Plant growth regulators affecting canola (Brasica Napus L.) biochemistry including oil yield under drought stress

The objective was to test the effects of PGR on canola (Brassica napus L.) biochemistry including oil yield under drought stress. A two-year (Y1 and Y2) split plot field experiment on the basis of a randomized complete block design with three replications was conducted. The main factor was, drought stress levels, including irrigation after a reduction of 40 (D1), 60 (D2) and 80% (D3) of field capacity (FC) moisture, and the sub-factor was PGR including control (S1), soil application of humic acid (S2), foliar applications of amino acid (S3), fulvic acid (S4) or seaweed extract (S5), and the combination of all PGR (S6). Although drought stress significantly decreased plant chlorophyll contents (a, b and total), oil percentage and oil yield, PGR significantly increased them. The D3 treatment, compared with control, decreased crop oil yield by 48.67 and 35.29% in the first and second year, respectively. However, treatment Y2D3S6 significantly increased oil percentage (43.10%) compared with control (40.97%). The PGR increased seed oil yield, in D3, by a maximum of 254 kg ha-1. The PGR numerically (p ≤ 0.0886) increased proline to 6.14 mg  g-1 LFW (Y1D3S6) compared with control (4.79 mg g-1 LFW). The PGR also significantly increased sugar content to 17.05 mg g-1 LFW, significantly different from the control (12.95 mg g-1 LFW). In conclusion, the tested PGR can improve the biochemical properties (quality) including oil yield of canola in drought stress conditions, which is of economic and health significance.