Effect of fruit-load on growth patterns of fruit at the middle nodes of gynoecious-type cucumbers

Abstract

SummaryThe effects of different timings of fruit thinning at the lower nodes (nodes 4 to 7) on fruit growth and abortion at higher nodes were investigated in a gynoecious, parthenocarpic cultivar of cucumber (Cucumis sativus L.), ‘NK x AN8’. Fruits at the lower nodes were removed 0, 5, 10, 15 and 20 d after anthesis of flowers at node 8 (DAA8).Total leaf areas and growth patterns of individual fruit were then monitored. When fruits at nodes 4 to 7 were thinned 0 or 5 DAA8, all fruits at nodes 8 to 12 grew to commercial size, without fruit abortion. When fruits were thinned 10 DAA8, the fruits at nodes 8 to 12 ceased to grow after anthesis, but growth was restored a few days after fruit thinning. Fruit thinning at 15 or 20 DAA8 forced most fruits at nodes 8 to 12 to abort, while fruits at node 13 and above ceased to grow for a while, but resumed growth after fruit thinning. In all treatments, total leaf area increased with time throughout the experiment. High fruit load depressed the rate of growth of leaf area slightly, 65 to 75 d after sowing. Fruit load (fresh weight) per leaf area was about 50 mg cm–2 just before fruits at nodes 4 to7 were thinned at 20 DAA8.These results suggest that fruit abortion occurs if fruits at the lower nodes persist for a long period, and fruits at the middle nodes senesce before enlargement. Fruit thinning at the lower nodes can restore the growth of fruits in the stagnant growth phase within 10 d.