Some aspects of growth regulation in pimiento pepper

The effects of pinching the seedling apex and of foliar applications of daminozide (succinic acid-2, 2 dimethyl hydrazide), ethephon (2 chloroethyl phosphonic acid), and gibberellin were studied to determine their ability to concentrate ripeness in pimiento peppers. The maximum increase in the proportion of fruit ripe at a given time was the principal criterion for these studies.

In 1977 several treatments produced favorable proportions of ripe fruit. Among these are one foliar application of daminozide .7, pinching at the 16 leaf stage .6, foliar applications of daminozide and ethephon .5, and (where a favorable ratio of size to number occurred) pinching at the 12 leaf stage .5. The ratio of ripe to total fruit for control plants was .2.

In 1978 favorable treatments and ratios were: 24 hour seed soak in a 1% solution of potassium nitrate .6, three applications of daminozide .7, and pinching at the 6 leaf stage .7. Control plants produced a proportion ripe of .2. In a pilot study, plants treated with foliar applications of gibberellin plus daminozide achieved a ripeness ratio of .9.

A study of local climatic data, together with dates of application of treatments, revealed that an improvement in the proportion of ripe fruit may be achieved by applying retardants at dry periods of time. It is concluded that late application of both daminozide and pinching are effective in concentrating ripeness. Effectiveness seems to depend on climatic conditions and the growth stage of the plants. Further study appears warranted.

In the 1977 greenhouse studies, the leading treatments were stripping of all but six leaves at the 12 leaf stage, pinching at the 8 leaf stage, and stripping of all but four leaves at the 12 leaf stage. All of these produced a significantly higher proportion of ripe fruit than did control plants.

Seeds, separated by air currents on a weight basis, were examined to determine radical emergence. It was found that seeds having the least density had more complete radical emergence than the most dense seeds.