Effects of Nutrient Concentration on Anatomy, Metabolism, and Bud Abscission of Sweet Pea

Abstract

Pisum lathyrus odoratus was grown in quartz sand with continuously percolating culture solutions of "low concns." (1/2 and 1 atm.) and "high concns." (2 and 3 atm.). A larger % of flower buds abscised with plants grown in the less conc. solutions. Abscission was caused by dissolution of the middle lamella of the cells in the separation layer which had failed to mature. This was correlated with high succulence and slow cell differentiation, relatively low carbohydrate content, and high N content, a large proportion of the N being present in form of amide-, amino- and nitrate N. Failure to abscise in "high concn." cultures was associated with xerophytic appearance of the plants and rapid differentiation and maturation of the tissues which contained a low % of N, mostly in the form of complex proteins. The carbohydrate content was high. This effect of high salt concn. on chemical composition is explained by the low power of mature root tissues to reduce nitrates, thus impairing their ability to synthesize proteins. As a result, the carbohydrates which would ordinarily be used in protein synthesis accumulate in the tissues.