Effect of seed invigouration treatments on physiological parameters and nodulation of grain cowpea [Vigna unguiculata (L.) walp]

The experiment was conducted at Coconut Research Station, Balaramapuram with an objective to assess the effect of seed invigouration with ZnSO₄ and borax alone and along with Trichoderma viride on physiological parameters and nodulation of grain cowpea. Seed invigouration treatments had significant effect on physiological parameters as well as nodulation parameters in grain cowpea. Leaf area index and total chlorophyll content were found to be higher in seeds primed in ZnSO₄ 0.025 and 0.05 per cent for 4h at both 30 and 60 days after sowing (DAS). From 30 to 60 DAS, crop growth rate (CGR) and relative growth rate (RGR) were the highest in seeds pelleted with borax 50 mg kg⁻¹ seed and from 60 DAS to harvest, seeds primed in ZnSO₄ 0.05 per cent for 4h registered the highest CGR and RGR. Total number of nodules and effective nodules per plant were found to be higher in seeds pelleted with borax 50 and 100 mg kg⁻¹ seed. However, the nodule fresh and dry weight were the highest in seeds primed in ZnSO₄ 0.05 per cent for 4h. Hence it can be concluded that compared to seed pelleting with borax, seed priming with ZnSO. was found better for nodulation as well as r re ‘re ₄ better expression of physiological parameters in grain cowpea.