Effects of Defoliation and Organic Fertilizers on the Budding Success of Rubber (Hevea brasiliensis Muell Arg) Seedlings

This study was conducted to determine the budding success of rubber in response to budwood defoliation and organic fertilizer application. The experiment was carried out in a 3x4 factorial arrangement in a randomized complete block design (RCBD). Budwood defoliations served as Factor A and both chemical and organic fertilizers served as the Factor B. Morpho-anatomical analysis was also done to determine the bud-union development of stock and scions of rubber seedlings. Defoliated budwood two weeks before budding significantly increased budding success (71.15%) and resulted in early sprouting 12.83 days after cutting back, compared to non-defoliated budwood. It also promoted the development of the longest shoots at 60 days from cutback. Organic fertilizers significantly improved budding success, early sprouting of scion buds, and development of scion shoot after cutback compared to the non-defoliated budwood (control). Vermicast application gave the highest budding success of 69.72% comparable to chicken dung (63.24%). Those fertilized with 16-20-0 had budding success of 45.80% similar to the control (43.66%). Generally, at 14 days after budding, cross-sectioned samples developed partial bud-union with profuse calli formation at their cambial contact leaving a conspicuous gap at the center of the bud-union. Cross sections from budded seedlings applied with vermicast proliferated better compared with those applied with ammonium phosphate. Those fertilized with chicken dung exhibited more callus formation at cambial contacts than the control. At 28 days after budding, cross-sections of budded rubber seedlings showed an almost complete bud-union regardless of treatments indicating success in budding.