Effect of irrigation duration on the growth and yield of thirteen genotypes of rice (Oryza sativa L)

Abstract

Water has become an impeding source for the agricultural sector, and in Iraq today we suffer from a water crisis that is worsening year after year, and as a result, it has led to a reduction in cultivated areas, especially for the rice crop. The limited water resources and the loss of large amounts of water during traditional irrigation operations prompted many researchers to try to find different methods to determine the quantities of irrigation water needed to be added to agriculture, and thus it became one of the necessities of agricultural progress to use modern irrigation methods. A field experiment was conducted at the rice research station in Al-Mishkhab, which is affiliated to Al-Najaf Research Department - Agricultural Research Department, which is 20 km south of the center of Al-Najaf Governorate, during the summer season 2022. Under the influence of three irrigation levels, the experiment was conducted in a split plot according to the randomized complete block design (RCBD) and with three replicates .The experimental parameters represented irrigation scheduling: daily irrigation, irrigation at intervals of 4 days, and irrigation at intervals of 8 days for thirteen genotypes of rice.The results of the experiment showed that there was a significantly of the KHA2 genotype on the rest of the cultivars under study in traits of plant height and the total number of seeds in the panicles, and it reached 121.22 cm, 174.67 grain. panicles^-1, respectively. As for the KHA4 genotype, it excelled in the traits of flag leaf area, weight of 1000, grain yield, harvest index, and water use efficiency, reaching 32.31 cm2, 24.30 g , 6.10 ton. ha^-1, 42.73%, and 0.2507 kg m^-3, respectively. The results also showed that there was a significantly excelled of the treatment of the daily irrigation interval in all traits of vegetative growth, yield and its components. As for the bi-interactions between genotypes and irrigation periods,The results showed that there is an effect in most of the traits, where the interaction treatment (KHA2 and daily irrigation) excelled in traits of plant height, flowerpot length, and total number of grains in the flowerpot, reaching 131 cm, 26.90 cm, and 205.00 seed grains -1, respectively, and the interaction treatment (KHA4) outperformed and daily irrigation) in traits of flag leaf area, weight of 1000 grains, grain yield, and harvest index, and the values were 35.63 cm2, 25.72 gm, 7.94 tons.  The results of the research showed that the water use efficiency was with daily irrigation 0.0945 kg m-3 and at the irrigation interval every 4 days 0.1999 kg m-3, while the irrigation interval every 8 days gave 0.2174 kg m^-3, the results indicate that there are significant differences for the effect of efficiency water use,The irrigation treatment every 8 days excelled compared to the daily irrigation schedule, which gave the lowest mean. Water stress negatively affected all vegetative growth traits and yield components.