Agricultural and Biological Research

Effect of the type of potassium supply on the physiological response of cowpea (Vigna unguiculata L. Walp. var. KN-1) under hydraulic constraints

Edmond Dondassé*, Adama Pascal Kihindo, Badoua Badiel and Gérard Zombré

The present study had the general objective of comparing KN-1 variety of cowpea cultivated according to the supply of different Potassium (K⁺) solution in a situation of water constraint. The test was carried out in the experimental garden of the Unit of Training and Research in Health, Life and Technology (UFR/SVT) in the open air during the rainy period (July to September) in pots. Three types of solution namely water, Potassium Dihydrogen Phosphate (KH₂PO₄) and Potassium Nitrate (KNO₃) were used to supply the plants. Then, after 6 days, the plants were subjected to a water deficit by stopping watering in the vegetative phase. At the end of the water restriction, the morphophysiological and biochemical parameters were assessed on all the plants. Note that all the plants underwent water restriction.

Our work shows that the different potassium solutions had a positive effect on the production Root Biomass (RB) (3.093 ± 0.180 g for KNO₃ and 2.826 ± 0.146 g for KH₂PO₄) and therefore on cowpea adaptation to drought, compared to control plants (2.671 ± 0.099 g). Plants supplied with potassium solutions have a lower water potential (-1.528 ± 0.054 MPa for KNO₃ and -1.683 ± 0.029 MPa for KH₂PO₄) than that of control plants (-1.283 ± 0.058 MPa). Similarly, RB (p<0,027), chlorophyll A content (p ≤ 0,000) and nodule mass (p<0,009) of plants were affected by the solution supply level in the KN-1 variety. Responses to water stress varied depending on the potassium solution used and the treatment supply level. On the basis of these results, potassium solutions and the KN-1 variety allow to improve cowpea production in Burkina Faso.