Studies on mineral nutrition of the coffee plant (Coffea arabica L. cv. Catuaí Vermelho): LXIV. Remobilization and re-utilization of nitrogen and potassium by normal and deficient plants

Abstract

Remobilization and re-utilization of 15N and 85Rb labelled nitrogen and potassium reserves for new growth and fruit formation was studied under greenhouse conditions using both normal and deficient young coffee plants. It was found that K reserves are used in higher proportion than is stored N by fruits and other organs. The export of N by organs of residence in the normal plants obeyed the following proportions of the total: leaves 47%-58%, branches and flower buds 21%-27%, roots 21%-32%. The corresponding figures in the case of deficient plants were: leaves 49%-65%, branches and flower buds 21%-27%, roots 14%-25%. Re-utilization of K took place in the following proportions in the normal plants: leaves 54%-64%, branches and flower buds 20%-21%, roots 30%-41%. In K deficient plants the figures were: leaves 62%-79%, branches and flower buds 1.2%-4.4%, roots 20%-33%. In tissues formed after the initiation of flowering buds, the demand for N is met by reserves as follows: normal plants: fruits 20.6%-24.8%, leaves 15.6%-19.4%, twigs 19%-20.5%; deficient plants: fruits 43.5%-48.5%, leaves 48.1%-51.9%, twigs 46%-53%. The K needs for new tissues are met in the order: normal plants: fruits 40%-45.8%, leaves 27%-37.6%, twigs 26%-33.1%; deficient plants: fruits 65.7%-81.5%, leaves 52.6%-68.4%, twigs 62%-86.1%. Fruits represent the main sink for both N and K. Re-utilization of both elements is higher in the case of deficient plants.

Concentration and accumulation of macronutrients in leaf of coffee berries in the Amazon, Brazil

“…This inverse behaviour observed for nitrogen and phosphorus between leaves and fruit, mainly at the initial period of evaluation, may be because of the source-sink effect occurring from leaves to fruit due to the nutrients required for fruit formation at this stage, as nitrogen and phosphorus are high-mobility nutrients that promote this phenomenon. Lima Filho & Malavolta (2003), Laviola et al (2006Laviola et al ( , 2008 report that when the absorption of nitrogen through soil is insufficient for bean formation, the remobilisation of nitrogen from leaves then occurs to meet the required demand. The mobilisation of phosphorus from leaves to fruits also tends to increase as a function of the amount of fruit produced; that is, greater production results in lower leaf concentrations of this element (Laviola et al, 2007d).…”

Nitrogen fertilizer (15N) leaching in a central pivot fertigated coffee crop

“…Several studies of N uptake have used 15 N as a tracer to quantify this plant nutrient in the different compartments of a soil-plant-system (Lara Cabezas et al, 2000;Boaretto et al, 1999;Boaretto et al, 2007;Fenilli et al, 2004;Oliveira et al, 2002;Lima Filho & Malavolta, 2003). However, the widespread adoption of advanced farming practices such as N fertigation requires further studies on the interactions climate-soil-coffee.…”