Nutrient deficiencies affecting peanut production in soils of northeast Thailand

Peanut is widely grown in the rainy season on upland soils (mostly Paleustults) in northeast Thailand. The nutrient status of these soils for peanut production has not been adequately assessed. Response to phosphorus, potassium, sulfur, and copper on a range of soil types of this region have been obtained in pot trials using pasture legumes (Wilaipon 1976). The present experiments were set up to identify nutrient deficiencies which could limit yield and kernel quality of peanut on an Oxic Paleustult (Khorat series)

The effect of copper on nitrogen fixation in subterranean clover (Trifolium subterraneum)

Copper deficiency decreased nitrogen fixation in subterranean clover. Three lines of evidence support this conclusion. Firstly, while both copper and nitrogen application increased the growth of the legume the interaction between copper and nitrogen on growth was negative. Secondly, the application of copper increased the concentrations of both total and protein nitrogen in the plant. Lastly, nitrogen fixation as measured by the acetylene reduction assay increased with copper application to the soil

An alternative nitrogenase is not expressed in molybdenum-deficient legume root nodules

Three legume root nodule bacteria systems (Medicago polymorpha L. ‐Rhizobium meliloti, Ornithopus sativus Brot. ‐Bradyrhizobium lupini and Trifolium subterraneum L.‐ Rhizobium leguminosarum by. trifolii) were grown in solution culture under conditions likely to lead to the production of alternative nitrogenases (molybdenum‐deficient, or molybdenum‐deficient but supplemented with vanadium). Addition of 1 μM molybdenum produced significant responses in both nodule and top weights while 2 μM vanadium did not. Ethane, which is produced as well as ethylene when acetylene is reduced by vanadium nitrogenase or nitrogenase‐3 from Azotobacter, was not found in significant amounts during assays of acetylene reduction in either molybdenum‐deficient or molybdenum‐deficient, vanadium‐supplemented treatments, suggesting that no non‐molybdenum nitrogenase was produced by these root nodule bacteria

Boron deficiency in grain legumes

Low levels of hot water soluble boron (Hiranburana and Chawachati, these proceedings) have been found in many series of the major soils of northern Thailand. Boron deficiency has been identified in farmers' peanut crops throughout the Chiang Mai Valley (Netsangtip et al., these proceedings). However, the four major food legumes of northern Thailand - green gram, black gram, soybean and peanut - have been found to differ significantly in their response to boron deficiency

Plant nutrition in the 20th and perspectives for the 21st century

This paper briefly presents the knowledge of plant nutrition in 1900 and its expansion since then in two areas the discovery of the micronutrients and the absorption of nutrients from soils. Application of macro- and micronutrient fertilizers has contributed substantially to the huge increase in world food production experienced this century. In developed countries, excessive fertilizer use has led to serious problems of nutrient pollution; here, plant nutritionists will be concerned with monitoring nutrient status of crops and soils to maintain crop production with minimum loss of nutrients to the environment, and development of cultivars with high nutrient efficiency in soils with luxury supplies of nutrients. In many developing countries, soil infertility limits productivity; here, plant nutritional research can raise productivity bY diagnosis of nutrient deficiencies and toxicities of crops on previously unfertilized soils, their correction with minimal fertilizer and treatment costs, and development of cultivars with high nutrient efficiency in deficient soils and high tolerance of natural toxicities. The pre-occupation of developed countries with pollution is blinding them to the urgent needs of developing countries for fertilizers and fertilizer research to increase crop production ha-1 as an alternative to clearing more land