Current Shoot Length Research Articles

Relationship between the Growth of Current Shoot and the Development of Inflorescence and Vegetative Buds in Oncidesa Gower Ramsey ‘Honey Angel’ Leaf Axils

The flowering control of Oncidesa Gower Ramsey ‘Honey Angel’ is important and in-demand by the industry. Therefore, an understanding of the development of inflorescence and vegetative shoot from the leaf axils on the current shoot is required. The internode of a young Oncidesa current shoot between the 0th (at the base of the pseudobulb) and 1st (immediately above the pseudobulb) nodes can enlarge to form a pseudobulb, and the axillary bud on the 0th or -1st (immediately below the 0th node) node can differentiate into an inflorescence bud. The axillary buds on the lower nodes (-2nd to -4th nodes) can remain vegetative. In this study, we investigated the growth and anatomical features of axillary buds at various stages during the growth of the current shoot. We sampled the axillary buds on the 0th to -4th nodes from the current shoots when they were 10, 15, 20, 25, and 30 cm in length for sectioning and anatomical observations. Vegetative buds on the -2nd to -4th nodes grew faster and had more nodes than the inflorescence bud when the current shoot grew from 10 to 25 cm. However, when the current shoot elongated from 25 to 30 cm, the length and node number in the inflorescence bud on the 0th node increased and the inflorescence branch primordia were observable. The length and node number of the inflorescence bud became the same as that of the vegetative buds, which had no further growth, whereas the current shoot grew from 25 to 30 cm. The pseudobulb began to emerge from the leaf sheath (unsheathing) when the current shoot had reached 30 cm in length. Therefore, the time when the pseudobulb started to unsheathe from its subtending leaf was critical for the reproductive growth of Oncidesa Gower Ramsey ‘Honey Angel’ when growth acceleration of the inflorescence bud occurred. Evaluating the current shoot length can be a nondestructive method of estimating the developmental stage of the inflorescence bud.

Growth of regenerated tree seedlings associated with microclimatic change in a mature larch plantation after harvesting

In order to further develop methods of sustainable forest management, we evaluated the effects of logging practices during the winter on microclimatic factors and growth of four seral deciduous broad-leaved tree seedlings regenerated in a larch plantation in northern Japan. We found that winter logging practices drastically changed microclimatic factors, especially in terms of light intensity and the vertical distribution pattern of CO2 concentration. Harvesting overstory larch trees increased photosynthetic photon flux (PPF), which may enhance the photosynthesis of understory plants. We examined the undergrowth for tree seedlings of the following species: two late successional species, Prunus ssiori and Carpinus cordata; one gap phase species, Magnolia hyporeuca; and one mid-late successional species, Quercus mongolica var. crispula. All of the four studied tree species responded well to the practices of winter logging after the second year of harvesting overstoried larch trees. The current shoot diameter and current shoot length increased significantly. Therefore, we conclude that winter logging practices should improve shoot growth of deciduous broad-leaved tree seedlings regenerated in a larch plantation through the change in environmental factors that accompanies larch harvest.

Ｙ字形棚整枝と主幹形整枝リンゴ樹‘ふじ’の乾物生産と器官別分配の比較

The dry matter production and assimilate partitioning ratio (APR) in each organ of 'Fuji' apple trees on M. 26/Marubakaido (Malus prunifolia var. ringo Asami) trained to a Y-trellis system were compared with those trained to a central leader to make clear the reason of superiority of trees trained to the Y-trellis in yield.1. No significant differences in current shoot length, shoot number, and leaf area index (LAI) were found between trees trained to the two training systems. The yield of the Y-trellis trained trees was 6, 945 kg/10 a, which is 22% higher than that of the central leader trained trees.2. The dry matter production of the Y-trellis trained trees was 2, 417 kg/10 a, or 23% heavier than that of the central leader trained trees. The fruit dry weight in the former was 1, 198 kg/10 a, or 43% heavier than that in the latter; the APR into fruit were 49.5% and 43.1%, respectively. The APR into the current shoot and older wood of the former were lower than those in the latter.3. There were significant positive correlations between the dry matter production and the current shoot length, LAI, and yield. The APR into fruit was positively correlated with the crown density, whereas it was negatively correlated with current shoot and older wood.4. We conclude that more efficient dry matter production and higher assimilate partitioning ratio into fruit of the Y-trellis trained trees gave rise to the superior yield over the central leader trees.

Shoot-length frequencies in black birch (Betula lenta)

Lengths of all parent and current shoots were measured on three 8- to 10-year-old black birch (Betulalenta L.) trees with branches <8 years old. Older branches had more short shoots (<1 cm long) and shorter long shoots (>2 cm long) than younger branches. Parent long shoots produced three to nine basal short shoots. Observations on short-shoot production were consistent with the hypothesis that only buds with adequate nutrition formed long shoots. Three growth rules were developed for a model that simulated individual branch growth: (i) a regression predicting lateral shoot number from each parent shoot length; (ii) probabilities for the number of short shoots produced by a parent shoot based on the total number of current shoots produced per parent shoot; (iii) a regression predicting current shoot length from parent shoot length, current shoot position (longest to shortest), branch age, and main-axis elongation in the current and previous year. Simulations of 81 branches using these rules predicted shoot numbers and total shoot lengths close to those of the actual branches (R2 = 0.73–0.84).

Growth of Current Shoot Populations on White Pine Branches: Test of a Model

WILSON, B. F. (Dept. Forestry and Wildlife Management, Univ. Massachusetts, Amherst, MA 01003). Growth of current shoot populations on White Pine branches: Test of a model. Bull. Torrey Bot. Club 117: 215-220. 1990.-Data from 49 8-year-old eastern white pine (Pinus strobus L.) branches were used to test a model which generates current shoot-length frequency distributions. The numbers and lengths of current shoots from parent shoots of all 1 cm length classes were determined. In the first simulation of each individual branch growth the annual elongation of the main axis for each year was specified for each branch; other population growth variables did not change from year to year. In simulated, compared to real, populations: total shoot numbers and lengths were similar (R2 of 0.60 and 0.66 respectively), but were overestimated in small branches and underestimated in large branches; shoot-length frequencies were similar except in the short length classes where the 1 and 2 cm classes were underestimated and the 3 cm class overestimated; and the number of long shoots was overestimated when annual elongation of the main axis decreased rapidly. A second simulation of each branch accounted for annual differences in terminal shoot elongation related to changes in elongation of the main axis. This simulation reduced, but did not eliminate, the systematic errors.