Comparative Vegetative, Nutritional and Anatomical Study of Two Almond Varieties Grafted on Bitter Almond and Nemaguard Peach Rootstocks

A comparative study was conducted during the 2017/2018 and 2018/2019 growing seasons for Nonpareil and Ne Plus Ultra almond cvs grafted on Bitter almond and Nemaguard peach rootstocks at the Experimental Research Station of National Research Centre at Nubaria, El Behera governorate, Egypt. The comparison was evaluated through the grafting success percentage, vegetative growth, determination of some leaf mineral composition, as well as, the anatomical examination of scion/rootstock union zone and cross-section of leaves. The obtained results clarified that the grafting success percentage was significantly affected by the different used rootstocks. Using Bitter almond rootstock recorded the highest percentage of grafting success, leaf chlorophyll content, root length, and a number of lateral root /plant in both cultivars. Using Nemaguard peach rootstock recorded significantly the highest values of scion length, stem girth above and below union zone, number of branches and leaves/plant, leaf area as well as seedlings fresh and dry weight. Leaves of both cultivars grafted on Nemaguard peach rootstock recorded the highest concentrations of leaf mineral contents as compared to those grafted on Bitter almond rootstock. Cross-sections of the graft union zone were taken after 28 days and 6 months from grafting for anatomical analysis. The callus cells developed 28 days after grafting, but cambial cells between the rootstock and scion tissues did not occur in all scion/rootstock combinations. After 6 months of grafting, cambial cells were established, vascular differentiation was observed, regular parenchymatic tissue properties and sclerenchyma bundles were seen in the graft union. There was no problem in terms of compatibility of Nonpareil and Ne Plus Ultra on Bitter almond and Nemaguard peach rootstocks. Comparing leaf cross-sections of almond grafted on both rootstocks demonstrated that the density of mesophyll cells was affected as a consequence of the rootstock–scion interaction. Nemaguard peach rootstock can be recommended for grafting Nonpareil and Ne Plus Ultra almond cultivars under Nubaria conditions to produce vigorous trees.