Foliage applications of jasmonic acid modulate the antioxidant defense under water deficit growth in sugar beet

Aims of study: Water deficit (WD) is becoming an alarming problem in many regions of the world. Jasmonic acid (JA) is considered an important intracellular plant growth regulator. The aim of the current research was to investigate the important role of JA in mitigating the negative effects of WD on plant growth. Area of study: Sugar beet production systems of two locations in Chaharmahal-Bakhtiari province, Iran. Material and methods: A field trial was conducted to assess the foliar applications of JA (0, 5 mu M and 10 mu M) and WD (50%, 75%, 100% plant water requirements) effects on physiological yield components of sugar beet (Beta vulgaris L.) plants. Main results: WD significantly (p<0.05) increased catalase, ascorbate and peroxidase activities, and malondialdehyde, hydrogen peroxide and white sugar content (WSC); however, it caused a reduction in white sugar yield and root yield (RY). JA foliage applications further enhanced the enzymes activity in WD treated plants resulting in higher WSC, potassium concentrations, white sugar and final RY. Interestingly the effects of JA applications were more pronounced under severe WD (50%) compared to mild (75%) or wellwatered plants (100%). JA (10 mu M) foliage applications increased the RY and white sugar production by 21% and 24% under severe WD. Research highlights: JA can ameliorate the adverse effects of WD and increase the WD tolerance of sugar beet crop by upregulating the antioxidant enzyme activities to withstand adverse environmental conditions.