| The cold type wheat (CTW) is idea germplasm resource because its leaf has a longer function period,higher chlorophyll content,higher transpiration rate and higher net photosynthesis rate,its root prospers,and meanwhile it has the good physiology characteristics under rainy and drought weather.At present,more studies on cold type wheat focus on the aspect of ecophysiology.The aim of this study is to open out the structure difference of different organ and leaf structure change under more water and drought conditions in grain-filling period between cold type wheat and warm type wheat (WTW) .The leaf structure characteristic in anthesis and dynamic change in grain-filling period were studied by means of temporarily preparing slice method and paraffin wax section method.The results reveal no significiant difference in size and density of leaf epidermis stomatal apparatus between CTW and WTW. Compared with WTW,CTW has shorter mesophyll cell,more cell layers, higher cell density,thinner leaf,larger vascular bundle transverse area and shorter interval between veins.In filling midterm and finalphase, chloroplasts disappearing rate in mesophyll cell is slower.In anthesis,more peculiar shape chloroplasts in mesophyll cell were observed under electron microscope ,ectoplast of which form outer cauda,some of which form vesiclewith monolayer membrane and solute and the other form chloroplast proplastid which develops new chloroplast at last.The percent of grana lamellae which is less than 10 is lower(CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 29.7%,21.1 % and 19.7%.WTW NR9405 respectively is 48.7%,32.1% and 20.1 %),chloroplast inner membrane system is more complex,plasmodesma in vascula bundle cell is more.The stem structures of CTW in grain-filling period were studied with paraffin wax section method.The results indicate that vascula bundle number of CTW is more compared with near spike grains. The vascula bundle number in unit stem transverse area and the rate of the total area of vascula bundle and stem transverse area is higher(CTW 1st internode below the ear average respectively is 22.7and8.5%, 2nd internode below the ear average respectively is 14.3 and 6.8%. WTW 1st internode below the ear average respectively is 20.0 and 7.4%, 2nd internode below the ear average respectively is 11.0 and 5.9%). In grain-filling period,the chloroplast disintegrate rate is slower.The starch grain shape in endosperm cell and the ultrastructure of caryopsis ventral canal in grain-filling final period were studied with optics and electron microscope .The results are : the large size starch grain number is more in endosperm cell of CTW,and the starch grain diameter clearly magnify from filling midterm to finalphase.In grain-filling final period,compared with WTW,the CTW grain ventral canal pigment strand cells have more cell organs ,cytoplasm, plasmodesma and fewer lipoid and tannin deposition.Thecell wall thicken no clearly.The seminal root and secondary root micro structure of CTW were observed with barehanded section method,the results indicate:the CTW root have many characteristics contrasted with WTW,the cortex of seminal root is thicker,the stele and vessel transverse area is larger,the vessel total number of secondary root is more.The CTW leaf structure and structure change characteristics were studied under drought and more water conditions ,and grana lamellae and grana amount in leaf chloroplast were counted,the results are: under the drought and more water conditions,the percent of grana lamellae which is more than 20 in CTW leaf chloroplast is clearly higher(under drought condition,CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 35.3 % ,23.1 % and 43.3 %. WTW NR9405 respectively is 17.8 % ,15.5 % and 39.4 %. under more water condition,CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 23.2 %,34.5% and 25.9%.WTW NR9405 respectively is 17.7%,17.4% and 18.6 %),and the percent of grana lamellae which is less than 10 is clearly lower(under drought condition,CTW shan229 fl... |
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