Seed priming with silicon dioxide and potassium nitrate alleviates the ill effects of water stress in chilli (Capsicum annuum L.) by suppressing reactive oxygen species (ROS) accumulation and improving antioxidant defence systems

Deficit soil moisture is one of the most critical limiting factors affecting crop growth and overall productivity. Because of its low membrane integrity, high stomatal conductance and increased transpiring leaf surface, the essential solanaceous crop chilli is highly vulnerable to drought. One crucial stress management technique for combating water stress is seed priming. Chilli seeds were subjected to different priming agents 2.5 % potassium nitrate (KNO3), 3 % silicon dioxide (SiO2) and unprimed seeds with distilled water for 24 hours. Prior to the flowering stage, the crop was subjected to moisture stress by withholding irrigation in both greenhouse and field conditions. Results of both experiments revealed that seed priming with 2.5 % KNO3, resulted in enhanced physiological traits like relative water content, specific leaf area, total chlorophyll and biochemical traits like malonaldehyde, H2O2, trehalose, α-amylase activity, superoxide dismutase, total soluble sugars and total soluble protein, followed by quality traits like capsaicin, vitamin C and yield traits viz., plant height, number of flowers plant-1, number of fruits plant-1 and fruit yield plant-1, whereas 3 % SiO2 primed seeds recorded significantly higher values for total proline content and cell membrane stability index compared to unprimed seeds. Seeds primed with 3 % SiO2 recorded early flowering, whereas seeds primed with 2.5 % KNO3 recorded the first fruiting stage. The results showed that seeds with 3% SiO2 can be recommended for seed formation in cases of water shortage and seeds primed with 2.5 % KNO3 demonstrated high antioxidant levels and the maximum capacity to absorb water.