Field performance of melon (Cucumis melo var. saccharinus Naud.) seedlings hardened by brushing or with paclobutrazol.

AYASTUY, M.E.; HERNÁNDEZ, L.F.; RODRÍGUEZ, R.A.; FERNÁNDEZ, J.A.; CANTAMUTTO, M.A.

ACTA HORTICULTURAE

ISHS

Año: 2011 p. 299 - 396

0567-7572

Excessive hypocotyl growth observed in greenhouse-grown melon (Cucumis melo var. saccharinus Naud.) seedlings makes post-planting establishment difficult. The objective of this work was to determine the effect of seedling’s chemical or physical hardening on its re-establishment, growth, development and production after transplanting. Seedlings of melon were transplanted after being chemically or physically hardened at phenological stages “expanded cotyledon” (ECS) or “first true leaf” (FTLS). Chemical hardening was madeby spraying Paclobutrazol (PBZ) at a concentration of 10 or 30 mg/L. Mechanical hardening were performed by brushing the seedlings one minute once a day during 10 days at two intensities: 10 or 40 strokes/min. Experiments and evaluations were made onfield trials during three consecutive years. The two chemical treatments and the 10 strokes/min mechanical treatment at the ECS had the same effect of improving by 70% seedling establishment in comparison to the control. The 40 strokes/minmechanical treatment did not show any improvement in the transplant response. Growth and yield from mechanically hardened plants was similar to those from control plants, whereas chemically hardened seedlings sprayed with PBZ produced plants that had a good post-transplant growth and higher fruit yield (25%) compared with to the control. The results demonstrated that, in order to improve the quality of melon seedlings and their growth after transplanting, a low concentration of PBZ hardening procedure or a low intensity brushing at an early growth stage is recommended.