Study On The Potential Of Two Citrus Somatic Hybrids Rootstocks And The Mechanism On The Interaction Between Scions And Rootstocks

Performance of the 3-year-old young trees of the two citrus somatic hybrids red tangerine + trifoliate orange and red tangerine + rough lemon, Troyer citrange, Swingle citrumelo and trifoliate orange rootstocks grafted with Guoqing No.4 satauma mandarine and Nice navel orange or not grafeted was studied through poted experiment for 2 years. Performance of some main combinations of interstock/rootstock highly grafted with Newhall navel orange in the area of the reseverior in three gorges and its resons were studed through field investigation. It was conducted with the combinations of Jincheng sweet orange on trifoliate orange and red tangerine and three interstocks Roberson 36 and Jincheng sweet orange and Guoqing No.l satsuma mandarin on trifoliate orange who all were adult trees before high graft. Effects of various rootstocks and intrstocks on the growth and the flower number and some physiological and biochemical indexes such as the contents of mineral nutrients and carbohydrates and the activities of anti-oxidant enzymes in leaves or roots were analysed. And then the potential of two somatic hybrids was primarily estimated, meanwhile the mechanism of the scion/rootstock interaction and the double effects of interstocks was discussed. The main results are the following. 1 The primary estimation of the potential of two citrus somatic hybrids 1.1 Red tangerine + trifoliate orangeNon-graft tree of red tangerine + trifoliate orange grew more vigoriously, and had larger trunk diameter with smaller root volume than trifoliate orange. The root activity and the activities of anti-oxidant enzymes (except CAT) in roots of the non-graft trees after cold resisitant training were higher than or did not differ from that of trifoliate orange. So it indicates red tangerine + trifoliate orange has the potential enough to make scions have high yield and have better cold resisitence than trifoliate orange. When Guoqing No.4 satsuma mandarine grafted on red tangerine + trifoliate orange, the trees grew more vigoriously and had larger flower number than that on trifoliate orange. When Nice navel orange grafted on red tangerine + trifoliate orange, the trees grew more vigoriously than that on Troyer citrange and Swingle citrumelo, and had larger flower number than or the flower number not differing from that on Troyer citrange. So redtangerine + trifoliate orange rootstock gets advantages of the tree growth and flowering during the early period. During the dormant term, Guoqing No.4 satsuma mandarine and Nice navel orange grafted on red tangerine + trifoliate orange respectively made the activities of SOD and POD in leaves higher than trifoliate orange and Troyer citrange and Swingle citrumelo, and also respectively made the contents of carbohydrates in leaves not differ from that on trifoliate orange and higher than Troyer citrange and Swingle citrumelo. So it shows red tangerine + trifoliate orange rootstock makes the cold resistance of the trees stronger than trifoliate orange and Troyer citrange and Swingle citrumelo. In short, red tangerine + trifoliate orange perhaps become a better rootstock in place of trifoliate orange hopefully. 1.2 Red tangerine + rough lemonNon-graft tree of red tangerine + rough lemon grew weaklier, and had larger root volume than trifoliate orange. The root activity and the activities of anti-oxidant enzymes in roots of the non-graft trees after cold resisitant training had opposite tendencies of difference comparing with trifoliate orange within 2 years. So it indicates red tangerine + rough lemon needs observing for a longer time. When Guoqing No.4 satsuma mandarine and Nice navel orange grafted on red tangerine + rough lemon, the trees grew more vigoriously than that on trifoliate orange and on Troyer citrange and Swingle citrumelo respectively, and had smaller flower number than that on trifoliate orange and on Troyer citrange and Swingle citrumelo respectively. So red tangerine + rough lemon rootstock gets advantage of the tree growth and disadvantage of flower number during the early period. During...