Physiological Effects on Cotton Plant Sown under Plastic Mulch
Jul 31, 2018
The physiology of the cotton plant was studied in cotton sown under plastic. This practice is widespread among cotton growers in the Guadalquivir River Valley (SW Spain). Field experiments were conducted in 1993, 1994 and 1995 at Alcalá del Rio (Seville). In one experiment, cotton was sown on two dates in March. This is very early and is not possible without plastic mulch because of low temperatures but it conforms to the usual custom of the growers. A second experiment was sown during the normal planting time for Spain in May, with and without plastic mulch. The first experiment used a split-split plot design with three splits, date of sowing followed by cultivars and then the number of days that the plant remained under plastic mulch (15-45 and 60 days). A similar design was used in the second experiment except that the date of sowing was replaced by the factor with or without plastic mulch. Physiological measurements on vigour, biomass accumulation (root and shoot biomass), LAI (leaf area index), horizontal and vertical flowering rates and boll setting and fruiting sites (plant mapping) were taken at several dates. Results showed that cotton growing under plastic mulch has a fast, luxurious vegetative growth at the beginning of season, with a rapid increment in LAI and a faster vertical flowering rate and an increase in the number of bolls on secondary sympodia than plants without plastic mulch. The root system was completely transformed, the main root being thicker and shorter. A remarkable increase in earliness and yield were shown with a serious propensity to suffer water stress. The increment in potential yield can only be realized with frequent, shallow.