Tải bản đầy đủ - 0 (trang)
V. Environmental and Agronomic Factors Affecting Lodging

V. Environmental and Agronomic Factors Affecting Lodging

Tải bản đầy đủ - 0trang

23 2


Increased internode elongation may be due to cell division as well as

to cell elongation. Both are subject to considerable environmental effects

which affect the growth-regulating mechanism within the plant. However,

the transverse growth of the subapical tissues which would increase culm

diameter and wall thickness, is usually quite limited (Sachs, 1965). Cell

number in the transverse direction is already complete before the onset

of internode elongation. Moreover, there exists an inverse relationship between the rate of cell elongation and transverse growth (Sachs, 1965).

Consequently, an increased length of the internodes will be accompanied

by a reduction in their diameter and wall thickness. This, together with

the increased hydration which accompanies cell elongation, results in a

conspicuous reduction in dry weight per unit length of culm, which has

often been associated with lodging susceptibility.



Light intensity is a decisive factor in internode elongation. It also controls the balance between longitudinal and transverse development of vascular tissues. High intensities block the action of natural gibberellin which

promotes both division an elongation of cells (Sachs, 1965). Consequently, low light intensity promotes internode elongation and reduces

culm-wall thickness. It will also reduce carbohydrate assimilation, which

may interfere with cell wall development and lignification (Percival,

1921). Furthermore, root growth may also be depressed by low light intensity (Campbell and Read, 1968).

The effect of light intensity on cereal culm internodes has been investigated in field and pot experiments where illumination was controlled by

shading. Shading resulted in an up to 25% increase in internode length

(Carles et al., 1960; Holmes et al., 1960; Mulder, 1954). Culm diameter

and wall thickness of oats were reduced (Mulder, 1954), solidness of the

lower internodes of wheat was decreased (Holmes et al., 1960), and the

bending resistance of barley culms was lowered (Hozyo and Oda, 1965).

Artificial shading of field plots, which reduced light intensity during the

period of elongation of the 2-4 lowest internodes by 35-75%, promoted

lodging of wheat (Holmes et al., 1960; Welton and Morris, 1931) and

of barley (Coenradie and Wilten, 1962; Wilten and Coenradie, 1958,


The effect of light intensity on lodging is evident from numerous studies

of plant density (Section VI, A, 3). In dense stands light interception

is reduced, which affects the lower culm internodes and promotes lodging.

It should be pointed out that the effect of shading, caused by dense stands,


23 3

may also be exerted by infestation with weeds, which does indeed promote

lodging in certain cases.

Very conspicuous effects of plant populations from 50 to 1600 plants

per m2, on culm elongation of barley, were reported by Kirby and Faris

(1970) and attributed to the effects of light on plant gibberellin.

Internode elongation may presumably be affected directly by the temperature prevailing during the pertinent growth period. A significant correlation was found between the culm length of barley and the temperature

during the period from seedling emergence to heading (Pasela, 1967). An

increase in temperature, however, may also promote tillering (Nanda et

al., 1959). This, in turn, will increase the density of the foliage, which

may reduce light interception and thus affect the lower culm internodes.

Another indirect effect on the promotion of internode elongation through

increased temperatures may be due to its effect on the release of soil





The promotion of lodging due to abundant nitrogen supply is well

known and has been established in many studies with various cereal crops

(e.g., Bremner, 1969; Dilz, 1967; Morey et al., 1970; Mulder, 1954; Nilsson, 1972). Usually, at high nitrogen levels there is a reduction in grain

yield. In most cases it may be attributed to lodging, although it should

be kept in mind that lodging is not the only factor limiting yield response

to high nitrogen levels (Fiddian, 1970).

It is of special significance that high N levels are conducive to lodging

also of semidwarf varieties. This has been reported, so far, for common

wheat (Asana and Chattopadhyay, 1970; Hadiiselimovik, 1969; Sage,

1970; Sharma et al., 1970), durum wheat (Scarascia Mugnozza et al.,

1965), and barley (Sage, 1970). In most cases lodging of these varieties

at high N levels was accompanied by a reduction in grain yield. Lodging

and reduction in grain yield of the semidwarf varieties commence at higher

N levels and seem to proceed more moderately than in the case of tall

varieties. Similarly, at those N levels which have been tested so far, no

complete lodging of the semidwarf varieties has been encountered. Considering the information from the above-cited sources and others (e.g., Sillampaa, 1971), as well as recent local experience (Weiss, 1972), we attempted to demonstrate the comparative response of tall and semidwarf

varieties to nitrogen supply (Fig. 4 ) .

The effect of nitrogen on lodging should be ascribed primarily to its

effect on the basal culm internodes. The results presented by Mulder

( 1954) indicate that nitrogen affected all the morphologic and anatomic

culm characters associated with lodging. An increase of 10-25% in the



length of the three lowest internodes due to high N level was observed

in the various crops (Carles et al., 1960; Friichtenicht, 1965). Enhanced

culm elongation following application of high N rates has been found also

in semidwarf varieties of wheat (Koltay, 1968; Woodward, 1966) and of

barley (Lovato and Venturi, 1968). High N rates may also bring about

restrictions in the development of the coronal roots (Mulder, 1954). In

this respect it is of special interest that root anchorage of a semidwarf

wheat variety was found to be weakened due to application of high N rates














- 1






Nitrogen supply


FIG. 4. The effect of increasing nitrogen supply on lodging and grain yield of

tall and semidwarf cereal varieties.

(Berlyand-Kozhevnikov et al., 1968). However, the information concerning the effects of N supply on the root growth of cereals is somewhat contradictory (Troughton, 1962). In general, it may be concluded that its

effect is less on root growth than on shoot growth and therefore increased

N supply will always result in an increased shoot:root ratio, which is conducive to lodging.

An increase in nitrogen supply may affect the basal culm internodes

also through the promotion of plant canopy development, which reduces

light interception. The interaction effects of nitrogen and shading on the

basal internodes have been investigated by Mulder (1954) and by Carles

etal. (1960).

The promotion of plant canopy and the weakening of the basal internodes due to increased nitrogen supply have been found to enhance the



incidence of eyespot disease (Bauer, 1963). This,in turn, may also promote lodging. In other studies, however, eyespot-induced lodging of wheat

was reduced by the application of N fertilizer (Bockmann, 1964).




The effect of these elements on lodging are less pronounced and less

consistent than those of nitrogen. In evaluating their effects, differentiation

should be made between those that originate in the repair of deficiencies

and those which are due to additional supply. The former may improve

lodging resistance because deficient plants in many cases suffer from poorly

developed culm walls or crown roots; such effects of P and K deficiencies

are evident from Casserly’s (1957) studies of lodging in oats. In many

experiments no effects on lodging, or only very slight ones, were exerted

following the application of either P or K (Chapman and Mason, 1969;

Hernes, 1965; Morey et al., 1970; Raheja and Misra, 1955).

An increased supply of phosphorus has been found to promote lodging

of wheat (Miller and Anderson, 1963; Mulder, 1954; Pyatpgin and

Semikhov, 1967; Shrivastava and Yawalkar, 1960) and of oats (Mulder,

1954). Reduced breaking strength of the culms was found by Miller and

Anderson ( 1963), whereas increased breaking strength of the roots was

reported by Spahr (1960). Increases in the length and diameter of the

basal internodes of wheat, following increased P application, were reported

by Skorda (1970). Based on the findings that phosphorus increases the

N content and decreases the lignin content of wheat culms, Miller and

Anderson ( 1965) suggested that it may promote lodging due to its enhancing of the nitrogen effect and by “reducing the ratio of mechanical tissues

to proteinaceous ones.’’

An increased supply of potassium has been found to reduce lodging

(Shrivastava and Yawalkar, 1960; Wahhab and Ali, 1962). It has also

been found to reduce elongation of the lower culm internodes and to increase their diameter (Shrivastava and Yawalkar, 1960; Wahhab and Ali,

1962) Koch, 1969). Increased wall thickness and number of vascular bundles was also found (Wahhab and Ali, 1962). Following applications of

K, an increase in culm rigidity, due to the modulus of elasticity (E), and

in straw strength, was also reported LHashimoto (1959) and Koch (1969),


Nightingale (1943) ascribes the culm-strengthening effect of K to its

positive effect on carbohydrate synthesis and states that “potassium is frequently recorded as favoring the development of thick cell walls and stiff

straw, but in perhaps as many cases this element is reported as having

the opposite effect.”



Koval’skii and Maslyanaya (1969) claim that lodging of cereals grown

on peat soil may be caused by Cu deficiency. Experiments in Germany

with wheat, barley, oats and rye indicated that on Cu-deficient soils, receiving high N-dressings, the application of copper resulted in the reduction

of lodging and subsequent increase in grain yield (Vetter and Teichmann,

1968). The application of manganese to barley grown on peat soil was

reported to increase the breaking strength of its two lowest culm internodes

(Loiko, 1968). However, Bachthaler (1969) did not find any effect on

lodging resistance of winter wheat, spring wheat, or barley through the

application of copper, manganese, or boron.





Abundant moisture supply may be conducive to lodging due to its promoting effect on culm elongation; it may also increase the incidence of

eyespot, and-when the surplus moisture is in the upper soil layerweaken the anchorage of the root system. On the other hand, dryness of

the upper layer may restrict the development of the coronal-root system

and thus promote lodging (Harlan, 1957). The lodging of spring wheat

stressed for moisture at the onset of culm elongation, in trials at Tucson,

Arizona, was attributed to the interference with normal development of

upper crown roots (Day and Intalap, 1970). The interference of dryness

in the upper soil-layer with coronal-root formation was also reported by

Boatwright and Ferguson (1967) and by Ferguson and Boatwright

(1968). Furthermore, lodging on clay soils under dry conditions may be

evoked by the cracking of the soil, which damages the roots. This has been

observed with wheat in Canada (Hurd, 1964).

Poor soil aeration may increase susceptibility to lodging due to the

effects of respiration inhibition on changes of metabolism which promote

cell elongation (Turkova et al., 1965). It may, presumably, increase lodging also through its harmful effect on root development (Troughton,

1962). The promotion of lodging due to poor aeration and high moisture

content of the soil is especially evident in waterlogged fields and in fen

soils. Soil aeration and soil structure, however, also affect nitrogen availability, which in turn affects lodging, and therefore the effects of these factors on lodging are not clear cut (Mulder, 1954).




The main effect of crop rotation on lodging is exerted through its effects

on the incidence of eyespot, which concerns primarily wheat in western



and central Europe. A close sequence of wheat and other cereals on which

the disease can survive will promote its incidence (Glynne, 1963; Lelley,

1965). Green manuring and underplowing of the stubble have been reported to reduce eyespot-induced lodging (Grootenhuis, 1968).

Other effects of crop rotation on lodging are probably due to its effects

on soil fertility and, in particular, on nitrogen availability. In this respect

the effects of the fertilizers applied to the preceding crop may be greater

than those of the crop itself. Thus, lodging of barley was found to be more

frequent and severe following root crops, alfalfa or well-fertilized grass

than after a grain crop (Beaven, 1947; Dyke, 1967; Gately, 1968; Widdowson and Penny, 1970).

Only little information is available on the effects of tillage practices on

lodging. More lodging of spring wheat was found on plowed land (at

Rothamsted, England) than after slit seeding into an unplowed grass sward

(Hull, 1967). In Czechoslovakia, Kopeckg (1970b) found that subsoiling

increased lodging of barley over that obtained on a regularly prepared seed

bed, whereas rolling after sowing decreased it (Kopeckp, 1970a). A similar effect of rolling was found in Norway (Njes, 1962). These effects may

perhaps be attributed to the impact of the respective seed bed preparation

on nitrification in the upper soil layer and subsequent N availability to

the crop. Thus, subsoiling may have increased nitrification whereas rolling

may have reduced it.



The interaction of lodging-promoting factors is apparently of a synergistic nature. Thus, increased nitrogen supply may promote lodging more

under irrigated than under dryland conditions and, similarly, more in dense

than in sparse stands. This may be illustrated by our (unpublished) observations in a field trial conducted by Dr. Z. Karchi (Table 111).


Lodging Rates (0 = No Lodging; 4 = Complete

Lodging) of Wheat as Affected by Plant Density

and N Application (En nor, Israel, 1965)

Basic dressing of N (kg/ha)

Plants per m*






1 .o













Prevention of lodging



From the information presented above it is apparent that the main lodging-promoting factors are abundant moisture and nitrogen supply, dense

stand, and warm temperature. All these factors, however, are also favorable to grain yield production, Therefore, cultural measures to control

lodging must aim at the achievement of an equilibrium between yield promotion and lodging prevention. Factors affecting the incidence of eyespot

should also be considered.

1 . Date of Sowing

The probability of the plants being at a growth stage particularly susceptible to lodging, during a period of high frequency of lodging-inducing

factors, may sometimes be reduced by a suitable sowing date. Furthermore,

the sowing date may affect lodging through its effects on tillering and on

the period during which stem elongation will take place. Early fall-sowing

of winter wheat will prolong the tillering period; and has been found to

increase lodging (Hanley et al., 1961; Vez, 1968), presumably because

it encourages profuse vegetative growth. Late sowing reduced lodging also

because it decreased the incidence of eyespot (Vez, 1968). On the other

hand, lodging of early-sown crops has sometimes been less than that of

later-sown crops (Henriksen, 1961), which may perhaps be ascribed to

a better developed coronal root system resulting from increased tillering.

In Mediterranean and other warm regions, where spring-type varieties

of cereals are grown in winter, late sowing may reduce the tendency to

lodge. This was demonstrated by the results obtained with irrigated barley

in Arizona (Day and Thompson, 1970), and it has been recommended

to farmers in Israel. Tillering, as well as the elongation of the lower culm

internodes of late-sown crops, in these regions, will occur at lower ambient

temperature and will therefore be restricted. This, and in particular the

restriction of the elongation of the basal culm internodes, may prevent


Spring-sown cereals will enjoy warmer temperature during the periods

of tillering and shooting when sown later. In this case early sowing may

contribute to the prevention of lodging due to a certain retardation of

growth (Rodger, 1956), as found with oats in Scotland (Bain and Morrison, 1961). On the other hand, late-sown plants also enjoy a longer daylength and will therefore reach the stage of head initiation sooner, which

in turn may restrict tillering and the number of elongating stem internodes.



This may have been the reason for the reduction in lodging of late-sown

barley in Belgium (Froidment, 1968).

It is concluded that adopting a suitable sowing date may contribute to

the prevention of lodging. The application of this measure will, of course,

be restricted to those cases in which it has no negative effect on grain yield.

2 . Depth of Sowing and Row Orientation

Deep sowing increases the depth at which the root crown is located

(Chambers, 1963; Foltjh and Mikala, 1971; Percival, 1921) and also its

length (Table IV). This may strengthen the anchorage of the plants in

the soil and thus increase their lodging resistance. However, because of

increased epicotyl elongation at deep sowing, the depth of the root crown


Effects of Sowing Depth on the Root Crown of Common Wheat

(Averaged over 10 Varieties Tested a t Rehovot, Israel, in 1964)

Sowing depth






Length of



Length of











Location of crown

below soil surface





does not reach the depth of sowing (Table IV). Therefore, it seems that

within the range of practicable variations in sowing depth, the effects on

the root crown may be rather small. Nevertheless, deeper sowing has, indeed, been found to increase lodging resistance of barley (Socittt d’Enccouragement de la Culture des Orges de Brasserie et des Houblons en

France; Rapports sur la campagne 1959).

Sowing in drill rows in a direction parallel to that of the prevailing

strong winds may reduce the incidence of stem lodging. This should also

be taken into account while the effects are considered of plant-row direction on yield due to their influence on light interception.

3. Spacing

Numerous studies, with all three cereals and in all parts of the world,

indicate that lodging may be prevented or reduced by a decrease in plant

density accomplished by a reduced seeding rate (e.g., Bengtsson and

Ohlsson, 1965; Furrer and Stauffer, 1970; JevtiC, 1971; Kirby, 1967;



Lowe and Carter, 1972; Nelson and Roberts, 1961). Up to a certain seeding rate, plant density will be compensated by tillering, resulting in a rather

constant shoot density. In this situation lodging resistance will benefit from

low seeding rates due to the promotion, through tillering, of coronal-root

formation. Beyond this rate, lodging resistance will be affected by the shading effects of plant density. The beneficial effect of low seeding rates on

lodging resistance applies also to eyespot-induced lodging (Salt, 1955;

Witchalls and Hawke, 1970).

The prevention of lodging through a decreased seeding rate must, however, be restricted to those levels where no reduction in grain yield is to

be expected in response. Moreover, the effect of plant population on grain

yield is of particular significance under fertile conditions conducive to maximum yields which may be challenged by lodging. [Regarding the relationships between plant population and yield, two reviews should be consulted:

Holliday (1960), and Willey and Heath ( 1969) .]

Reduction in the effect of shading and concurrent maintenance of high

plant population may be obtained by decreasing interrow spacing. Narrower spacing, without any change in the seeding rate, was indeed found

to reduce the length and increase the diameter and wall thickness of basal

culm internodes of wheat (Furrer and Stauffer, 1970; Watson and French,

1971). It also reduced lodging of wheat (Furrer and Stauffer, 1970;

Humphries and Bond, 1969), and of barley (Delhaye, 1971; JevtiC,

1971), and the incidence of eyespot (Furrer and Stauffer, 1970). No effect

of row spacing on lodging of wheat was obtained by Kinra et al. (1963),

but in their experiments lodging was rather slight. In most of the abovecited experiments, the narrower spacing between rows, usually within the

range of 8-25 cm, resulted in a certain yield increase (up to 10%) which

may have been due to the reduction in lodging. Furthermore, in a review

on “the effect of row width on the yield of cereals,” Holliday (1963)

shows that reduced spacing ( <18 cm) has consistently given a small increase in grain yield, amounting to 2-1 0 %.

In addition to its effects on lodging resistance, narrow row spacing may

contribute to an increase in yield also by improving light interception. This

should be of particular significance at high plant populations, which are

required for the attainment of top yields (Duncan, 1969).

Lodging of wheat was also reduced owing to a change in the spatial

arrangement by sowing groups, 15-20 cm apart, of about five seeds per

group (Forneris, 1964; Lemaire et al., 1969). It is doubtful whether high

plant populations can be attained by this method, and its practical application seems to be complicated.

In conclusion, narrow interrow spacing should increase lodging resistance without interfering-to say the least-with grain yield production.



24 1

4 . Timing and Form of N Application

The highest rates of nitrogen uptake are during the period of shooting.

Its adequate supply at this time is decisive for grain yield. However, with

the exception of very low available soil N, the demand for N fertilizer

during the earlier growth period is rather limited. An abundant supply during this period will promote surplus tillering and extensive elongation of

the lower culm internodes, which is conducive to lodging. In contrast, later

application of N fertilizer hardly affects the basal culm internodes and may

supply the necessary nitrogen for the attainment of a high grain yield without increasing the susceptibility to lodge.

The advantage in lodging resistance and subsequent grain yield, of N

dressing after the onset of stem elongation, rather than earlier application,

has been reported for winter wheat (Bremner, 1969; Hadiiselimovit,

1969; Widdowson et al., 1961 ), spring wheat (Vetter and Assadolahi,

1962), barley (Prikryl, 1970; Vetter and Assadolahi, 1962), and oats

(Brouwer et al., 1961; Ulmann, 1966).

Under conditions of low availability of soil N, which require a basic

N dressing, it has been shown that lodging of wheat could be decreased

and grain yield increased by applying the nitrogen in split dressings, i.e.,

a certain minimum basic dressing and an additional top dressing after

the onset of stem elongation (Chowdhury and Bains, 1967; Karchi and

Rudich, 1964). Reduced lodging and subsequent increase in grain yield

due to split spring applications of nitrogen to winter wheat, have been reported from the Netherlands (Dilz, 1967; Jonker and de Jong, 1966),

Sweden (Fajersson, 196 1) , and Switzerland (Geering, 1964). Similar results have been obtained for winter-sown barley (Jonker and de Jong,

1966). Split application in these cases implies an early dressing at the onset

of growth in spring and a second one during the period of intensive stem

elongation. However, regarding spring barley in England, Widdowson

(1962) warns against late N topdressing which may in wet years delay

ripening and thus increase the risks from lodging induced by storms.

It should also be mentioned that lodging following high N dressing in

the form of calcium cyanamide was less severe than when equivalent

amounts of N were applied as calcium nitrate or calcium ammonium nitrate (Bauer, 1963). This should be attributed to the slower N availability

of the calcium cyanamide and, in the case of eyespot-induced lodging, also

to the fungistatic effects of this fertilizer (Bauer, 1963; Diercks et al.,


5 . Irrigation Practice

Discussing the results obtained from irrigation experiments of spring

wheat at Prosser, Washington, Robins and Doming0 (1962) concluded:



“Reductions in early vegetative growth and plant height greatly reduce susceptibility to lodging during and following later irrigations. This suggests

the advisability of withholding spring irrigation as long as possible, preferably until the early boot stage.’’

Irrigation per se is conducive to lodging (Fig. 2), which is particularly

detrimental during the period of grain development (Section 111, B, 1 ) .

Therefore, if the moisture requirement during this period is to be supplied

or supplemented by irrigation, it may presumably be least risky at the late

boot stage, in order to secure recovery by the time of heading (Section

11,C) .

Trials with winter wheat in the northern Caucasus showed that lodging

was promoted less by sprinkler irrigation than by furrow irrigation

(Pyatggin and Semikhov, 1967).

6. Blends of Crops or Cultivars

Lodging of susceptible varieties may be reduced through admixture with

other varieties, preferably with more resistant ones. The blends were generally found superior to the average of the individual components grown

alone. This has been reported for wheat (BorojeviC and MiSiC, 1962) and

for oats (Grafius, 1966; Patterson et al., 1963). In Bulgaria, lodging of

feed barley was reduced considerably by blending it with 30-50% wheat

(Petrov, 1968). Improved lodging resistance of barley mixed with about

10% oats was reported from Scotland (Anonymous, 1954).

The beneficial effect of blends may be ascribed to the support extended

by the shorter or otherwise more resistant varieties and also to mutual

support of varieties differing in growth rate and maturity. It seems that

the practical use of this lodging-control measure will be restricted to feed

grains or to very susceptible cereals grown for forage.

7 . Clipping and Grazing

Lodging due to excessive foliage during the period of elongation of the

lower culm internodes may be prevented by clipping or grazing. This

should be done before culm elongation has proceeded sufficiently for the

apices to be damaged. Early studies on this method have been reviewed

by Holliday ( 1956). It was successful in controlling lodging and in certain

cases caused a subsequent increase in grain yield. However, in most cases

grain yield was reduced following grazing or clipping. More recently, successful application of this method-which did not reduce grain yield and

sometimes even increased it-has been reported from Arizona (Day el

al., 1968), Britain (Aldrich, 1959; Hayes, 1959), and South Africa

Tài liệu bạn tìm kiếm đã sẵn sàng tải về

V. Environmental and Agronomic Factors Affecting Lodging

Tải bản đầy đủ ngay(0 tr)