Three trials were planted at CIAT, Colombia, with selected lines of red seeded beans (Phaseolus vulgaris L.), representing the best that has emerged from breeding of each growth habit, in order to study the relationship between growth habit and competitive ability with maize (Zea mays L.) when intercropped. Treatments included sole cropping without stakes, and with stakes that varied in height from 1 m to 2 m, and intercropping with short and tall maize cultivars. Highly significant interactions of bean lines by cropping systems were found. Correlations between yields of bean lines in sole cropping without stakes and intercropped were negative or zero, whereas correlations between sole cropping with stakes and intercropping were significant and positive. Internode length increased with growth habit, from bush to climbing types, and indeterminate types were stimulated to develop more main stem nodes either by the presence of a stake or a maize plant. Climbing types (Type IV) tended be later to flowering and maturity and were more competitive with the maize than bush types. Harvest index was reduced less in the Type IV lines when intercropped with maize than in the bush lines (Types I, II, and III). In a breeding program, selection in crosses among growth habits will tend towards bush types of beans when selected in sole cropping, and climbing types in intercropping.

Quinone derivatives like 2-(4-hydroxyphenyl) amino-1,4-naphthoquinone (Q7) are used as antitumor agents usually associated with adverse effects on the cardiovascular system. The objective of this study was to evaluate the cardioprotective effect of ascorbate on Q7-induced cardiovascular response in Wistar rats. In this study, blood pressure, vascular reactivity, and intracellular calcium fluxes were evaluated in cardiomyocytes and the rat aorta. We also measured oxidative stress through lipid peroxidation (TBARS), superoxide dismutase- (SOD-) like activity, and H2O2 generation. Oral treatment of rats with ascorbate (500 mg/kg) for 20 days significantly (p < 0.05) reduced the Q7-induced increase (10 mg/kg) in blood pressure and heart rate. The preincubation with ascorbate (2 mM) significantly (p < 0.05) attenuated the irregular beating of the atrium induced by Q7 (10−5 M). In addition, ascorbate induced endothelial vasodilation in the presence of Q7 in the intact aortic rings of a rat and reduced the cytosolic calcium levels in vascular smooth muscle cells. Ascorbate also reduced the Q7-induced oxidative stress in vivo. Ascorbate also attenuated Q7-induced SOD-like activity and increased TBARS levels. These results suggest a cardioprotective effect in vivo of ascorbate in animals treated orally with a naphthoquinone derivative by a mechanism involving oxidative stress.

Efectos de distintas concentraciones de boro y pH en el crecimiento de Zea mays var. Capia blanco, un maíz ancestral de Chile Effects of different boron concentrations and pH on growthZea mays var. Capia blanco, an ancestral corn from Chile

No abstract