Irrigation in significant moments of the biological cycle of cotton (Gossypium hirsutum L.) for a better irrigation water use efficiency
1992
Foti, S. | Copani, V. | Guarnaccia, P. (Catania Univ. (Italy). Istituto di Agronomia Generale e Coltivazioni Erbacee)
In the framework of a research on cotton (Gossypium hirsutum L.) carried out for four years since 1987 to 1990, different irrigations limited to significant stages of growing period, to analyse the effects on yield (seed +lint), on irrigation water use efficiency (IWUE) and on mean maturity date were studied. In the first year the average yield was 3.2 t ha-1; the best results (4.83 t ha-1) were obtained by treatment with the highest number of irrigations: at sowing (common to all treatments), at floral bud, at flowering, at boll period, for a total volume of water of 329 mm. Among the treatments with only two irrigations the best results (4.3 t ha -1) were obtained with irrigations at the appearance of the floral buds and during boll period which has also shown the maximum values of IWUE (Irrigation water use efficiency). When the crops benefitted of one irrigation only, the treatment receiving the water at flowering gave the best result (2.83 t ha-1). In the subsequent three years yields were much lower than the first year (1.07 t ha-1, 1.38 t ha-1 and 1.57 t ha-1). Yield of all treatments was not significantly higher than treatment irrigated only once at flowering. In this case the irrigation water use efficiency was higher with irrigations, including the one of sowing, of a total volume of about 120 mm of water supplied once during the phases of appearance of floral buds or at flowering. The higher yield and IWUE of the first year compared to the others must be related to the stored water in the soil determined by highest rainfall during the previous winter season. Generally, the highest the volume of water the longest the biological cycle
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