The productivity of pastures and forage is increasingly limited due to climate variability and prolonged drought periods. For that reason, it is necessary to cultivate plants that are tolerant and productive under conditions of seasonal drought. The objective of this work was to characterize the agronomic and productive performance of new drought tolerantCenchrus purpureus cultivars. Three cultivars (CT-601, CT-603, and CT-605) were used at different regrowth ages (60, 80, 100, and 120 days) in two climatic periods: rainfall and low rainfall from 2013 to 2014 in a representative ecosystem of Cauto Valley, Cuba. The cultivars were grown on Vertisol and were fertilized with organic fertilizer at a rate of 25 t/ha. Some agronomic variables and dry matter (DM) yield (t/ha) were evaluated under rainfed conditions. A randomized block design with factorial arrangement and its interaction (3x4x2) was used. DM yield was affected by the second order interaction, during the period of rainfall, CT-605 at the age of 120 days reached the best average (p≤0.001) and during the period of low rainfall, CT-603 and CT-605 were highlighted (p≤0.001). Weather-season interaction on cultivars had a significantly positive impact (p≤0.001) on the length of leaves of CT-601 in the period of rainfall. CT-605 increased (p≤0.001) the percentage of leaves and green stems in the period of rainfall, superscripts were equalized in the dry season. Cultivars showed an acceptable DM yield during the low rainfall period, morphological changes neither affected the development nor the productivity.

<p><strong>Background:</strong> It was noted in 2012 that the Cenchrus genus absorbed the Pennisetum genus, within which grass varieties that accumulate a large amount of standing dry matter (DM) are currently included, which is favored by the rainfall regime and assistance with fertilizers. <strong>Objective:</strong> To evaluate the effect of different fertilization variants (NPK, ferti-forage and without fertilization (control)) on the agronomic morpho response in varieties of <em>Cenchrus purpureus</em> (King grass verde, Elefante, Morado, Maralfalfa and Cuba CT-115) in different regrowth ages (45 and 60 days) in the conditions of the Santo Domingo Canton, Ecuador. <strong>Methodology:</strong> A study was carried out in a randomized block design with factorial arrangement, and its interaction (5x3x2) with five replicates. Yield of green biomass (t YG ha^-1), total dry matter, leaves and stems (t DM ha^-1) and morphological variables were considered. <strong>Results:</strong> The interaction of the second degree affected (P≤0.001) the performance of YG in favor of the Maralfalfa variety at 60 days of regrowth with the application of complete formula (83.60 t YG ha^-1), also this variety in this same age and fertilizer, provided the highest (P≤0.001) values in the total DM and stem yield (20.90 and 11.71 t DM ha^-1, respectively), the highest (P≤0.001) dry leaf yield was provided by the Cuba CT-115 at 60 days with application of ferti-forage (9.49 t DM ha^-1). <strong>Implications:</strong> The use of fertility provides greater accumulation of DM at the leaf level, where, under the conditions in which the study was carried out, it was the CT-115 that showed the best response to this alternative. All the varieties showed at the age of 60 days the greater accumulation of DM. <strong>Conclusion:</strong> The varieties Maralfalfa, Morado and CT-115 stood out in the productive response and morphology during growth under the combination of the factors of interest in this investigation.</p>

Cichlasoma festae es un pez nativo tropical continental de Ecuador insuficientemente conocido desde el punto de vista productivo, reproductivo y ecológico. El éxito reproductivo de la especie se considera básico para la implantación de programas de desarrollo territorial en áreas fluviales. Se seleccionaron 30 reproductoras de C. festae distribuidas en tres estanques en función del peso vivo (PV) con el objetivo de evaluar el efecto del peso de la reproductora sobre la producción de alevines en condiciones de cría semicontroladas. Las condiciones físico-químicas del agua fueron adecuadas y la reproducción fue progresiva en cautividad sin encontrarse diferencias significativas entre estanques (P > 0,05). La densidad de cría fue de 3 m 2 por reproductor, así como de 83,2, 119,17 y 151,67 g de reproductora/m 2 en el estanque 1 (T1), 2 (T2) y 3 (T3), respectivamente. La proporción de machos por hembras fue de 1:2, disponiendo durante toda la experiencia de alimento vivo y concentrado. Los alevines fueron recogidos cada cinco días, siendo la biomasa promedio de 11,14 alevines/g de PV. Las reproductoras de mayor peso (T3 = 455 g) anticiparon el desove y duplicaron la productividad numérica frente a las de menor peso (T1 = 249,6 g) (P < 0,05). No obstante, la biomasa total (nº de alevines por g de PV reproductora) fue homogénea en todos los casos (P > 0,05). El cultivo de especies nativas como C. festae representa una oportunidad y alternativa necesaria para la conservación de la especie, particularmente donde las poblaciones naturales están viéndose diezmadas.Palabras clave: Reproducción, planes de conservación, cíclidos, cría en cautividad. Effect of the size of breeders stock in the fingerlings production of Cichlasoma festae under semi controlled conditions in Ecuador

Tropical root crops, a major source of food for subsistence farmers, varied in their sensitivity to soil acidity factors. Tolerance to soil acidity is an important characteristic of crops for the humid tropics where soils are often very acid and lime‐scarce and expensive. Experiments on two Ultisols and an Oxisol showed that three tropical root crops differed markedly in sensitivity to soil acidity factors. Yams (Dioscorea alata L.) were very sensitive to soil acidity with yields on a Ultisol decreasing from 70% of maximum when Al saturation of the effective cation exchange capacity of the soil was 10 to 25% of maximum when Al saturation was 40%. On the other hand, Cassava (Manihot esculenta Crantz) was very tolerant to high levels of soil acidity, yielding about 85% of maximum with 60% Al saturation. Taniers (Xanthosoma sp.) were intermediate between yams and cassava in their tolerance to soil acidity yielding about 60% of maximum with 50% Al saturation of the soil. Foliar composition of cassava was not affected by soil acidity levels and that of yams and taniers was also unaffected except for Ca content which decreased with decreasing soil pH and increasing Al saturation. Response of these tropical root crops to soil acidity components was far more striking on Ultisols than on the Oxisol. For yams, soils should be limed to about pH 5.5 with essentially no exchangeable Al3+ present whereas high yields of taniers can be obtained at about pH 4.8 with 20% exchangeable Al3+ and of cassava at pH as low as 4.5 with 60% exchangeable Al3+.

The main limitation of tropical grasses is their high content of structural carbohydrates, which determine the use of grass by animals. When pastures or forages grow in adverse ecosystems there are important changes in the ruminal degradability of the compounds of interest. The objective was to characterize, at different ages of regrowth, the in situ ruminal degradability of the organic matter of different varieties of Cenchrus purpureus genetically improved to tolerate dry environments. Three drought tolerant varieties (CT-601, CT-603, and CT-605) were taken at different regrowth ages (60, 80, 100, and 120 days). Two fistulated Creole cows of 400 ± 50 kg of live weight were used. The bags were introduced in the rumen for 0, 4, 6, 8, 12, 24, 48, and 72 hours, the estimation of the rumen degradation was made fitting the data to the exponential equation (a + b) * (1-e (-c * t)). The best performance in situ ruminal degradability of the potentially degradable fraction (a + b) of leaves was observed at the age of eighty days, while the effect of the degradation dynamics due to the effect of regrowth age was common for leaves and stems. Fraction degradation values did not exceed 10% for leaves and stems; however, the degradation of b showed values that exceeded 71% for leaves and 30% for stems. The new varieties showed a ruminal fermentation pattern close to 50%, characteristic of tropical grasses.