Five different bean varieties (Phaseolus vulgaris L.) from Kenya, which were obtained either freshly collected or after having been stored for 5 years in tropical conditions (30−40 °C, >75% RH), were compared for their cooking characteristics. Beans under storage were susceptible to the hard-to-cook (HTC) defect, and the bean cooking time was up to 12 times that of the fresh beans, limiting their acceptability. A study was undertaken to investigate changes in nutritionally relevant physicochemical properties of beans during storage. Chemical analysis showed that storage resulted in a decrease in pH and an increase in titratable acidity in all varieties. Total polyphenol, non-tannin polyphenol, tannin, and lignin contents were determined; storage-induced HTC beans contained lower levels of total polyphenols (especially, non-tannin polyphenols) than the fresh beans but higher levels of tannins in all cultivars. Significant increases in lignin and lignified protein were also detected and accompanied by increases in cooking time. A reduction in phytic acid was also observed. These results are discussed in relation to the mechanisms which may underlie the development of the HTC defect. Keywords: Beans; hard-to-cook; phenolic compounds; storage

Soil crusting is a serious problem in numerous irrigated soils of Aragon. It reduces water infiltration rate, seedling emergence and crop establishment, and enhances runoff and soil erosion. This paper analyses the efficiency of soil conservation practices (direct drilling and mulching) and chemical amendments (gypsum) on the control of soil crusting, and its effect on seedling emergence and corn production. The experiments were carried out in Sierra de Luna (Zaragoza) in a soil prone to crusting. The experimental design was a randomised complete block with six treatments and three replications: T1 (sowing and several irrigations until emergence, a practice known as «aguacive-ra» in Aragon; considered as the control treatment), T2 (sowing and delayed irrigation until post-emergence), T3 (direct drilling over nearly bare soil), T4 (direct drilling over legumes), T5 (T1 + gypsum), and T6 (T2 + gypsum). In all the treatments, except for T1 and T5, irrigation was delayed until post-emergence. Measurements were made on plant emergence, penetration resistance of the crust, final infiltration rate and corn production. All variables were significantly affected by the treatments. T6 was the most effective treatment in reducing soil crusting and enhancing water infiltration into the soil, whereas both T6 and T2 were the most effective at enhancing seedling emergence and corn production. The «aguacivera» treatments (T1 and T5) induced the highest crusting and emergence reduction and, together with T3, they were the least productive, whereas the direct drilling treatments (T3 and T4) followed an intermediate pattern. For crusting reduction, treatment T4 was more effective than treatment T3. The addition of gypsum coupled to a delay in irrigation until corn emergence was thus the most effective treatment of those tested in this work to reduce soil crusting.Key words: infiltration, soil conservation practices, direct drilling, gypsum, irrigation, legumes. Resumen Técnicas de control del encostramiento de los suelos y su efecto en la emergencia y producción de maízEl encostramiento del suelo es un problema serio en muchos de los regadíos aragoneses: reduce la infiltración, aumenta la escorrentía y erosión y reduce la emergencia y producción de los cultivos. Este trabajo evaluó la eficiencia del laboreo de conservación (siembra directa, acolchado) y de enmiendas químicas (yeso) para minimizar el encostramiento y su efecto en la emergencia y producción de maíz. El estudio se realizó en Sierra de Luna (Zaragoza), mediante un diseño experimental de bloques al azar con seis tratamientos y tres repeticiones: T1 (siembra y riegos hasta nascencia, conocido como «aguacivera» en Aragón, y considerado como control), T2 (siembra y retraso de riegos hasta después de nascencia), T3 (siembra directa sobre suelo casi-desnudo), T4 (siembra directa sobre leguminosas), T5 (T1 + yeso), y T6 (T2 + yeso). En todos los tratamientos, excepto T1 y T5, se retrasaron los riegos hasta después de nascencia. El número de plantas emergidas, el grado...