Effects of hand-pollination, paclobutrazol treatments, root temperature and genotype on pollen viability and seed fruit content of winter-grown pepper

Abstract

SummaryPepper plants were cultivated under optimum (30/20°C, day/night) and suboptimum (24/12) temperature regimes. Low night temperature significantly reduced pollen fertility, seed content per fruit and fruit size. Hand-pollination of cold affected flowers of hybrid Latino with pollen collected from plants grown at optimum night temperature slightly increased the seed content per fruit and fruit length. However, fruit weight and diameter were not modified by this treatment. Application of paclobutrazol, at concentrations of 1 and 0.1 mg 1−1 to ‘Latino’ plants growing at suboptimum temperature diminished the cold induced pollen abortion and increased the seed content per fruit. These fruits were smaller than those produced by non-treated plants of the same temperature regime. When the root temperature of ‘Latino’ plants growing in the cold regime was maintained at 20°C, pollen viability 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 affected by cold but to different degrees. Capsicum baccatum, C. frutescens and C. annuum cvs Miguelino and Guindilla had the most cold tolerant pollen.