Yield and some productivity elements of sweet maize varieties and hybrids with different sowing time as main and secondary crops

The aim of the research is to comprehensively evaluate varieties and hybrids of Zea mays L. saccharata sweet corn in the conditions of old-irrigated light-gray soils of the southern region of Kashkadarya region, select adaptive, promising varieties suitable for cultivation as the main and secondary crop, develop optimal sowing dates as the main element of the technology for obtaining a sustainable, high and high-quality yield. 13 varieties and hybrids of sweet corn were studied, including 7 varieties and 6 hybrids in terms of growth, plant development, formation of leaf surface, photosynthetic potential of sowing, productivity indicators, grain and silage yield, adaptive potential and adaptability coefficient. The selected adaptive varieties and hybrids Sherzod, Yangi hayot and Megaton F1 were cultivated in the main crop in 4 dates: 10.03, 20.03, 30.03 and 10.04 (control); as a repeat crop also in 4 terms: 30.06, 10.07, 20.07 and 30.07 (control). Field experiments were laid out in 2022-2024 on old-irrigated light-gray soils in the Turdiyeva Gulzoda farm in the Karshi district of the Kashkadarya region, Uzbekistan. The depth of groundwater in the experimental area is 3-4 m, the soils are medium loamy in mechanical composition. Agrochemical indicators of the arable layer are characterized by a low content of humus (0.70-0.82%), nitrate nitrogen (6.70-7.15 mg/kg), mobile phosphorus (12.20-15.27 mg/kg), and exchangeable potassium (209-214 mg/kg) of the soil.