Studies On Cambium Activity Rule And Its Response Mechanism In Juglans Regia L

In order to provide a theoretical basis to determine the suitable grafting time, enhance the grafting survival rate and cultivate high quality grafted seedlings of Juglans regia L, one-year-old seedlings of walnut were used as experimental materials to study the active characteristics of cambium with the method of High Performance Liquid Chromatography(HPLC), Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE), xylotomy and Microscopic observation from March of 2009 to November of 2010. The results were as follows:1. The cambium dormant period was in mid-March when the temperature was from 5℃to 6℃, the cambium cell wall was relative thick; the cambium recovery period was from late-March to late-April when the temperature was from 6℃to20℃, the cambium cell wall was thinner and expansion, the cambium cell layers increased from 3-4 to 6-7; The cambium vigorous period was from mid-May to mid-June when the temperature was between 23℃and 27℃, the cambium cell wall was thinner further and the cambium cell layers increased to 11^-12 significantly; from early-July to mid-September when the temperature was between 35℃and 29℃, the activity of cambium was restrained and it became waker, the cell layers decreased to 6-7; the cell layers increased to 8-9 in late-September with the temperature falled down; the cambium transforming period was from early-October to mid-November when the temperature was below 15℃, the activity of cambium became waker, the cell wall became thicker and its size became smaller, and the cell layers decreased from 8-9 to 2-4. The optimum temperature that favored the cambium activity was 23℃²7℃; the suitable temperature was 15℃³2℃; and the other temperature was sub-suitable or unsuitable temperature for cambium activity.2. The contents of endogenous IAA increased rapidly at the cambium recovery period; they were 600 ng/g-652 ng/g at the cambium vigorous period; and decreased rapidly at the cambium transforming period; and reached the lowest level in mid-October, then maintained at about 200 ng / g. The IAA content above 600 ng/g was the indicator of vigorous activities. The contents of endogenous GA3 increased slowly at the cambium recovery period; and increased rapidly to the maximum of 48.47μg/g at the cambium vigorous period; then decreased slowly till late-Augest, and decreased rapidly from the beginning of September to mid-October, it reached the lowest level in mid-October, then maintained at about 3μg/g or so.There was a relationship between the content of endogenous GA3 and the degree of cambium activity, and the the increasing of GA3 content had a hysteresis effect. The change of the content of endogenous ABA showed a double-peak curve, it increased rapidly when the cambium actived prosperous at spring, and reached to the first peak of 3.53μg/g at mid-May; then it decreased gradually with the temperature rising, and dropped to the trough at early July; and increased gradually at early August, and reached to the second peak of 4.07μg/g at mid-September; then decreased rapidly with the temperature falled down and reached to the lowest content. The optimum temperature that favored the cambium activity was from 22℃to 32℃, and the content of ABA was lower at this condition.3. SOD activity in cambium began to decrease at the cambium recovery period, and it was 0.08 OD which was the lowest; it maintained at 0.08 ⁰.15 OD at the cambium vigorous period; then increased rapidly and reached to 0.36 OD at the cambial transforming period, and then entered into the dormant period. POD activity in cambium decreased to 31.40 OD rapidly, and then increased to the peak of 57.48 OD at the growing season, then keeped invariant, from early July to mid-September it decreased to the lowest point of 13.07 OD; then increased to 52.29 OD with the temperature falled down, and entered into the dormant period. CAT activity showed a upward trend of line and reached the maximum of 0.60 mg at the cambium recovery period, then decreased rapidly, and maintained a lower level of 0.20 0.13mg.4. The special protein bands of 76KDa,55KDa,32KDa and 16KDa appeared at different periods of cambium activity: from mid-April to mid-June, the colour of 55KDa,32KDa and 16KDa faded then disappeared; from early July to defoliation, the colour of 55KDa and 32KDa deepened gradually; while the 76KDa and 16KDa changed lately; after late-October, the colour of these protein bands faded and finally disappeared.5. From mid-March to mid-June, the stored starch in parenchyma cells of branches decreased and disappeared; from early-July to mid-September, the starch content increased gradually; from mid-September to the end of September, the starch content decreased gradually; from end of September to mid-November, the starch content increased gradually.