A preliminary investigation into the root systems of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) using a prescribed sampling method for the study

A PRELIMINARY INVESTIGATION INTO 'l'HE

ROOT SYSTEMS OF PERENNIAL RYEGRASS

(LOLIU1-A PERENNE) ANJ WHI'l.b. CLOVER ('1R1?OLIU ,,r REPE.rs) USING A PRESCRIBED

SA.,.PL:NG ME'THO.J

FOR

THE S'IUDY.

BY

BRICK.

r

C O N T E N T S.

---A. INTRODUCTION.

B. OBJECT OF THE WORK.

C. lvIETHOD OF THE EXPERIMENT.

I. General Description.

II. The Plots:

( a) Plan of the Plots.

(b) Laying down the Plpts.

(c) Routine care.

-III. Trucing the Samples.

(a) Method of taking.

(b) Position of sampling.

IV. Treatment of the Sample.

( a) Washing.

(b) Examination.

( c) Weighing the roots.

V. The Pots.

( a) Purpose.

(b) Laying down.

(c) Method of studying the roots.

VI. Method of Measuring the Production of Leaf.

( a) Cutting.

(b) Weighing.

D. RESUL1

rs

AND

_DISCUSSIONS.

I. Ef'f'ect of' Dif'ferent Rates of Def'oliation.

(a) Perennial Ryegrass.

(b) White Clover.

(c) Combinations of' Perennial Rye and White Clover.

(d) Discussion.

II. Ef'f'ect of' 111 _{and 3}11 _{Spacing of' Plants.}

III. Ef'f'ect of' Combination of' Perennial Rye and

White Clover.

IV. Seasonal Variation.

(a) Root Weight

(b) Tiller nuraber.

v.

General Abservations on Occurrence of Nodules on White Clover.

E. CRITICISM OF TECHNIQUE.

(a) General.

(b) Border Effect.

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L16flAf,f .,,LML.•

LIST OF DIAGRAMS AND ILLUSTRATIONS.

-

---Fig. 1. Diagrarn of original plan of the plots.

Fig. 2. Diagram of plan of the plots as modified.

Fig.

3.

Diagram of the frame used for planting.

l c,,, "ll f 1-t. N.Z

Fig.

4.

Adapted shears used for cutting the herbage.

Fig.

5.

Sampler in position to take a root sample.

Fig. 6. Sampler driven in.

Fig.

7.

Sampler being excavated.

Fig. 8. Sampler unscrewed, showing sample.

Fig. 9. 10. 11. Sample being transferred to box.

Fig. 12. Sample ready for transport.

Fig. 13. Diagram to show position of sampling 1" plots.

Fig.

14.

Diagram to show position of sampling

3"

plots.

Fig.

15.

Diagram to show different number plants possible per sample from 111 _plots.

Fig.

16.

View of laboratory apparatus.

Fig. 17. The sieve.

Fig. 18. Method of 'filtering' out the smaller roots.

Fig. 19. Plan of the pots.

Fig. 20. Diagram to show method of planting the 111 _pots.

Fig. 21. Diagram to show plants 311 _{apart in the pots.}

F::.g. Illu~tration of 'bord~r eff ct'.

Fi

0 •

2;

.

DiPgra□ to show posit~on o~ sampling t0

ascertain the effect of the

L18RJ ",-L.rv<•><'C R~ H N.Z

A. INTRODUCTION:

"The roots of plants ar_e the least known,

least understood and least appreciated

part of the plant.11

Weaver and Bruner.

The fundamental importance of an extensive, well

developed and healthy root system cannot be over emphasised.

It must hold the plant firmly in the ground, provide a large

effective absorptive area through which ample nutrients will

become available for growth, and, by penetrating deeply, or

by building up reserves, it must protect the plant against

the exigencies of a dry season.

The study of the roots then, important as they are,

would appear to have been unduly neglected when one considers

the amount of research carried out using as a basis some above

ground feature of the plant. In this connection W.F. Loehwing

( 1) may be quoted - "As one surveys the monumental literature

dealing with crop production, the small fraction thereof devoted

to roots and the absorption processes seems entirely out of

proportion to their importance".

This state of affairs may emanate from the failure to

admit the possibilities of investigations of the roots or may be

due to the difficulty of studying them, but whatever the cause

i t is very noticeable in the case of many of our pasture plants.

These have been the objects of intensive breeding and selection

based on their ability to produce foliage and this work has

affected a marked and creditable improvement in the last few

years.

2.

An examination of the present accepted methods of root

study reveals that they are usually slow, tedious and e~pensive.

Weaver (2) used a method wherein a large hole is excavated

adja-cent to the plant to be studied and each root is laboriously

traced out by picking the soil away. Pavlychenko (3) has used

a method which involves the removal of large blocks of soil

which have to be hoisted from the ground. These methods, while

being suitable for giving a picture of the nature of the root

system of a particular species would be quite inadequate to show

the effects of various treatments on that species. In the main

such studies involve the use of single plants and/or the use of

boxes of soil which innnediately set up artificial conditions.

Sprag~

(4)

has used a system essentially similar to that

described here wherein he digs out a small prism of soil and

then trims it to a giv~ size.

However, the method adopted here is very much simplified

but is as yet untried and must be critically examined step by

step and its value as a means of studying root behaviour under

different experimental conditions ascertained. In view of this

the investigation of several general points would appear to

present wider scope for such preli1ninary exploration. Results

which could be satisfactorily subjected to statistical analysis

evolved and proven and the prerequisites of a statistically

accurate experiment known.

3

.

Many pro1:ierns would immediately present themselves for

investigation following the evolution of a suitabl e technique.

The effect on root development of placement of ferti lizers, of

the time of sowing down the pastures, of the various cult ivation

practices, are all points that could well be studied Tith a view

t o ascertaining the adequacy of existing systems of husbandry.

Work done by Bertram ( 5) shows the depressing effect on the -root

system of allowing the water table to approach the surface of

the soil, work by Jacques in N.Z. (6) demonstrates the detri

-mental results of too frequent grazing, while Bates (7) has

amply illustrated the inhibiting effect of an acid soil.

Similarly more work may bring to light new, or provide additional

confirmation of known effects of mis-management.

The accumulation of a detailed knowledge of the roots

themselves and the factors influencing their development might

lead to much more important work being done. Some· practical

application may be found in the matter of soil erosion which is

a very serious problem both from the individual farmer's point

of view and perhaps more so from the national aspect.

Further, it is not impossible that a strain of grass may

be evolved which is suited to dry or sandy areas by virtue of a

root system which penetrates deeply or which is capable of storing

considerable reserves or which in other ways allows the plant to

While realising tre value of root studies one must not lose

sight of the fact that the ultimate test of a strain of grass

4.

is the amount of food material produced. Actually a high total

production may not be so important as a lesser production with

much of it at a period of normally low production or during a

period. of adverse conditions for growth. The point is, however,

that only insofar as they increase the value of the species have