The effect of organic mulch on morpho-physiological and biochemical characteristics of forage sorghum (Sorghum bocolor L.) in response to different irrigation regimes

This study was conducted to investigate the effect of mulch application from organic matter residues in forest area, rice fields, tea and peanut orchards and irrigation water deficit on different morpho-physiological and biochemical characteristics of forage sorghum in field conditions. This research was carried out as a factorial experiment in a randomized complete block design with three replications in selected research farms in Deilman area of Siahkal city under the supervision of Tarbiat Modares University, Department of Agronomy and Lahijan Agricultural Jihad Extension Experts in 2018. Factorial combinations of three levels of water deficit stress 15%, 30% and 45% of less than FC and six organic mulch, no mulch, rice straw mulch, paddy rice husk mulch, peanut shell mulch, tea waste mulch and leaf mold mulch were used. The results showed that under moderate stress conditions, rice straw mulch and rice paddy husk treatment showed the highest forage yield and plant photosynthesis rate of 39.13 and 26.65%, respectively, compared to the control treatment. Also, under conditions of severe stress, rice straw mulch, rice paddy husk and peanut shell mulch increased the economic efficiency of water and dry weight of weeds by 63.48, 55.21 and 46.40%, respectively, compared to the control. Application of organic matter mulch, especially rice straw, rice paddy husk and peanut shell mulch, prevented a reduction of 6.08, 13.70 and 16.75% of grain yield compared to the control under moderate stress conditions, respectively. In general, organic matter mulch has a high ability to increase grain and forage yield, photosynthetic rate, antioxidant activity and economic efficiency of water, as well as reduce field weeds in stress conditions and make a significant contribution to improving drought resistance in Forage Sorghum. Finally, the use of organic matter mulch in the cultivation of forage sorghum under seasonal drought stress conditions is recommended.