No abstract

The moisture, ash, free reducing sugar, starch, ether extractive, crude protein, amino acid and the heat energy contents of young and mature cladodes of Opuntia ficus-indica, with or without fruits, are described. The measurements were made in each of the following stages of development: vegetative growth (March), full vegetative development, and at the beginning of fructification (October). Independently of developmental stage (different cladode types) the highest values were reached always in young cladodes in the following months: moisture content in March and October; ash and free reducing sugars in March; starch and ether extractive in September and October; crude protein in March and July. Crude fibre was maximal in September and global heat energy in October. The nutritive and caloric value of cladodes are compared to other products used for livestock nutrition .

Using prickly pear cladodes and fruits and different yeast strains of the genus Saccharomyces, both the chemical composition of the plant material and alcoholic fermentation were studied under controlled conditions. Before fermentation, fresh or previously dried cladodes were hydrolysed using cellulase or acid (HCl). The yield was determined by measurement of ethanol production by gas-liquid chromatography. Two conversion indices, representing either the percentage of reducing sugars or the energy converted into ethanol, were considered. Using fresh or dried cladodes without fruits, the best results were always obtained after performing both types of hydrolysis. The enzymic method gave the highest sugar yield. However, ethanol production was similar to that obtained by acid hydrolysis of fresh cladodes, and only slightly higher than that of previously dried cladodes. The potential ethanol production that could be obtained from prickly pear cultivation in various regions (arid, semi-arid and irrigated) is discussed.

We studied the sensitivity of reference evapotranspiration (ET o ) to global warming in Spain at the end of the 21st century. The FAO-56 Penman-Monteith equation was used to estimate ET o , and we examined the sensitivity of the latter to changes in temperature and relative humidity. Changes in stomatal resistance in response to increased CO 2 concentration were not evaluated, nor were the changes in wind velocity and solar radiation. Different scenarios were used for estimation of future . Four scenarios were simulated that considered the variations in linear tendency of the maximum and minimum temperatures and maximum and minimum relative humidities. The trends of the 4 scenarios were incorporated with the data from 338 agrometeorological stations to estimate future ET o . In all cases, there was an annual increase in ET o of 11, 21, 36 and 7% above the annual ET o (1196 mm) for Scenarios 0, 1, 2 and 3, respectively. The river basin most affected by these changes was the Ebro River valley. The most affected months

Abstract. The impact of climate change and its relation with evapotranspiration was evaluated in the Duero River Basin (Spain). The study shows possible future situations 50 yr from now from the reference evapotranspiration (ET o ). The maximum temperature (T max ), minimum temperature (T min ), dew point (T d ), wind speed (U ) and net radiation (R n ) trends during the 1980-2009 period were obtained and extrapolated with the FAO-56 Penman-Montheith equation to estimate ET o . Changes in stomatal resistance in response to increases in CO 2 were also considered. Four scenarios were done, taking the concentration of CO 2 and the period analyzed (annual or monthly) into consideration. The scenarios studied showed the changes in ET o as a consequence of the annual and monthly trends in the variables T max , T min , T d , U and R n with current and future CO 2 concentrations (372 ppm and 550 ppm). The future ET o showed increases between 118 mm (11 %) and 55 mm (5 %) with respect to the current situation of the river basin at 1042 mm. The months most affected by climate change are May, June, July, August and September, which also coincide with the maximum water needs of the basin's crops.