Loquat And Its Different Germplasm Choice Of Different Form Nitrogen Absorption And Utilization Of Features

In order to explore the absorption and utilization character of different form nitrogen of loquat?Eriobotrya japonica Lindl.?, identify nitrogen efficient loquat germplasm and providing scientific reference for nitrogen management in loquat cultivation and explore loquat germplasm efficient in nitrogen utilization, ‘Big Five-Star' and wild loquat seedlings in different provenance were used as material, determined nitrate and ammonium nitrogen absorption kinetics parameters of loquat seedlings root using conventional exhaustion method; determined the effect of six treatments of different forms and ratios of nitrogen in rain preventing culture of soil and sand on ‘Big Five-Star' seedling absorption dynamics, growth situation and root morphological characteristics, photosynthetic characteristics, root and leaf enzyme activity, root activity, nutrition elements content, uptake and utilization efficiency of different organs, main microbial population and number and organic acid content, enzyme activity of rhizosphere soil. Comprehensive compared the absorption and utilization features of nitrogen in different forms and ratios of ‘Big Five-Star' seedling. Authenticated the nitrogen absorption and utilization efficiency characteristics of 10 wild loquat germplasm resources, appraised the uptake and utilization efficiency of nitrogen of these germplasm resources, the following results are obtained.1. In the different concentration and proportion of NH_4⁺ and NO_3^- ion nutrient solution, the rule of the root system of ‘Big Five-Star' seedling was in accordance with the Michaelis-Menten enzyme kinetics equation. No matter how the NH_4⁺ and NO_3^- ion concentration changes, the intrinsic potential and affinity of Loquat seedling root system was to NH_4⁺ absorption and its flow rate in root was larger than that of NO_3^-. Under the condition of pure nitrate supply, the absorption of NO_3^- in loquat was not promoted. In the treatment of different ammonium nitrate supply ratio, with the increasing of ammonium nitrogen, maximum absorption rate?Imax? and root??? velocity of total nitrogen increased significantly in the roots of the ‘Big Five-Star' seedlings, but Michaelis Menten constant values?Km? significantly decreased; with the increasing of nitrate nitrogen, root total nitrogen Imax and ion flow rate??? decreased obviously while Km values increased significantly. Increased the proportion of ammonium nitrogen could promote the nitrogen uptake of ‘Big Five-Star' seedlings root system while increased the proportion of NO_3^--N had an adverse effect on Loquat root nitrogen resorption. Loquat had a preferred absorption characteristics on NH_4⁺-N.2.Loquat root system had characteristics of absorb nitrogen at lower temperatures. From 5 to 15?, with solution temperature increased, root NH_4⁺ absorption rate, NH_4⁺ inflow rate to root and root affinity of NH_4⁺ were significantly increased but decreased when temperature higher than 15?. Loquat roots could absorb NH_4⁺ quickly under lower temperature.Absorptive capacity was strongest at 15? and weakest at 30?, the affinity of NH_4⁺ also reached minimum. At 5 and 10 ?, ‘Big Five-Star' seedling root could not absorb NO_3^-, NO_3^- absorption rate,inflow rate to root and ion affinity were nearly zero but slight increased when temperature rose to 15-30?. NO_3^--N was not the preferred nitrogen source for loquat.3.In soil and sand culture conditions, the plant height, base diameter, biomass weight, root-shoot ratio, root morphology and leaf growth index of ‘Big Five-Star' seedling in treatment of different forms and ratio of nitrogen were significant difference. Increasing NH_4⁺-N ratio could significantly increase plant height, base diameter, weight biomass, root-shoot ratio, leaf width, leaf length, individual leaf area, total leaf area, main root length, first lateral root length and amount, second lateral root length and amount, first and second lateral root densit, total root length, total surface area, volume, average diameter, total tips and fractal dimension. Largest value of indexes mentioned above all appeared at the treatment of 100% NH_4⁺-N; in the mixture treatment of NH_4⁺-N and NO_3^--N, value of indexes mentioned above deceased with the increasing of NO_3^--N proportion, and achieved minimum value at the treatment of 100% NO_3^--N. Indexes value in 100%NH_4⁺-N treatment were all lower than that of mixture treatment of NH_4⁺-N and NO_3^--N. NH_4⁺-N could significantly promote the growth and development of loquat seedling.4.Application of different forms and ratio of nitrogen fertilizer could significantly affect ‘Big Five-Star' seedling's leaf net photosynthetic rate?Pn? and chlorophyll?Chl?, soluble sugar and starch content and size of chlorophyll fluorescence parameters. 100% NH_4⁺-N treatment was most beneficial to promote photosynthesis and improve photosynthetic efficiency of loquat, had highest contents of chlorophyll, soluble sugar and starch and highest value of Pn, PS? light energy conversion efficiency, Fo ', Fm, Fs, Fv '/ Fm, q P, Phi PS2; In the mixture nitrogen treatment,value of indexes mentioned above decreased significantly with the increasing of NO_3^--N proportion and got minimum at 100%NO_3^--N treatment. Different forms and ratios of nitrogen fertilizer had significantly different effect on loquat leaf light saturation and light compensation point and also had obviously effect on roots organic acid, root enzyme activity, leaf and root activity. 100%NH_4⁺-N treatment obviously increased the type and content of organic acid of ‘Big Five-Star' seedling root and activities of glutamine synthetase, alkaline phosphatase, acid phosphatase of ‘Big Five-Star' seedling's leaf and root, so as to root vigor, and had significant difference?p<0.05? with application of CO?NH2?2, NO_3^--N and mixture of NH_4⁺-N and NO_3^--N.5. Organic acids types and content, p H, main microbial population and quantity, enzyme activity of ‘Big Five-Star' seedling rhizosphere soil were obviously different in different form and ratio of nitrogen fertilizer treatments. Oxalic acid in rhizosphere soil was detected in all nitrogen treatment, and had higher content than other kinds of acid. Oxalic acid, tartaric acid, citric acid, malonic acid and total organic acid contents in rhizosphere soilwere highest in the treatment of 100%NH_4⁺-N, Rhizosphere soil in treatment of NO_3^--N only detected oxalate and its content was lower than other treatments, the same as treatment of 100%CO?NH2?2, in that treatment, type and content of organic acid were all the least. Different forms and ratio of nitrogen fertilizer could significantly change the loquat rhizosphere soil microorganism quantity and enzyme activity. Rhizosphere soil in 100%NH_4⁺-N nitrogen treatment with the largest amounts of bacteria, fungi and actinomycetes and decreased with the increasing of NO_3^--N ratio. Protease, invertase, amylase, acid phosphatase, alkaline phosphatasein rhizosphere neutral phosphatase activitysoil achieved their highest activities in 100%NH_4⁺-N treatment and decreased significantly with the increasing of NO_3^--N ratio. CO?NH2?2 treatment was concerned with highest activity of urease. 100%NH_4⁺-N fertilizer treatment increased rhizosphere soil effective content of N, P, Ca, Mg, Fe, Mn, Cu, Zn, but 100%?CONH2?2 and 100%NO_3^--N had no promote effect on effective content of elements above. For available K, 50%NO_3^--N+50% NH_4⁺-N was the best treatment to promote its content, and showed adverse effect when NH_4⁺-N more than 50%.6.In the treatment of 100%NH_4⁺-N, N, P, Ca, Mg, Fe, Mn, Cu and Zn element contents were highest in above ground, under ground and whole plant of ‘Big Five-Star' seedling, but the highest contents of K and B in overground and underground part and total plant of ‘Big Five-Star' seedling were appeared in the treatment of 50%NO_3^--N and 50%NH_4⁺-N. In the application of 100%NO_3^--N, N, P, Ca, Mg, Fe, Mn, Cu and Zn element content in ‘Big Five-Star' above ground, leaf and whole plant were lower than other mixing treatments of N fertilizer. Application of NH_4⁺-N could promote the absorption of various nutrients. Loquat seedling whole plant, above ground and under ground part's nitrogen absorption and utilization efficiency was highest in the treatment of 100%NH_4⁺-N.7. Loquat belong to ammonia plant. There had obviously difference in absorption and utilization efficiency of NH_4⁺-N of 10 wild loquat germplasm resources, among them, the plant-1had the highest absorption rate,affinity of and inflow rate to root of NH_4⁺-N and nitrogen absorption and utilization efficiency was highest. The NH_4⁺-N absorption and utilization efficiency order of 10 wild loquat germplasm resources was plant-1 > plant-2, plant-7> plant-4, plant-5, plant-6 >plant-3, plant-8> plant-9 >plant-10. Relatively speaking, plant-1 was the most efficient genotypes in NH_4⁺-N absorption and utilization in the 10 wild loquat germplasm resources.This article also discussed the interaction relations of growth, physiology and the response of the rhizosphere ecological environment factors of loquat seeding in treatments of different form and proportion of nitrogen, and also analyzed and explored the absorption mechanism and mechanism of loquat efficient absorption and utilization of ammonium nitrogen.