Effects Of Fertilizer Levels And Plant Density On Chlorophyll Contents, Its Fluorescence And Grain Yield Of &Itsetaria Italica &It

Maximizing the use of light is essential to increase grain yield of foxtail millet (Setaria italic L.). However, extensive research has been undertaken to optimize the cultivation of conventional foxtail millet by single-factor or orthogonal test. In this study, a quadratic general rotation combination design with five factors was employed to evaluate the effects of fertilizer levels (N, P(2)O(5 )and K2O) and plant density (row and plant spacing) on leaf photosynthesis and grain yield of a hybrid, Zhangzagu 5. Leaf chlorophyll contents (Chl, SPAD value), and fluorescence induction were measured at the mid-filling stage, and grain yield was determined at harvest. The N effect was found significant for Chl, effective photochemical quantum yield of photosystem II (Y(II)), coefficients of Chl fluorescence quenching (photochemical-qP and non-photochemical-qN), and maximum photochemical quantum yield (Fv/Fm). With increasing N, Chl, Y(II) and qP first increased and then declined, opposite to qN; Fv/Fm elevated linearly. The P2O5 effect was significant for Y (II) and qN, while the K2O effect reached significance for Y(II) and qP. With decreasing row spacing, Y(II) and qP displayed an increase followed by decrease, opposite to qN. Grain yield was more affected by N and row spacing compared with P2O5 and K2O. N x K2O, N x plant spacing, and K2O x plant spacing showed significant effects on Y(II), qP and yield, while the effect of P2O5 x row spacing was significant for Fv/Fm. Multivariate quadratic regression analysis revealed a relationship between these factors and grain yield, which can be used for crop production forecasts. Recommended cultivation conditions were: 186 kg ha(-1) N, 95 kg ha(-1) P2O5, 60 kg ha(-1) K2O, 23 cm row spacing, and 13 cm plant spacing to achieve an expected yield of 6,683 kg ha(-1). (C) 2018 Friends Science Publishers