Mepiquat chloride effects on yield and photosynthesis cotton (Gossypium hirsutum L.) var gossica MC23

Efectos del cloruro de mepiquat en la fotosíntesis y parámetros del rendimiento en algodón (Gossypium hirsutum L.) var Gossica MC23

The present work was carried during second semester of 1999 at the Turipaná Research Center of Corpoica Regional 2, deparment of Córdoba, altitude of 14 m.a.s.l, temperature of 28°C, RH of 85% and annual rainfall of 1,200 mm. The main objective was to determine the effect of mepiquat chloride (MC) application on cotton yield and photosynthesis. A complete block randomized design was used with 4 replicates, where treatments consisted of four dose of MC (0, 25, 50 and 75 g of a.i. ha ^-1) on cotton plants Var. Gossica MC-23 at beginning of flowering. Every week total chlorophyll concentration and photosynthesis rate were evaluated. The other variables were: weigh pcr speck, fiber percentage, fiber index and yield of cotton seed, and fiber yield. The results showed that 25, 50 and 75 g of a.i. ha ^-1 of CM decreased the fiber index and the seed number pcr speck, while the weight of the speck was not affected. The variable yield of cotton seed, fiber percentage and fiber yield decreascol when the dose of CM was increased. Since day 34^th after spraying the CM (94 days after planting) and with increasing the dose, the chlorophyll concentration also increased; however these did not have any influence on the photosynthesis rate.

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