[Molybdenum requirement of groundnut and black gram]
1994
Pichit Pongsakul | Samnao Phetchawee | Suwapan Ratanarat | Phoemphun Kiratikasikon | Bell, R.W. (Department of Agriculture, Bangkok (Thailand). Soil Science Div.)
Effects of molybdenum (Mo) supply on the relationships of Mo concentrations in soils and plant parts to yield, dry matter production and nitrogen (N) content was examines in peanut (Arachis hypogaea L.), blackgram (Vigna mungo L.) sown with and without Mo on many sites with ammonium oxalate extractable Mo levels from 0.025 to 0.72 mg/kg. On six soils peanut shoots had pale green foliage and decrease N concentrations. Seed dry matter of untreated peanut plants was depressed on two of the soils. Molybdenum concentration 7000 and 130 ng/g in nodules and youngest fully expanded leaves (YFEL) respectively, diagnosed deficiencies for N2 fixation at early pegging in peanut. For prediction of seed and shoot dry matter at maturity, concentrations of Mo in YFEL at early peggging were less reliable than those at pod-filling for which the critical values was 15-18 ng/g. In soils, ammonium oxalate extractable Mo levels at higher than 0.05 mg/kg were adequate for N2 fixation by peanut on sandy soils. Blackgram requires approximately 5 mg/kg in nodules for optimum yield. Molynbdenum concentration in soil solution at 0.002 mg/L is likely to be enough for blackgram needs.
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