Air humidity, transpiration and blossom-end rot in soilless sweet pepper culture

Abstract

A study has been carried out in order to know the possibilities of reducing BER by means of air humidity regulation with high pressure fog system in the minimum range 60 to 65% RH and by the use of antitranspirant (pinolene 3.5; 7.0% vol.) spraying on the plant during the risky season, from Spring on. A sensible cultivar, Atol F-1, has been grown in perlite (0-5mm) 40 liter bags, in two polythene greenhouse compartments, one provided with humidification system. Results show till 15% lower leaf transpiration rates (E), associated to lower leaf conductance (gs) in the antitranspirant sprayed plants during Spring. Also a decrease up to 16% in the transpiration rate and higher gs is recorded in plants grown under a minimum of 60 to 65% RH conditions. Calcium levels both in leaves and fruits are higher in the treated plants. Fruits from antitranspirant sprayed plants have more Ca contents both in the proximal and distal half (till 17% increase in the distal half) compared to control. Antitranspirant effects are however no stable and consistent along time. The effect of humidified environment is more stable in terms of Ca contents in the fruit. Levels up to 15% increase in the whole fruit and up to 50% increase in the distal half have been shown. The use of antitranspirant has increased fruit yield some 1 kg per plant, but the effects on BER have not been sufficient (0.9 to 4.6% less BER affected yield). Plants grown under humidified conditions showed a 5% BER affected yield versus 18% in the control.