Effect of different mediums and salinity on drought tolerant half sib sugar beet family

Green house studying especially for salinity stress needs suitable medium. It is necessary to determine suitable medium in greenhouse studies for screening germplasm, which is easily available, stable in terms of electrical conductivity and cost-effective. Soil, and Perlite are common mediums which are used in green house researches generally, but there weren’t enough reports for study hydroponic system for screening sugar beet germplasm. Drought and salinity stress happens at the same time in most regions of Iran and because of similar tolerance mechanisms for these stresses, drought tolerant germplasm could be used in screening for salinity.so the goal of this project was to evaluate different medium especially hydroponic to screening sugar beet drought tolerance genotype in salinity stress.

The project was conducted in two experiments: (a) A factorial experiment based on completely randomized design with four replications was conducted in SBSI research greenhouse. The first factor was three planting media in combination with nutrition solution as follows: 1) loamy soil with about 5% organic matter, 2) perlite with Hoagland solution, 3) hydroponic environment with Hoagland solution. The second factor consisted of two levels of salinity including normal and salinity (16 dS m-1) treatments and the third factor consisted of two sensitive and tolerant genotypes. (b) 17 selected genotypes were investigated in greenhouse with perlite medium under control and salinity 16 dS m-1 in factorial experiment based on completely randomized design with four replications. Different quantitative and qualitative traits such as root. Shoot and total dry weights, K/Na, Soluble carbohydrates, glycine betaine were measured in both experiments and statistical analysis were done by MSTATC and SPSS and mean were compared in Duncan multiple range test at (α=0.05).

Cross effects of medium and salinity were significant on total and shoot dry weights, P, K/Na. Cross effects of medium, salinity and genotypes were significant on most of the traits. Crop yields under salinity stress were less in soil in comparison to other mediums, also salinity had significant effect on soil EC and Na (P≤0.01), soil and perlite were salinized respectively 6 and 2 times in comparison to normal condition. Which shows that soil is not stable medium for salinity study in green house. The highest yield (3.31 g p-1) was obtained from hydroponic. Yields achieved from hydroponic and perlite mediums were similar under salinity, but water consumption was more in hydroponic than perlite. In establishment stage, the total dry weight, soluble carbohydrates, glycine betaine and K/Na ratio were suitable for selection of sugar beet genotypes under salinity stress. According to all measurements, the clustering in establishment stages and Stress Tolerance Index (STI), HSF-91018, HSF-91040, HSF-92870, HSF-92881, HSF-92884, genotypes were selected as tolerant genotypes as controls.

Sensitive and tolerant genotypes were not distinguished well in hydroponic medium, which related to its potential and was mentioned in other reports. Hydroponic and perlite were in the same group for different traits especially they became less salty than soil but hydroponic system is not useful for root beet but it would be suitable for forage beet because biomass production is more in this condition. Also, soil is not suitable medium for study salinity researches because it became seven times more salty than normal condition. As a result perlite is the best medium for salinity studies in sugar beet because it becomes less salty, it has low weight and cost and has less side effects on environment. According to all measurements, the clustering in germination and establishment stages and Stress Tolerance Index (STI), HSF-91018, HSF-91040, HSF-92870, HSF-92881, HSF-92884, genotypes were selected as tolerant genotypes as controls.