Rice growth and development depending on cultivation conditions in the Tersko-Sulak sub-province of Dagestan

The purpose of the current research is to study of the biological characteristics of rice growth and development, as well as the productivity of the new promising varieties in the Tersko-Sulak sub-province; to identify the optimal doses of mineral fertilizers and the best forecrops for the cultivation of these varieties by herbicide-free technology; to recommend the varieties identified by grain productivity and quality for regionalization in the republic. The novelty of the research is that for the first time in the RD conditions there have been studied the biological characteristics of growth and development, as well as the productivity of new promising rice varieties ‘Flagman' and ‘Kuboyar' in comparison with the standard variety ‘Regul' spread in the republic. The rice cultivation contributes to productivity increase of saline lands and the development of soils in the solonetz complex. The conditions of the Tersko-Sulak sub-province, the presence of large rivers (Terek, Sulak), a favorable thermal regime make it possible to obtain here high yields of rice meeting the requirements of agricultural technology. The ability of rice to withstand soil salinity from 0.05 to 1.5%, depending on the nature of salinity, makes it possible to significantly increase the productivity of saline lands, the area of which is more than 50%. There have been studied two forecrops (winter wheat, alfalfa), four doses of mineral fertilizers (N₁₁₀P₅₀K₇₀, N₁₄₀P₈₀K₁₀₀, N₇₇P₃₅K₄₉, N₉₈P₅₆K₇₀) and three rice varieties ‘Regul', ‘Flagman', ‘Kuboyar'. For two years of research, the variety ‘Flagman' sown after alfalfa with a dose of mineral fertilizers N₉₈P₅₆K₇₀ produced the largest yields of 6.79 t/ha in 2018 and 6.85 t/ha in 2019, which was on 1.81 t/ha and 1.32 t/ha more than in the variant without fertilizing. The varieties ‘Regul' and ‘Kuboyar' with the same doses of mineral fertilizers produced the average yields of 5.76 and 6.20 t/ha, respectively. The highest efficiency of mineral fertilizers was established where the soil was well supplied with organic matter, i. e. when the varieties were sown after alfalfa.

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