ASSESSMENT OF OSMOLYTES AND CHLOROPHYLL CONCENTRATION IN DROUGHT RESPONSE OF COWPEA VARIETIES

Abstract

Global warming and climate change are factors that leads to increase in droughts.Drought

impairs plant growth and development consequently affecting crop yield thus plants develops

certain measures that leads to adaptation of the drought stress for better plant growth under the

stress condition. The effect of drought stress on osmolytes (glycine betaine and carbohydrate)

and chlorophyll concentrations was studied in three cowpea varieties.The experiment was

conducted between June to October 2019 at the greenhouse of Faculty of Agriculture, Bayero

university, Kano. Two cowpea varieties drought tolerant (Dan”ila) and drought susceptible

(TVU 7778) were obtained from IITA Kano and a local variety from a local market in Kano. The

seeds were sown in plastic containers arranged in a completely randomized design. Each pot was

irrigated to field capacity every other day with borehole water and water deficit was introduced

at six weeks after sowing by totally withholding irrigation for a period of two weeks. After the

stress treatment, irrigation was resumed for five days to assess recovery. Plant leaves samples

were collected at 0, 5, 10 and 15 days drought and 5 days after resumption of irrigation

(recovery). Results showed a significant increase in the concentration of carbohydrate and

glycine betaine as the stress period increased and significant decrease at the re-watering period in

the drought-tolerant and local varieties. However, there was a significant decrease in the

concentration of chlorophyll in all the three varieties studied as the stress period increased.

Osmolyte and chlorophyll played a role in the drought response of cowpea.