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Jatropha is promoted as a pro-poor bioenergy plant, while basic information about its productivity, age of maximum production, and oil content are missing. This study aims to determine the seed yield (dry weight) for three INIAP elite jatropha accessions, and to evaluate the changes in physical and chemical seed traits at the different fruit ripening stage in a split-plot design. Maximum seed production occurred four years after planting for the accessions CP041 and CP052, while for accession CP054, it occurred after the first year. CP041 was the most productive, with a mean of 316.46 g tree−1 year−1 (±76.50) over the 8-year study period. No significant differences in oil content were found among accessions, fruit ripening stage, and their respective interactions. Seed moisture content decreased drastically as the fruit ripening stage increased, from 40.5% ± 1.0% at fruit ripening stage 1 (greenish-yellow) down to 13.8% ± 0.4% at fruit ripening stage 4 (black-brown). No significant differences in seed weight were found among accessions, but it decreased as maturation progressed. Yellow fruits (stage 2) were the heaviest (62.4 g ± 1.5 g) and the black-brown fruits the lightest (44.3 g ± 1.9 g). The oil content (%) increased with seed weight up to the point of 58.3 g, but then decreased for heavier seeds.

Balsa trees are native to neotropical forests and frequently grow on fallow, degraded land. Balsa can be used for economic and ecological rehabilitation of farmland with the aim of restoring native forest ecosystems. Although Ecuador is the world’s largest producer of balsa, there is a lack of knowledge about production indicators for management of balsa stands in the country. The aim of this study was to develop growth and yield models (i.e., site index (SI) curves and stem volume models) for balsa plantations in the coastal lowlands of Ecuador. Balsa trees growing in 2161 plots in seven provinces were sampled. Here we present the first growth and yield models for the native, although underutilized, balsa tree. Three curve models were fitted to determine SI for balsa stands, differentiating five site quality classes. Eight volume models were compared to identify the best fit model for balsa stands. The mean annual increment was used to assess balsa production. The generalized algebraic difference approach (GADA) equation yielded one of the best results for the height–age and diameter–age models. The Newnham model was the best volume model for balsa in this comparative study. The maximum annual increment (i.e., for the best stand index) was reached in the second year of plantation. The fitted models can be used to support management decisions regarding balsa plantations. However, the models are preliminary and must be validated with independent samples. Nevertheless, the very fast development of the native balsa tree is particularly promising and should attract more attention from forest owners and politicians.

Jatropha seed is a biomass suitable for bioenergy production that can be produced by smallholders, even on marginal lands. However, the current oilseed production is too low to meet the needs of the planned renewable electricity system in the Galapagos Islands. Pruning and fertilization are management options that can be used to increase the dry seed yields. The effects of both treatments were tested in a split-plot design with jatropha trees, which were monitored during a three-year production period. The average seed production was 643±58 kg ha-1 year-1 in the unpruned trees and 696±50 kg ha-1 year-1 in the pruned trees. Although this difference is small, it is expected to increase over time. The pruned trees developed more slowly than the unpruned trees but showed higher (and still increasing) yields at the end of the three-year test period, while the unpruned trees appeared to have reached their maximum production by the second year of the trial. The low fertilizer doses approved by the smallholders did not have a significant impact on the dry seed yield, and the management options that show benefits in the long term are generally not accepted or adopted by them. Cost-effective nutrient enhancement should be investigated, such as inoculation with arbuscular mycorrhizal fungi.

Tomato (Solanum lycopersicum L.) processing industry requires varieties with increased production and quality, and also with resistance to pest, in order for producers to cultivate these. The aim of this study was to carry out an evaluation of 112 tomato cultivars for production and quality characteristics from the following providers: Orsetti Seed, Heiz Seed, Ohio University, United Genetic and Harrys Moran. The experiment was conducted at the Experimental Research Station Portoviejo of INIAP. Statistical analyses used were principal components analysis for a group of 112 cultivars based on production parameter: yield (t.ha -1 ), average fruit weight (g), number of fruits per plant, defective fruits per plant; in addition to quality parameters as: brix degrees, pH, and acidity. Data were analyzed through an analysis of variance and a Tukey test to establish statistical differences and significance ranges among industrial tomatoes. Results showed that ca. 9 % of the total tomato varieties assessed showed superior characteristics. Five statistical significance ranges were detected, where the first three were materials developed by Ohio University. The best material evaluated was the cultivar SG 07-627, and all materials showed diverse resistance to pests, with potential for genetic breeding as part of an integral pest management strategy for tomato.Key words: Variability; production; quality; paste; food processing; breeding program. ResumenLa industria de procesamiento de tomate (Solanum lycopersicum L.) requiere cultivares con producción y calidad superiores, además de resistencia a plagas, para que los productores prefieran sembrar estos cultivares. La presente investigación se efectuó con el objetivo de evaluar 112 materiales en relación a parámetros de producción y calidad, provenientes de los siguientes proveedores: Orsetti Seed, Heiz Seed, Ohio University, United Genetic y Harrys Moran. El experimento se realizó en la Estación Experimental Portoviejo del INIAP. Para el análisis estadístico se emplearon metodología de análisis de componentes principales para la agrupación de 112 cultivares basados en parámetros de producción como: rendimiento (t.ha -1 ), peso promedio de fruto (g), número de frutos por plantas, número de frutos defectuosos; y además los parámetros de calidad son: grados brix, pH y acidez. Los datos se analizaron mediante análisis de varianza y pruebas de Tukey para establecer diferencias estadísticas y rango de significancia entre tomates industriales. Los resultados mostraron que cerca del 9 % de los materiales evaluados presentaron características superiores. Cinco rangos de significancia estadística se encontraron, donde los tres primeros fueron representados por los materiales desarrollados por la Universidad de Ohio. El mejor material evaluado fue el cultivar SG 07-627, y todos los materiales presentaron distintivos de resistencias a plagas, con potencial para el mejoramiento genético como parte de la estrategia de manejo integral de plagas en tomate.Palabras clave: Variabilida...