THE EFFECT OF MULCHING ON CHANGES IN MICROCLIMATE AND ON THE GROWTH AND YIELD OF SWEET PEPPER GROWN IN PLASTIC TUNNELS

The effect of white and black polyethylene mulches on the microclimate in plastic tunnels and on the growth and yield of green pepper was investigated in 1990 and 1991. Plants were transplanted in the first ten-day period of May and fruits were harvested at the stage of physiological maturity from August 15 - October 15. Temperature measurements at 8.00 a.m. showed that heat accumulation in the soil was greater under the black mulch. As related to bare soil, the temperature was higher by 0.5°C on the average, though the differences sometimes reached 1.5–2.0°C. Under white mulch, the temperature of the soil was lower than that of bare soil by 0.5°C on the average. White mulching resulted in a 187.6 % increase in reflected physiologically active radiation (PAR) as compared with bare soil in the tunnel. The marketable yield of plants grown over white mulch was higher by 6.1 % and over black by 10.3 %. The average weight per fruit of mulched plants was also increased.