Growth of varieties of three sorghum species at different levels of salinity

Abstract

The growth of twenty-four varieties of three sorghum species was studied at four different salinity levels. The species were : Sorghum sudanense, two varieties ; S. verticilliflorum, one variety ; S. almum Parodi, twenty-one varieties. The salinity stress was maintained for 29 days and eventually led to breakdown of sorghums at the higher levels. Treatments were imposed when the plants were 7 cm high, at day 12. Sorghums showed a high resistance to salinity stress that compared favourably with other plant species. This is a valuable agronomic quality. There were significant differences in yield between sorghums at all salinities and these effects were in the same proportion at all levels. The distinctive feature of the study is that the nature of these differences was studied in detail, supported by chemical analysis. These results for this large number of sorghums made a general interpretation of the responses possible. At control levels the differences in yield were not due to differences in rate of growth, nor were there any differences in rate of growth between sorghums at any salinity level. Differences between sorghums, then, were a reflection of differences at control level, which appeared to be impressed on a sorghum before the treatments began.