Three trials were carried out in Três Pontas, Brazil, from November 2002 to January 2003, to evaluate the effects of Supa Potássio® doses on yield and quality of crisphead lettuce. Five doses of Supa Potássio® (0.0; 4.5; 9.0; 13.5 and 18.0 L/ha), with 20% SiO2 and 15% K and three foliar application times (14; 21 and 28 days after planting date) were tested using a randomized complete blocks design with four replications. Each application time was considered one trial. The total fresh mass presented quadratic effect and the dose 9.1 L/ha of Supa Potássio® resulted in the largest revenue. There were significant differences between time of foliar application for plant fresh weight and plants with 706,0 g were harvested when Supa Potassio® was applied 14 days after transplant. The application of 10.5 L/ha of Supa Potássio® promoted the highest commercial fresh matter. Applications at 21 and 28 days after planting date showed a quadratic effect and the doses of 4.3 and 9.8 L/ha of Supa Potássio® presented the best post-harvest storage of the crisphead lettuce. Supa Potássio® had no significant effect on head circumference and stem length.
Yield; nutrition; quality
