SU MMARYField work on rainfed cowpea (Vigna unguiculata (L.) Walp. cvs TC-9-6 and M-28-6-6) was conducted in the Orinoco lowlands to explain the changes in dry-mass partitioning and radiation-use efficiency (RUE) as compared with other cultivars over four consecutive seasons. Growth features were assessed in early-maturing, prostrate-canopy (TC-9-6), and medium-maturing, erect-canopy (M-28-6-6) cowpeas. These cultivars were sown in consecutive middle-wet and late-wet seasons in double peak rainfall conditions. Dry mass accumulation by cultivars was assessed as a function of leaf-area duration and the efficiency with which radiation was converted into dry mass throughout the season (i.e. radiation-use efficiency). Cultivar differences in canopy architecture and duration of leaf area had a minor effect on the total dry mass production. In the early-maturing TC-9-6, RUE for a middle-wet and a late-wet season was 0 . 90¡0 . 04 and 0 . 65¡0 . 05 g/MJ, respectively. In the medium-maturing M-28-6-6, the values were 0 . 97¡0 . 05 and 0 . 72¡0 . 03 g/MJ, respectively. A season with rainfall below 100 mm had a negative effect on phenology and RUE. When average rainfall was above 100 mm, the total dry mass accumulation was not affected by differences in cultivars and seasons. The rate of harvest index (HI) changes was negatively related to pod-filling duration. The changes in assimilation distribution depended on the process of partitioning as modulated by the limited pod-sink and the photosynthate supply. However, the photosynthate source was not depressed by the sink activity of the pod-filling. Partitioning to non-reproductive sinks was maintained. M-28-6-6 with high dry-mass production and delayed senescence did not effectively divert a large amount of assimilate to pod-filling. Pod sink activity in cowpea was limited by genotype. Harvest index in M-28-6-6 decreased with the increasing dry mass. The final HI and rate of linear increase in HI differed between cultivars and were lower in M-28-6-6. The results of the present work in the Orinoco lowlands are relevant for a wide range of savannahs with a late wet season.
Aleados de Mg conteniendo 20% y 40% masa de Ti (Mg20Ti) (Mg40Ti), han sido sintetizados por aleación mecánica y caracterizados mediante difracción de rayos-X (DRX) y microscopia electrónica de barrido (MEB con EDS) Los estudios DRX sugieren la incorporación de Ti en la fase Mg, y luego de 40 horas de molienda se aprecia la aparición de dos reflexiones identificadas como óxidos de Mg-Ti. El oxígeno se incorpora al proceso de síntesis debido a las continuas fracturas y soldaduras que ocurren durante la molienda, y hace posible también la formación de una solución sólida de Ti, TiMg. A medida que el tiempo de molienda se incrementa, la talla de cristalitas (D y DS) muestra un decrecimiento hasta valores cercanos a 10 nm, corroborándose este comportamiento mediante microscopía, donde la disminución de talla de partículas alcanza aproximadamente 20 nm. La morfología del aleado va variando, hasta observarse de forma globular o conglomerados de partículas. El análisis EDS confirmó además de Ti y Mg, la presencia de otros elementos.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.