| In south China,Eucalyptus robusta and Acacia mangium produce a large amount of bark waste during processing and utilization.In order to develop and use bark,In this study,Eucalyptus bark and Acacia mangium bark were used as main research objects.Water,alkali,and natural rotting treatments were used to analyze the changes of physicochemical properties of different bark treatments and their effects on the germination of crop seeds.At the same time,the matrix was compounded with mature Eucalyptus bark,decomposed Acacia bark and cow dung as raw materials,and indicators of physical and chemical properties of the mixed substrate and the growth index of Chinese cabbage were used as evaluation indicators,so screen out the bark matrix formula suitable for the growth of Chinese cabbage.The main results are as follows:(1)The processing densities of different barks were in the range of 0.26-0.52g/cm3,the total porosity was in the range of 71.34%-85.84%,the air-water ratio was in the range of 0.96-1.69,and the pH was in the range of 5.4-7.72.EC values ranged from 0.84 to 1.23 mS/cm,and C/N ratios ranged from 34.28 to 94.06.N,P,K and other nutrients were abundant in each treatment.Among them,the gas-water ratio of each treatment is too high,the C/N ratio of the water treatment and the alkali treatment is too high,and the pH of the alkali treatment is too high.This shows that the physical and chemical properties of different bark treatments cannot meet the growing demand of crops,and they need to be compounded with other materials to improve their physical and chemical properties.(2)The density of the compound matrix ranges from 0.28 to 0.39 g/cm3,the total porosity is in the range of 73.89%to 79.44%,the air permeability porosity is in the range of 9.17%to 33.06%,and the water holding porosity is within the range of 45.56%to 64.72%,the ratio of gas to water is in the range of 0.30 to 0.73,the pH is in the range of 6.12 to 6.93,the EC value is in the range of 1.09 to 1.46mS/cm,and the C/N ratio of compound matrix is in the range of 23.14 to 34.01.Inside,various treatments such as N,P,and K are rich in nutrients.Compared with the single bark treatment,the bulk density of the composite decreased,the total porosity increased,and the air-water ratio decreased.The results showed that the decomposed bark,decomposed bark of acacia bark and cow dung decreased the ratio of substrate to air-water,increased the aeration and water holding capacity of the substrate,and the pH reached a reasonable level.The EC value increased and the nutrient content increased,C/N ratio is reduced to a reasonable level.The physical and chemical properties of the substrate are optimized to meet the crop growth requirements.(3)Compared with soil control,the treatment of ripe eucalyptus bark and matured Acacia bark had no obvious effect on the germination rate and germination potential of Chinese cabbage and Brassica chinensis L.The germination rate and germination potential of Chinese cabbage and Brassica chinensis L were affected by water treatment and alkali treatment.The germination indexes of Chinese cabbage in water soaked with fresh bark for 30 days were 76.59%and 70.03%,respectively,which were all greater than 50%.It showed that after 30 days of water soaking,the toxicity of the bark had basically disappeared;the treatment of ripe eucalyptus bark and matured Acacia bark,the germination index of chinese cabbage were 121.21%and 100.28%respectively,the seed germination index of pakchoi were 122.31%and 108.62%,respectively,in the bark of decomposed bark and the bark of decomposed Acacia mangium,which were all greater than 80%.It is believed that the decomposed bark has been non-toxic and has no effect on the germination ability.Compared with the control,the treatment of decomposed bark of eucalyptus and the treatment of decomposed Acacia mangium are beneficial to the growth of root length,plant height,and fresh quality of two kinds of vegetables.The correlations between seed germination and physicochemical properties of bark substrates were analyzed,the results showed that the seed germination rate,germination potential,germination index,and root length increased with the increase of total nitrogen and alkali-hydrolyzable nitrogen content.The higher available potassium and C/N will inhibit crop germination.It shows that the bark of natural rotten eucalyptus bark and natural decomposed Acacia bark can be used directly.When using it,it is necessary to adjust the physical and chemical properties of the bark matrix to facilitate seed germination.(4)In the experiment of compound substrate cultivation,compared with soil co ntrol,Eucalyptus peel:Acacia mangium bark:Cow dung =2:1:1,the emergence rate,stem diameter,leaf length,and aboveground fresh quality,underground fresh qualit y,aboveground dry quality,underground dry quality,vitamin C content,and soluble sugar content increased by 1.18%,6.45%,13.6%,1.97%,1.89%,23.76%,33.33%,12.75%,15.91%,nitrate content decreased 45.87%,chlorophyll content,plant heigh t,leaf number and control no significant difference.The main components of the g rowth index of Chinese cabbage were analyzed,and the emergence rate,plant heigh t,stem coarse,leaf and aboveground fresh weight were the important indexes to ref lect the seedling characters of Chinese cabbage,the main component score and the comprehensive score were calculated,the matrix treatment was sorted,the matrix was favorably to inferior:B6>CK>B4>B3>B5>B1>A5>B2.Therefore,the rotten ripe Eucalyptus peel:Eucalyptus peel:Acacia mangium bark:Cow dung =2:2:1 this ratio matrix planting the cabbage effect best,may act as the seedling growth medium of the cabbage. |
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