Production And Composition Of Chinese Cabbage Under Plastic Rowcovers In Southern Spain

Abstract

SummaryThe effects of plastic rowcovers on the growth and quality of Chinese cabbage (Brassica pekinensis (Lour) Rupr. `Nagaoka 50') were investigated in Granada, southern Spain (latitude: 378. 10 9.21 99 N; longitude: 38.38 9 E; .10 99 elevation: 600.m), for three years. Polyethylene (T1) and polypropylene (T2) covers increased air temperature by 7K and 5K, and soil temperature (5- and 15.cm depth) by 3±4K and 2K, respectively, compared with plots in the open (T0). In contrast, radiation levels in T1 and T2 were reduced by 12% to 16%, respectively. Thus, total shoot fresh weight was 111% (T1) and 108% (T2) greater under rowcovers, and the commercial head weights were 105% (T1) and 96% (T2) greater, and dry weights 21% (T1) and 13% (T2) greater than T0. These differences in plant production were reflected in higher yields under plastic, and a higher proportion of marketable heads (23% in open air compared with 68% and 65% under T1 and T2, respectively). The concentration of soluble sugars and pigments were also lower in the shoot under rowcovers than in plants in the open air. There were only small differences between the two plastic covers. Slightly warmer conditions and less shade under polyethylene compared with polypropylene provided greater plant production, yields and sugar concentrations, but lower pigment concentrations. Growing Chinese cabbage plants under plastic rowcovers in southern Spain increased production without significantly affecting composition.