Mechanical height control for tomato plug transplants: effects on yield

Abstract

Mechanical conditioning is an efffective method for limiting excessive stem elongation in tightly grown plants. It is particularly effective in tomatoes. Any treatment that reduces growth of transplants has the potential to also reduce subsequent growth, and thereby reduce yield. Giving plants 0, 10, 20 or 40 strokes daily showed a maximal height reduction with 20 strokes, but further reduction in leaf area with 40 strokes. The potential redution in growth rate was about 25%. Harsher treatment to provide greater growth control appears unproductive. For studying the effects of stroking on yield, 288-size transplants were grown as they would in commercial production, and 3 flats of each transplanted in grower-cooperators' fields in 1991 and 1992. There was no significant yield reduction in either year. In 1991, the stroked plants had more severe blossom end rot than the controls, resulting in about 1 kg/m more culls. The weather in each year caused low yields and high sample variation. When the plants experience less stress duiring the growing season, the transplant treatments would be expected to have a larger effectControl Stroked1991 10.7 ± 1.31 9.4 ± 1.6 NS1992 4.3 ± 0.6 4.2 ± 0.4 NS1Yield (kg/m) ± s.d.