Mechanism Of Water Transportation And Distributing With Partial Rootzone Irrigation In Apple

In this test, a new economize irrigation technology-Partial Root zone Irrigation was studied. It studied the theory of water transportation and distributing conditions in partial root zone irrigation in apple. Using three-year pot apple trees called Royal Gala with their roots equably partitioned by a compound basin, which is band by four plastic basins with 20cm in both length and width and 36cm in height. The test designing of the three methods: (1) sandy clay, 1/4 root zone irrigation with deuterium-oxide (irrigating one fourth of the root); (2) loam, 1/4 root zone irrigation with deuterium-oxide; (3) loam, 2/4 root zone irrigation with deuterium-oxide (irrigating two fourths of the root zone); water amounts of irrigation is 750mL per basin. The effects of partitioned root irrigation on soil water potential, leaf water potential, stomatal conductance, transpiration rate and net photosynthetic rate, were studied under 3 different treatments. It proved the mechanism of water transportation in apple, landscape orientation transport of water existed in roots, the ability of root water uptake and apple moisture in the distribution of various organs. The results showed that:1. It is different that the impact of different irrigation to soil water potential and leaf water potential. The soil water potential and leaf water potential were increased with 1/4 Root, 2/4 root and 4/4 root volume of irrigation water treatment. The greater volume of water, more soil moisture, soil water potential higher and leaf water potential is high, the more beneficial plants absorbing moisture from the soil. Soil water potential and leaf water potential of 1/4 root volume of irrigation water treatment is significantly lower than the 4/4 root volume of irrigation water treatments, and it is not significant difference between the soil water potential and leaf water potential of 1/4 and 2/4 root volume of irrigation water treatment. It is no differences that the impact of soil water potential and leaf water potential between deuterium-oxide irrigation treatment and general water irrigation treatment.2. It has a marked impact of stomatal conductance, transpiration rate and net photosynthetic rate with the same volume of water in different irrigation district irrigation on the root of Apple. The same amount of water, irrigation smaller size, apple's stomatal conductance, transpiration rate and net photosynthetic rate the lower. Apple's stomatal conductance, transpiration rate and net photosynthetic rate of 1/4 root volume of irrigation water treatment is significantly lower than the 4/4 root volume of irrigation water treatment's, and it is not significant difference between the apple's stomatal conductance, transpiration rate and net photosynthetic rate of 1/4 and 4/4 root volume of irrigation water treatment. It is no difference that the impact of apple's stomatal conductance, transpiration rate and net photosynthetic rate between deuterium-oxide irrigation treatment and general water irrigation treatment.3. When irrigation deuterium-oxide, apple root quickly absorb moisture and above-ground transportation. When irrigation water , the deuterium-oxide abundance of absorbing root first reached the maximum, followed less than 2 mm in diameter root, root diameter of 2-5 mm, larger than 5 mm in diameter roots, rhizome, trunk, the central stem, annual branch, new shoot, and leaves deuterium-oxide abundance has reached the maximum, it shows that water level by level uphill .transport to the leaves from absorbing root. With the passage of time, to reduce soil moisture, soil water potential decreased, the roots absorb moisture from the soil to increase the difficulty, apple plant in the various organs of deuterium-oxide abundance are gradually reduced, but it is different to reduce the trend, the deuterium-oxide abundance of leaves, rhizome and root to quickly lower the maximum, and then reduce the trend tends to slow; and deuterium-oxide abundance of new shoot, annual branch, the central stem and trunk decrease in wave, in irrigation 96 hours after the rapid decrease. Transpiration by the impact, the deuterium-oxide abundance of leaves, absorb moisture and less than 2 mm in diameter root to be significantly lower than all other organs of the Apple.4. It is clear impact to apple root absorbent capacity with the same volume of water in different irrigation treatment. The less the volume of water, soil water potential the lower, plant water stress by the stronger, the stronger root absorption capacity. The results showed that the root absorption capacity of 1/4 root volume of irrigation water treatment is obviously stronger than the 2/4 root volume of irrigation water treatment, and the root continued ability to absorb water of 2/4 root volume of irrigation water treatment is stronger than the 1/4 root volume of irrigation water treatment. The maximum deuterium-oxide abundance of absorbing root with the maximum deuterium-oxide abundance when the time for irrigation is basically the same, it shows root can be completely absorbed deuterium-oxide, it is no effect deuterium-oxide to the root absorption capacity.5. There is landscape orientation transport of water existed in roots with partial root zone irrigation in apple. When irrigation deuterium-oxide, water landscape orientation transport from the root of irrigation to the root of no irrigation, there is no significant difference in the amount and time that water landscape orientation transport from the root of irrigation to the no irrigation root. With the passage of time, the water of landscape orientation transport from the irrigation root to the no irrigation root is less and less. The root with no irrigation, water step by step transport to absorbing root through larger than 5 mm in diameter roots, root diameter of 2-5 mm and less than 2 mm in diameter root. It is obvious differences landscape orientation transport of water existed in roots with different size of irrigation, transported water quantity of 2/4 root of the volume of irrigation is higher than the 1/4 root of the volume of irrigation.6. Water distribution is not the same in various organs in apple where different degrees of drought in the soil. In the initial period after irrigation, the water of root is the most. With the passage of time, the moisture content of the root is gradually reduced, and the moisture content of other organs in apple is gradually increased. By the impact of the transpiration, leaves the water content is to quickly lower then it up to the maximum. Afterwards, the soil is increasingly arid, and leaf transpiration and the stomatal conductance are decreased, so leaves and roots of water are gradually increase, and other organs (rhizome, trunk, the central stem, annual branch and new shoot) water content is significantly reduced. Go a step further, the toot water content is increased significantly when soil serious drought. It shows water supply preferential to growth of above-ground in plant when the soil moisture is high, but water supply preferential to root growth and survival when water stress is severe.