The Effect of Controlled drainage and Irrigation Management on Growth Characteristics and Rice Yield in the arid and semi-arid

Rice is one of the cereals that are widely used food in the world as staple.Rice is the largest consumer of water among agricultural products.At the field level, rice receives up to 2–3 times more water per hectare than other irrigated crop for producing of one kilogram of rice.Accordingto water resources limitation in Iran, According to water resources limitation in Iran, careful planning is essential to optimal use of water resources in agriculture as the largest consumer. One of the methods to reduce water consumption in rice cultivationis changing the traditional irrigation methods (flooding) to periodic irrigation. Change of management from traditional water-logging irrigation to unsaturated improves the irrigation water use efficiency. Due to water scarcity problems, the aim of this study was to evaluate controlled drainage and the impact of irrigation management on growth characteristics and yield components of rice in the arid and semi-arid.
To Considering the effect of water table level on water productivity in rice cultivation, the study was done in Shahrekord university. The experiments conducted in pots with 40 cm diameter and 45 cm hight. The experiment was arranged following a completely randomized design with four treatments (water table level) and five repetitions. The water table managements including: control water table 2 cm on the top of the soil (FI),the control water table 20 cm below the soil surface (CD20), control water table 36 cm below the soil surface (CD36) and Intermittent irrigation(AI). Tocontroll the water level, two tanks were used, one as stabilizer water table and another to measure the amount of water used. The Treatmentsares are completely water logging for a week, in second week treatments were applied. Sampled four times during the growing season was performed to determine the dry matter content of leaf, stem and leaf relative swelling and at the end of the growing season, the volume of water consumed, harvest index, the amount of grain produced and thousand grain weight was measured and recorded. The data obtained were analyzed using SAS software and LSD test was performed for comparison of means.
The results showed reduced yield treatments for CD20, CD36 and AI for each unit reduction in water consumption respectively as much 0.36, 0.46 and 0.38 units. Also results showed irrigation management caused significantly decrease in swelling relative only in the first and Second measuring stages respectively at the 5 percent level and in the fourth measuring stages at 1 percent level. Dry matter productive also was reduced under irrigation management in the Second and fourth measuring stages respectively in 1st and 3rd measuring stages at the 5 percent level. The impacts of irrigation management are no statistically significant on the rice harvest index and thousand grain weights but water consumption was reduced in CD20, CD36 and AI. Resulted to increment 5 percent water use efficiency based on performance and a significant increase 1 percent in the efficiency of water use was based on biomass. The highest and lowest harvses index belongs to FI (39.1) and CD36 (35.4) respectly. The highest and lowest thousand grain weights belong to FI (1247 kg/ha) and CD36 (1101 kg/ha) respectly.
High water Stress causes roots gone to sleep and their growth will slow after re-watering. Water scarcity is not only the hinder root growth but causes the root fuzzy and reduce its ability to absorb substances. The results showed that water reduction, a significant decrease in grain yield not occurred, Lack significant differences in grain yield mean that the water supply was adequate at all levels and in none of irrigation regimes, the plant was not affected by water stress and plant roots grown have enough at critical stages that needs greater water and has access to available water at greater depths. Results showed that T2 (control water table level at 20 cm below surface of soil) for each unit reduction in water consumption, 0.36 units reduces seed productionand 16% reduction in the amount of dry matter, That these lowest values are in the between treatments. With this irrigation management and reduce water consumption by 23% compared to control treatment area under cultivation can increased by as much as 30% and the grain production increase from 3424 to 4210 Kg per hectare.