Формування продуктивності сорго цукрового під впливом строків сівби

Abstract

The scientifically based choice of sowing terms for sorghum depends on the climatic conditions, type, state and humidity of the soil, biological characteristics of varieties and hybrids, the economic purpose of sowing, rate of positive temperatures growth. The purpose of the research was to determine the effect of sowing terms on the growth, development and the yield of green mass of sugar sorghum. In the experiment, the variety of sugar sorghum Silosne 42 and the hybrid Dovista were sown in three terms when the soil temperatures at the depth of seeding were: І – 6–8 °С, ІІ – 8–10 °С, ІІІ – 10–12 °С. Biometric indexes of sugar sorghum depended both on sowing terms and varietal characteristics. The plants most intensively developed and formed the above-ground mass in a variant where the soil temperature at the depth of seeding was 10–12 °С, and plants height was 151.7 and 193.7 cm in the period of flowering – respectively in the Silosne 42 variety and the Dovista hybrid. The highest indexes of the leaf area (51.87 and 57.25 thousand m2/ha), photosynthetic potential (4.26 and 4.32 million m2×days/ha) and the net productivity of photosynthesis (3.50 and 3.54 g/m2 per day) of sugar sorghum were on varieties, sown when the soil temperature at the depth of seeding was 10–12 °С, respectively in the Silosne 42 variety and the Dovista hybrid. It was noted that the increase in the surface of leaf area and the duration of vegetation result in higher photosynthetic potential and, consequently, the growth of the green mass yield. Maximum indexes of pure productivity of photosynthesis are observed in the flowering period, that is, during the period of the most intense growth of the above-ground mass and the leaf surface of sugar sorghum. From the flag leaf stage until flowering stage there is an intense growth in sugar sorghum, and increment of green mass is 57.3-78.6% compared with the growing point differentiation stage. The sorghum biomass indexes had the highest values at all stages of the third sowing term. Increment of the green mass continues to the hard dough stage, while dry matter grows throughout the growing period. The highest yield of the green and dry mass of the Silosne 42 variety and the Dovista hybrid is observed in the hard dough stage, when the soil temperature at the depth of seeding was 10–12 °С – 74.8 and 17.4 t/ha and 83.7 and 20.2 t/ha. The Dovista hybrid prevailed on the yield of the green mass on 9.8–12.7% and dry matter on 4.5–7.8% than the Siloshne 42 variety.