Fruit growth patterns and abortion in multi-pistillate type cucumbers

SummaryTo clarify the process of fruit abortion in multi-pistillate type cucumber, the growth patterns of individual fruits (ovaries) were monitored from pre-anthesis to harvest. Two types of multi-pistillate cultivars, i.e. ‘028’ (monoecious, 2–4 pistillate flowers per node) and ‘NK × AN8’ (gynoecious, 1–2 pistillate flowers per node), were grown in a glasshouse. In both cultivars, the ovary length of all flowers increased exponentially until anthesis. Ovary sizes at anthesis in ‘028’ did not differ among the primary and the secondary flowers, while the ovary of primary flowers at anthesis in ‘NK × AN8’ was longer than that of secondary flowers. The patterns of ovary growth in length after anthesis are classified into three types in both cultivars as follows: (1) the ovary continues to grow exponentially after anthesis, the same as before anthesis; (2) the ovary stops growing for several days after anthesis and then resumes growth; and (3) the ovary stops growing for 10–14 d after anthesis and then aborts. Fruits showing growth patterns (2) and (3) were found in the middle nodes regardless of ovary size at anthesis. Fruits showing no growth for a while start to grow again just after fast growing fruits at the lower nodes are harvested. These results show that ovary size at anthesis does not determine whether the ovary stops growing temporarily or aborts. It is likely that the growth patterns of fruits at the middle nodes are influenced by the presence of growing fruits at lower nodes.