Reduction of Growth Period Prior to Budding in Lime (Citrus aurantifolia) Seedlings and Budtake by Use of Plant Growth Regulators and Pinching

Today, the production of disease-free and identical rootstock seedling in protected environments is a common practice in citrus industry. The process is time consuming, laborious and expensive. Shortening the period to reach suitable size for budding results in the reduction of the costs. It is possible to shorten the period for budding in citrus seedlings through the application of growth regulators. As lime is used widely as a rootstock in Southern Iran, this research attempted to study the effect of paclobutrozol (PP333), ethephon and pinching following gibberellic acid (GA3) treatment on height, diameter and budtake of lime seedlings. To do the research, seedlings with 4-6 leaves were sprayed with 100 mg/L GA3. After GA3 treatment, uniform seedlings 50 cm height were selected, potted and sprayed with PP333 (500 and 1000 mg/L), ethephon (150 and 300 mg/L) or pinched. All treatments, compared with control, increased height, diameter and fresh weight of shoot significantly. GA3 alone caused internode elongation. The effect of all treatments on the number of node, fresh and dry weights of root was not significant. Ethephon reduced chlorophyll content of leaf. And ethephon (300 mg/L) and PP333 (1000 mg/L) reduced budtake percentage of lime seedlings.