The Research On Flowering And Pollination Biological Characteirstics Of Walnut Varieties Cultivaitng In Xinjiang

In order to learn the biological characteristics about flowering and pollination of walnut varieties inXinjiang, using Xinjiang main cultivated walnut varieties ‘Xinxin2’ and ‘Wen185’ as test materials, on buddifferentiation, pollen characteristics, powders scattering regularities, the stigma receptivity, pollination andfertilization, apomixes and other aspects of the study, the main findings were as follows.(1) The morphological differentiation of female flower buds were divided into: morphologicaldifferentiation early, female flower primordium differentiation stage, bract primordium differentiation stage,perianth primordium differentiation stage and pistil primordium differentiation stage. Differentiation ofmale flower buds were divided into male inflorescence differentiation stage, male flower primordiumdifferentiation stage, sepal primordium differentiation stage, stamen differentiation stage and antherdifferentiation stage. Female and male flower bud spent about one year for completing the wholedifferentiation process, every differentiation stage needed different time, and there were overlappingphenomenon for adjacent stage.(2) The east and south female male flower bloom phenophase of crown earlier than west and northabout1-3days, the upper crown phenophase earlier than lower about1-2days. It spent4days for femaleand male flowering to encounter. but only ‘Xinxin2’ could self-pollination. Male flower bud spent16-20days from enlargement to powders scatter, inflorescence longitudinal diameter were116.63-132.90millimeters and transverse diameter were13.01-16.73millimeters when powders scattered.(3) The optimal solid medium was0.005%boric acid and15%sucrose for ‘Xinxin2’ germinating,the pollen germination rate reached41.51%. It was0.01%boric acid and15%sucrose for ‘Wen185’germinating, and germination rate reached37.98%. The vitality of pollen preserved at room temperaturereached16.60%during3days, lowered than3%after6days. The optimal solid medium group of secondtimes flower in pollen germination was0.001%boric acid and20%sucrose, the germination rate only10.78-18.19%.(4) There were diversity about different varieties pollen morphology, pollen polar axis length were33.55-41.68microns, equatorial axis length were37.78-43.46microns, pollen was nearly spherical or flatsphere, medium pollen, surface ornamentations of pollen was grain shape. The inflorescence pollen amountof ‘Xinxin2’ and ‘Wen185’ were8880200and8765800grain.(5) The male inflorescence powdered lasted for around10days. and powdered centralized scatterabout4days, if the daily mean temperature was20to24℃. Generally, the large powder shedding amountwas in east, south and central position of crown. It all can powder in the range of19to27℃, and theoptimal temperature was20to23℃. It was showed outbreak resistance on powder.(6) The angle and surface mucus were changed gradually when two-lobed stigma in opening process.Female flowers in bag developed earlier. Fruit setting rate was the highest and reached70-100%whenfemale flower bloomed from1to4days. Effective receptive period of stigma was6to7days.(7) In the natural conditions, fruit set rate of ‘Xinxin2’ and ‘Wen185’ reached87.39-90.00%. Indifferent flower pollination, fruit set rate reached the maximum of96.67-97.96%. Fruit set rate couldimprove8.84-10.68%through artificial pollination. The inbred fruit set rate of ‘Xinxin2’ reached72.50%,but ‘Wen185’ was only20.00%.(8) The rate of walnut apomixis was during17.8to58.8%, and contrast nuts were significantlyhigher than the other nuts. Walnut’s ovule was orthotropous, and had monolayer integument. Matureembryo sac belonged to polygonum type which had seven cells and eight nucleus. The two polar nucleusbecame endosperm cells after its fusion by the several times of division, the egg cells became of two cellsproembryo, four cells proembryo, eight cells proembryo and till the multicellular proembryo by celldivisions. Later stage developed into apomixes embryo going through the globular stage, heart-shapedperiod, torpedo-stage period and mature period.