Influence of the Rootstock/Scion Combination on the Grapevine’s Behavior under Salt Stress

Abstract

The practice of grafting, which combines a scion and a rootstock to form a new plant with a blend of characteristics, is a technique known from ancient times both in fruit trees and viticulture. It has been used historically to change variety, enhance vigor, or increase limestone tolerance. Since the late nineteenth century, grafting became a common practice in viticulture after the phylloxera epidemic. Grape growers usually select their rootstock for their vineyard mainly depending on their vigor and resistance to diseases, particularly phylloxera and nematodes; assuming that rootstock confers its properties to the scion. Practically, this is not as simple for some characters; indeed, extensive research on rootstocks revealed that several aspects of scion behavior such as adaptation to abiotic stresses were yet dependent on rootstock features but also related to rootstock-scion interactions. The different genotypes of grapevine tested by ref. [1] displayed different behaviours with regard to salinity, behaviors that oscillate between sensitivity and tolerance. However, genotypes that seem to better cope with abiotic stresses (salinity in particular) are more often susceptible to diseases or calcareous soils. For example, 140R genotype is considered to be the one who better resists to salinity; while SO 4 is famous for its nematodes resistance, even very sensitive to saline and calcareous soils. By integrating the results of several authors works [1-10] the following classification of grapevine genotypes according to their degree of salinity tolerance could be postulated and used: Superior Seedless>Muscat d'Italie>110R>1103P>Syrah>SO 4 Our present work aims to the analysis of interactions between scions and rootstocks also under saline stress. Three grafting combination have been used, their choice was largely imposed by the availability of plant material. In a first attempt, analysis and interpretation of results will be done for each combination lonely; then, in order to better understand rootstock/scion relationship under saline condition, a comparative analysis will be performed within all combinations. Material and Methods Plant material and culture procedure Three varieties (Superior Seedless, Syrah and Muscat d'Italie) and 3 rootstocks (110 Richter, 1103 Paulsen and SO 4) were used in our study according to the following grafting combinations:-Superior Seedless/110 Richter corresponding to a tolerant variety grafted on moderately tolerant rootstock,-Muscat d'Italie/SO 4 corresponding to a moderately tolerant variety grafted on a very sensitive rootstock,-Syrah/1103 Paulsen corresponding to a very sensitive variety grafted on a moderately sensitive rootstock. Grafted cuttings are soaked at their base in exuberone solution (commercial IBA) in order to promote rhizogenesis, paraffined, then Citation: Hanana M, Hamrouni L, Hamed KB, Abdelly C (2015) Influence of the Rootstock/Scion Combination on the Grapevine's Behavior under Salt Stress. J Plant Biochem Physiol 3: 154. Abstract In order to better understand and elucidate the influence of rootstock/scion interactions under salinity constraint, three grafting combinations have been used: Superior Seedless/110R, Muscat d'Italie/SO 4 and Syrah/1103 Paulsen. Superior Seedless/110R combination behaves and displays the same results as ungrafted Superior Seedless variety under both control and stress conditions. On the other hand, since the sensitive rootstock SO4 could improve the behavior of Muscat d'Italie variety against salinity, it highlights the beneficial effect of this combination even the two genotypes are not really tolerant. This gain of performance at both vigor and salinity tolerance levels would result from hybrid vigor. Likewise, even the rootstock 1103P is moderately sensitive, it reaches to improve the behavior of Syrah which is a very sensitive variety. Comparative analysis of the different combinations showed that rootstocks do not behave the same in cases they are used individually or in combination with scion. Indeed, the more or less sensitive rootstocks SO 4 and 1103P (taken individually) behave better at the salinity tolerance level since combined with their respective scions. Moreover, varieties tested individually display a different pattern when used with a rootstock. Generally, they behave better (Muscat d'Italie and Syrah cases) or at least stay unchanged (Superior Seedless case) against salinity when they are grafted. The displayed behaviors among the different combinations reveal the existence of interactions between genotypes of rootstock and scion, and that not only rootstock dictates the global phenotype. These interactions enhance and improve generally the phenotype of the grafting combination. With a sensitive rootstock (whatever scion is, tolerant or sensitive), we always obtain a gain of performance which is more pronunciated with sensitive rootstocks.