جستجوی مقالات مرتبط با کلیدواژه « cwsi » در نشریات گروه « آب و خاک »

The Crop Water Stress Index (CWSI) is a practical method for monitoring plant water status, detecting the onset of moisture stress, predicting crop yield, and irrigation schedule for variouscrops. The CWSI values range from zero to one, where zero indicatesthat the plant is not uunderwater stress and has the most ideal conditions for transpiration, while a value of one signifies maximum water stress and complete cessation of transpiration. The present research was conducted to calculate the CWSI,determine the moisture stress threshold for safflower and identify optimal irrigation management practices by analyzing the relationship between the CWSI and various deficit irrigation managements  approaches.The research was carried out over two agricultural seasons, 2020-2021 and 2021-2022at Khuzestan University of Agriculture and Natural Resources. The experiment used a randomized complete blocks design with a conventional irrigation treatment (CI) and four deficit irrigation treatments including (RDI80, RDI60: deficit irrigation adjusted by supplying 80% and 60% of soil moisture deficit, respectively) and (PRD80, PRD60: deficit irrigation in the form of partial root zone drying methods with 80% and 60% of soil moisture deficit, respectively) and with four repetitions. Results showed that the CI treatment had the lowest value of 0.17 and the RDI60 treatment had the highest CWSI at0.67. Irrigation planning was done with the aim of achieving the maximum efficiency of water productivity, and based on this, the relationship between the permissible limit of the temperature difference of the Canopy cover of the plant and the air for the months of March ((Tc-Ta)a = 1.618 - 0.215 VPD), April ((Tc-Ta)a = 2.46-0.220 VPD) and May ((Tc-Ta)a = 4.636-0.164 VPD) were obtained. The moisture stress threshold for safflower was obtained from the regression relationship between the CWSI and the temperature difference of the Canopy cover of the plant and the temperature of the surrounding air (Tc-Ta) equal to 0.61, which was introduced for the study area and with the research conditions

By using the temperature of the canopy cover of the plant, a practical parameter called the crop water stress index (CWSI), it was determined that this index is one of the methods of checking the water requirement of the plant and it can be considered as a suitable tool for irrigation management in the field. Therefore, this research was carried out with the aim of determining the water stress index of sugarcane in two methods of surface irrigation (CI) and subsurface drip irrigation (SDI) at research station number one of Khuzestan Research and Training Institute for Development of Sugarcane and Related Industries, in June 2022. The fields included the third field culture (Ratoon 3), of the CP69-1062 variety, and were selected with four repetitions in both methods. First, the equation of upper and lower base lines for the surface irrigation method was determined as (Tc-Ta)ul=1.7 and (Tc-Ta)=-0.09VPD+1.27, respectively. Then, using the equations of the lines based on the surface irrigation method, the average of crop water stress index for subsurface drip irrigation method and surface irrigation was calculated as 0.28 and 0.66, respectively, and the equation was presented according to the irrigation scheduling of the Sugarcane in June.

This study aimed to calculate the crop water stress index (CWSI) of Quinoa. This study was conducted in a completely randomized design with four irrigation levels of 100 (T1), 75 (T2), 50 (T3), and 25 (T4) % of crop water requirements in three replications, and experimental treatments and measurements were mainly carried out during Quinoa growing season at 2017-2018 years. The results revealed that the highest of leaf, stem, root, inflorescence dry weights, and biomass by 11.3, 8.8, 2.8, 16.8, and 39.7 g were in the T1 treatment. Using the T2, T3, T4 compared with T1 were decreased grain yield (by 37.6, 52.5, and 64.8%), harvest index (by 30.4, 34.5, and 30.7%), Biomass (by 16.4, 29.7, and 51.1%). But, using these treatments was increased WUE (by 19.4, 36.6, and 77.4%) compared with T1. CWSI correlated significantly (P < 0.01) and negatively with grain yield and biomass. The results revealed that increased CWSI values with reduction of quinoa grain yield. Also, the results showed that the highest and lowest quinoa grain yield at average CWSI values of almost 0.05 and 0.61. Therefore, to achieve the highest grain yield in irrigation, the quinoa crop should be irrigated at 0.05 of the CWSI. The lowest CWSI values were observed in T1(by 0.04) and the highest in T4 (by 0.72). In this study, the average CWSI was calculated in the days before irrigation in T1, T2, T3, and T4 treatments, and its values were 0.05, 0.19, 0.48, and 0.72, respectively. The results also revealed that with crop water requirement change from 100 to 75 percent, the CWSI was about 3.8 times higher. Accordingly, the CWSI can be used to plan irrigation. The best irrigation time is based on T1 treatment when (Tc-Ta)a=2.41-0.21 VPD (5≤VPD≤20).

One of the effective ways to increase water productivity in arid and semi-arid regions is Irrigation management. Due to the fact that the plant is exposed to water stress in low irrigation, so it is necessary to study the water stress status of the plant. The purpose of this study is to investigate the water stress status of forage maize in different irrigation levels using different soil and plant indices. Hence a study in the form of a randomized complete block design with four levels of irrigation; (I50, I75, I100 and I125) were performed in the Faculty of Agriculture of Lorestan University. The results indicated that different levels of irrigation on CWSI, RWC, KS and residual soil moisture, crop yield and water productivity affect significantly at confidence level of one percent. The CWSI index increased from 0.18 in I125 treatment to 0.47 in I50 treatment. Decrease in soil moisture content from 68% in I125 treatment to 42% in I50 treatment, decreased the value of relative leaf water content index (RWC). The highest and lowest mean values ​​of water stress coefficient (KS) during the growth period related to I50 and I125 treatments were 0.32 and 0.94 respectively. Also, with a 50% reduction in plant water requirement, the yield compared to full irrigation conditions decreased by about 42% and treatments I100 and I50 with values ​​of 2.75 and 2.53 kg / m3, respectively, had the highest and lowest water productivity. In this study, the relationship between crop yield and indices of CWSI, RWC, KS and residual soil moisture () was obtained with a high correlation.Finally, it can be said that in water stress in forage maize can be investigated through water stress indices.

Irrigation scheduling is very important under water stress condition. To investigate the crop water stress phenomena, several indices have been presented, of which one is CWSI. In order to investigate the ability of this index in irrigation scheduling of Maize (SC704), a research in a randomized blokes design with four experimental treatments was conducted in Khoram Abad region in 2011. Experimental treatments including IR1: 100% water requirement, IR2: 80% water requirement (by Regulated deficit irrigation), IR3: 60% water requirement (by Regulated deficit irrigation) and IR4: 50% water requirement (by Partial root zone drying management).  The results showed that the amount of CWSI was significantly affected by water stress.  The CWSI index for IR1, IR2, IR3, and IR4 treatments were 0.17, 0.21, 0.39, 0.29 and the amount of yield were 21560, 19500, 12560 and 14860 Kg/ha, respectively. In this study, the best treatment was IR1 (with the minimum CWSI and the maximum Yield) and the worst treatment was IR3 (with the maximum CWSI and the Minimum Yield).  Based on CWSI index, the value of water stress in IR4 treatment was less than the water stress value of IR3 treatment (The CWSI index dropped by 11.4 percent and the amount of yield increased by 18.3 percent). In this research, the relationship between the corn forage yield and CWSI index was obtained with high correlation. Regarding the variation of CWSI under different treatments, it can be stated that the CWSI index is able to evaluate the water stress and estimate the corn forage yield.

Irrigation scheduling with salinity and stresses, is much more difficult than Full irrigation. Using canopy temperature for plants irrigation scheduling is one of the methods that have been attention by many researchers. On of the usual method is presented by Idso. This research intends to investigate irrigation scheduling of summer maize using crop canopy temperature in Ahvaz climate (2013-2014) using surface irrigation with two levels of salinity irrigation water( S1=2.5 ds/m ,S5=5 ds/m).Crop water stress index(CWSI) is calculated for the two treatments. The experiment had three replications. With due to the obtained results, The CWSI for the two treatments S1 (minimum salinity) and S5 (maximum salinity) in September 14 and October 15 were 0.26 and 0.22. Upper baseline for the S1, in September and October are 5.05 C0 and 4.975 C0 respectively. For the S5 treatment the upper baselines in September and October were 2.85 C0 and 2.60 C0 respectively. Lower baseline also were calculated for the treatments. That was represented It is found that the S1 lower baseline is lower than the S5 treatment. This is due to the S5 treatment was effected By tension more than the S1 treatment. By using of measured data for scheduling irrigation maize in October and September with surface irrigation methods, some equations were determined. By using of the equations and comparing measured with the calculated canopy and air temperature, time of irrigation can be detected.

Determination of the appropriate time to irrigation is an important decision that farm planners are faced to it. Using canopy temperature for plants irrigation scheduling is one of the methods that have been attention by many researchers. In this way, several indicators have been proposed among which can be noted Idso Crop Water Stress Index (CWSI) method. This research intends to investigate irrigation scheduling of summer maize using crop canopy temperature in Ahvaz climatic condition in farming years 2013-2014 under sprinkler irrigation (fixed irrigation system) with two levels of salinity irrigation water ( S1=2.5 dS/m ,S5=5 dS/m) in three replications. Accordingly, the amount of crop water stress index in September was estimated for two treatments S1 (minimum salinity) and S5 (maximum salinity), respectively, 0.14 and 0.29 and in October, 0.18 and 0.27, respectively. Upper baseline equations for the S1 treatment, in September and October was calculated (Tc – Ta)u.l= 5.75 ºC and (Tc – Ta)u.l= 4.70 ºC, respectively. For the S5 treatment the upper baselines equations in September and October were (Tc – Ta)u.l= 2.94 and (Tc – Ta)u.l= 2.85 ºC, respectively. Lower baseline equations were calculated in S1 and S5 treatments and showed that the water stress in S1 treatment was lower than to S5 treatment due to the lower baseline. By using of measured data, for scheduling irrigation of maize in October and September with sprinkler irrigation method, some equations were determined. By using of the equations and comparing difference between leaf and air temperature measured by leaf and air temperature calculated (calculated allowable amount) can be detect time of irrigation in both treatments.

Use of canopy temperature for plants irrigation scheduling is one of the methods that have been attention by researchers. Several indexes have been provided for this method and one of them is Idso index . This research intends to investigate irrigation scheduling of summer maize using canopy temperature in Ahvaz climate in farming years 2013-2014 (summer cultivation) under sprinkler (fixed irrigation system) and surface irrigation with five levels of salinity irrigation water (S1, S2, S3, S4 ,S5). The experiment had three replications. Based on the obtained results, The CWSI for sprinkler irrigation in september and october estimated 0. 14 and 0.18 respectively. Also for surface irrigation in september and october estimated 0.14 and 0.15. Calculated equation for lower base in sprinkler and surface irrigation present less water stress in surface irrigation than sprinkler irrigation. of course, this does not mean that sprinkler irrigation has been stressed, but in these two types of irrigation CWSI values ​​indicate non-stress conditions for both irrigation. By using of measured data for scheduling irrigation maize in octobar and september with sprinkler and surface irrigation methods, some equations was determind.Than by using of the equations and comparing difference between leaf and air temperature measured by leaf and air temperature calculated can detect time of irrigation.