Seed Germination, Plant Establishment, and Yield of Sugar Beet Genotypes under Salinity Stress

It is well known that sugar beet is sensitive to salinity stress at the germination stage. Three separate experiments were conducted to study the effects of salinity on seed germination, plant establishment, and yield of sugar beet genotypes for screening purposes. These included: (a) A laboratory study using four water salinity levels (with EC values < 0.1 as the control, 16, 20, and 24 dS m-1) with 20 sugar beet genotypes, which were evaluated in a factorial completely randomized design with four replications, and seedling characteristics were measured; (b) A greenhouse experiment where the same statistical design as the lab study was used for seed germination and establishment of 19 sugar beet materials, with irrigation water EC= 3 and 16 dS m-1; and (c) A field experiment that was carried out to study the response of nine selected genotypes to irrigation waters with EC= 4 and EC= 16 dS m-1, using a split plot design with three replications. Interaction effects of salinity and genotypes were statistically significant (α= 0.01) for percentage of germination, abnormal seedling, and root and hypocotyls lengths. Indeed, sugar beet germination decreased to 35% and dead seedlings increased to 80 % under salinity stress (EC= 16 dS m-1) in the greenhouse. Genotypes were ranked from tolerant to susceptible. The results of field experiment were consistent with that obtained in the greenhouse. It can be concluded that salt stress decreased seed germination and, later on, crop establishment by increasing dead seedlings; consequently, sugar beet yield decreased. It seems that establishment is more susceptible to salinity than germination. Root length and abnormal seedling are good indexes for screening sugar beet genotypes for salinity tolerance at the primary growth stages.