Dynamics of graft formation in fruit trees: a review (original) (raw)
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Agricultural Reviews, 2021
Grafting is a widely used propagation technique in fruit trees. Anatomical proximity between scion and rootstock is the prerequisite for the successful graft-take and survival of the grafted plants. The success of grafting, subsequent growth of scion shoot and development of the successful grafts depend upon several factors like climatic conditions, the growth stage of scion and rootstock, methods of grafting, etc. The grafting response of fruit crops differs due to seasonal variability and environmental condition where grafting is carried out. A controlled environment with the congenial conditions for faster healing and callus formation results in better graft success, survival and growth of grafted plants.
Seasonal Variability and Environmental Condition to Grafting Success in Fruit Crops-A Review
Grafting is a propagation technique for the multiplication of plants. It is of paramount importance in fruit trees as it results in the highest success and field establishment. There are different type of grafting techniques involved in fruit crops depending upon the nature of fruit trees and purpose of utilization. The prerequisite for a graft to be success, both the stock and scion should be compatible. Anatomical study of graft union aimed to facilitate an understanding regarding graft union formation process for compatibility or incompatibility of grafts through the changes in the graft union at different stages. Also, grafting success is determined by various other important factors such as grafting seasons, grafting methods, propagation environment etc. Different fruit crops grafts responds in different seasons. A controlled environment condition showing congenial condition for faster healing and callus formation results in better graft success and survival. So, there is a need to studythe season, grafting technique as well as propagation environment to obtain the highest graft success, graft survival and commercial production of grafts. Plant propagation is an important part of fruit crop improvement. Fruit trees are propagated both sexually and asexually. However, at present the majority of nursery owners utilize sexual method of propagation for the multiplication. As most of the fruit crops gained importance due to their medicinal and nutritive value, the orchardists are demandinggenuine true-to-type planting materials in order to optimize production of quality fruits having an early bearing and dwarf tree stature. But poor germination, slowgrowth of rootstock seedlings, lack of information on season and suitable method ofpropagation has rendered the clonal multiplication process more difficult to produce largescale planting material to meet the growing demand. Looking at the utility of the fruits and high price value the demand for planting material is also increasing. Grafting is of paramount importance in fruit trees as it results in the highest successand field establishment. There are different
Early detection of graft incompatibility in apricot (Prunus armeniaca ) using in vitro techniques
Physiologia Plantarum, 2001
compounds have been studied during the first 3 weeks after Graft compatibility has been studied in vitro using callus tissues of apricot (Prunus armeniaca) and different Prunus grafting in both compatible and incompatible combinations. Differences were observed at the second and the third week of rootstocks to form scion/rootstock combinations with different callus co-culture in most of the characters determined, al-degrees of graft compatibility. In these species, incompatibilthough these differences were present as early as the first week ity is manifested by a breakdown of the trees at the union area that can occur some years after grafting. Here, the possibility in the case of phenolic compounds. The behaviour of the grafts grown in vitro was correlated to that of the same combinations of obtaining an early detection method to determine graft incompatibility is explored by callus fusion in vitro. The in the field, suggesting that callus fusion in vitro could be a possible and reliable method for an early detection of graft adhesion of the two callus partners, the development of the incompatibility in different Prunus combinations. cells at the contact surface (cell arrangement, intensity of cell-wall staining), and the presence of lipid and phenolic Gebhardt and Goldbach 1988, Wang and Kollmann 1996, Schö ning and Kollmann 1997). However, incompatible grafts can grow for several years without any external symptom of incompatibility (Errea and Felipe 1993, Hartmann et al. 1997), indicating the presence of functional vascular connections (Mosse 1962). Anatomical studies on these unions have shown an abnormal development of the structure of the union. The observed abnormalities, that include poor vascular connections, phloem degeneration and cambial or vascular discontinuity in the union area, cause mechanical weakness and subsequent breakdown of the union (Herrero 1951, Buchloh 1960, Hartmann et al. 1997). These manifestations of incompatibility have been observed at least 1 year after the establishment of the graft (Schmid and Feucht 1981, Simons 1987, Hartmann et al. 1997). Previous studies on early graft establishment in apricots have indicated that while no differences have been found in the process of graft healing, differences exist in the level of differentiation of the callus in both compatible and incompatible combinations (Errea et al. 1994
Anatomical studies on graft formation in Cashew (Anacardium occidentale L.)
Agriculture and Biology Journal of North America, 2012
The research studied the changes in the graft union with influence on graft success and subsequent performance until the 98 th day after initial side grafting of Anacardium occidentale rootstock seedlings. Thirty days after grafting, the necrotic layer and calli cells began enlarging between scion and stock. There was gradual disappearance of the necrotic layer, preceding callus formation and the fusion of the scion and stock at 60 day after grafting. Results at 98-days after grafting showed cambium linkage and a healed union edge. Unsuccessful grafts at 98-days after grafting showed a wide gap at the cortex of scion and stock. Graft union success is a key factor in successful graft-take and subsequent performance of grafted seedlings.
Anatomical Analysis of Graft Compatibility in Some Almond ScionRootstock Combination
Tarim Bilimleri Dergisi-journal of Agricultural Sciences, 2019
In this study, graft compatibility between almond cultivar Lauranne and almond seedling and Rootpac R, Rootpac 90, Rootpac 70 and Rootpac 40 clonal rootstocks was anatomically investigated. The anatomical analysis of scion/ rootstock combinations was performed by taking cross sections for 30 days and 12 months after T-budding in June, 2017. It was determined that, 30 days after grafting, the callus cells developed but cambial continuity has not occurred between the rootstock and scion tissues in all scion/rootstock combinations. 12 months after grafting, cambial relation was established, vascular differentiation was observed, regular parenchymatic tissue properties and scleroid (petrosal cell) cells and sclerenchyma bundles were seen in the graft union. There was no problem in terms of rootstock-scion compatibility in Lauranne almond cultivar which was grafted on almond seedling and some Rootpac clonal rootstocks.
The aim of this research was to observe histological developments during the early stages of graft formation between some spur apple varieties and apple rootstocks in order to assess compatibility/incompatibility related to different growing rate of the plants used. As rootstocks, one year-old clonally propagated A2, B118, M111 (vigorous) and M7, M16, Pj80 (semi-dwarfing) were used. Scions were taken from one-year-old shoots of Scarlet Spur, Red Spur and Redchief spur apple varieties. Rootstocks were planted in the field in winter 2007 and whip-grafted in April 2008. An evident incompatibility was not observed in the combinations. Sufficient callus proliferation was visible in all the combinations. Successful cambial and vascular connection was apparent in the 90-day sections. In the 120 th and following sections, it was observed that callus usually filled all the gaps between the rootstock and the scion. Xylem and phloem strands successively bridged the union. However, especially Pj80/Redchief and M16/Red Spur should be followed up in subsequent years in the field conditions because of the excessive callus formation between the stock and the scion.