Thinning, whether mechanical or chemical, prevents the development of some fruits, allowing the remainder to become larger and more marketable. Chemicals used for thinning either prevent fruit set or increase the proportion of fruits that fall in the “June drop”; some, however, are effective even after this drop. The mechanisms involved in blossom thinning are straightforward. Either pollination is prevented, or some of the flowers are injured, causing their abscission. The mechanisms involved in fruit thinning are more complex; physiologists continue to debate the effects of thinning agents on phloem transport, endogenous hormone content/production, seed development, and other physiological processes. The effects of ethephon in thinning have led to the suggestion that the response to applied hormones is mediated by their effects in stimulating ethylene biosynthesis. Hypotheses as the mechanisms of action of thinning agents will be reviewed, emphasizing those most often invoked today.
Increased Phloem Transport of S-Methylmethionine Positively Affects Sulfur and Nitrogen Metabolism and Seed Development in Pea Plants
