Abstract
A field experiment was conducted for two years to evaluate the effect of four herbicides, glyphosate, paraquat, atrazine, and sencor on the effect of weeds in a mango (Mangifera indica L.) nursery. Glyphosate was sprayed at 7.5 ml and 10 mL L-1 three times, at 20 days prior to sowing, at sowing, and 20 days after seed germination. Paraquat was sprayed at 3.0 mL and 4.0 mL L-1 20 days after germination. Atrazine at 2.0 kg and 3.0 kg ha-1 and sencor at 0.5 kg and 1.0 kg ha-1 were applied at sowing. Glyphosate at 20 days prior to sowing and the weed-free treatment significantly increased seedling leaf number, photosynthetic rate (Pn), chlorophyll content, nitrate reductase activity (NRA), protein, and total sugar levels. Paraquat significantly increased seedling leaf number, temperature, transpiration rate, and chlorophyll a content, while post application of glyphosate and higher concentrations of atrazine, sencor, and paraquat significantly decreased Pn, but they increased leaf temperature and transpiration rate. Glyphosate application at 10.0 mL L-1 at 20 days prior to sowing completely controlled Saccharum spontaneum L., Crotolaria medicaginea Lamk, and Trichodesma indicum R.Br. in the rainy season while in the following winter, it controlled S. spontaneum L., Medicago lupulina, and Erigron bonariansis. At sowing it did not completely control S. spontaneum L. Paraquat controlled Dechantheum annulatum, Fimbristylis tenera L., Launea pinnatifida, and T. indicum R.Br. but did not completely control S. spontaneum L. and did not affect winter weeds except E. bonariansis. Atrazine and sencor both completely controlled D. annulatum, F. tenera L., T. indicum R.Br., and L. pinnatifida in the rainy season and only M. lupulina in the following winter. Higher concentrations of atrazine and sencor were more effective. Generally, all the herbicides decreased the weed population and their dry weight.
