Biochemical properties and pigment contents of genotypes affected by plant growth regulators and temperature stress.

There is little data, to our knowledge, on the biochemical properties of different sp. genotypes affected by plant growth regulators (PGR) under temperature stress. A split plot research on the basis of a complete randomized block design with three replicates examining temperature stress (planting dates, 8th of April, May and June) (main factor), and the factorial combination of plant growth regulators (PGR, control (CO), gibberellic acid (GA), fertilization (MI), and amino acid (A)), and genotypes (Khuzestani, Mutika, and Bakhtiari) on plant biochemical properties, was conducted. Plant pigment contents (chlorophyll a, and b and carotenoids (car)), antioxidant activity (catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GP)), and leaf protein were determined. Treatments significantly and differently affected the genotypes performance. PD3 and PD1resulted in significantly higher activity of APX (0.059 U. mg) and GP (0.190 U. mg), respectively ( ≤ 0.05). Temperature stress significantly affected plant CAT activity (U. mg) at PD1 (0.084) and PD3 (0.820). Higher temperature significantly enhanced leaf Pro, MI increased plant APX (0.054) and CAT activities (0.111 U. mg) significantly, and GA resulted in the highest and significantly different GP activity (0.186 U. mL). Treatments T1 and T3 significantly enhanced Chla and Car content, and MI resulted in significantly higher Chlb content (0.085 mg g leaf fresh weight). Car and CAT are the two most sensitive biochemical traits under temperature stress and can more effectively regulate growth and activity. It is possible to alleviate temperature stress on biochemical properties by the tested PGR.