A methodology for evaluating the manganese tolerance of cowpea (Vigna unguiculata) and some preliminary results of field trials

摘要: Abstract Cowpeas (162 cultivars) were grown across soil pH gradient (4.8–7.1) which had been established by liming a manganiferous Oxisol of Hawaii. In the early stages growth low was associated with chlorosis first trifoliate leaves some cultivars. A more frequently observed symptom “freckling” on unifoliate and leaves. Many varieties growing in acid developed multiple shoots petiole axes after flowering. This symptom, when severe, always aborted flowers. The Mn contents 35-day-old cowpea tops, at three levels, ranged from 600 to 2800 μg/g. As group, cultivars responded most lime additions, if they not limed, contained almost twice as much nonresponsive group. maximum content young possible range 2500–2800 Cultivars fixed increasing amounts N (decreasing plant Mn). vigorously plants about 1000 μg Mn/g top. nutrient solution culture this 1–2 Mn/ml solution. Potential yield 4.8 favorable estimated regression curves vs. distance variable. Responsiveness evaluated slope line. scheme classified for tolerance developed. five main groups based potential each cultivar subgroups 4.8. indicated order listing within subgroups. Based 10 qualified subgroup A1 required > 1500 kg/ha optimum 50%