| Pear pruning is a by-product of the winter pruning process of pear tree. It’s an effective way to recycle the nutrients in prunings by pruning-composting technology to increase the organic matter in pear orchard. In our research, by analyzing the content of mineral nutrients in the prunings of Yali pear and Huangguan pear, we found a large amount of mineral mineral nutrients would be removed from the tree. If the nutrients could not be effectively returned to the soil, it would lead to a serious waste of nutrient resources. However, the lignin of pear prunings is difficult to degradate. In order to solve the problem, colorful reactions of guaiacol plates and decolorizations of Aniline blue plates were adopted to isolate lignin-degrading strains, and then by enzymes activities test and solid pruning degradation test, the excellent strain were selected with the highest lignin-degrading enzymes activities and the strongest ability of pruning lignin-degradation. In addition, a field experiment was carried out to study the effects of pruning-composting on the soil property, fruit yield and quality. The results are as follows:1. There are significant differences in the different age of pear tree shoots. The contents of each element were reduced with the increasing age of the pear shoot except Ca, Fe and Cu. For two varieties of pears, N, P, and K content in one-year shoot were18-129.9%,29.5-165.8%and19.8-63.2%higher than the other age of shoots, respectively. The content of mineral nutrition elements was Ca>N>K>Mg>P>Fe>Zn>Cu. The total amount of elements removed by the pruning was155、60.3、32.9、8.12、5.47、0.92、0.17and0.14kg·hm-2, respectively. The ratio of total N, P and K amount removed from the tree by pruning was6:1.1:4. The total amount of N and P removed by pruning from the tree was similar between the two varieties, while the total amount of K, Ca, Mg, Fe, Zn and Cu removed from Yali pear tree was higher than that in Huangguan pear tree.2.6lignin-degrading strains were isolated including four fungi and two bacterias. All the4fungi could secrete Lac, Color zones could show in1-2days on the culture medium of guaiacol plates post inoculation, and the color zones diameter could reach7cm within10days after inoculation. All the selected6strains coule secrete Lip and Mnp. Decolorizations of L2by Aniline blue plates showed at the second day after inoculation, but3-4days was needed for the other strains. All the diameter of fade zones of the selected fungi were bigger than7.5cm. The fade zones diameter of X7and L2were7mm and20mm as two bacterias. The results of the liquid fermentation test carried out by strains showed that:4fungi selected showed strong ability to produce Lac, Lip and Mnp, and D8showed the strongest ability to produce Lac and Lip among them, the largest enzymes activities were13.05and47.53U·mL-1respectively. D10showed the strongest ability to produce Mnp, the largest enzymes activities were152U·mL-1. L2was a bacteria that showed a stronger ability to produce Lip and Mnp, the largest enzymes activities were21.7and106.3106.3U·mL-1of this two enzymes respectively. The solid fermentation test carried out by the6strains showed a similar result with the results of enzyme activity assay, colorful reactions and decolorizations of plates.3. The effects of pruning-compost on soil property, tree growth and pear yield were showed as follows:Pruning-composting could increase the soil microbial quantity during the whole growth period compared to the treatment of fertilizer, especially in the first and second expanding stage of pear. Pruning-composting could improve bacteria and fungi quantity during the first expanding stage of pear in comparison with the treatment of sheep manure, and the effect is more obvious by adding Bio-organic fertilizer (BIO). The content of soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) showed the same change trend with the soil microbial quantity. To compared with the treatment of fertilizer, both of sheep manure and pruning-composting could improve the content of SMBC and SMBN during the whole growth period. The treatment of pruning-composting showed a higher content of SMBC than the treatment of sheep manure during the first expanding stage of pear. The effects were more obvious by adding of BIO. The content of soil mineral nitrogen of pruning-composting treatment was lower than that of sheep manure treatment, but higher than that of fertilizer treatment; the gap gradually decreases with the development of the growth period. Pruning-composting had no significant effect on pear growth and fruit development. |
PDF Full Text Request