Effect of different irrigation managements on morphological traits and yield of rice (Oryza sativa L.) cultivars in Gonbad-e-Kavus

  Rice is the main source of calories in more than one-third of the world's population, increasing by 30 to 35 percent by 2050, according to demand, Iran supplies 50 percent of imports of rice, the import figure in 1993 was about 185 million tons worth one billion and four hundred and ten million dollars (Jedari, 2017). Drought is the most important limiting factor in rice production in 40 million hectares of rice cultivated land in Asia (Ghiasi et al., 2014). Water stress during the vegetative stage reduces the buds; if the stress at the reproductive stage and grain filling causes a decrease in the number of seeds and weight (Rahman et al., 2002). Water stress in the vegetative stage affects the overall biomass reduction, which results from reduced photosynthetic rates and dry matter weights (Tahmasebi et al., 2008). Due to lack of water resources, low irrigation efficiency in rice field, the necessity of increasing water productivity and sensitivity of rice plant to drought stress. In this research, the effect of low irrigation management on morphological traits and yield of rice varieties, as well as determining the best level of irrigation for production Desirable performance in rice varieties has been evaluated. In order to investigate the effect of irrigation management on morphological traits and yield of rice cultivars, four separate experiments were carried out in a randomized complete block design in a research farm of GonbadKavus University in 1395. Four experiments were carried out separately in 5, 10 and 15 days irrigation and irrigation periods. The irrigation treatments were applied for 40 days after planting in the field at maximum tillering stage. The second factor also includes six rice cultivars (An Iranian cultivar Domsiah and three cultivar IR66424–1-2–1-5، IR70360–38–1-B-1, IR 55411-50 and the two lines are being introduced 87.110 and 87.5.103). Morphological traits included : 1- Main cluster length, 2- Plant weight, 3- Leaves number, 4- Plant Height As well as yield and yield components including number of tillers per plant, number of pods in the main cluster, number of filled seeds in the main cluster, Fertility percentage, full grain weight in main cluster, grain weight per plant, grain yield and harvest index As well as the number of days to be considered. Analysis of variance showed that there is a significant difference between all experimental treatment levels. Exerting stress reduces grain yield. The mean comparison results in terms of flood waters showed a cultivar of 87.110, Minimum time to treat and grain yield, which had no significant difference in grain yield in comparison with native damsayah cultivar. In drought stress, 5 days the highest grain yield and the lowest number of days till the cultivar was 87.5.103 was observed. Grain yield in 10-day irrigation stress was significant in IR 55411-50 cultivar compared to other cultivars. Also, the results showed that the figure 87.5.103 was early childhood. In the irrigation round 15 days, while the figure is 87. 110 did not have the highest grain yield, However, there was no significant difference between Damsayeh variety, Also, the Cultivar 87.110 is the earliest and best cultivar in the region.