Morphological and Physiological Responses of Arachis hypogea L. to Salinity and Irrigation Regimes in Screen House

Aims: The K3237-80 groundnut variety from IRAD Nkolbisson is widely preferred in the Central African sub region for its sizable seeds and high yields, thus its contribution to livelihoods and food security. Apart from yield rating studies, responses to abiotic stress have not been done for this variety. The aim of this research was to investigate the responses of K3237-80 groundnut variety to salinity and water stress in screen house, in order to predict growth and yield performance under predicted conditions of soil salinity and rainfall variability.

Materials and Methods: The experimental design was a 4 by 3 factorial design. There were three levels of irrigation corresponding to 1100 mm, 2200 mm and 3300 mm crossed with four salinity levels of 0, 4, 8 and 12 ppt. Treatments were maintained till maturity and growth, yield and physiological parameters measured. Data were subjected to Factorial Analysis of Variance through the GLM approach, in the MINITAB Version 17 statistical package, followed by Spearman Rank Correlation and Factor analyses, all at α = 0.05.

Results: It was found that this variety is mildly tolerant to salinity, as growth and yield decreased at salinity levels above 4 ppt. It is however resistant to irrigation water variability which explains why it does well in all five agroecological zones of Cameroon. Both salinity and irrigation treatments significantly influenced WUE, transpiration rate and TUE (p<0.05). Water use efficiency decreased from 3.23 g/l in plants irrigated with freshwater to 1.76 g/l in plants treated with water of 12 ppt salinity. Transpiration rate increased from 0.04 l/hr/plant at 0ppt to 0.06 l/hr/plant at higher salinities, while transpiration use efficiency correspondingly decreased significantly. Correlation analysis revealed that growth, yield and biomass parameters of A. hypogea are highly salinity-driven, while transpiration and water use efficiency are highly irrigation-dependent.

Conclusion: Therefore groundnut can be grown to maturity at salinity of up to 12 ppt, the trade-off is reduced growth and yield, caused by disruptions in photosynthesis and water relations.