NUTRIENT UPTAKE AND DISTRIBUTION

Tagliavini, M1, Zanotelli, D1

massimo.tagliavini@unibz.it

1 Faculty of Science and Technology, Free University of Bozen-Bolzano, Italy

KEYWORDS Calcium, dynamics of nutrient uptake, magnesium, nitrogen, nutrient partitioning, phosphorus, potassium, tree growth, uptake rate, yields. ABSTRACT Annual uptake of nutrients from the soil, and sometimes from the leaves, at desired rates and timings, is necessary for apple and pear trees to successfully complete their vegetative and reproductive cycle, produce high quality fruits, and become economically viable. Nutrient uptake provides for an optimal concentration of nutrient in tree organs to sustain growth, yields, flower bud formation, and the building of nutrient reserves. Nutrient uptake occurs with rates and dynamics depending on tree factors like growth rate (Figure 1) and yields, but also on environmental factors and nutrient availability.

Figure 1 – Example of total annual new biomass (NPPtot) produced by apple trees and its partitioning to fruits (NPPfruits). Data are in t D.W. per hectare and refer to cv. Fuji on M9 with fruit yields around 60-65 t fresh weight ha-1 (27-29 t/acre)

Our quantitative knowledge about the amounts of absorbed nutrients under field conditions is derived either by 1) quantification of new biomass produced every year and its nutrient concentration or 2) by stable isotope techniques. For mature fruit trees, regularly subjected to pruning, it is often assumed that the increment of biomass of the framework of adult trees could be approximated to the amount of pruning wood, as secondary growth is considered low and negligible. Under these situations, nutrient uptake can be estimated by considering the amount of nutrients in the yield, in the pruning wood and in the abscised leaves (Table 1). Calcium (Ca), nitrogen (N) and potassium (K) are often the most absorbed nutrients. The partitioning of the absorbed nutrients within tree organs depends on their relative growth (Figure 1) and on specific nutrient needs. Most absorbed N is allocated to shoots and leaves, while most absorbed Ca is partitioned to leaves and woody organs. Pome fruits have low protein content and relatively low N requirements, while contain relatively high potassium. Therefore, the higher the yields the higher the K uptake and the need for K fertilizers. The rate of nutrient uptake varies along the season with dynamics that differs according to the nutrient. In apple, the uptake rate of N, phosphorus (P), Ca and magnesium (Mg) increases along the spring, slightly decreases in summer and markedly decreases approaching fruit harvest; K uptake rate, on the contrary, decreases only slightly in summer and approaching fruit harvest. Predicting annual amount and dynamics of the nutrient uptake, and their distribution in organs is a fundamental step for developing rational fertilization strategies in apple and pear orchards. Table 1 – Example of nitrogen uptake, assumed equal to the nitrogen content in fruits, abscised leaves and woody organs yearly produced. Tree organ Biomass

(t D.W. ha-1) N concentration

(% D.W.) N content (kg N ha-1)

Abscised leaves 2.3 0.85 20

Fruit 12 0.27 32

Woody organs yearly produced

4.1 0.7 29

Total 18.4 - 81

2015 WSU Fruit School Physiology of Apple and Pear

17-18 November 2015

Nutrient uptake

and distribution

Massimo Tagliavini and Damiano Zanotelli

Introduction

• Nutrient availability in tree organs are necessary to adequately support vegetative growth and productivity.

• Both nutrient deficiencies and excesses should be avoided to reconcile economic and ecological aspects of sustainability in fruit production.

2005 2008 2011 2013

Urea 210 500 410 320

Ammonium

phosphate

250 900 600 450

Triple

phosphate

200 850 520 380

Potassium

chlroride

180 550 420 380

REFERENCE PRICE FOR SELECTED FERTILISERS IN THE

INTERNATIONAL MARKET ($/t)

Nutrient uptake

• Nutrient uptake rates depend on environmental (soil) and

tree internal factors

• An increase in soil nutrient availability normally increases

uptake (especially true for N)

• Adequate root density (and new roots) and root C

availability needed to support nutrient uptake

Source of nutrients for tree growh and

production

• Soil «native» fertility and fertilisers provides nutrients for

root uptake

• Foliar nutrient supply might contribute to fulfil the nutrient

needs (to different extent depending on the type of

nutrient)

• In spring, nutrients remobilised from storage organs

support N metabolism during early vegetative growth

phases, flowering and fruit set

Remobilized N supports the early vegetative and

reproductive stages in apple (Neilsen et al., 1997) and

pear (Tagliavini et al., 1997)

Nitrogen uptake (1)

• Both NH4+ and NO3

- absorbed by apple and pear roots

(Tromp and Ovaa, 1979)

• NH4+ sometimes taken up preferentially as compared to

NO3- (Mota et al. 2011)

• NO3- uptake stimulates shoot growth more than NH4

+

uptake, but the latter is sometimes reported as having

positive effect on flower bud formation (Gao et al., 1992).

Nitrogen uptake (2)

• Presence of both NH4+ and NO3

- in soil is often beneficial

(evidences from other fruit crops).

• Not always easy to control NH4+ : NO3

- ratio in soil due to

microbial transformation of the N molecules.

• The higher the uptake, the higher the growth and the

higher the uptake needs for other nutrients as well!

Phosphorus (P) uptake rate by apple roots as affected by their

age (Bouma et al. 2001)

Root age (days)

Rela

tive P

upta

ke

rate

The need for nutrient uptake ultimately

depend on

• Vegetative and reproductive tree growth

• Specific needs (concentrations) of single organs

Tagliavini, Failla and Xiloyannis, 2012

Pome fruit mineral concentrations

• Pome fruits (apple and pear) mainly contain water and

carbohydrates and are low in protein and therefore are

relatively low in N (0.5-0.8 kg/t F.W.)

• Their Ca, P and Mg concentration is low (approx. 0.05-

0.1 kg/t F.W.)

• But they contain relatively high concentrations of K (1.4-

1.6 kg/t F.W.)

Nutrient concentration (on D.W. basis) ranges of main apple organs

Organs N % P % K % Ca % Mg %

Leaves (July) 2.10 - 3.07 0.16 - 0.32 1.19 - 2.37 1.20 - 2.00 0.18 - 0.36

Leaves (senescent)0.78 - 0.94 0.11 - 0.13 1.46 - 1.56 2.35 - 2.65 0.40 - 0.44

Fruits0.19- 0.29 0.07 - 0.08 0.65 – 1.05 0.04 - 0.05 0.03 - 0.05

Woody organs0.45 - 0.88 0.06 - 0.15 0.29 - 0.45 0.58 - 1.18 0.06 - 0.13

Roots0.74 - 0.78 0.19 - 0.21 0.44 - 0.48 0.99 - 1.07 0.16 - 0.18

Example of total annual new biomass in apple trees and its partitioning to fruits in two years (cv. Fuji on M9 with fruit yields

around 60-65 t fresh weight ha-1)

Apple tree growth rate along the season (data from Zanotelli e al. 2013 and 2015)

Accumulation of N in apple fruits and shoots

Accumulation of P in apple fruits and shoots

Accumulation of K in apple fruits and shoots

Accumulation of Ca in apple fruits and shoots

Accumulation of Mg in apple fruits and shoots

Period

(DaFB)

BIOMASS

mg D.W.

/day

N

mg/day

P

mg/day

K

mg/day

Ca

mg/day

Mg

mg/day

0-36 90 1.90 0.19 1.72 0.63 0.18

37- 81 280 2.45 0.39 3.63 1.36 0.28

82-117 320 1.52 0.22 2.79 0.58 0.15

118-158 260 0.88 0.17 1.63 0.26 0.07

Biomass accumulation and influx rates of nutrients in apple bourse shoots (with one fruit) from ful bloom (day 0 ) to harvest (day 158) (average of Golden del. and

Nicoter. Zanotelli et al., 2014)

Yearly new biomass and N uptakeby apple and pear trees

Organs

Biomass (t D.W./ha) N (kg/ha)

Pear(Abbè F.) 35 t/ha

Apple (Fuji)

60 t /ha

Apple (Gala)

40 t /ha

Pear(Abbè F.) 35 t/ha

Apple (Fuji)

60 t /ha

Apple (Gala)

40 t /ha

Leaves (senescent) 2 2 2 19 19 16

Fruits 6 10 6 16 28 16New woody organs

(above ground) 5 2 4 27 17 23

Roots 2 3 1 7 19 10

Total 15 17 13 69 83 65

OrgansN

(kg/ha)P

(kg/ha)K

(kg/ha)Ca

(kg/ha)Mg

(kg/ha)

Leaves (abscised) 19 2 15 28 2

Fruits 16 5 39 4 4

Woody organs (aboveground) 27 3 5 42 7

Roots 7 1 8 22 3

Total 69 11 74 96 16

Yearly nutrient uptake by pear trees (cv. Abbè Fetel). Data areaverges of three rootstocks – average yields 35 t/ha.

Tagliavini and Quartieri, 2008

Different N concentration of apple leaves asaffected by the genotype

Nit

roge

n (

% o

f d

ry w

eig

ht)

Days after full bloom

Source: Beratungsring Manual Boden und Pflanzenernhärung in Obstbau, Weinbau und Bioanbau, 2004

Foliar uptake versus soil uptake

Foliar uptake alone is inadequate to meet the magnitude of

plant demand from macronutrients, but can complement root

uptake.

If soils are well endowed with Ca, but Ca-related disorders

occur, then direct uptake of Ca by fruit cuticle can solve the

problem.

Bitter pit disorder

Courtesy Neilsen G., 2001

Foliar uptake versus soil uptake

Foliar uptake alone is inadequate to meet the magnitude of

plant demand from macronutrients, but can complement root

uptake.

If soils are well endowed with Ca, but Ca-related disorders

occur, then direct uptake of Ca by fruit cuticle can solve the

problem.

Foliar absorbed micronutrients represent an important way to

supply them, due to

– Small amounts requested

– Low availability of micronutrients in many soils

– Soil deficiency and toxicity thresholds often very close

When foliar uptake is likely to be effective

1. At growth resumption in spring, when remobilization has finished and root uptake is suboptimal

2. During the growing season, when nutrient soil availability does not meet nutrient demand

3. When we see symptoms or analysis show deficiencies that need to be quickly overcome

4. When the nutrient is unavailable if soil-applied (es. when no irrigation is available)

5. In late summer to rebuilt nutrient reserves, for those nutrients with phloem mobility

Final remarks

• Nutrient partitioning affects the fate of the absorbed nutrients

treeFramework

“woody

Organs“”

leaves

abscised leavespruning wood

fruits

SOIL

uptake

Uptake and partitioning Fluxes at “Tree scale”

Nutrients contained in decomposing leaves are released and

become available again for uptake

Tagliavini et al., 2007

Final remarks

• Nutrient partitioning affects the fate of the absorbed nutrients

• Nutrient uptake dynamics data should be used together with tools able to assess soil nutrient availability to fine tune the fertilisers supply in order to match nutrient needs and nutrient availability.

THANKS FOR YOUR ATTENTION