Yield of chinese white cabbage (pak choi) (jBrassica campestris var. chinensis), hybrids Canton and Chouyou were evaluated under 17 and 25 g/m-2 of non woven white polypropylene in winter, compared to open field at Campos Gerais, Brazil. Sowing date was in March, 11th and plants were transplanted to the field at the stage of 4 - 5 leaves in june, 23rd. A randomized block experimental design was used with five replications in a factorial scheme 3x2. Non woven polypropylene was used as row cover after transplanting. At the harvest according to plant maturity, the number of leaves, plant height, diameter of plant basis, plant fresh weight and dry matter were evaluated. The percentage of plants with bolting was evaluated at 51 days after transplanting. Under field conditions, plants from hybrid Canton were damaged showing the leaf extremity entirely nipped by frost but the hybrid Chouyou was resistant. Non woven protected the plants against frost and promoted a faster plant development and early crop at 38 days after transplanting with the use of a grid of 25 g/m-2, at 42 days with 17 g/m-2. Under open field conditions harvest was made only after 46 days. The superior quality under non woven when compared to open field conditions was observed with the characteristics of higher plant fresh weight, dry matter of plants, number of leaves, plant height and diameter of plant basis. Between both hybrids taken into account at the current study Canton was more precocious than Chouyou; however Canton initiated bolting at 36 days after transplanting. Non woven with a grid of 25 g/m-2, compared to that one of 17 g/m-2 was superior to hybrid Canton for the characteristic of earliness at the winter season in Campos Gerais, Paraná State, Brazil.
Brassica campestris var. chinensis; protected cultivation; row cover
