Lettuce and Celery Responses to Both BAP and PBZ Related to the Plug Cell Volume

Aims: Decreasing vegetable transplant costs involves decreasing the plug cell volume, which is known to have negative effects during post-transplant growth. The objective of this work was to evaluate the impact of different plug cell volume and hormonal regulators on both lettuce and celery yield.
Study Design: Two genotypes of lettuce (‘Dolly’ and ‘Shirley’) and two of celery (‘Golden Boy’ and ‘Green Fox’) were used in the experiments. Plants grown in 288- or 200-cell trays and were sprayed with different solutions of BAP and PBZ.
Place and Duration of Study: Experiments were conducted at the INTA Balcarce Experimental Station, Argentina (37º45′S, 58º18′W) during the 2008-2009 and 2010-2011 growing seasons.
Methodology: Three experiments were performed. In the experiment 1, base temperature from lettuce and celery plants grown in 288- or 200-cell trays were determined through the method of temperature summation. Experiment 2 showed the response to 100 mg L-1 BAP of both vegetables grown in two plug cell volume. Experiment 3 showed the combined effect of different BAP and PBZ concentrations related to different plug cell volume.
Results: Results showed that spraying lettuce and celery plants with a single pre-transplant application of BAP or PBZ increased post-transplant fresh weight. On the other hand, the different genotypes of lettuce and celery evaluated showed significant differences in the Tb.
Conclusion: We proposed that the use of larger plug cells and growth regulator sprays may allow plants to overcome the root restriction imposed by the cell volume, with a correlative increase in post-transplant productivity of lettuce and celery. A significant decrease in Tb would partially explain the highest growth rate in the largest cell size volume.