Interrupted nitrogen nutrition effects on growth, sucrose accumulation and foliar development of the sugar beet plant

Abstract

Cnder natural conditions, nitrogen supply is frequently limit­ ing to the growth of plants. This may result from seasonal varia­ tions in the nitrogen content of soils and in rates of nitrogen absorption and assimilation by plants as well as from a low supply of native nitrogen. In agricultural environmeri.ts, nitrogen nutri­ tion may be maintained at an optimum level with suitable fertilizer practices. This usually involves more than simply sup­ plying sufficient nitrogen for luxury consumption since the yield and quality of the economically useful yield of many crop species are maximal when nitrogen has been in marginal or deficient supply during critical stages of plant development (8)3. Thus, the response of plants to fluctuations in nitrogen supply is of importance agriculturally as well as biologically. Sugar beet is well suited to studies on the effects of fluctuating nitrogen nutrition on plant growth . It has an indeterminate vegetative growth habi t and tissue analysis procedures (15) have been developed for assessing plant nutrient status. Considerable information has been obtained concerning the responses of sugar beet to nitrogen starvation, (4,5,6,9,11,12) but, except for an experiment by U lrich (9), much less is known about its recovery ' from the deficient condition . Such information should have ecological significance as well as having practical application to commercial production. The experiment reported here was designed to provide in­ formation on the time course of the nitrogen starva tion and recovery responses of sugar beet. Particular attenti01; was given to changes in leaf gro·wth.