rootpoint narrated

Root Structure & Function:

Root Structure & Function There is a recorded narration with this slide show. 1

Roots Statistics---Oh My!:

Roots Statistics---Oh My! Roots of a single rye plant: 300 miles Deepest known living roots: 190 feet Florida record sweet potato 44 lb. 2 oz. 2

Problems with root research:

Problems with root research 1. Most research on little plants But…… 2. Extrapolated to roots of large trees 3. Which roots go with which plant? 3

Question 1.:

Question 1. What are the real configurations of tree roots beneath the soil? Do the artists have it right? 4

Slide 5:

5

Do the horticultural textbooks have it right? Which is true? A. B. C. = neither:

Do the horticultural textbooks have it right? Which is true? A. B. C. = neither A B 6

Should we use this to illustrate our belief?:

Should we use this to illustrate our belief? 7

Deep roots matter too:

Deep roots matter too 8

Root depths:

Root depths 9

You do the math:

You do the math Y = 1- β d Y = fraction of root mass above depth d (cm) β = approx. 0.962 (guesstimate for FL) ---------------------------------------------------------------- d = 6 cm (2.5”) Y = 22% d = 30 cm (1’) Y = 69% d = 100 cm (3’) Y = 98% 10

This is too simple!:

This is too simple! 11

Hydraulic Lift :

Hydraulic Lift First suggested in 1930s 80s to now, Prof. Todd Dawson Go look: you find it Known in > 60 deep-rooted species 12

Slide 13:

13

Hydraulic Lift:

Hydraulic Lift Raises water at night to shallow soil Protects feeder roots from drying Releases nitrogen and other nutrients Boost in photosynthesis can be 40% 14

Reverse lift---to 43’:

Reverse lift---to 43’ 15

Hydraulic Lift and the Understory:

Hydraulic Lift and the Understory 16

Soil Conditions Limit Root Depths:

Soil Conditions Limit Root Depths In South Florida: High Water Table Hardpan Spodic Horizon Shallow water & fertilizer 17

Oopsie daisy:

Oopsie daisy 18

Root Distribution---The “1H Rule”:

Root Distribution---The “1H Rule” 19

1H sucks---Roots can extend 7X the tree radius:

1H sucks---Roots can extend 7X the tree radius 20

Ideal root conditions:

Ideal root conditions 21

Slide 22:

22

Question 2. How is a dicot root put together?:

Question 2. How is a dicot root put together? 23

Basic Root Parts:

Basic Root Parts Root Cap Border Cells Mucigel Root Hairs Apical Meristem Cortex Endodermis Pericycle Stele Xylem Phloem 24

Root Hairs:

Root Hairs 70% of root surface area Increase absorptive capacity 27X 25

Slide 26:

26

Endodermis:

Endodermis 27

Slide 28:

28

Root Branching:

Root Branching Roots: Branch anywhere Branch from deep within Branch even when thick Branch in direct response to environmental cues Stems: Branch only from buds Branch from the outside Branch mostly when thin Branch largely in response to hormonal signals 29

Branching “hormone” (Glutamate released by organic decay stimulates branching):

Branching “hormone” (Glutamate released by organic decay stimulates branching) 30

Low P also causes bushy branching…:

Low P also causes bushy branching… Low phosphorus causes increase in root mass Low phosphorus stimulates root hairs Low phosphorus turns on P transporters 31

Then, what’s up with this stuff?:

Then, what’s up with this stuff? Fertilome Root Stimulator, a liquid suspension fertilizer that is high in phosphorous MISSPELLED, and potassium USELESS as well as Vitamin B1 HUH? and a rooting hormone IBA. IBA INHIBITS ROOTS The combination of these nutrients, vitamin B1 and IBA rooting hormone promotes quick root development needed to stabilize the necessary growth & healthy of landscape plants. BS 32

Exudates and mucigel:

Exudates and mucigel 33

Exudate from root hairs:

Exudate from root hairs 34

WHY EXUDE?:

WHY EXUDE? Lubrication Moist soil contact and N uptake Promotion of microbes Attracts N-fixing bacteria Enzymes and organic acids release P Carboxylic acid Phosphatases Ties up toxic aluminum Natural chelation Inhibit nematodes and bacteria 35

Question 3. Why do roots grow where they do?:

Question 3. Why do roots grow where they do? 36

Adjustable geotropism:

Adjustable geotropism 37

Feeder Roots Follow Water & Nutrients:

Feeder Roots Follow Water & Nutrients 38

Feeder root turnover:

Feeder root turnover 39

Split root experiment:

Split root experiment 40

Roots and drought:

Roots and drought Drying 41

Slide 42:

Growth Pressure Proline Enzyme Activity Abscisic Acid Squares = irrigated Dots = dry 42

Question 4. What are the important ecological relationships of roots?:

Question 4. What are the important ecological relationships of roots? 43

Nitrogen Fixation:

Nitrogen Fixation Legumes Australian Pine Silverthorn Wax Myrtle Cycads ( Cycas ) Azolla (floating ferns) 44

Allelopathy:

Allelopathy 45

Allelopathy:

Allelopathy Root-to-root murder Toxic exudates Allelochemicals can cause dinitrification with high ammonium content 46

P vs. N in roots:

P vs. N in roots Phosphorus taken up by root interception Mycorrhizae Cluster roots Low P growth stimulation Nitrogen taken up in mass flow (drought causes N deficiency) 47

Mycorrhizae:

Mycorrhizae 48

Mycorrhizae:

Mycorrhizae 49

Slide 50:

50

Cluster Roots:

Cluster Roots 51

Slide 52:

52

Cluster Roots Examples:

Cluster Roots Examples Australian Pines Perhaps Silverthorn Ficus benjamina Wax Myrtle 53

The End:

The End 54