Plant and Soil 122, 97-104 (1990). © Kluwer Academic Publishers. Printed in the Netherlands.

PLSO 8381

Stem deformity in Pinus radiata plantations in south-eastern Australia: L R e s p o n s e to copper fertiliser

PETER HOPMANS Department of Conservation, Forests and Lands, 378 Cotham Rd., Kew, Fic. 3101, Australia Received 31 July 1989. Accepted October 1989

Key words:

copper, deficiency symptoms, foliage nutrients, Pinus radiata, stem deformity

Abstract

Visual symptoms of stem deformity similar to those of Cu deficiency are common in P. radiata established on fertile sites previously used for agricultural production in south-eastern Australia. In this study, Cu fertiliser was applied at rates of 0, 2, 5, 10, 20 and 50kgha -l to deformed P. radiata at ages 3 and 6 years. Available soil Cu and contents of Cu in the foliage increased significantly only in the younger plantation. Cu fertiliser did not affect growth nor did it improve stem form. Levels of N, Cu and Cu/N ratios in foliage of straight and deformed trees were similar. However, contents of Cu in apical buds were significantly lower in deformed trees. It was concluded that stem deformity in P. radiata as observed on these fertile pasture sites, cannot be corrected by application of Cu fertiliser. Differences in Cu levels in apical buds of straight and deformed trees suggest that Cu may still be involved in this syndrome. There was also no indication of other nutrient deficiencies that could be associated with the deformity.

deficiency may vary according to the N status of the trees. For example, deficiency concentrations reported for Cu in the foliage of P. radiata ranges between 1.5pgg -1 and 4 # g g -~ (Raupach and Clarke, 1978; Ruiter, 1969; Turvey, 1984; Will, 1971). This makes diagnosis of Cu deficiency on the basis of foliar Cu contents questionable unless other factors such as N status are taken into account. It has therefore been suggested that Cu/N ratios in foliage are a more sensitive indicator of Cu deficiency than Cu content alone (Turvey, 1984). In recent years there has been a trend in southeastern Australia towards establishment of plantations of P. radiata on land formerly used for pasture production. Plantations on these sites are highly productive because past fertiliser inputs and the introduction of Trifolium species has raised soil fertility considerably. However, many of these plantations have a high incidence of stem deformity causing serious losses in merchantable wood. The visual symptoms of the deformity are similar to those induced by Cu deficiency, although foliar contents of Cu are mostly above deficiency levels of

Introduction

Copper is one of the essential micronutrients affecting a multitude of physiological processes in the plant including photosynthesis, protein synthesis and cell wall lignification (Bussler, 1981). The role of Cu in many of these processes has been investigated for agricultural plants, but little is known about the function of Cu in conifers except that it appears to affect lignin synthesis (Downes and Turvey, 1986). Visual symptoms associated with Cu deficiency have been reported for several conifer species including P. radiata D Don. (van den Burg, 1983; Oldenkamp and Smilde, 1966; Ruiter, 1969; Will, 1971). The features common to the various descriptions of these symptoms are distorted growth of stem and branches characterised by angular kinking and twisting. Symptoms of Cu deficiency can be induced by the application of N or N + P fertilisers (van den Burg, 1983; Ruiter, 1969; Turvey, 1984). These studies also showed that levels of Cu in the foliage corresponding to Cu 97

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Hopmans

2 to 3#gg ~ (Carlyle et al., 1989; Pederick et al., 1984). This paper reports the results of a field experiment designed to determine the effect of Cu fertiliser on growth, stem deformity and nutrient uptake of P. radiata on fertile pasture sites.

Methods

Site and experiment The trial was established in 1982 in the Koetong and Avondale localities of the Upper Murray plantation (36 ° I I'S., 147° 33' E) in north-eastern Victoria, Australia (Fig. 1). Elevation ranges between 500 m and 900 m above sea level and the topography is moderately inclined. Mean annual rainfall is l164mm (ranging from 481mm to 1781 mm) two-thirds of which falls from May to October. Mean daily maximum temperature ranges from 26.6°C in February to 9.9°C in August, and mean daily minimum temperature from 12.7°C in February to 0.2°C in July. Most of the plantations in this region have been established on land cleared of native eucalypt forest. Soils are predominantly krasnozems classified as Gn 4.11 and Gn 4.14 (Northcote et al., 1975) derived from Upper Silurian granodiorite. Since 1976 the majority of new plantations have been established on farmland with a long history of P fertiliser inputs and pasture improvement with legumes, mainly Trifolium subterraneum L. The incidence of stem deformity resembling visual symptoms of Cu deficiency in these young P. radiata plantings is generally high. Plantings with moderate to severe deformity were selected at Avondale (1976 planting) and T

T

Fig. 1. Location of the study areas in north-eastern Victoria.

Koetong (1979 planting) to establish a Cu fertiliser trial. Treatments of 0, 2, 5, 10, 20 and 50 kg Cu ha-l as copper sulphate were laid out in plots of 20 m x 20 m with a 2 m untreated surround in a randomised block with three replicates at each locality. The original stocking was around 1,200 trees ha l, though harsh winter weather conditions during the second year of the plantation at Avondale caused some mortality. As a consequence the number of trees per plot varied between 32 and 48.

Assessment of trial Growth of trees and deformity of stem and branches were assessed prior to treatment with copper sulphate in 1982 and again in 1984. Height and diameter at 1.3 m over bark of all trees were measured and degree of deformity was assessed on a scale of 1 to 6 of increasing severity using the scoring system of Pederick et al. (1984). Examples of stem deformity in young trees are shown in Figure 2. In June 1982, stem form of the whole tree was assessed. However, the second assessment was done on new growth since 1982. Trees were assessed from approximately 1 m upwards to avoid growth deformities such as butt sweep which was prevalent at Avondale as a result of heavy snow falls in the early stages of plantation development.

Soil and foliar analysis Foliar samples were taken in June 1982, 1983 and 1984. One year-old needles were collected from the second major whorl in the upper crown of six randomly selected trees of each plot and bulked on an equal dry weight basis. In June 1984 additional samples were collected from 0 and 50 kg ha-l Cu treatments of one of the replicates at Koetong. One year-old needles from the second major whorl and apical shoots were taken from six severely deformed and six straight trees of each treatment. Samples from each tree were analysed separately. Needle samples and shoots were dried at 80°C Fig. 2. Stem deformity in 3 year-old P. radiata planted on fertile pasture. Photographs show stem deformities typical of classes 3, 4, 5 and 6 of the scoring system used in this study. Trees with straight stems and branch deformities only are included in classes 1 and 2 (not shown in this figure).

Stem deformity in P. radiata and Cu deficiency ~ (! i i

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Hopmans

and milled prior to chemical analysis. N and P were determined colorimetrically on a sulphuric acidhydrogen peroxide digest using a Chemlab autoanalyser (John 1970; Eastin 1978) and K was determined by flame photometry on the same digest. In addition Ca, Mg, A1, Fe, Mn, Zn, Cu, S and B were determined by ICP-AES on a nitricperchloric acid digest. One year after application of copper sulphate, soil samples ( 0 - - 10 cm depth) were taken from six random points within each plot and bulked on an equal volume basis. Samples were air-dried and analysed for EDTA-extractable copper (Williams and McLaren, 1982).

Table 2. Distribution of stem deformity in P. radiata at Avondale (site 1) and Koetong (site 2) before and 2 years after treatment with copper

Site

1

2

Results

Growth data were analysed using an analysis of covariance because of initial differences in height, diameter and stem deformity between sites and replicates. Growth of P. radiata was rapid at both sites. Average increment in tree height and diameter for the 2 year period was 3.4 m and 6.1 cm at Avondale and 3.1 m and 7.0cm respectively at Koetong (Table 1). Stocking at both sites is around 1,200 trees ha -~ and basal area increased from 6.5m2ha -~ to 19.5m 2 at Avondale and from 0.9m2ha ~ to 9.6m2ha 1 at Koetong. Differences Table 1. Growth of P. radiata established on pastures at Avondale (site 1) and Koetong (site 2) and treated with copper

Year

Replicate

Percentage of trees in each deformity class 1

2

3

4

5

6

1982

1 2 3

4 31 57

4 4 1

20 26 27

16 14 8

29 15 5

27 10 1

1984

1 2 3

48 72 78

4 1 3

21 16 14

6 4 3

7 3 1

14 4 1

1982

1 2 3

17 37 51

3 3 2

44 46 38

22 9 6

9 2 2

5 3 1

1984

I 2 3

35 48 46

8 2 2

26 23 28

14 12 8

9 6 6

8 9 9

between treatments were not significant indicating that Cu fertiliser had little effect on growth. The distribution of stem deformity classes at each site (Table 2) showed a high incidence of severe deformity (classes 4, 5 and 6) at Avondale in 1982 and an improvement in the stem form of new growth between 1982 and 1984. In contrast, there was no obvious change in stem form over the same period at Koetong. Average stem deformity of the Cu fertiliser treatments are given in Table 3. Changes in stem deformity indicate an improvement in form at Avondale but not at Koetong. Treatment with Cu did not significantly affect stem form.

Site

Treatment

Height (m)

Diameter (cm)

(Cu kgha 1)

1982

1984

1982

1984

0 2 5 10 20 50 Mean SD

4.0 4.4 4.4 4.2 4.0 3.8 4.2 0.8

7.4 7.8 7.9 7.5 7.6 7.3 7.6 1.I

8.2 8.7 9.0 8.4 8.1 7.2 8.3 2.2

14.4 15.1 15.0 14.3 14.4 13.5 14.4 2.7

0 2 5 10 20 50 Mean SD

2.3 2.3 2.2 2.2 2.2 2.3 2.3 0.3

5.5 5.4 5.4 5.3 5.5 5.4 5.4 0.7

3.3 3.1 3.2 2.8 3.0 3.3 3.1 0.8

10.2 10.1 10.0 i0.1 10.0 10.0 10.1 1.6

Nutrient concentrations in foliage of P. radiata one year after treatment with Cu fertiliser are given in Table 4. Foliar levels of N, P, K, Ca and Zn were higher and levels of A1 and Fe were lower at Koetong. However, nutrient concentrations in the foliage were well above levels considered necessary for satisfactory growth (Raupach, 1975; Will, 1985). Foliar concentrations of N and Cu before and after treatment are given in Table 5 together with levels of EDTA extractable Cu in the soil. The latter shows a considerable increase in available Cu at the higher rates of fertiliser application. This was reflected in the foliar levels of Cu at Koetong but not at Avondale. In addition, there was a significant increase in foliar levels of Cu and N during the 1982--83 growing season. Foliar levels of N were not affected by Cu fertiliser.

Stem deformity in P. radiata and Cu deficiency Table 3. Stem deformity in P. radiata established on pastures at Avondale (site 1) and Koetong (site 2) before and after treatment with copper Site

I

Treatment

Stem deformity

(Cu kg h a - I )

Rep. 1

Rep. 2

Rep. 3

1982

1984

1982

1984

1982

1984

0 2 5 10 20 50 Mean a

4.7 3.8 4.8 4.7 4.0 4.6 4.5

2.8 2.2 2.7 2.6 2.4 2.5 2.6

4.0 3.5 3.1 3.7 3.7 3.2 3.5

1.8 1.7 2.1 1.8 1.4 1.8 1.8

2.5 2.4 1.7 1.2 1.7 2.7 2.0

1.9 1.4 1.4 1.4 1.3 1.2 1.4

0 2 5 10 20 50 Mean ~

3.0 3.3 2.4 2.8 3.1 2.5 2.8

2.7 3.1 2.3 3.2 2.7 2.8 2.8 NS

2.3 2.2 2.5 2.7 2.7 2.6 2.5

2.2 2.7 2.7 2.5 2.2 2.6 2.5 NS

1.8 2.0 1.5 2.5 2.0 2.2 2.0

2.4 2.3 2.4 2.9 2.8 2.5 2.6 **

Differences between means for each replicate are significant at P < 0.05 (*), P < 0.01 (**) and P < 0.001 (***) or not significant (NS).

Levels of N in foliage and apical shoots of straight and deformed trees did not differ significantly with one exception (Table 6). Concentrations of Cu in the foliage were well above deficiency levels and were similar for straight and

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deformed trees. However, apical shoots of straight trees were consistently higher in Cu compared with deformed trees. In contrast, concentrations of S, P, K, Ca, Mg, A1, Fe, Mn, Zn and B in foliage and apical shoots of straight and deformed trees were not significantly different (Table 7).

Discussion

Growth deformities in P. radiata on fertile expasture sites are characterised by severe angular kinking and twisting of stems and branches (Fig. 2). It has been shown that growth deformities due to Cu deficiency in P. radiata are associated with reduced lignin content of tracheid cell walls (Downes and Turvey, 1986). Because of similarity of symptoms it was proposed in this study that temporary deficiency of Cu during periods of rapid growth may reduce cell wall lignification sufficiently to cause structural weakness and collapse of new growth. If indeed Cu deficiency was the underlying cause of the growth deformities, then treatment with Cu should alleviate these symptoms as observed in other studies (Ruiter, 1969; Turvey, 1984; Will, 1971). However, results of this study quite clearly show that application of Cu at rates as high as 50 kg hadid not significantly affect either growth or stem deformity. Treatment with Cu increased available

Table 4. Nutrient concentrations in foliage of P. radiata established on pastures at Avondale (site 1) and Koetong (site 2) one year after treatment with copper Site

1

Treatment (Cu kg h a - i )

N

P

K

Ca

Mg

(%)

AI

Fe

Mn

Zn

(~g g ')

0 2 5 10 20 50 Mean

1.89 1.84 1.83 1.83 1.82 1.82 1.84

0.17 0.19 0.16 0.17 0.16 0.16 0.17

0.63 0.79 0.71 0.63 0.63 0.70 0.68

0.19 0.20 0.18 0.19 0.20 0.21 0.20

0.12 0.11 0.10 0.11 0.I1 0.11 0.11

680 690 720 650 690 660 680

88 104 90 95 94 99 95

246 269 252 270 238 210 247

35 40 35 31 35 32 35

0 2 5 10 20 50 Mean a

1.89 1.84 1.96 1.88 1.98 1.81 1.89 NS

0.20 0.19 0.18 0.18 0.18 0.16 0.18 *

0.75 0.74 0.69 0.76 0.72 0.82 0.75 *

0.29 0.34 0.31 0.30 0.31 0.30 0.31 ***

0.10 0.12 0.11 0.11 0.12 0.12 0.12 NS

480 530 560 530 540 570 540 ***

74 80 79 82 83 72 78 *

258 312 264 283 289 268 279 NS

43 45 40 38 45 30 40 **

a Differences between means for each site are significant at P < 0.05 (*), P < 0.01 (**) and P < 0.001 (***) or not significant (NS).

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Hopmans

Table 5. Effect of copper fertiliser on E D T A extractable copper in the soil and concentrations of nitrogen and copper in the foliage of P. radiata established on pastures at Avondale (site 1) and Koetong (site 2) Site

EDTA-Cu a O g g - t soil) 1983

N (%) and Cu ( # g g - l ) in foliage

Cu

N

Cu

N

Cu

N

0 2 5 10 20 50 Mean

2.1 2.3 2.3 3.0 5.0 11.3 4.3

a a a ab b c

3.9 3.6 3.5 3.7 4.0 3.5 3.7

1.43 1.41 1.39 1.38 1.43 1.35 1.40

4.5 5.4 5.2 4.7 5.4 5.2 5.1

1.89 1.84 1.83 1..83 1.82 1.82 1.84

5.0 5.8 4.9 5.0 5.1 5.7 5.2

1.93 2.04 1.98 1.95 2.00 1.93 1.97

0 2 5 10 20 50 Mean b

4.4 4.6 4.1 5.1 6.7 14.3 6.5 **

a a a a b c

3.6 3.5 3.5 3.7 3.6 3.8 3.6 NS

1.64 1.62 1.62 1.57 1.64 1.62 1.62 ***

5.0 a 7.8 cd 8.0 d 6.9 bc 7.2 bcd 6.4 b 6.9 ***

1.89 1.84 1.96 1.88 1.98 1.81 1.89 NS

4.8 5.2 4.8 5.0 5.2 5.2 5.0 NS

1.87 1.90 1.86 1.85 1.91 1.90 1.88 **

Treatment (Cu kg h g - J)

1982

1983

1984

a Treatments followed by the same letter are not significantly different at P < 0.05. b Differences between means for each site are significant at P < 0.05 (*), P < 0.01 (**) and P < 0.001 (***) or not significant (NS).

Table 6. Concentrations of nitrogen (%) and copper (pg g-~ ) in foliage and apical shoots of straight and deformed P. radiata at Koetong two years after treatment with copper Treatment a (Cu kg h a - t )

50

Stem form

Foliage Cu

N

Cu/N

Shoots Cu

N

Straight Deformed

5.4 5.7 NS

1.74 1.68 NS

3.1 3.4

16.3 12.3 **

1.68 1.73 NS

9.7 7.1

Straight Deformed

5.8 6.5 NS

1.79 1.57 *

3.2 4.1

18.3 13.9 **

1.59 1.60 NS

11.5 8.7

Cu/N

a Differences between straight and deformed trees for each treatment are significant at P < 0.05 (*), P < 0.01 (**) and P < 0.001 (***) or not significant (NS).

Table 7. Concentrations of nutrients in foliage and apical shoots of straight and deformed P. radiata at Koetong two years after treatment with copper Stem form

S

P

K

Ca

Mg

(%)

A1

Fe

Mn

Zn

B

(~ugg-l)

Foliage Straight ~ Deformed

0.14 0.13

0.21 0.19

1.08 1.15

0.28 0.22

0.09 0.09

720 600

60 52

498 450

50 45

14 16

0.14 0.15

0.40 0.38

1.27 1.33

0.14 0.20

0.13 0.17

220 260

52 54

191 296

55 60

26 29

Shoots Straight a Deformed

a Differences between straight and deformed trees are not significant.

Stem deformity in P. radiata and Cu deficiency

Cu in the soil considerably as indicated by changes in EDTA extractable Cu. In addition, foliar levels of Cu increased well above the range associated with Cu deficiency. The general increase in foliar levels of N and Cu observed in this study was not due to treatment but is likely to have been associated with the considerable variation in annual rainfall during the study period. Annual rainfall recorded for the region varied from 604 mm to 1514mm during 1982 to 1984. It has been shown that annual variations in nutrient concentrations in the foliage of P. radiata are well correlated with rainfall during summer and autumn (Lambert and Turner, 1988). Critical foliar concentrations of Cu associated with visual symptoms of Cu deficiency in conifers increase with high N levels in the foliage as shown by van den Burg (1983) and Turvey (1984). Visual symptoms of Cu deficiency in P. radiata may occur at foliar Cu concentrations ranging from 1.5 to 4 #g g-~ depending on N status. Cu/N ratios associated with these symptoms were 1.3 or less (Turvey, 1984). Initial concentrations of Cu in the foliage of P. radiata in this study varied from 3.5 to 4.0#gg -~ (Table 5) and are within the range associated with Cu deficiency. However, Cu/ N ratios varied between 2.2 and 2.8, well above the critical ratios reported for P. radiata (Turvey, 1984) and other conifers (van den Burg, 1983). Treatment with Cu fertiliser increased foliar Cu levels to 8#gg -l and Cu/N ratios to 4.3. These results indicate that the growth deformities in P. radiata on fertile pasture sites are unlikely to be associated with chronic Cu deficiency despite similarity in visual symptoms. Further evidence for this was obtained by comparing N and Cu levels in foliage and apical shoots of straight and severely deformed trees (Table 6). Straight trees had slightly higher levels of N in the foliage but not in the apical shoots. Concentrations of Cu in the foliage were well above deficiency levels and ranged from 4 to 6/~g g- 1in control trees and from 4 to 9/~gg -~ in trees treated with Cu. Furthermore, Cu/N ratios in the foliage were above values associated with Cu deficiency. Differences in foliar Cu between treatments were not significant, neither were differences between straight and deformed trees. However, it is of interest that concentrations of Cu in apical shoots were consistently higher in straight trees. This suggests differences in either root uptake, translocation or mobilisation of

103

Cu from older tissues between straight and deformed trees. This would be consistent with the strong genotypic variation in stem deformity of P. radiata (Pederick et al., 1984). However, interpretation of this result with respect to the cause of stem deformity is beyond the scope of this study and needs further investigation. In contrast to Cu, concentrations of other nutrients in foliage and apical shoots of straight and deformed trees were not significantly different. It is unlikely that deficiencies of other nutrients are associated with these growth deformities as foliar levels of most nutrients were well above levels necessary for satisfactory growth (Raupach, 1975; Will, 1985). Similar findings have been reported for a comparison of foliar nutrient status of young P. radiata on former pasture and eucalypt forest sites (Carlyle et al., 1989). This study also showed, inter alia, higher N mineralization, in particular nitrification, and greater Mn availability under pastures. These changes in soil properties were attributed to previous land use rather than differences in soil type or lithology. In this study, stem deformity varied significantly both within and between sites. Furthermore, an improvement in stem form was observed in the older plantation at Avondale. It is likely that this variation in stem form was due to differences in soil fertility due to previous land use at each site and this was to some extent reflected in the nutrient status of the foliage. The relationship between stem deformity in P. radiata on pasture sites and soil fertility was examined in a separate study.

Acknowledgements I gratefully acknowledge the guidance and support of Dr D W Flinn for this project and the assistance of Mr J Collopy and Mr G Cameron with the installation of the experiment and the collection of samples. I also wish to thank Mr M K Kitching and Mr G Croatto for undertaking the chemical analyses of plant material and soils.

References Burg J van den 1983Copper uptake by some forest tree species from an acid sandy soil. Plant and Soil 75, 213-219. Bussler W 1981 Physiological functions and utilisation of copper. In Copper in Soilsand Plants. Eds. J F Loneragan,A

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Stem deformity in P. radiata and Cu deficiency

D Robson and R D Graham. pp 213-234. Academic Press, Sydney, Australia. Carlyle J C, Turvey N D, Hopmans P and Downes G M 1989 Stem deformation in Pinus radiata associated with previous land use. Can. J. For. Res. 19, 96-105. Downes G M and Turvey N D 1986 Reduced lignification in Pinus radiata D. Don. Aust. For. Res. 16, 371-377. Eastin E F 1978 Use of an autoanalyser for total nitrogen determination in plants. Commun. Soil Sci. PI. Anal. 9, 107-I 13. John M K 1970 Colorimetric determination of phosphorus in soil and plant materials with ascorbic acid. Soil Sci. 109, 214-220. Lambert M J and Turner J 1988 Interpretation of nutrient concentrations in Pinus radiata foliage at Belanglo state forest. Plant and Soil 108, 237-244. Northcote K H, Hubble G D, Isbell R F, Thompson C H and Bettenay E 1975 A Description of Australian Soils. CSIRO Division of Soils, Glen Osmond, South Australia, 170 p. Oldenkamp L and Smilde K W 1966 Copper deficiency in Douglas fir. Ned. Bosb. Tijdschr. 38, 203-214. Pederick L A, Hopmans P, Flinn D W and Abbott I D 1984

Variation in genotypic response to suspected copper deficiency in Pinus radiata. Aust. For. Res. 14, 75-84. Raupach M 1975 Trace element disorders in Pinus and their correction. In Trace Elements in Soil-Plant-Animal Systems. Eds. D J D Nicholas and A R Egan. pp 353-369. Academic Press, New York. Raupach M and Clarke A R P 1978 Soil-trce relationships in a forest of Pinus radiata with micronutrient deficiencies. Aust. J. Soil Res. 16, 121-135. Ruiter J H 1969 Suspected copper deficiency in radiata pine. Plant and Soil 31, 197-200. Turvey N D 1984 Copper deficiency in Pinus radiata planted in a podzol in Victoria, Australia. Plant and Soil 77, 73-86. Will G M 1971 Copper deficiency in radiata pine planted on sands at Mangawhai forest. N.Z.J. For. Sci. 2, 217-221. Will G M 1985 Nutrient Deficiencies and Fertiliser Use in New Zealand Exotic Forests. FRI Bulletin No 97, New Zealand Forest Service, Rotorua, New Zealand, 53 p. Williams J G and McLaren R G 1982 Effects of dry and moist incubation of soils on the extractability of native and applied soil copper. Plant and Soil 64, 215-224.