DYNAMICS OF LEAF AREA FORMATION IN MAIZE CROPS DEPENDING ON LIMING AND FERTILIZER RATES IN THE CONDITIONS OF WESTERN POLISSIA

Abstract

Improving maize productivity is closely related to enhancing the efficiency of photosynthesis. One of the key factors in this process is the development and active functioning of the plant's leaf area. This study investigated how chemical soil amendments and different fertilizer rates affect the growth of leaf surface area and the photosynthetic potential of maize under the conditions of Western Polissia, Ukraine. The research was carried out in 2023–2024 on sod-podzolic sandy loam soils. The experiment included several treatments: an unfertilized control, liming with dolomitic or calcitic limestone at different doses, and mineral fertilizers applied at rates based on nutrient removal or general recommendations. Liming alone (with CaMg(CO) at 1.0 Hh) slightly increased the leaf area at the 12-leaf stage (17.7 vs. 17.0 thousand m²/ha) compared to the control. However, applying mineral fertilizers after liming had a much greater effect. The largest leaf area – 45.4 thousand m²/ha – was recorded at the tasseling stage with a fertilizer rate of N200P70K150, calculated based on nutrient removal by both grain and by-products. This treatment increased leaf area by 21.8 thousand m²/ha compared to the control. The photosynthetic potential (PP) of maize was significantly influenced by fertilization, liming, and growth stage. The highest PP values were found during the 12-leaf to tasseling phase, ranging from 791 to 1656 thousand m²·day/ha. These values were 13.6–50.6% higher than those in the earlier phase (emergence to 12 leaves). During the tasseling to milk ripeness period, PP decreased by 16.6–26.6% due to the aging and death of lower leaves. The best results for both leaf area and photosynthetic potential were achieved with full mineral fertilization applied on limed soil.