Response of wheat germplasm selected for hot environments to Saline Conditions

Salinity is the most important factor that limits the expansion of wheat production in Sudan, particularly in the River Nile and Northern States. Identification of wheat genotypes tolerant to salinity is becoming one of the top priorities. Two hundred and thirty genotypes of bread wheat were evaluated in the first season (2004/05) in high terrace soil, affected by salinity, and under non - saline soil condition at Hudeiba Research Station, Eddamer, Sudan. Twenty eight genotypes were identified to have some degree of tolerance to saline stress. In the second season (2005/06), the 28 wheat genotypes selected from the experiment of the first season and two Egyptian salt - tolerant cultivars, Sakha 69 and Sakha 93, as checks, were evaluated in a randomized complete block design (RCBD) with three and five replications under non - saline and saline condition, respectively. The same 30 genotypes used in field experiments were grown on pot experiment in a completely randomize design (CRD), replicated twice. Three irrigation water differing in salinity levels, namely tap water (EC = 0.45 ds/m) (control) and two salt solutions (EC = 4 and 8 decisiemens per meter) were used. Under non -stress experiment genotypic effect was significant for all measured traits ( days to 50% heading, days to 90% maturity , plant height , number of grains 1 spike , number of spikes /square m, 1000 - grain weight , grain yield (kg/ha), biomass and harvest index ). Under saline conditions the results showed that salinity stress affected all the parameters measured in this study . The stressed plant heights were shorter with fewer numbers of spikes / square m, number of grains / spike and lighter 1000 - grain weight. Similarly, salinity stress hastened all the phenological characters studied in this experiment and reduced grain yield, harvest index and biomass. Also the data of the present study clearly demonstrated that there is great genetic variability among the tested bread wheat genotypes for grain yield. The high yielding cultivars under saline conditions were no.8, 25, 6, 22, 9, 4 and 30, their grain yields were 1766, 1589, 1531, 1493, 1448, 1403 and 1402 kg/ha, respectively. Among the commercial cultivars, the cultivar EI-Neilain was moderately tolerant to salinity while the cultivars Condor, Wadi El Neel and Sasareib were sensitive to salinity. In pot experiment Salt tolerance of the genotypes tested were significantly different at various salinity levels. In general, plant height , number of spikes / pot , shoot dry weight , number of spikelets / spike, 1000 - grain weight , number of grains / spike , weight of grains / spike and grain yield per plant (g) decreased as the salt stress increased. Among the cultivars tested the cultivars no. 10, 17, 18, 19, 20 and 23 proved to be most tolerant while the cultivars nO. 2 (Sakha 69),4,5 and 29 showed the least tolerance except at the vegetative stage. The results obtained indicated that, biomass (kg / ha) and harvest index (HI%) were significantly and positively correlated with grain yield (r = 0.652** and 0.402*) while, days to 90% physiological maturity and 1000 - grain weight were non - significantly and negatively correlated with grain yield (r = 0.120 and -0.020) at the saline site. Both field and pot experiments can be used to screen wheat germplasm for salt tolerance. Although the size of the wheat germplasm tested in this study was limited and originally selected for heat tolerance still a few lines with some tolerance to salts were found among them. Reliance on the results of one technique (pot or field) and grain yield only could be misleading