نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی دکتری زراعت، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران.
2 نویسنده مسئول، استاد گروه زراعت، پژوهشکده ژنتیک و زیست‌فناوری کشاورزی طبرستان، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران.
3 استادیار پژوهش، مؤسسه تحقیقات برنج کشور معاونت مازندران، سازمان تحقیقات، آموزش و ترویج کشاورزی، آمل، ایران.
4 دانشیار پژوهش، پژوهشکده ژنتیک و زیست‌فناوری کشاورزی طبرستان، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives:
Along with nitrogen (N), light is one of the determining factors for the growth and yield of cereals, especially rice. Since few studies have been done regarding the interaction of these two factors on the growth and yield of rice; therefore, the current research was carried out with the aim of evaluating the effects of radiation reduction in different stages of growth on the yield and yield components of the high-yielding cultivar of Shiroodi in different amounts of N.
Materials and methods: A field experiment was conducted at four different levels of N fertilizer with amounts of 0, 100, 200, 300 kg of urea per hectare, shading treatments including natural light, 70 and 40% natural light in the three stages of vegetative, reproductive and seed filling. The rice plots exposed to different radiations using shading nets. Experiment was laid out in split-split plot based randomized complete block design with three replications in 2017. At the harvest stage, various traits related to yield and yield components were measured.
Results:
The results showed that the amount of N, shading stage (S) and percentage (SP) as well as their interaction were statistically significant in terms of yield and yield components. Shading stress led to a sharp decrease in Shiroudi rice yield components such as the number of filled grains, the number and the length of panicle. The highest amount of yield (8910 kg/ha) was assigned to the treatment of 200 kg of N fertilizer and the treatment without shading stress. By comparison, in the condition of shading stress paddy yield decreased up to 35%. The results of the interaction between the S and SP also indicated that the highest yield per unit area was recorded when rice plant grown without light stress and the lowest yield (5000 kg/ha) was assigned to the light stress of 60% in the grain filling stage. The less incident radiation at the reproductive and grain filling stages markedly decreased the percentage of filled grain (17-50%), the 1000 seeds weight (7-12%) and the paddy yield (15-38%) of the rice plants.
Conclusion:
According to the results of this research, despite the fact that the optimal amount of N fertilizer for the Shiroudi cultivar was calculated to be 200 kg urea/ha, but under shading conditions (30 and 60%), the treatment of 100 kg urea/ha resulted in better yield and yield components (about 10%) compared to those plots which received 200 kg urea/ha. The 50% increment of unfilled grain number in the panicle in the shading treatment at the seed filling stage indicates that the lower radiation incident in the grain filling stage is very critical. Therefore, the amount of reduction in rice yield (especially the Shiroudi cultivar) by shading stress depends on the growth stage, and the adverse effects of stress can be reduced with proper management of N nutrition.
کلیدواژه‌ها [English]
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