کاربرد آبیاری قطره‌ای نواری در خشکه‌کاری برنج (مطالعه موردی لنجان اصفهان)

Rice is one of the most important food products for more than 50% of the world's population (more than 3.5 billion people). This plant is one of the crops that can be cultivated in various ways in different areas of the world. In most areas, rice is traditionally grown by transplanting seedlings into puddled field known as puddled transplanted rice (TPR). The other method of cultivation of this plant is dry seeded rice (DSR). While, direct dry seeded rice (DDSR) is the direct cultivation of rice seeds in a dry, non-submerged bed, without plowing and mulching. Other benefits of this method, in order to implement sustainable agriculture, can be mentioned as: reducing the movement of agricultural machinery on the farm, developing crop rotation, reducing environmental pollution and greenhouse gases, increasing the efficiency of consumption of high-consumption fertilizers and micronutrients.
Regarding the worldwide prevalence of DDSR and some successful experiences in Golestan and Khuzestan Provinces, Iran, the current study was conducted to investigate the possibility of dry direct seeded rice by trickle irrigation (T-tape). A field study was conducted using split plots based on randomized complete block with 3 replications at Lenjan region, Isfahan Prov., during 2019-2020. Main plots included drip irrigation at 80, 100, and 120×pan (E-pan) which were called I₁, I₂ and I₃, respectively and flood irrigation (I₄) as a control. Two cultivars of Sazandegi rice and line No. 2 were considered as sub plots. The dimensions of the main plots and the sub-plots were 20 × 5.5 meter and 20 × 2.5 meter, respectively. All amount of phosphorus and potassium fertilizers and one third of nitrogen fertilizers were used at the time of bed preparation. In addition, the remaining two thirds of urea was divided and consumed equally during tillering and flowering stages. During the period of plant growth, the amount of irrigation water was calculated and applied based on the cumulative evaporation from the Class A evaporation pan. For this purpose, by installing a Class A evaporation pan at the project site, the amount of daily evaporation was calculated and by considering the relevant coefficients, the amount of irrigation water depth was calculated and performed. Statistical analyzes and graphs were performed using SAS ver. 9.1, Excel software and comparisons of means were performed using Duncan's multiple range test.
The results showed that grain yield, water consumption and irrigation water use efficiency were significantly affected by irrigation regimes. The maximum grain yield (4709.8 kg. ha^-1) was obtained in treatment I₄ which was 59.31%, 25.60% and 17.72% higher than the grain yield in treatments (I₁), (I₂) and (I₃), respectively. The higher yield in continues flooding treatment can be attributed to the absence of drought stress in this treatment, as well as higher number of full seeds per panicle and 1000-grain weight, reduction of percentage of porosity and more effective weed control. Comparison of means showed that the maximum water consumption (21008.3 m³. ha^-1) in continues flooding treatment and the minimum (8193.3 m³. ha^-1) in irrigation treatment based on 80% evaporation from evaporation pan occurred. The reduction of water consumption in drought treatments was mainly due to the reduction of deep and lateral infiltration of water into the soil and the reduction of evaporation rate, which has been mentioned in other studies. This was while the highest rate of water saving in treatments (I₁), (I₂) and (I₃) was equal to 61.00%, 50.95% and 41.21%, respectively, compared to the control treatment. In addition, the maximum efficiency of irrigation water consumption was calculated in treatments (I₁), (I₂), (I₃) and (I₄) to be 0.34, 0.34, 0.31 and 0.22 kg.m^-3, respectively. The results also showed that drought treatment led to a decrease in plant height, plant tillering power, total number of paws and the number of fertile paws per unit area. The maximum plant height was obtained in the treatment of continues flooding of plants (99.11 cm), while the height in drought treatments with an average height of 85.3 cm showed a decrease of about 13%. Based on the results of this study, grain yield and optimal irrigation water efficiency obtained in treatment (I₃) indicated that Dry Direct-Seeded rice can be used as a substitute for continues flooding of rice to increase production and save water consumption.