Genetic Variation Of Traits In Relation To Yield Among Populus Clones During The First Year

This paper uses rooted cuttings of 9 genotypes of sections Aigieros of Populus in acontrolled pot test which were put in the field as the research object. We systematicly studiedgenetic variation patterns of the phonological traits, morphological traits, gas exchangecharacteristics, leaf development characteristics, root-crown ratio and micro-traits by using aLi-6400 portable photosynthesis system equipment, a LI-3000C portable area meter,Anatomical method, resolvable sugar and starch measured method and SPAD portable meter.Then we use the data of all these traits to do correlation and regression analysis in order toknow which traits were kept by superior clones, and whether these traits can be used as thecriteria to select good clones, this traits can be useful for the future MAS breeding program.The pot test results showed that:(1) Yield traits of 9clones presence significant difference. The fast growing clones whichwere used very commonly in the field got higher height, basal diameter and biomass contrast toslow growing clones. The fast 4 growing clones are clones: 107, 108, 111 and Por, While theslow growing clones are Be and 113. Biomass showed significantly correlation with height,basal diameter and stem volume index. Results here have confirmed that height, diameter andstem volume index are indicative of yield.(2) There was much different in the 8 phenological phases among the 9 clones, especiallythe phenological phases at the late growth stage. The different stages at the later phenologicalphases could be as a reference for early selection of poplar clones. But the biomass the clonesare harvested during the high growth effienicy in the high growth period. This result alsoshowed the growth efficiency is an important index for selection superior clones.(3) The 7 morphological traits and 2 indirect traits of leaves showed significantlydifference just besides leaf water content. The specific leaf area exists difference between 9clones, but the genetic heritability is low. The radiation has a strong positive effect on leaf size,leaves in the upper canopy are larger than the leaves in the lower canopy, and the petiole lengthand diameter is also superior in the upper canopy than leaves in the lower canopy. The leaflength, leaf width and leaf area of the upper canopy is more appropriate as a selection index.(4) As the leaf development characteristics, total leaf area, leaf expansion rate, leafproduction rate, the length between two leaves and the total leave number all can be used as a reference index to superior clone selection.(5) The root-crown ration showed that appropriate photosynthesis production allocate isvery important to plant development. The ratio is too high or too low is not good to plantgrowth and development. Appropriate root-crown ratio can be used as the index for superiorClone selection.(6) The gas exchange parameters result showed that just the means of net photosynthesisof different leaf location can be the index for superior clone selection breeding program,superior clones haven't show good result in other parameters. The result also showed that thereis no significant correlation between net photosynthetic rate and water use efficiency, so it ispossible to select high yield and high water use efficiency clones.(7) The fast growing clones have the characteristics: more stomatal in the adaxial leaf,stomatal is smaller, the number of stomatal in adaxial side/abaxial side is more bigger,Epidermal cell area is bigger, Epidermal cell number per leaf is greater, the palisade tissue ismore thicker, the leaf cell has more cholorphll body and cholorphil body is more smaller.(8) There is no difference between the non-structural carbon-hydrate content of the cuttingbefore planting. And TNC have no linear correlation with number of shoot per cutting, but dryweight per shoot has correlation with TNC and number of shoot per cutting. TNC can affectthe dry weight of shoot, so it is very important for the early growth of shoot.(9) We can use the SPAD to speculate the cholorphll and nitrogen content. But there is nodifference of the SPAD value between the clones. The SPAD value of leaves exits differenceby different leaf location and season. So when use the SPAD value to forecast the poplarproduction and the cholorphll content and nitrogen content we should be caution.