EVALUATION OF GROWTH PARAMETERS OF BOTH DOG RIDGE, SALT CREEK ROOTSTOCKS AND SHOOT TIP MICRO-GRAFTING OF SUPEROIR AND THOMPSON SEEDLESS CULTIVARS Through in vitro CULTURE

Abstract

This investigation was carried out to establish a suitable growth media for two grape rootstocks namely, Salt Creek and Dog Rige and to evaluate micrografting of Thompson seedless and superior cultivars on these stocks through in vitro culture. Plant height, leaves and shoot number increased with increasing the concentrations of 2ip from 3 to 7M. Different concentrations of BAP and GA3 showed that rootstock responded higher height than concentration of BAP only, except 4 M BAP associated with Dogridge which had significant effect than all combinations. On the other hand, Salt Creek grown in media supplemented with (0.5 M IBA) had the lowest root length.Micrografting of Thompson seedless and Superior cultivars were evaluated using two methods of micro-grafting (shoot-tip and cleft) under in vitro conditions on the studied rootstocks. Shoot-tips had higher successful (take) of graft union compared to cleft method which failed to introduce any successful plantlet. Micrografting derived from shoot-tip explants of the two grapevine cultivars showed satisfactory growth characteristics (plantlet height, leaf number and shoot number). Whereas, significant difference between the cultivars and the rootstocks regarding successful graft union and subsequent growth related traits were obtained. Salt Creek rootstock gave the higher rate of success of two scions, respectively if compared to Dog Ridge for both scions. Moreover, shoot length of Thompson seedless scion on Salt Creek rootstock was higher than Thompson seedless scion on Dog Ridge rootstock. In addition, superior cultivar on both of Salt Creek and Dog Ridge showed the same trend. In conclusion, micro-grafting proved to be an alternative suitable propagation method leading to vigorous growth potential of grafted cultivars.