Physiological quality and biomass production of Pennisetum glaucum as a function of manganese application

Abstract

The use of pearl millet (Pennisetum glaucum) for biomass production has increased significantly across much of the Brazilian Midwest. This region is characterized by weathered soils with low pH and low in fertility. Phosphorus and micronutrients are particularly low in these soils. Therefore, studies evaluating the management of micronutrients, especially manganese (Mn), are essential to improve the productivity of pear millet. This study aimed to assess the effect of Mn fertilization on the physiology traits and biomass production of pearl millet. The study was conducted in a greenhouse using a completely randomized design with four replications. Five Mn rates were applied (0 (control), 3, 6, 9, and 12 kg ha−1, as MnO) at planting. Biometric (plant height, stem diameter, and leaf area index) and physiological quality (cholorpyll index, transpiration, photosynthesis, leaf CO2 concentration, and stomatal conductance) were evaluated 30 and 65 days after emergence (DAE). Millet biomass, at harvest, was also evaluated. Pearl millet response to Mn fertilization was significant on measurements taken 65 DAE, with exception of leaf area index. Regardless of time of measurements, applying 6 kg Mn ha−1 provided the best results at the end of the experiments. Increased Mn rates, above 6 kg ha−1, caused a decrease in the physiological traits of millet but did not affect the biomass production. Moreover, greater Mn utilization efficiency by plants was found at the 6 kg ha−1 Mn rate, suggesting that this is the recommended rate for improving biomass production of pear millet grown under similar soil and weather conditions.