Effect of humic and fulvic substances and Moringa leaf extract on Sudan grass plants grown under saline conditions

Abstract

Salinity is the major stress factor that limits crop cultivation, especially in developing countries. A randomized complete block, factorial (3-factor) experiment was conducted on Sudan grass grown on nonsaline and saline soils to assess humic substances with or without foliar spraying Moringa leaf extract (MLE). Factors were (i) soil (three different levels of salinity), i.e., S1: nonsaline [electrical conductivity (EC) = 3.01 dS m-1], S2: medium saline (6.12 dS m-1), and S3: highly saline (12.33 dS m-1); (ii) humic substances, i.e., B0: no addition, B1: humic acid (HA) as potassium (K) humate, B2: fulvic acid (FA) as K fulvate, and B3: HA and FA; (iii) foliar spray with MLE, i.e., C0: nontreated and C1: foliar spray. Results indicated that total chlorophyll, nutrient uptake, available nitrogen (N), phosphorus (P), and K significantly decreased within each humic substances application, and MLE with increasing salinity concentration. The highest values of fresh, dry weight, total chlorophyll, and NPK uptake under different salinity levels were observed with application of substances and MLE. Spraying of MLE increased cumulative yield and nutrient uptake by Sudan grass compared with the untreated ones. The treatment of HA and FA with or without spraying MLE gave the highest values of available NPK under the salinity levels.