| Eucalyptus cloeziana has a wood value much higher than that of the short circulation period industrial raw material forest.It is called "Australian Dalbergia Odorifera"and is listed as a precious tree species with broad development prospects.The seasonal drought in southern China greatly affects the afforestation survival rate of forest trees,especially fast-growing tree species,and causes serious damage to the growth of young trees.Therefore,water conservation is an important measure to improve the forest growth environment.The microbial super water-absorbent polymer not only has the soil water retaining function of the general agricultural and forestry water retaining agent,but also has the function of decomposing the soil macromolecular nutrients,improving the soil structure and promoting the absorption of the fertilizer by the plant.In this experiment,a new type of microbial super water-absorbent polymer and eucalyptus special fertilizer are jointly applied to the Eucalyptus cloeziaina potted seedlings to improve the soil and reduce the application of fertilizer.Three gradients of microbial super water-absorbent polymer were set:2.5g/strain,5g/strain,10g/strain,which were represented by B1,B2 and B3 respectively;eucalyptus special fertilizer(N:P:K=15:6:9)was set with 3 gradients:50g/strain,100g/strain,150g/strain,respectively,represented by A1,A2 and A3;at the same time,there are three kinds of treatments,such as no eucalyptus special fertilizer,no eucalyptus special fertilizer,super water-absorbent polymer,and no application as comparison.The growth,physiology,photosynthetic index and soil chemical properties of Eucalyptus cloeziana seedlings were determined and analyzed under the conditions of simulated drought,rewatering and re-drying.The main findings are as follows:(1)Application of microbial super water-absorbent polymer and eucalyptus special fertilizer can significantly promote the growth of high-altitude and biomass accumulation of Eucalyptus cloeziana seedlings,but there is no significant difference between the promotion of the two.With the advancement of the experimental stage,B3A2 treatment,The treatment of seedling height and ground diameter was the most effective;the accumulation of total biomass was most obvious under B2A3 treatment;the water content of seedling leaves was the highest under B3A3 treatment;the root activity of seedlings was the highest under B3A1 treatment.(2)Microbial super water-absorbent polymer and eucalyptus special fertilizer can significantly enhance the physiological metabolism ability of the leaves of Euca.lyptus cloeziana.The application of microbial super water-absorbent polymer can significantly promote the SOD and POD activities of the leaves of Eucalyptus cloeziana.The SOD,POD and PPO activities of the leaves of Eucalyptus cloeziana were higher than that of CK,which proved that the application of microbial super water-absorbent polymer promoted the activity of the enzyme resistance of Eucalyptus cloeziana.(3)The application of microbial super water-absorbent polymer and eucalyptus special fertilizer had significant effects on photosynthesis index.The application of microbial super water-absorbent polymer significantly promoted the chlorophyll a,chlorophyll b and total chlorophyll content of the leaves of Eucalyptus cloeziana.Under the same fertilizer level of the same eucalyptus,the above chlorophyll content increased with the increase of the amount of microbial super water-absorbent polymer.Under the same microbial water retaining agent level,the chlorophyll content increased first and then decreased with the increase of the application amount of eucalyptus special fertilizer.The net photosynthetic rate and leaf transpiration rate of the leaves of Eucalyptus cloeziana reached the maximum under the treatment of B2A3;for the stomatal conductance of the leaves,they reached the maximum under the treatment of BOA3.(4)The application of microbial super water-absorbent polymer and eucalyptus special fertilizer significantly promoted the increase of total nutrient(N,P,K)in the potted soil of Eucalyptus cloeziana,and reached the highest in the treatment of B2A2,and the content of available phosphorus and nitrate nitrogen also Under the treatment of B2A2,the content of available potassium and ammonilum nitrogen reached the maximum under B3A2,the content of Ca reached the maximum under the treatment of B3A3,the content of Na reached the maximum under B3A2,and the content of Fe,Cu,Mn and Zn were all in B2A2.(5)The application of microbial super water-absorbent polymer and eucalyptus special fertilizer significantly promoted the absorption of N,P,K,Ca,Fe,Cu,Mn and Zn by Eucalyptus cloezi.ana seedlings.With the increase of the amount of microbial super water-absorbent polymer,the contents of N,P and K reached the maximum under the treatment of B2A3,and the contents of Ca,Na,Fe,Cu,Mn and Zn reached the maximum under the treatment of B2A2.(6)The application of microbial super water-absorbent polymer and eucalyptus special fertilizer had significant effects on soil enzyme activity.The activities of soil urease,soil invertase and soil acid phosphatase were the highest under B2A2 treatment.In summary,the microbial super water-absorbent polymer can reduce the amount of special fertilizer,the subordinate values of the microbial super water-absorbent polymer 10g and the eucalyptus special fertilizer 100g were the highest,and the growth index,root activity,photosynthetic index,and seedlings of the seedlings were the highest.Leaf nutrient and soil nutrient content were at a high level,and plant growth was the best. |
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