Response of local mustard germplasm to water stress

摘要

A preliminary study was conducted to compare three wild mustard (Brassica species) landraces with respect to germination capacity and seedling emergence under two water regimes. Seeds of three landraces [Isaha, Masihlalisane (both Brassica juncea (L.) Czern & Coss) and Kwayimba (Brassica nigra (L.) W.D.J. Koch)] were characterised according to seed colour: black, brown, grey, greyish-black and reddish-brown. Seed quality was determined by germination test and seedling establishment in response to two water regimes [25% and 75% field capacity (FC)]. There were highly significant (P < 0.001) effects of landrace and seed colour with respect to germination capacity. Masihlalisane showed 99-100% germination for brown, grey and black seeds. For lsaha brown seeds displayed 85% germination, grayish-black seeds showed 95% germination and reddish-brown seeds showed 82% germination. Kwayimba showed the least germination capacity, and black seeds were the most dormant (close to 0% germination). Brown seeds of Kwayimba had 14% germination and reddish-brown seeds showed 22% germination. There was no significant effect of seed colour on seedling establishment. Seedling establishment under 25% FC was similar to 45% for Isaha and Masihlalisane, and Kwayimba did not emerge. At 75% FC, there was similar to 80% emergence for all landraces. However, by the end of the experiment (21 days after emergence) only seedlings grown under 75% FC were harvestable and the darker the seeds the better was the biomass (P < 0.01). It is concluded that water stress tolerance in wild mustard maybe associated with the trait of seed colour.