RESPONSE OF 4 BRASSICA SPECIES TO DROUGHT STRESS

The relative drought tolerance of four Brassica species, Brassica campestris (Sarson), B. carinata (Ethopian mustard), B. juncea (Brown mustard), and B. napus (Oilseed rape) was assessed after having subjected them to repeated drought cycles for 24 days. There was a close relationship between biomass production and water content, and water relations of all four species in response to repeated drought cycles. B. carinata produced significantly lower fresh and dry biomasses and had less water content, wax on leaf surface, and total protein content in shoots and roots, but had a higher leaf water potential (Ψw) at wilting and osmotic potential after rehydration ({music sharp sign}H) than the other species. By contrast B. napus produced relatively greater fresh and dry biomass and had higher water content, chlorophyll content and protein content in shoots and roots, but had lower leaf water and osmotic potentials. On the basis of results presented here it can be concluded that B. napus was the most drought tolerant, B. juncea and B. campestris intermediate, and B. carinata the most sensitive to drought stress. The data support the postulate that osmotic adjustment is a probable component of drought tolerance in these species. © 1989.