EFFECTS OF HAND-POLLINATION, PACLOBUTRAZOL TREATMENTS, ROOT TEMPERATURE AND GENOTYPE ON POLLEN VIABILITY AND SEED FRUIT CONTENT OF WINTER-GROWN PEPPER

Pepper plants were cultivated under optimum (30/20 degrees C, day/nigh t) and suboptimum (24/12) temperature regimes. Low night temperature s ignificantly reduced pollen fertility, seed content per fruit and frui t size. Hand-pollination of cold affected flowers of hybrid Latino wit h pollen collected from plants grown at optimum night temperature slig htly increased the seed content per fruit and fruit length. However, f ruit weight and diameter were not modified by this treatment. Applicat ion of paclobutrazol, at concentrations of 1 and 0.1 mg l(-1), to 'Lat ino' plants growing at suboptimum temperature diminished the cold indu ced pollen abortion and increased the seed content per fruit. These fr uits were smaller than those produced by non-treated plants of the sam e temperature regime. When the root temperature of 'Latino' plants gro wing in the cold regime was maintained at 20 degrees C, pollen viabili ty and fruit size remained as low as in plants of the same temperature regime with unheated roots. The evaluation of the cold sensitivity of different pepper genotypes indicated that all the accessions were aff ected by cold but to different degrees. Capsicum baccatum, C. frutesce ns and C. annuum cvs Miguelino and Guindilla had the most cold toleran t pollen.