| Acacia cincinnata clone is one of the fastest growing trees introduced into China in recent ten years,and one of the pioneer species for afforestation and site environment improvement in barren mountains.The current introduced Acacia species is still in a mixed stage.The selection of clones is very important,so it is necessary to develop genetic breeding of Acacia cincinnata clones.In this paper,the genetic selection and comprehensive evaluation of the growth traits,wood properties,photosynthetic characteristics,chlorophyll fluorescence characteristics and nutrient use efficiency and other indicators of 15 7 years old Acacia cincinnata were studied.The results are as follows:(1)The results of analysis on the growth characteristics of 15 clones showed that the population of Acacia cincinnata showed a normal distribution,which indicated that the whole stand structure was stable.Secondly,there were significant differences among clones for various traits in many years,and there was abundant genetic variation among clones.The correlation analysis showed that there was a significant correlation among the characters,and the annual correlation showed that the relationship between the early characters of clones was close,and the close type decreased in the later stage.By principal component analysis(PCA),the clones were divided into stable type(ZJ29,Zhong4),ascending type(Tingxia2,SS3,SS2),undulating type(ZJ12,Jin18,NS2)and descending type(SS1,ZJ31,ZJ 17,ZJ 1)clones.According to the correlation analysis,principal component analysis selected the diameter of breast height and volume as the main economic characters of Acacia cincinnata clones.The results of multiple comparison of the two clones showed that the clones with volume and diameter at breast height were selected as follows:ZJ22?ZJ18?Tingxia2?SS3?SS2?Zhong 2?NS2.In addition,the repeatability of DBH and volume was estimated,and the results showed that the mean value of repeatability was between 0.3 and 0.8,which was the middle and high genetic range.The genetic gains are calculated as follows ZJ22,ZJ18,Tingxia2,SS3,SS2,Zhong2 with high volume genetic gain,31.97%,17.58%,7.19%,22.81%,14.35%,respectively.(2)The results showed that the coefficient of variation of each character of the clones was relatively small,which indicated that the characters of the clones were relatively stable.The results of ANOVA showed that there were significant differences in fiber width and wood basic density among clones.Multiple comparison of various wood Properties of clones,the results showed that according to the requirement of pulping,the fiber needs to be slender and the ratio of fiber length to width is more than 30,then there are ZJ29,Tingxia2,SS3,Zhong 4 and Zhong 2 under the pavilion.In addition,the repeatability of wood traits was estimated.The results showed that the repeatability of fiber traits was lower than 0.3,which was low inheritance,and the basic density repeatability was 0.463,which was moderately inherited,with high genetic stability.The correlation analysis between wood quality index and growth index showed that the correlation between wood quality and growth index were not significant.Thus,the average membership function and principal component analysis were calculated for growth and wood properties.The results of the two kinds of analysis were roughly the same.The clones of ZJ22,Zhong2,2SS3,Zhong4 and Jin 18 were selected.(3)Analysis of photosynthetic characteristics and chlorophyll fluorescence characteristics of clones,the results showed that among the four clones,Zhong2,Jin 18,Tingxia2 and SS1 grew well and the net photosynthetic rate was higher.The clones of Zhong2,SS3,Jin 18,SS1 grow well,and the water use efficiency was higher.The clones with lower transpiration rate and better growth include Zhong4,SS3,SS1 and Zhong2.According to the concentration of intercellular CO2,the clones with better utilization of light energy and better growth were SS1,Jin 18 and Tingxia2.Among the chlorophyll fluorescence characteristics,Jin 18,SS3,ZJ17,Zhong2,ZJ18,Tingxia2,ZJ22 have higher SPAD values,showing that the seven clones have strong adaptability to the growth environment and high physiological activity of leaves.PS ? maximum light energy conversion efficiency and better growth of clones were Zhong2,Jinl8,SS3,ZJ22.The potential activity of PS ? was stronger and the clones with better growth were Zhong2,Jin18,SS3 and ZJ22.According to the combined selection of these indexes,the selected clones were approximately the same,that is,Zhong2,Jin18,SS3,ZJ22 were selected for chlorophyll fluorescence and growth.In addition,the correlation analysis between growth and photosynthetic physiology showed that there was a significant correlation between FV/Fo and growth,but there was no significant correlation between other photosynthetic indexes and growth.Finally,the photosynthetic physiological index and growth index were analyzed by principal component analysis,and ZJ31,NS2,ZJ18,Tingxia2,SS1,Jin18,ZJ22 were selected as two excellent clones of Acacia cincinnata.(4)The nutrient physiology of clones was analyzed.The results showed that there were significant differences between clones in the content of C,N,P,K,which indicated that it was feasible to select nutrients among clones.The nutrient utilization efficiency of clones was compared.The results showed that the carbon nutrient use efficiency was higher in the clones ZJ17,ZJ12,Tingxia2,ZJ22,ZJ31,ZJ18,SS3.Carbon nutrient efficiency of selected clones was 48.9%higher than that of unselected clones.ZJ18,ZJ31,ZJ29,ZJ22,SS1 which have higher nitrogen use efficiency,were selected.Nitrogen use efficiency of selected clones was 18.14%higher than that of unselected clones.Phosphorus utilization efficiency was higher in Zhong2,Jin 18,NS2,SS3,Tingxia2,ZJ31 and ZJ17 were selected.P use efficiency of selected clones is 33.16%higher than that of unselected clones.The higher utilization efficiency of potassium was SS3,SS2,Jin18,NS2,ZJ29 and ZJ31 respectively.The use efficiency of the selected clones is 44.16%higher than that of the non selected clones.The correlation analysis between nutrient use efficiency and growth showed that there was no significant correlation between growth and nutrient efficiency.The repeatability of nutrient use efficiency was calculated,and the results showed that the repeatability was more than 0.5,which was moderately genetic.Finally,the membership function method was used to evaluate the nutrient use efficiency and growth traits.The clone of Acacia acacia with high nutrient efficiency and good growth performance was selected,which is Zhong2,SS3,Tingxia2,Jin18,ZJ18,ZJ31,NS2.(5)Finally,through the comprehensive evaluation of the Tingxia2 as a comprehensive total optimal clone.Second,ZJ22,ZJ18,SS3 and SS2 slightly less than Tingxia2,as the medium superior clone.In addition,the improved Analytic hierarchy process(AHP)was used to evaluate the clones of Acacia cincinnata.The results showed that SS3,Zhong2,Jin 18,SS2 and Tingxia2 were selected into the better clones. |
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