Influence of rootstock age and propagation methods on scion physiology and root morphology of Khasi mandarin (Citrus reticulata)

In Khasi mandarin (Citrus reticulata Blanco) influence of rootstock age (i.e. 05, 06, 07, 08, 09, 11, 12, 13, 14 months) and propagation methods (i.e. wedge grafting and T-budding) on graft/bud success, plant survival, scion physiology and root morphology were studied. The wedge grafting performed on six months old rootstock (T2) recorded maximum graft success (90.0%) and plant survival (88.87%) followed by T3 (80.0 and 77.17%), i.e. wedge grafting on seven months old rootstock, which was significantly (P=0.05) higher than T7 (68.33 and 67.78%), i.e. conventional T-budding on twelve months old rootstock. Morpho-physiological traits, viz. higher individual leaf fresh weight (0.42g) and dry weight (0.16 g), specific leaf weight (5.19 mg/cm(2)) and leaf thickness (496.67 mu m) were recorded in T2. In addition, the leaf pigment contents, viz. chlorophyll 'a' (0.77 mg/g tissue) and total chlorophyll content (1.12 mg/g tissue) was found higher in T2 followed by T3 (0.76 mg/g tissue and 1.07 mg/g tissue). Similarly, carotenoid content was recorded maximum in T2 (47.07 mu/g) at par with T-budding on eleven (43.15 mu/g) and 12 (42.94 mu/g) months old rootstock. Relative leaf water content was recorded highest in T3 (61.29%) and T2 (60.68%). Further, T2 recorded higher total root length (385.36 cm) and root surface area (721.20 cm(2)) while, root volume was recorded maximum in wedge grafting on five month old rootstock (156.29 cm(3)) at par with T3 (155.01cm(3)) and T2 (152.31 cm(3)). The root diameter was recorded highest in T7 (7.54 mm), whereas the root to shoot ratio was found highest in T2 (0.88) followed by T3 (0.75) and T7 (0.70). The results suggested that wedge grafting method could be gainfully exploited for Khasi mandarin propagation.