Effects of Biochar, Foliar Application of Amino Acid, and Drought Stress on Physiological and Morphological Traits, Yield Componenets, and Water Use Efficiency in Spinacia Oleracea

In this research, attempts have been made to investigate the effects of drought stress, foliar application of amino acid and biochar fertilizer on the morphological traits of spinach subjected to the conditions of the research greenhouse of Gonbad Kavous University within the timerange of 2021-2022. The experiment was conducted as a factorial in the form of randomized complete blocks with 3 replications. The experiment factors included 5 levels of drought stress of 0, 10, 20, 30 and 40 percent Maximum allowable depletion(MAD), 2 levels of amino acid foliar application (0 and 2 Lit/ha) and 2 levels of biochar fertilizer (0 and 4% weight of soil). The results of data analysis variance indicated that the effect of drought stress is significant at a level of 1% on the length of the longest root (cm), length of the largest leaf (cm), chlorophyll (mg.g-1 fresh leaf), total water use (mlit) and water use efficiency (g.lit-1). Also, the effect of amino acid on the total water use and that of biochar on the length of the largest leaf and chlorophyll content were significant at a level of 0.01. Moreover, the effects of biochar and amino acid in antioxidant (µg.ml-1) were significant at a level of 5%. A comparison of mean results showed that the highest value of the length of the largest leaf (cm), dry weight (gr), plant fresh weight (gr) is associated with the biochar application treatment. The highest amount of total use water was also found in the treatment without biochar. The highest and lowest amounts of chlorophyll content were found to be associated with the treatments with (14.52 mg.g-1 fresh leaf) and without (11.92 mg.g-1 leaf leaf) biochar application, respectively. Furthermore, the comparison of mean results showed that the highest amounts of chlorophyll, dry weight (gr) and plant fresh weight (gr) are corresponding to the amino acid application treatment.