CHANGES IN PROXIMATE COMPOSITION, BIOCHEMICAL AND ANTIOXIDANT ATTRIBUTES OF BROCCOLI (BRASSICA OLERACEA L.) IN RELATION TO FOLIAR APPLICATION OF SELECTED PLANT GROWTH REGULATORS

Abstract

Field experiments were conducted to investigate the effect of foliar application of selected plant growth regulators (PGRs) on the proximate composition, biochemical and antioxidants attributes of broccoli (Brassica oleracea L.) leaves. Different concentrations of exogenously applied PGRs such as humic acid (HA), cytokinin (CK), gibberellic acid (GA3) and GA3+CK exhibited variable effect on the tested parameters. The foliar spray with HA (0.6%), GA3+CK (20+20 ppm), GA3 (20 ppm) and CK (40 ppm) increased the contents of moisture, ash, crude fiber and crude protein in broccoli leaves. With few exceptions, the antioxidant capacity of broccoli leaves, in terms of estimation of total phenolics content (TPC), total flavonoids content (TFC), reducing power and DPPH radical scavenging activity, was also improved due to foliar spray of PGRs. The results showed that maximum contents of total chlorophyll (1.98 mg/g FW), protein (7.09 mg/g FW), and proline (0.62 µg/g FW) were exhibited by GA3+CK (10+10 ppm), GA3 (20 ppm) and GA3+CK (20+20 ppm) treated samples, respectively. Meanwhile, GA3+CK (10+10 ppm) was found to be the most effective growth promoter in lowering melondialdehyde (MDA) content (0.89 µM/g FW) of broccoli leaves. In conclusion, it can be revealed that optimized foliar spray of selected PGRs, and especially of HA and mixture of GA3 and CK, is practically applicable towards improving biochemical and antioxidant attributes of broccoli leaves with potential nutritional benefits.