| In order to determine an optimum pruning method for adult precocious walnut trees, 10 a walnut trees of Lvling were used as materials to study physiological characteristics of four pruning methods(heavy cutting-back, bending branch, heavy cutting-back with bending branch and natural pruning).The results were as follows: 1. The crown relative humidity of heavy cutting-back,bendingbranch,heavy cutting-back with bending branch and natural pruning were 34.37%,34.09%,33.60% and 36.11% respectively at 12:00 in the middle August, the decreased range of heavy cutting-back with bending branch was the biggest; the crown temperatures of these four pruning methods was 38.69℃,40.28℃,40.43 ℃and 38.30 ℃respectively, and that of heavy cutting-back with bending branch was the biggest; the crown illuminations of these four pruning methods were 53380 lx、61422 lx、86800 lx and 42088 lx respectively, and that of heavy cutting-back with bending branch was the biggest. 2. The crown net photosynthetic rates of these four pruning methods were 5.18 μm ol·m-2·s-1,7.27 μmol·m-2·s-1,8.22 μmol·m-2·s-1 and 2.54 μmol·m-2·s-1 respectively,and that of heavy cutting-back with bending branch was the biggest; the transpiration ra tes of these four pruning methods were 2.69 μmol·m-2·s-1,2.97 μmol·m-2·s-1,3.33 μm ol·m-2·s-1 and 2.39 μmol·m-2·s-1respectively,and that of heavy cutting-back with ben ding branch was the biggest; the stomatal conductances of these four pruning metho ds were 0.19 mmol·m-2·s-1, 0.21 mmol·m-2·s-1,0.24 mmol·m-2·s-1 and 0.16 mmol·m-2·s-1;the intecellular CO2 concentrations of these four pruning methods were 270.00μmol·mol-1,257.33 μmol·mol-1,233.00 μmol·mol-1 and 286.67 μmol·mol-1,the decreesed range of heavy cutting-back with bending branch was the biggest. 3. The Fv/Fm values of these four pruning treatments at 7:00 were 0.86,0.863,0.87 and 0.848 respectively,and those of the other three pruning treatments reached the lowest values at 13:00 except that heavy cutting-back reached the lowest value at 15:00, and those of the lowest value of these four pruning treatments was 0.843,0.842,0.837 and 0.846 respectively,the decreased range from high to low was heavy cutting-back with bending branch,bending branch, heavy cutting-back and natural pruning; the daily Fo average values of these four pruning treatments were 186.87,184.52,201.83and183.64 respectively,and that of common pruning(heavy cutting-back with bending branch) was the biggest; the ETR values of these four pruning treatments were 3.08,3.33,3.28 and 3.52 respectively at 8:00, and that of these four pruning treatments reached 7.79,8.10,8.17 and 7.66 at 11:00 respectively, and the decreased range of these four pruning treatments from high to low was heavy cutting-back with bending branch, bending branch, heavy cutting-back and natural pruning. 4、Whether it was sunny or cloudy day, sap flow velocity variation of natural pruning was the biggest in all the treatments, which was 6.63 cm·h-1, next were bending branch and heavy cutting-back, which were 4.80 cm·h-1 and 4.03 cm·h-1, and that of heavy cutting-back with bending branch was the smallest, which was 2.76 cm·h-1; with the pruning degree rising, leaf water potential variation increased, but the whole day leaf water potential also increased: predawn leaf water potentials of the four treatments from high to low were heavy cutting-back with bending branch(-0.355 MPa), heavy cutting-back(-0.410 MPa), bending branch(-0.494 MPa)and natural pruning(-0.603 MPa), the day average leaf water potentials of the four treatments from high to low were heavy cutting-back with bending branch(-0.879 MPa), heavy cutting-back(-0.880 MPa), bending branch(-0.881 MPa), and natural pruning(-0.917 MPa), walnut leaf water potential variations of the four treatments from high to low were heavy cutting-back with bending branch(0.299 MPa), heavy cutting-back(0.258 MPa), bending branch(0.231 MPa) and natural pruning(0.159 MPa); walnut leaf water losing rates of heavy cutting-back, bending branch, heavy cutting-back with bending branch and natural pruning were 7.27%,7.10%,6.75% and 6.77%, respectively, there were no significant differences among the four treatments; walnut leaf relative water deficits of heavy cutting-back, bending branch, heavy cutting-back with bending branch and natural pruning were 34.87%,35.14%,35.13% and 39.83%, respectively, those of the former three treatments were significant lower than that of natural pruning, and there were no significant differences among the former three treatments; leaf water use efficiency of the four treatments were 1.50 μmol/mmol, 1.69 μmol/mmol, 1.93 μmol/mmol and 1.30 μmol/mmol respectively and that of heavy cutting-back with bending branch was significant higher than that of natural pruning, there were no significant differences of leaf water use efficiency among heavy cutting-back, bending branch and natural pruning. 5、The number of shoots of these four pruning treatments were 32.33,22.67,26.67 and 12.67, and that of heavy cutting-back with bending branch was the biggest; 6、Root activities of these four pruning treatments were 193.22 μg·g·h-1,181.53μg·g·h-1,231.65 μg·g·h-1 and 150.60 μg·g·h-1 respectively, and that of heavy cutting-back with bending branch was the highest. 7、Nut weights of these four pruning treatments were 11.16 g,10.53 g,12.22 g and 11.58 g respectively, and that of heavy cutting-back with bending branch was the highest; the yields of these four pruning treatments were 129.36 kg/667 m2,154.44 kg/667 m2,155.32 kg/m2 and 97.24 kg/m2 respectively, and that of bending branch was the highest, next was bending branch;kernel oil content s of these four pruning met hods were 65.43%、67.55%、68.52% and 64.77% respectively; kernal total protein c ontents were 20.68%、21.23%、21.77% and 19.83% respectively; the soluble protein content of these four pruning methods were 2.16%、2.23%、2.27% and 2.11% res pectively, and these three items of heavy cutting-back with bending branch were all the highest ones among all the treatments. |
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