Leaf photosynthesis of 'Cat Hoa Loc' mango (Mangifera indica L.) and 'Nam Roi' pummelo (Citrus grandis (L.) Osbeck.) in the rainy season.

With an EARS--Plant photosynthesis meter we determined gross photosynthesis (P) of leaves of 'Cat Hoa Loc' mango on 4 years old trees planted in the Fruit Tree Experiment and Production Station, Campus 2, Department of Crop Science, College of Agriculture, Can Tho University in the rainy season of the year 2000. The same experiment was conducted on 'Nam Roi' pummelo on a farm located in the Binh Minh district, Vinh Long province. In the rainy season the calculated gross photosynthesis of 'Cat Hoa Loc' mango leaves at flowering stage was higher than that at the vegetative stage. However, the photosynthetically active radiation and quantum yield of 'Cat Hoa Loc' mango leaves in both stages did not reach the light saturation point when compared with values from estimated equation of photosynthetic light curve. The same holds true for 'Nam Roi' pummelo in the vegetative stage.

Propagation of 'Nam Roi' pummelo (Citrus grandis (L.) Osbeck.) by cuttings.

'Nam Roi' pummelo is a famous fruit tree in the Mekong Delta of Viet Nam. Therefore, in recent years, growers extended the cultured area because it guarantees a high income. As a consequence there is a high demand for planting material, and we studied the possibilities of vegetative propagation by cuttings during the period from March 1999 to February 2000. The results of our study showed that a rice husk substrate was better than sand, and that naphthalene acetic acid (NAA) 1000 ppm stimulated rooting (84% rooted). The type of cutting was also a factor affecting the success rate; we studied three types of cuttings.