INFLUENCE OF PLANT DENSITY AND MINERAL NUTRITION LEVEL ON CHLOROPHYLL CONTENT IN CORN LEAVES

Abstract

one of the main factors that significantly affect the chlorophyll content in leaves and corn yield is the optimal plant density and level of mineral nutrition. Purpose. The aim of our work was to determine the chlorophyll content in corn leaves and the formation of grain yield depending on plant density and fertilization. Materials and Methods. The experimental design included the sowing of four hybrids belonging to different maturity groups: early-maturing DMS Lord, mid-early DMS Prime, mid-maturing DMS 3015, and mid-late DMS Shuttle. For each hybrid, three fertilization backgrounds were applied (no fertilizers; N30P30K30; N60P60K60). The hybrids were sown at densities of 30, 40, 50, and 60 thousand plants per hectare. The methodological support of the experiment was carried out according to generally accepted recommendations and national standards (DSTU). Results. A gradual increase in the number of leaves in corn was found, from 9.8–10.4 leaves per plant in the early-maturing hybrid DMS Lord to 12.5–13.5 leaves in the mid-late DMS Shuttle, which is clearly related to the biological characteristics of the hybrids. It was also established that the application of mineral fertilizers promoted an increase in the number of leaves by 7.50–10.60%. The leaf area of corn depended on the number of leaves per plant. The smallest leaf area was observed in the control variants, ranging from 319.9–528.8 cm². The application of mineral fertilizers, especially at the dose of N60P60K60, led to an increase in leaf area by 25.3–28.3%. Increasing plant density to 60 thousand plants per hectare tended to reduce leaf area by 7.3–9.2% due to increased competition between plants. Fertilizer application at doses of N30–60P30–60K30–60 resulted in an increase in chlorophyll content in corn leaves compared to the control (SPAD 50.6–55.4) by 2.6–13.9 SPAD units, or 4.10–24.70%. It was also noted that a higher dose of mineral fertilizers (N60P60K60) significantly increased the chlorophyll content in the early-maturing hybrid DMS Lord and the mid-early DMS Prime compared to the mid-maturing DMS 3015 and mid-late DMS Shuttle. The optimal plant density for various corn maturity groups was found to be 50–60 thousand plants per hectare, as it provided the highest biometric indicators and grain yield at 4.60–6.02 t/ha and 4.38–5.81 t/ha, respectively. Conclusions. For the conditions of the Northern Steppe of Ukraine, it is recommended to sow mid-maturing corn hybrids at a density of 50 thousand plants per hectare with the application of fertilizers N30–60P30–60K30–60, particularly the hybrid DMS 3015, which demonstrated the highest yield of 6.93–6.02 t/ha.