The Relationship Between Canopy Microclimate,Fruit Yield And Quality Of Different Planting Densities In Korla Fragrant Pear

To grasp the relationship between different planting density of pear microclimate change chara-cteristics and with the yield and quality of Korla Fragrant Pear,of 6 different planting densities of Korla Fragrant Pear orchard crown structure,microclimate,photosynthetic fluorescence parameters,yie-ld and fruit quality were measure and analyzed.The results show that?1? The plant height of 5.0m×6.0m Korla Fragrant Pear was high,the canopy diameter and ind ividual tree crown volume were maximum,the leaf area index?LAI?,orchard coverage rate and orcha-rd canopy volume were large;while these indicators showed the lowest value in the density of 3.0 m×5.0m.There was no significantly difference in individual tree crown volume between 5.0m×6.0m, 5.0m×8.0m and 6.0m×7.0m,and there was a very significant difference between 3.0m×5.0m.6.0m×7.-0m LAI maximum,and there was a very significant difference with other density;4.0m×6.0m LAI minimum,only 2.3.2.5m×7.0m orchard canopy volume was the large st,reaching 1998.19m³/666.7m2, 6.0m×7.0m only 1050.36m³/666.7m2.5.0m×8.0m leaf area and hundred leaf weight were largest,the maximum numoer of new snoots,tnere were significant differences with otner density. ine new sno-ots of 5.0m×6.0m were the longest,reaching 118.64cm,the new shoots of 4.0m×6.0m were the shor-test,as 80.25cm.?2? The light intensity at different direction showed a regular change in a day.In 8:00?12:00,th-e light is mainly on the east, south and north.In11:00-1/:00,the light is mainly on the west In the middle of the tree canopy,the light is the weakest and the most even in a day.Under the different planting density,the reality photosynthetic ayailable radiation?PAR? of Korla Fragrant Pear canopy showed a trend which "increased first and then tend to decrease".The average relatrve PAR at 4.0-m×6.0m was nignest,the one at 2.5m×7.0m ayerage relative PAR. was lowest.unuer the same gap b-erween every two piants and me same gap between every two lines,the larger the crown is, the g-reater of the LAI. inereiore,tne PAR and LAI in the canopy of Koria rragrant rear relate to the planting density the canopy diameter,the canopy position and canopy height.?3? The different planting densities of Koria Fragrant rear canopy lemperaiure and numidily i-n central difference less man canopy outside.The relative temperature on upper level in the canopy was higner man than on lower ievei;tne relative numiaity, on upper level in the canopy was less t-nan that on lower level, ine difference of temperature and numiaity in me same canopy was less than the difference between the temperature and humidity of the canopy.The temperature of the ca-nopy was the higher in the west and north,the humidity was the smaller.The central temperature w-as lowest and the humidity is biggest.Difterent directions and high air temperature relative duty c-hange roughly "first increased and then decreased" trend,the diurnal variation of air humidity was "first decreased and then increased trend. Diurnal of relative temperature is "single peak" curve,th-e relative humidity on diurnal showed "high low high" rules.?4? There were significant differences in photosynthetic fluorescence parameters of Korla Fragr-ant Pear among the different planting densities.The net photosynthetic rate?Pn? of 3.0m×5.0m was maximum, Pn and photochemical quenching?qP? of 5.0m×6.0m was minimum.Pn and stomatal cond-uctance?Gs? and transpiration rate?Tr? were "double peak" curve,the intercellular CO₂ concentration ?Ci?,water use efficiency?WUE?,maximal fluorescence?Fm?,maximal efficiency of primary conversion of light energy of PS??Fv/Fm? and maximal potential of primary conversion of light energy of PS? (Fv/Foj was the trend of first decreasea men increased.Stomatal limitation value?Ls? and act-ual photochemical elliciency of PS? ??PS?? change thelaw was not the same. Planting density h-as a great influence on photosynthesis.The Pn of Korla Fragrant Pear were highest under the plan-ting density of 3.0m×5.0m and 6.0m×7.0m,and the lowest under the planting density of 4.0m×6.0-m and 5.0m×6.0m.The inhibitory ability to light were:2.3m×7.0m>5.0m×6.0m>5.0m×8.0m>4.0m×-6.0m>3.0m×5.0m>6.0m.?5? Fruit yield of the 6 different planting density orchard increased as the increase of planting density,and there were significant differences in the yield of different planting density orchard.The tree structure of planting aensity of 5.0m×6.0m ana 4.0m×6.0m were well,tne orcnara population structure were more rational,got more adequate photosynthetic area;One day,the canopy temperature and humidity and PAR changes were small,and the canopy was evenly distributed,which was cond-ucive to the balanced distribution of fruit yield and quality in the canopy;light compensation point ?LCP?and light saturation point?LSP?,CO₂ compensation point?CCP?and CO₂ saturation point?CSP?sho-wed lower,had stronger adapt capacity for low light and low-concentration CO₂.This resulted in th-e maximum fruit weight,medium yield,higher soluble solids content and total sugar content,and lo-w fruit hardness.So,we primary determined that the 5.0m×6.0m and 4.0m×6.0m were the ideal plan-ting aensity in the 6 planting aensity orcnara of Koria Fragrant rear.