Search

ブドウサンショウ樹を切り返しせん定し，切り返し程度が翌年の発芽や着果に及ぼす影響を検討した．結果母枝長によって3段階に分け，3段階の各々に対してせん定程度を無せん定，弱せん定，中せん定および強せん定の4区を設けた．切り返しせん定処理を行った翌年の発芽率，着花穂新梢率，花数および果房当たり果粒数を比較した．その結果，弱せん定区で花数，果房当たりの果粒数および結果母枝当たりの果粒数が多くなった．結果母枝長に関しては中程度の長さで花数，果房中果粒数および結果母枝当たりの果粒数が多い傾向を示した．発芽率はせん定程度が強いほど高くなり，着花穂新梢率は中せん定区および強せん定区で高い傾向であった．

The transpired mass flow of water from the inflorescence was monitored continuously and compared with the flow in the whole shoot attached to the inflorescence by the stem heat balance method. The transpiration was compared with the chamber method. The stem heat balance method is able to continuously measure the intact sap flow of water. Modified sap flow gauges were adapted to obtain precise measurements of minute fluctuations in the flow. The stem sap flow fluctuated with the solar radiation, reaching a maximum at midday. The flow was also affected by the saturation deficit. At midday, a sap flow rate was 60 g · h−1 at the shoot base (11.5 mm in diam.); the shoot subtended 55 leaves between the shoot base and the terminal inflorescence. At the peduncle of the inflorescence, the maximum sap flow rate occurred during the morning. Subsequently, the flow tended to decrease gradually and steadily, hardly affected by the solar radiation and the saturation deficit. An entire inflorescence with a peduncle diameter of 11.2 mm exhibited a maximum transpiration rate of 15 g · h−1 during late morning. The daily water consumption of the inflorescence was estimated to be 130 g, representing 22% of the water consumption by the entire shoot. The chamber method indicated similar results as the stem heat balance method.

To clarify the floral inhibition in cherimoya in warm environments, the number of flowers, floral morphology, nodal position, days to flowering, and flowering period were determined under 20/15°C and 30/25°C day/night temperature conditions throughout two years. Floral differentiation of cherimoya was more favorable at 20/15°C than at 30/25°C. More flowers were produced at 20/15°C and the flowering period was longer. Flowers were also larger at 20/15°C, however, the growth rate of floral organs was faster at 30/25°C. The temperature effects were more pronounced in the second year. The floral responses to temperature were different depending on the nodal positions, because of the different developmental processes. The number of the floral buds at the basal part of new shoot (at the 1st-3rd nodes) at 30/25°C was similar to that at 20/15°C in the first year, but it became smaller than that at 20/15°C in the second year. On the other hand, no distal buds of new shoot (at the 4th-more distal nodes) were produced at 30/25°C throughout the experiment period. The floral buds at the basal nodes differentiated almost a year previous to their anthesis, whereas the distal buds differentiated in synchronization with the shoot extension, about 5 weeks before anthesis. The axillary buds for basal flowers of the next season had already differentiated even in one-week-old leaf axils. Cherimoya produced an axillary multiple bud complex for the subsequent bloom and flush. In a 4-week-old leaf axil, a few floral buds with one or two vegetative buds usually developed at 20/15°C, while none or one floral bud with several vegetative buds developed at 30/25°C. The bud differentiation period was found to be the most temperature sensitive stage to influence flower number and morphology. Thus, exposure of cherimoya trees to a warm environment a year previous to the flowering and during shoot extension, respectively, was suggested to inhibit flowering at the basal and distal nodes.