physiological characteristics of two varieties of sorghum forage (Pegah and Speedfeed) under drought stress conditions in order to provide beneficial and functional recommendations to farmers in the study area. This study was performed as a spit-plot plot in a complete randomised design with 3 replications for two years in Esfahan, Iran. Experimental treatments included drought stress at three levels for two varieties of sorghum. Mechanisms of sorghum response to drought stress, including physiological and morphological  alterations, were also proposed. Treatment means were compared by the Duncan test at 5% and 1% levels of probability. The statistical analysis was applied to the data using the R software. Lower irrigation showed a gradual decrease in plants height, number of leaves per plant, stem diameter, nitrogen and crude protein, with an increase in the length and weight of their panicle. Compared to Pegah variety, Speedfeed cultivar with 12% increase enhanced the contents of chlorophyll (1.7 times) in the two years of experiment. It could be concluded that Speedfeed variety exhibited better yield and quality characteristics against drought stress compared to Pegah variety. Considering the tolerance index and the harmonic mean index, Pegah showed the highest sensitivity to drought stress. This study indicated that sorghum had several adaptive mechanisms for dealing with drought stress, so that it could be applied as a suitable alternative for other crops with higher water needs such as Zea.

In recent years, canola cultivation in Iran has been considered as oil production, and in 2014-2015, it has been allocated to 7.7% of the cultivation area of industrial products of the country. The yield of canola oil and seeds depends on the availability of sufficient water resources during the growth period. In the Mediterranean, with the cultivation of canola autumn, the high- temperature occurs in the stages of formation and growth of seeds in the spring can increase the water requirement of this plant and irrigation management at this time is important in increasing plant yield. Due to the weather conditions of each area, type of variety and soil conditions may vary the need for canola. In one study in Hamedan water use efficiency of canola in two ways drip and furrow irrigation were calculated as 1.09 and 0.63 kg m-3, respectively. The present study was conducted with the purpose of evaluating the net water requirement of canola plant in different cities of Isfahan province into different climatic zones and considering the phonological stages.

In order to estimate the net water requirement of canola under two different climates (arid-cold winter with temperatures above freezing point - hot summer A-C-W) and (Semi-arid-cold winter with a temperature equal to or less than zero-hot summer SA-K-W) in Isfahan province, a research was conducted in 2014-2015 using a completely randomized, unbalanced design. The study was carried out in different cities of Isfahan province, which have canola cultivation. The required statistical information was obtained from 28 stations of synoptic and climatologic meteorology in Isfahan province and some neighboring provinces. Soil data was used to calculate the soil evaporation coefficient (Ke), which describes the evaporation component in the trait (ETc). In order to calculate the soil properties, in addition to the sampling of existing fields, a database of 1600 soil profiles in the Soil and Water Research Department of Isfahan province was also used. The plant growth stages were considered based on FAO’s 56 irrigation and drainage journal. For analyzing data in each climate, a completely randomized, unbalanced design (with inequality repeat) was used, and the meanings were compared with Duncan’s multiple range test (at 5% level).

There was a significant difference (α=1%) between the different cities in terms of total water consumption and the net water requirement of different phenological growth stages. In the SA-K-W climate, the net water requirement for each hectare of canola cultivated in the cities of Fereydoun Shahr, Friedan, Golpayegan, Khansari, Semirom, Tiran and Karvan, Shahreza, Chadegan, Dehaghan, and Boein va Mian Dasht was 3936, 4069, 4258, 4011, 3991, 4147, 3964, 3961, 4035 and 4055 m-3, respectively. In the SA-K-W climate (with ten cities), the net water requirement of canola was estimated at 4,000 m-3 ha-1. The difference between the highest and the least water requirement in this climate were 322 m-3 ha-1 and related to cities of Frieden and Fereydoun City, respectively. In the climate of A-C-W (12 cities), canola net water requirement was 892 m-3 ha-1 more than the net water requirement of this crop in the SA-K-W climate. On average, the initial, developmental, and (middle and final) net water requirements of the canola in the A-C-W climate were 540, 2150, and 2200 m-3 ha-1, respectively. The net irrigation requirement estimated for each ha-1 of canola cultivation in Isfahan, Ardestan, Khomeini Shahr, Falavarjan, Kashan, Lenjanat, Naein, Najaf Abad, Natanz, Shahin Shahr, Mobarakeh, and Borkhar cities was 4747. 4807. 4797, 5,105, 4885, 4908, 4750, 4785, 4974, 4971, 4879 and 5097 m-3, respectively.

Based on the results of the 10 cities in the SA-K-W climate, canola production per hectare requires an average of 4,000 cubic meters of net water per hectare. In the A-C-W climate of 12 cities, the average net water requirement per hectare was 4892 m-3. The difference in water requirement between this climate and the climate of SA-K-W was related to the middle and late stages of canola growth.

Estimation of seepage is essential prior to lining of earth canals. In Iran such investigation has been achieved in some irrigation networks using empirical relationships derived in other countries. Estimation of water loss in canal is required in design, operation and management of water distribution systems. Water seepage may be determind by using empirical equations proposed by F.A.O. These equations are applicable for different soils and hydraulic parameters. However, the appropriate estimating equation should be determined for each region. Therefore, these equations should be calibrated for local usage and different canal vegetation conditions. In this investigation water losses in canals at the Rudast region of Isfahan were measured by inflow and outflow procedure. Different canals reaches were selected in soils of relatively heavy, medium and light textures. The density of vegetation population in canals were low, medium and high. The estimated seepage losses by different empirical equations were not corresponded to those of measured values. Therefore, by using the measured seepage at different soil textures and vegetation densities the empirical coefficients of six empirical equations of F.A.O. (Ingham, Davis and Wilson, Affengendon, Moritz, Molesworth and Yennidumia, Misra) were modified for the study region. The relationships between measured seepage and estimated seepage before and after modification of the empirical equations were determined by regression analysis. These equations estimated the seepage loss much smaller than the measured values. The regression parameters (selope, intercept, and coefficient of determination of regression equation) indicated that after modification, the Ingham and moritz equation with higher slopes (0.91, 1.01), lower intercepts (-0.096, -0.039) and higher coefficient of determination (0.96) estimated the closest seepage values to the measured values respectively. The misra equation was the next best equation for seepage estimation. The results of present investigation indicated that the modified Ingham and Moritz equations were the most appropriate ones for estimation of seepage losses at different soil textures and vegetation densities in the study region.