Evapotranspiration of sugarcane in semiarid climate.

Cabrera R., Luis A., Hernandez I. Evapotranspiration of sugarcane in semiarid climate.

Sugar cane, Vol. 14 (2): 81-89, 1996, Cuba.

Studies were conducted to determine the evapotranspiration of sugarcane in the semiarid region of the sugarcane growers in the province of Guantanamo in Cuba, in irrigation areas where there are greatest drought problems in the country, rainfall is about 800 mm annually and there are significant dry periods so the water needs for this region are higher than the rest of the country. Experimental plots were used in alluvial soils of the Central Paraguay from 1986-1992, under controlled irrigation. Two blocks with sprinkler irrigation were selected, adjacent to the town of Cecilia, 43 ha and planted in October 1986, harvesting the plant cane and five ratoon with the variety C 266-70.

The other area used was the experimental block of Paraguay, where were installed two experiments to study the irrigation regime: one, planted in December 1987 and other one in June 1988. In both were harvested plant cane and two ratoon of the variety C 266-70. The harvest of the cold plant cane was conducted in April after 15 months of planting, and spring, in February after 21 months, so the actual evapotranspiration shoots studied correspond to each of these dates, with between 12 and 14 months respectively.

The results showed that actual evapotranspiration determined by field sampling have a close correlation with mean air temperature. The months of greatest demand for water in this region corresponded to May to September depending on the date of planting or harvest.
Significant differences between the results of the empirical equations for calculating evapotranspiration proposed by different authors and actual evapotranspiration, adjusting a model that takes into account the temperature was obtain.

The analysis of the behaviour of the curves of actual evapotranspiration ( ETR mm / day) in the different cane studied, smoothed and simulated by the mathematical procedure proposed by Luis and Cabrera allowed estimation of ETR values of the cane of spring planting April. Thus, it was observed that the cane of spring there are two peaks of the ETR, which coincide with the months of higher temperature from May to September, the highest daily values was obtained at 16 months in April and at 14 months in planting June, in both cases coinciding in July with values 4.90 and 4.93 mm / day, respectively.

The total ETR reached values of 2070 mm and 1920 mm for the planting of April and June. In the cold cane, the highest values of ETR were obtained at nine months of age with 4.96 mm / day in October planting, and at 8 months with 4.95 mm / day in December planting; ETR was the total of 1486 mm and 1303 mm, respectively. In no irrigated conditions the total ETR December planting was 868 mm, with a maximum of 4.61 mm / day. In February and April shoots, peaks of ETR were found for both dates in the month of August, with 4.69 mm / day and total ETR values of 1045 mm and 893 mm respectively.

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