Effect of foliar application of naphthalene acetic acid on physio-morphological attributes and green biomass production of sorghum [Sorghum bicolor (L.) Moench.]

Abstract

The present study was aimed to evaluate the impact of foliar application of naphthalene acetic acid (NAA) on the physio-morphological attributes and green biomass production of sorghum under field conditions at the Agronomic Research Field, Gomal University, Dera Ismail Khan, Pakistan. Varying concentrations of NAA (0, 45, 90, 135, and 180 mL ha^-1) were applied to sorghum seedlings at different intervals [30 and 90 days after emergence (AE)]. All plots equally received recommended agronomic practices and crop protection measures. The NAA foliar application in different levels caused a significant influence on the growth and biomass production of sorghum. The maximum plant tallness (434.3 cm), plant leaf area (419 cm²), number of nodes (17.01 plant^-1), number of tillers (19.03 m^-2), and chlorophyll contents (56.97 µg cm^-2) were observed due to NAA supplementation at 90 days AE, while, the stem thickness (8.82 cm), photosynthetic efficiency (2.56%) and green biomass (34.72 t ha^-1) were observed in the plots which received the foliar spray of 180 mL ha^-1 NAA followed by 135 mL ha^-1, that showed improvement in plant tallness (423.1 cm), plant leaf area (402.07 cm²), number of nodes/plant (16.71), tiller numbers (189.81 m^-2), chlorophyll contents (56.59 µg cm^-2), stem thickness (8.69 cm), photosynthetic efficiency (2.56%) and green biomass (36.10 t ha^-1) compared to those in the control treatment. The findings of the study clearly depict that foliar application of NAA as 120 mL ha^-1 at 90 days AE showed promising results in terms of enhanced production of green biomass of sorghum under arid agro-ecological conditions of Pakistan.