Nutrient uptake in cotton in relation to plant architecture
SummaryThe studies on uptake of nitrogen, phosphorus and potassium by two morphologically contrasting varieties of cotton MCU-1 and PRS-72 (bothGossypium hirsutum L.) at weekly intervals, showed that till the bursting of early formed bolls, the former type accumulated these nutrients in larger quantities in leaves and stem than in the fruiting parts unlike the latter type where differences in nutrient contents of these organs were very narrow till the active bolling phase. From flowering onwards, the fruiting parts of PRS-72 contained more phosphorus. Because of its bushy habit more dry matter accumulated and more nutrients remained unutilised in leaves and stem of MCU-1 at harvest compared with the short-branch variety PRS-72. Though both the varieties gave the same yield of seed cotton per unit area, PRS-72 removed considerably less quantities of nitrogen, phosphorus and pottassium. The short fruiting branch character in cotton therefore appears to contribute substantially towards balanced and economic utilization of nutrients.
Rendimiento, componentes del rendimiento y calidad de fibra del algodón en relación con la dosis de nitrógeno y la densidad poblacional
Resumen es: Las variedades mexicanas de algodon (Gossypium hirsutum L.) son mas precoces y de menor tamano vegetativa que las variedades extranjeras tradicionalmen...
Redistribution of Mineral Elements During Development
In the course of a recent address on the control of growth and reproduc­ tion in plants, Gregory (13) drew attention to the fact that over 90 per cent Of the nitrogen and phosphorus taken up by the developing cereal plant had been accumulated when the dry weight was only 25 per cent of the final value. This store of accumulated nutrient was the reserve on which all later growth and development depended, and its level determined the final yield. The nitrogen and phosphorus which was set free from the senescent leaves and tillers was reutilized for production of further leaves which, in turn, provided for the development of the inflorescence. Gregory also stressed the significance of the meristems with their potentially unlimited demand for nutrients, and their capacity to initiate "internal starvation" and senes­ cence. These observations serve very well to introduce the review which is to follow for, in examining the evidence for the redistribution of mineral ele­ ments during development, the reviewer has attempted to relate this to the wider problems of growth. From the outset it should be emphasized that we are primarily concerned with the demonstration and explanation of net losses of mineral elements from specific plant parts. To be relevant, therefore, papers for review had to cover two or more plant parts at several stages of growth. Relatively few of the many papers on the mineral composition of plants fulfil these require­ ments. It seems probable that some elements simultaneously enter and leave the same organ in the course of the normal metabolic flux, and may be regarded as being redistributed from organs which are still undergoing net intake. Such phenomena are not considered here, and it is for this reason that little reference is made to recent work with radioactive tracers. A borderline case is provided by Phillis & Mason (34) who found diurnal variations in the mineral content of the leaf of the cotton plant. The six elements studied showed increases by day and no change or decrease by night. Although the existence of dew losses complicated the picture, it does seem likely that phloem export was responsible for some losses even before maximum absolute contents had been attained. This evidence is a reminder that there can be no hard and fast line between redistribution resulting from normal metabolic activity within the organ considered and redistribution which is conditioned by senescent changes and by demands which arise externally to that organ.