Studies On Nutritional Environment And Primary Physiological Characteristics Of Chlorotic Cinnamomum Camphora

The nutrient status and primary physiological characteristics of chlorotic Cinnamomum camphora trees,which were grown in Hefei city,were studied in this thesis.The results were as follows.Difference analysis of soil factors around root systems between healthy trees and chlorotic trees showed that significant difference existed in seven factors,including pH value,organic matter,bulk density,hydrolysable N,available Zn,available Fe and Mn;while the difference in available P,available K,available Cu and S were not obvious. The approach of the variance maximum rotation was adopted to transform eleven soil elements around healthy root systems into seven major factors.The different major factors from 1 to 7 were orderly composed of pH value and organic matter (No1),hydrolysable N and available K (No2),available Cu (No3),available Zn (No4),available Fe and S (No5),available Mn (No6) and bulk density (No7).The contribution value of different major factors from 1 to 7 was 17.24%,15.77%,14.41%,13.95%,13.60%,13.32% and 11.98% respectively,which indicated that,within a certain range,the effects of these different soil factors on healthy trees were almost the same.By the same method,eleven soil factors around chlorotic root systems were transformed into four major factors.And the different major factors from 1 to 4 were orderly decided by pH value,organic matter,bulk density,hydrolysable N,available Zn and Fe (No1);by available P and Cu (No2);by available Mn (No3) and available K (No4).The contribution value from 1 to 4,however,were 50.13%,19.68%,17.87% and 4.60% respectively,which showed that the first major factor with seven soil elements was probably important reason for chlorosis of the trees.The components of four different major factors from 1 to 4 transformed from seven nutrient elements in heathy leaves were Zn,Fe and N (No1);K and Cu (No2);P (No3) and Mn (No4) respectively.And the contribution value of these major factors from 1 to 4 was 41.29%,24.13%,15.76% and 12.90% orderly.By the same method,seven nutrient elements in the chlorotic leaves was changed into four major factors with Zn,Fe and N (No1);Cu (No2);K (No3);P and Mn (No4) being the component of these factors from 1 to 4 orderly.The contribution value of the different factors from 1 to 4 was 44.13%,19.36%,14.76% and 13.66% respectively.It was thus clear that Zn,Fe and N played important roles in maintaining health of Cinnamomum Camphora trees.The results from correlation analysis showed that good correlations were found between nutrient elements content in healthy leaves and these in their soils.As for chlorotic trees,except N,P,K,Cu and Mn,however,litter correlation was found between Zn and Fe content in the leaves and these in their soils.Further analyzing indicated that the lower ratio of Zn/P in the soil was probably an important factor restraining chlorotic trees from absorbing more Zn element from the soil.Meanwhile,higher pH value reduced the activity of iron in the soil to some degree.The other regression analysis was done in the paper.The results were as follows.The accumulation of chlorophyll in the slightly chlorotic leaves was influenced by some soil factors,including bulk density,content of hydrolysable N,available Zn and Fe;The content of chlorophyll in the leaves of secondary chlorosis was related to the more soil factors composed of bulk density,hydrolysable N,available Zn and Fe,pH and organic matter content;The combined action of much more soil factors ,which were bulk density,hydrolysable N,available Zn and Fe,pH,organic matter and available Mn,resulted in serious chlorosis of the trees.In initial growing season during spring,the daily courses of net photosynthesis rate of all kinds of leaves were single peak curves,the maximum rates with maximum PAR (680μmolm-2s-1) being 5.4μmolCO2m-2s-1 (healthy leaves),4.5μmolCO2m-2s-1 (slightly chlorotic leaves),and 1.5μmolCO2m-2s-1 (seriously chlorotic leaves) respectively.In late growing season during autumn,the daily courses of photosynthesis rate were similar to these in initial growing season,the maximum rates with maximum PAR(720μmolm-2s-1) being 8.9μmolCO2m-2s-1 (healthy leaves),4.8μmolCO2m-2s-1 (slightly chlorotic leaves) and 1.4μmolCO2m-2s-1 (seriously chlorotic leaves) respectively.In middle growing season,however,the daily courses of net photosynthesis rate were very complicated.As for healthy leaves,the daily course was double peak curve with two peaks 9.8μmolCO2m-2s-1 and 6.6μmolCO2m-2s-1 occuring at 13:00 and 15:00 respectively.With slightly chlorotic leaves,the daily course was unobvious double peak curve.As for seriously chlorotic leaves,however,an obvious photoinhabition occurred at maximum of PAR with minimum of daily net photosynthesis rate 0.5μmolCO2m-2s-1 .In any growing season,the daily courses of the transpiration rate of all kinds of leaves were single peak curve with that of healthy leaves>slightly chlorotic leaves>seriously chlorotic leaves.