INDUCTION OF FLOWERING ON LETTUCE (Lactuca sativa L.) CAPITATA VARIETY WITH GA3 AND ITS EFFECT ON SEED YIELD

Abstract

The seed is one of the most expensive inputs for lettuce (Lactuca sativa L.) production in Mexico because it is imported. For commercial purpose GA₃ has been used for the induction of floral stem, flowering and increase in seed yield, but the response of plant to hormonal action of this product under conditions of high valleys is still unknown. For this reason this investigation was made in the Spring-Summer cycle of 1996 at Chapingo Mex., to determine the effect of five concentrations of GA₃ (10, 20, 30, 40 and 50 ppm) in three application stages (8 and 12 leaves, 100 % of the dose and 8 and 12 leaves, 50 % of the dose) on flowering and yield of lettuce seed var. Capitata cv. Great Lakes 407. The two factors and their interactions were studied in a field experiment in a randomized complete block design with factorial arrangement 5 x 3 using four replications. The results were: a) With respect to stages of application the first floral stem emergence (78 days after planting) was obtained with 40 ppm (100 % of the dose) applied at 8 true leaves; b) The best yield (114 kg ha^-1) of seed, regarding to stage of application, were obtained at 8 (50 %) and 12 (50 %) true leaves, and c) In general, the highest yield (142 kg ha^-1) of seed was obtained with the application of 40 ppm of GA₃ at 8 (50 %) and 12 (50 %) true leaves.