Effect Of Interaction Between Rootstock And Scion On Cold Resistance Of Grafted Eggplant

Eggplant is a crop in regions where the temperature is high, it always meets with low temperature stress in winter and spring greenhouse. Have already known now, vegetable grafting could enhance the ability to resist chilling, promote root absorption of nutrient and development and growth, which has been a lot of study in melon. There were many researches on vegetable grafting, but most of them were systemic research on the modified role of root stock to scion. But the effects of scion to grafted seedling were reported very little. As the grafted seedling is a organic whole by combination of rootstock and scion, there were many transport exchange of water, mineral and carbon assimilation between them. Thus rootstock and scion effect each other by grafted. In order to study the contribution of root and scion to cold resistance of grafted eggplant seedlings, two rootstock eggplant cultivars, Daidaro susceptible to cold and Hiranasu more resistant, were used to be grafted on each other. The main findings are followed:1. Different combination grafted eggplant had different cold resistance. H/H was the strongest anti-cold, followed by DH/H, DH/DH, DH/D; D/D was the weakest anti-cold. Though DH/DH had double roots, it's cold resistance was less than DH/H. 2. After low temperature treatment electrolyte leakage and MDA content in D-leaves of DH/DH, DH/H, DH/D was significantly higher than H-leaf in the same combination, but were observably lower than that of D/D; meanwhile, the content of soluble sugar, soluble protein and proline in H-leaves of combination of grafted seedlings was notably higher than that of H/H. Our experiment results showed that low temperature stress resulted in SOD and CAT activity reduced and then increased, but with stress time extened, SOD,POD activity reduced; POD activity were increased and then reduced. During low temperature stress, in the same grafted seedlings , SOD,POD,CAT activity of H-leaves were higher than those of D-leaves; enzyme activity of H-leaves and D-leaves, H/H>DH/H>DH/DH,H>DH/DH,D>DH/D>D/D. The results above indicated that both root and shoot of Hiranasu can enhance cold resistance of Daidaro; both root and shoot of Daidaro can weaken cold resistance of Hiranasu through grafting experiment.3. Low temperature stress resulted in root activity of different grafted eggplant seedlings reduced, but the reduced level of Daidaro was bigger than Hiranasu, after stressed 5 days, root activity of DH/DH(D) and DH/DH(H) separately reduced 76.15% and 70.89%. With stress time extened, osmotic adjustment substances including soluble sugar,soluble protein,proline and MDA content increased; but SOD,POD and CAT activity were maximum at stressed 3 days and then were reduced. Through the low temperature stress, osmotic adjustment substances content and protective enzymes activity: H/H>DH/H>DH/DH(H)>DH/DH(D)>DH/D>D/D, but MDA content is opposite. The results above indicated that both root and shoot of Hiranasu can enhance cold resistance of Daidaro; both root and shoot of Daidaro can weaken cold resistance of Hiranasu through grafting experiment. DH/H was more cold resistance than DH/D, so root had more contribution than shoot to cold resistance of grafted seedlings.4. After low temperature treatment Fv/Fm,ΦPSII,qP,Chl content,Pn,Gs in H-leaves of DH/DH, DH/H, DH/D was significantly higher than D-leaf in the same combination, but were observably lower than that of H/H. All the results above indicate both root and shoot of Hiranasu can enhance cold resistance of Daidaro through grafting experiment. Although DH/H had more resistance than DH/DH and DH/D which is the most sensitive to cold, all three of them were in the shade compared to H/H. So it can be concluded that both root and shoot of Daidaro had a negative effect on cold resistance of scion Hiranasu. DH/H was more cold resistance than DH/D, so root had more contribution than shoot to cold resistance of grafted seedlings.5. After low temperature treatment, ABA/GA content in D-leaf (or D-root)were lower than H-leaf (or H-root). ABA /GA content in D-leaf (or D-root) of DH/DH,DH/H,DH/D were seperately higher than D/D; ABA/GA content in D-leaf (or D-root) of DH/DH, DH/H, DH/D were seperately lower than H/H.