Saline-water drip irrigated sorghum varietal response
to limited available soil water in dune sand was assessed using salinity
response function. In a randomized complete block design three sorghum
varieties (Local sorghum, BK 16 and EC 90) were grown with drip irrigated
saline-water, at four salinity levels (5.47, 7.32, 9.38 and 12.50 dS m-1)
and with quality water of 0.11 dS m-1 serving as the control.
Four salinity response models were used to assess their ability to discriminate
salinity-induced grain yield differences under limited available soil
water. Response analysis indicated the four models were equally good in
fitting that the grain yield data, but the modified discount model produced
the consistently the best fit. Analysis of the data indicated that the
impact of salinity stress on varieties was best discriminated by the parameters
salinity threshold (Ct), Salinity Tolerance index (ST-index) and the salinity
at which 50 % grain reduction (C50) occurred. The analysis
indicated that the variety BK 16 was the most tolerance to salinity stress.