2017 年 55 巻 2 号 p. 59-64
The effect of water stress on the number of first-flush flowers was investigated in Meiwa kumquat trees. Treatments of soil water deficit (SWD), soil water deficit combined with mist (SWM), and non-treated controls (CONT) were established in a greenhouse in 2009 and 2010. The leaf water potential in SWD and SWM decreased significantly after 10 d of the treatment. In 2009, the number of first-flush flowers in SWD and SWM was 133.8 and 142.4, respectively, and these were significantly greater than that in CONT. Second- or third-flush flowers were significantly greater in CONT. In 2010, the number of first-flush flowers increased with a decrease in the leaf water potential down to −1.7 MPa. It was also positively correlated with leaf abscisic acid (ABA) content, but did not significantly change once ABA levels exceeded 5 nmol g−1. These results suggest that water stress increases the number of first-flush flowers. The severe water stress represented by leaf water potentials below −1.7 MPa, or over 5 nmol g−1 of leaf ABA content, did not appear to have the same effect. Approximately 150 flowers per 100 nodes of shoots appeared to be the maximum number of first-flush flowers produced by Meiwa kumquat trees.