Grafting has been a common technique, often undertaken by many fruit tree nursery operators to achieve fruiting precocity, tree dwarfing characteristics depending on type of rootstock (Simons, 1987), avoiding termite attack on some fruit trees (such as the use of lemon rootstocks for orange trees), alkalinity tolerance (Colla et al., 2010), and improving fruit productivity (Mitani et al., 2008; Mng’omba, 2007). Many tropical and subtropical fruit trees (such as mango, avocado, citrus, etc.) and other temperate fruit trees are commonly propagated by grafting because other methods of vegetative propagation (such as the use of stem cuttings and marcots) may not be successful as a result of difficulties in root development.
Graft success of many nursery plants can be improved when a number of factors are considered. For instance, skills of grafters have been critical for the success of grafted mango plants (Mng’omba et al., 2010). This is because proper alignment of parenchymatous tissues of both scions and rootstocks greatly influences the graft success (Pina and Errea, 2005) and this art is likely to be low among many unskilled grafters. Time of grafting and stem diameter (thickness) of both scions and their respective rootstocks are also important factors influencing graft success in many fruit trees (Mng’omba et al., 2010). A rootstock of ≈10-mm thick stem diameter has been considered ideal for better graft-take and success (Hartmann et al., 1997). Mng’omba et al. (2010) reported a high graft-take and success with thicker (7-mm stem diameter) mango rootstocks compared with those with thinner (less than 5-mm) rootstocks.
It is a well-established fact that close proximity of cambium (parenchymatous) tissues of both the scions and rootstocks improves graft success because it ensures quick callus union formation from both graft partners. Many reports on graft success have been centered on rootstock diameter (thickness), proximity or proper alignment of vascular tissues of graft partners, callus development, graft compatibility, phenols, and callus development among other factors influencing the graft success (Mng’omba et al., 2008; Pina and Errea, 2005; Pina et al., 2012). To our knowledge, there has been limited knowledge on the effect of diagonal cut surface length (wounded area) in the splice graft method. Furthermore, there could be differences in terms of diagonal cut surface lengths made during grafting fruit trees, even among skilled grafters.
It remains unclear whether a longer wounded area or contact surface area of both scions and their respective rootstocks would improve graft success. It is unclear whether there has been a specific (correct) length of the diagonal cut surface (contact area) for each tree species that effectively improves graft success. It can be hypothesized that at a certain length of a contact surface area between graft partners (scions and rootstock), graft-take can be improved in many fruit trees. In view of the present knowledge gap, an experiment was undertaken to improve our understanding on the effects of diagonal cut surface lengths made during grafting of fruit trees. The objective was to assess the effect of different diagonal cut surface lengths (wounded area) on the graft success of Mangifera indica (mango), Persia americana (avocado), and Prunus persica (peach) fruit trees. We selected these three tree species because they are among the commonly grafted fruit trees in the tropics although peach is a temperate fruit tree. It is hypothesized that this study will help other grafters and fruit tree nursery operators to improve their grafting success, especially those using manual tree grafting.
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