Uniform and virus-free citrus rootstocks production via nucellus culture

Abstract

Prevalence of various virus and virus-like diseases is among the main reasons for the decrease in quality and quantity of citrus crops. These diseases are mainly spread through the propagation method in citrus which is budding. Using nucellus culture of bitter orange and Mexican lime seeds, uniform and virus-free rootstocks could be produced so that the diseases prevalence could be prevented. In order to generate adventitious shoots from nucellus culture in each of the two rootstocks, direct organogenesis method is used. In all conducted experiments, Murashige and Skoog (MS) medium were used. Two plant growth regulators of benzyl adenine (BA) in 0, 1, 1.5 and 2 mg l-1 concentration and gibberellins (GA) in 0, 1 and 2 mg l-1 concentration were used in the medium and the main effects of each plant growth regulator were studied separately and their interaction on shoot generation were also surveyed. Considering the retrieved data, it was determined that the interaction of BA and GA have a higher impact on shooting, comparing to the cases where each of the regulators is used alone. In Mexican lime rootstock, the best culture medium for generating shoots from nucellus culture is the culture medium containing 2 mg l-1 BA and 2 mg l-1 GA and in bitter orange rootstock, the highest shooting rate was attributed to the culture medium containing 2 mg l-1 GA and 1 mg l-1 BA. For the Mexican lime and bitter orange shoots rooting, indole butyric acid (IBA) was used. The concentrations of this plant growth regulator used in Mexican lime were 0, 0.5, 1 and 1.5 mg l-1 and for bitter orange were 0, 1 and 1.5 mg l-1. The highest rooting rate for Mexican lime was in culture medium containing 0.5 mg l-1 IBA and for bitter orange, it was the culture medium containing 1 mg l-1 IBA. The obtained plantlets were gradually adapted with the external environment.