Abstract
Two-year results of studies on the effect of fertilizing nitrogen fertilizers and nutrient levels on the accumulation of sweet by plants of varieties of sweet sorghum on irrigated light chestnut soils of the southeast of Kazakhstan are presented. The accumulation of sweet in sorghum plants continued throughout the entire vegetation period, but its maximum content was observed in milk-waxy ripeness stage of the grain. The quantitative composition of the juice significantly changed along the internodes of the stem. Most of sweets were contained in the middle internodes (5–9) as the main shoot, and lateral shoot. This pattern was traced in all phases of development, beginning with the flowering of plants. It is shown that up to 7.1–8.3% of sweet was accumulated in the sorghum at flowering stage in both varieties and backgrounds of provision. With the growth and development of plants, the sweet content in the main shoot increased, depending on the fertilization with nitrogen fertilizer against the background of varieties and the availability of soils with mobile phosphorus. So, if the content of sweet on the control variant was 13.9–14.3% at the milk waxy ripeness stage, when fertilizing in the initial stages of plant growth with nitrogen fertilizer in a dose of N 50 , it increased to 15.4–15.5% for Kazakhstanskoye 16 and 15.0–15.2% for Kazakhstanskoye 20. The dose of N 100 contributed to a further increase in its content, respectively, to 17.1–17.6% and 16.2–16.9%.