The response of finger millet (eleusine coracana (L) gaertn) to salinity
In a set of experiments, both in the laboratory and in the greenhouse, two varieties of finger miIlet (Enakura and EK-I) were subjected to salinity of graded concentrations; namely -I the control, 4, 8 and 12 mnho cm ,Ec (as measured in a conductivity bridge at 250Cl. The laboratory experiments comprised the germination of sterilized grain in paper-lined petridishes . The salt S-JI'8SS effectively reduced rates and percentages of germination, the root and shoot Ii~ear growth, and the final seedling dry weight. The stress also delayed the peak a-amylase activity in the seedlings. The comparison between the two varieties showed that Ek-I had higher rates and percentages of germination, higher Iinear growth, higher amylase activity and higher hydration levels than Enakuru under alI experimental conditions. The salt stress induced a significant loss of the cations; sodium, potassium and calcium from the Seediness , The comparison between the effect of sail and that of solicitor at equiosmotic concentrations show~d that in most aspects the two solutes affected germination in a quantitative similar way. The except ion was recorded for- lase activity and the final seedling dry weight. The greenhouse experiments comprised the culturinq of plants in salinised soils. The soils were salinity seed by irrigation with saline water prepared to the specification already mentioned above. iii Under the greenhouse conditions the salt stress effectively reduced the rate of heading, the final plant height and grain yield. Physiological processes such as the leaf carbon dioxide flux rates, and transpiration were effectively reduced by the soiI salinity. The leaf chlorophyll I content was also reduced by the salt stress, but the tissue protein content was not. So I salinity induced an increase in the tissue sodium content, and a decrease in the tissue calcium concentration. But the stress did not affect the potassium and chloride concentration in the tissues. The soiI salinity lowered the soiI and leaf water potentials in both varieties. In most of the aspects studied it appeared that the salt stress affected the plants primarily Iy via water stress-I ike processes. Both varieties showed moderate degree of resistance to salinity. The inter-varietal assessment showed that Ek-I had higher potential resistance to salinity than Enakuru, even though the latter variety had higher grain yield under the stress. It would be expected that the results from the greenhouse experiment would be very relevant for field trials because the conditions under the open greenhouse systems could easily apply in the field. The implications of the results from this set of experiments are discussed in the light of the relevant literature.