Mineral Nutrition of Plants: A Short History of Plant Physiology

摘要

The development of the knowledge on the mineral nutrition of plants begins between the 17th and 18th centuries when some European naturalists gave the first experimental evidences of what had been empirically known for about two millennia. The works of Hales and Ingenhousz were of absolute importance in relation to the transport of water and solutes, and assimilation of "fixed air" (carbon dioxide), respectively. The early chemistry introduced by Lavoisier benefited the first physiologists Senebier and De Saussure to reject the "theory of humus", which imposed the soil as the unique source of carbon. During the first half of the 19th century, Sprengel and Liebig investigated on the problems related to some indispensable mineral salts, while Boussingault and Ville attempted to prove the nitrogen fixation from air without giving any convincing evidence. Liebig was the pioneer of the agricultural chemistry: he epitomised the knowledge of that period by imposing the so-called "law of the minima", already acknowledged by Sprengel, and patronised the use of mineral fertilisers in Europe by devis- ing several formulas of mineral manure. He, however, did not recognise the needs of external supplies of nitrogen salts for the crops, in open dispute with the English school of Lawes and Gilbert, who were instead convinced assertors of such needs. At the end of the 19th century Hellriegel showed that leguminous plants presenting peculiar nodules on their roots could really fix the gaseous nitrogen. From these nodules Beijerinck and Prazmowski isolated for the first time some bacteria which were recognised as the real agents fixing nitrogen. This discovery was of fundamental importance for plant nutrition, only second to the discovery of photosynthesis. Another basic contribution came from early research of Sachs on plants grown on aqueous solutions: these techniques allowed to impose the concept of "essential elements", which was fixed as a principle by Arnon and Stout in 1939. This principle benefited further research concerning the effects of states of deficiency on plant growth and development through investigation on the anatomical, histologic and biochemical nutritional disorders of plants.%Lo sviluppo delle conoscenze sulla nutrizione minerale delle piante si è articolato come storia della Fisiologia vegetale nel corso degli ultimi quattro secoli. Tra il Sei- e Settecento, alcuni naturalisti europei ottennero le prime dimostrazioni sperimentali di quanto era empiricamente noto da circa due millenni, e cioè che acqua, aria e terra erano i costituenti indispensabili per la crescita e lo sviluppo delle piante. In assoluto, furono fondamentali i lavori di Hales e Ingenhousz per ciò che riguarda, rispettivamente, il trasporto dei soluti e l'assimilazione di un componente dell'aria in seguito riconosciuto come anidride carbonica. Le conoscenze della Chimica, modellate alla fine del Settecento da La-voisier, beneficiarono le ricerche dei primi fisiologi Senebier e De Saussure anche per respingere la cosiddetta "Teoria dell'humus", che considerava il terreno quale unica sorgente di carbonio assimilabile dalla pianta.