Investigation of betaine spray on freezing tolerance of chickpea (Cicer arietinum L.) in controlled conditions

Document Type : Research Article

Abstract

Betaine as an osmoprotectant has an important role in plant tolerance in abiotic stresses. Therefore, the effect of exogenous application of betaine on increasing tolerance to cold and freezing tolerance of two chickpea genotypes were studied. Electrolyte leakage was used in this study for determination of injury percentage. This experiment carried out in factorial experiment based on complete randomized design with three replications containing two genotypes of chickpea (MCC426 and MCC505), three levels of betaine (0, 20 and 40 mM) and six temperature treatments (0, -3, -6, -9, -12 and -15 °C). The plants were sprayed with betaine in 6-7 leaves stage and transferred to cold room for cold acclimation. Then
the plants were transferred to thermo-gradient freezer and determined the electrolyte leakage
percentage (as freeze injury index), survival percent and some vegetative details in each temperature. The results showed that there was a significant difference (p≤0.05) between genotypes in electrolyte leakage and LT50. Increasing of betaine in tolerant genotype caused decrease of electrolyte leakage but was not effective in sensitive genotype. In addition, there was relative high correlation between electrolyte leakage and LT50 (r=0.47). This indicates that electrolyte leakage has high efficiency for determination of injury percent and freezing tolerance. There was a significant difference between genotypes for LT50 and RDMT50 but no difference among betaine levels so it is necessary to use high levels of betaine for exogenous application. Response of genotypes for survival percent and some vegetative details was different but finally tolerant genotype had better recovery ability in comparison with sensitive genotype.

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