EFFECT OF GROWTH-RATE ON TIPBURN OCCURRENCE IN LETTUCE

The occurrence of tipburn in lettuce was correlated with relative growth rates for 6 cultivars grown under a range of controlled environments differing in temperature and light intensity. The results presented support the theory that many of the conditions previously reported as causing tipburn may do so by affecting growth rate. A reduction in the growth rate of field-grown plants brought about by close spacing resulted in a lower incidence of tipburn for some cultivars, but because of the associated reduction in plant size at maturity this method is unlikely to be of economic importance. Speculation as to the reason why rapid growth encourages tipburn involves nutritional aspects related to Ca utilization.