The Effects Of Root Restriction On Grape Berry Development, The Structure Source And Sink Organs, Their Conducting Tissue Vines

In this thesis, effects of root restriction on the growth of grape vine and berry, the anatomical structure of source and sink organs, conducting tissue of phloem ultrastructure, and sugar accumulation and its relative enzymes activity were studied. This study explored the mechanism of berry growth and development, and the sugar accumulation. The main results were indicated as follows:1 In terms of effects of root restriction on the biomass allocation of grape vine, the total biomass accumulation of grape vine under root restriction was less than control, but the biomass accumulation of grape berry under root restriction was more than control treatment. Root restriction inhibited the growth of leaf and shoot, decreased the aboveground biomass accumulation of grape vine, but increased the biomass accumulation of grape berry; the biomass accumulation of grape cluster took up 39% for root restriction, and 31% for control.2 In terms of the berry development and main nutriments accumulation in berry under root restriction, during all stages of berry growth, the firmness of berry and berry skin under root restriction were lower than control treatment. During phaseⅢ, the berry turgor pressure under root restriction had higher peak value compared with the control treatment, but the cell wall content of flesh and berry skin under root restriction was lower than control treatment. Root restriction also decreased the pectin and cellulose content. During phaseⅢ, the TSS content under root restriction was higher than control treatment, showed a significant difference at P≤0.05 level with control treatment; root restriction also increased the anthocyanin content, the total protein content and free amino acid content.3 In terms of anatomical structure of root leaf and berry, root restriction increased the thickness of epidermis and cortex, 18.3μm and 579.1μm respectively, but the cross sectional area of pericycle of absorbing root was 0.004mm2 for root restriction, which was significantly less than control; the thickness of leaf for root restriction and control treatment were 456.8μm and 319.4μm respectively, root restriction also increased the cutin layer thickness, stockade tissue thickness, and sponge tissue thickness. The diameter of leaf main vein and side vein under root restriction were 904.2μm and 756.3μm, which were longer than control treatment; the cross-sectional area of dorsal and central vascular bundle under root restriction were 0.09mm2 and 0.21mm2, the amount of central vascular bundles in grape berry under root restriction was also more than control.4 In terms of the transport and distribution rule of dye stuff in grape berry under root restriction, during phaseⅠ, the dorsal and central vascular bundles were colored mostly under root restriction and control treatments, and the speeds of dye stuff transport in vascular bundles were the highest among three phases of berry development, the speeds for root restriction and control treatment were 1.72cm/h and 1.63cm/h respectively; after phaseⅡ, the distribution of dye stuff decreased under root restriction and control treatments, the amount of colored vascular bundles and speeds of dye stuff transport decreased under both two treatments the speeds in central vascular bundles were 0.72cm/h and 0.70cm/h respectively; during phaseⅢ, the distribution of dye stuff increased under root restriction and control treatments, but lower than phaseⅠ.5 In terms of the changes of unltrastructure of source organs and sink organs, The number of plasmodesmata between companion cell (CC) and sieve element (SE) in minor vein under root restriction is more than control treatment, this showed root restriction promoted the symplast transport in leaf; During the second rapid growth phase of the grape berry, CC under root restriction showed more serious plasmolysis. Cytoplasmic contents such as vesicles were fused into the vacuole of which the tonoplast nearly disappeared in the phloem parenchyma cells, and cytoplasmic contents in fruit cells produced under root restriction became denser than the control treatment.6 Total sugar content of berry under root restriction was higher than that of control berry. The peak concentration of glucose and fructose in grape berries from the control plants was 56.2 and 55.3mg﹒ g-1FW, while concentration in root restriction berries was 65.2 and 62.1 mg﹒g-1FW, which was higher than in control. Acid invertase (AI) activity, which increases with berry development, was significantly higher in root-restricted berries than in control berries. Neutral invertase (NI) activity showed a similar trend to AI, but the amount of NI activity was lower than AI in both treatments. Sucrose phosphate synthase (SPS) and sucrose synthase (SS) activity changed slightly with berry development, and there was no significant difference in SS and SPS activity between root restriction and control treatments. Therefore, AI appears to be the key enzyme induced by root restriction that explains the higher sugar content found in grape berry produced under root restriction.From all above,root restriction decreased leaf growth, but promoted the berry growth. During phaseⅢ, root restriction promoted the berry expanding growth, increased the main nutriment content and AI enzyme activity, these results explain why root restriction could improve berry quality. Root restriction led the change in anatomical structure of root leaf and berry, especially the ultrastructure of the phloem in leaf and berry, these results showed that root restriction changed the anatomical structure of source and sink organs, led to the pathway of photosynthate loading and unloading. Therefore, the findings of the present study may provide a scientific base for promotion of root restriction.