Growth, yield and nutritional performance of sweet sorghum and legumes in sole and intercropping influenced by type of legume, nitrogen level and air quality

Abstract

Sweet sorghum is a drought-tolerant cereal widely grown as pure stand in water-scarce areas. In the context of ongoing climate change, some agronomic adjustments are required for sustainable food production. Intercropping sweet sorghum with mungbean and soybean was assessed under three N levels (30, 60, 120 kg ha-1) and two types of air quality environments (charcoal filtered air and ambient air). Grain yield of sweet sorghum was significantly (P≤0.001) reduced in intercropping with mungbean (4.5 t ha-1), but remained on par (P>0.05) between sole cropping (5.1 t ha-1) and intercropping with soybean (5.1 t ha-1). Nitrogen application at 60 kg ha-1 optimized the grain yield, LER (1.8-1.9) and nutritional outputs of carbohydrate, protein, fat, and energy in intercropping (4.7 t, 1.0 t, 0.2 t, and 102.5 MJ ha-1, respectively) compared to that in sole cropping of sweet sorghum (3.6 t, 0.5 t, 0.1 t, and 74.6 MJ ha-1, respectively). Charcoal-filtered air with reduced air pollutants of O3, NO2 and SO2 significantly (P≤0.05) improved the growth and seed yield of intercropped mungbean (2.1 tha-1) and soybean (1.8 tha-1), and overall land productivity compared to ambient air (1.7 and 1.2 t ha-1, respectively).