Ratio of grafted and ungrafted shoot on the survival of top working in cashew (Anacardium occidentale L.)

Cashew has an important contribution towards Indonesian economy especially for eastern Indonesia, which has a dry season throughout the years. However, most of cashew trees have low yield and are more than 10 years old. Top working is one of the methods to rejuvenate cashew plantations commonly practiced in the field. The top working method is able to substitute old cashew trees with the desirable cultivars. The experiment was carried out in January 2016 at the experimental garden of the Indonesian Spice and Medicinal Crop Research Institute (ISMCRI), Cikampek District, West Java Province, Indonesia which is located at 50 m a.s.l., 107°27'20.99”E longitude and 6°25'10.99”S latitude. The research aimed to obtain the optimal ratio of grafted shoot as sinks and ungrafted shoots as a source of photosynthates for cashew tree. The trial was arranged in split plot design with 3 replications. Main plot was the age of tree (7 and 10 years old) and sub-plot was the ratio of grafted shoots and ungrafted shoots with 10 shoots for each tree (4/6, 6/4, 8/2). Observations were recorded on the grafting survival rate (%), shoot length increment of grafted shoot (cm), leaf number per grafted shoot, field determination of compatibility constant (FCC) and chlorophyll content (%).The ratio of 4 grafted shoots and 6 ungrafted shoots (4/6) proved to be the most effective one, indicated by better grafting survival rate and growth of shoot grafts than others.