Cotton growth and boron distribution in the plant as affected by a temporary deficiency of boron

The knowledge of nutrient mobility is an important tool to define the best fertilizer management and diagnosis techniques. Patterns of boron (B) mobil ity in plants have been reviewed, but there is very little information on B distribution and mobility in cotton. An experiment was conducted to study plant growth and B distribution in cotton when the nutrient was applied in the nutrient solution or to the leaves, and when a temporary deficiency was imposed. Cotton(Gossypium hirsutum, Latifolia, cv. IAC 22) was grown in nu trient solutions where B was omitted or not for 15 days. Boron was applied to young or mature cotton leaves in some of the minus B treatments. Root gr owth decreased when the plants were transferred to B solutions, but there w as a full recovery when B was replaced in the nutrient medium. Boron defici ency, even when temporary, reduced cotton shoot dry matter yields, plant he ight and flower and fruit set, and these could not be prevented by foliar a pplication of B. Because of decreased dry matter production, leaves of defi cient cotton plants actually showed higher B concentrations than non defici ent leaves. This would be misleading when a mature leaf is sampled for diag nosis. If there is any B mobility in cotton phloem, it is very low.