Download Hellin, J. J. and R. Gomez R. The nursery performance of thirty

Hellin, J. J. and R. Gomez R. Forest Conservation and Tree Improvement Project
(CONSEFORH), Apartado Postal 77, Siguatepeque, Honduras, Central America.
THE NURSERY PERFORMANCE OF THIRTY-NINE LEU C AEN A
SEEDLOTS IN HONDURAS
Introduction. The 33 Oxford Forestry Institute seedlots described by Hughes (this volume) and
six seedlots provided by the Nitrogen Fixing Tree Association described by Stewart et al. (this
volume) were sown in the nursery in Siguatepeque at the end of March, 1989. The plants were
raised for the establishment of a Leucaena trial at the Comayagua valley trial site of The Forest
Conservation and Tree Improvement Project (CONSEFORH) (see Stewart et al., op. tit.). The
germination percent at 14 days was calculated, and every two weeks after sowing the plants were
measured for height and root collar diameter (r.c.d.). The height and r.c.d. measurements in
Table 1 are those from 84 days after sowing when the plants were considered to have reached
a suitable size for planting. The establishment of the Leucaena trial was delayed because of
unusually dry conditions in the Comayagua valley, and the plants therefore remained in the
nursery until 112 days after sowing.
The Project’s nursery is at Siguatepeque in Honduras (latitude 14°34’ N, longitude 87°49’ W,
and 1,078 meters above sea level). The mean annual rainfall is 1,141 mm, and the main rainfall
period is from May to October. The mean temperature during the nursery period is 23.5° C.
Methodology. The Leucaena seeds were longitudinally scarified before sowing. This seed
pretreatment was recommended by Hawkins and Ochoa (this volume). The seeds were sown
in root trainers. These are made of black plastic and form four containers/ cells when the two
halves of the root trainer book are closed. Each root trainer cell measures 3.5 x 4.0 x 11.5 cm
and therefore holds 161 cubic cm of soil. Each box of root trainers contains eight books (32
cells). The sides of the root trainer cells are longitudinally grooved and this facilitates the
straight growth and air pruning of the roots. The soil used was a mixture of four parts of soil
from the Comayagua valley planting site, two parts of humus, and one part of sawdust. No
specific Wiizobium inoculation was used because previous experiments in the nursery using the
same soil mix showed that Leucaena nodulated well. The nursery soil was well drained with
a good texture, but no detailed chemical analysis is available.
A total of 512 seeds per seedlot were sown (1 seed per root trainer cell). In the case of 11
seedlots, a smaller number of seeds was sown because of reduced seed availability. The root
trainer boxes were placed on a 1 meter elevated bench and shade cloth was used for the first
two weeks after sowing. Within each seedlot, 24 plants from the inner-most root trainer boxes
were selected and marked for the subsequent measurements.
Psyllid (Heteropsylla cubana). In mid-April L. greggii (82/87) (see Table 1 for Project ID nos.)
began to show symptoms of what was thought to be a fungal attack. The plants began to wilt
and the leaves turned yellow. The attack was temporarily checked by a fungicide application.
In mid-May L. salvadorensis (34-88) began to show symptoms of what was again believed to be
a fungal attack. The leaves turned yellow and this was followed by a severe defoliation. The
disease spread to some of the other Leucaena seedlots. A variety of fungicides were applied
without success. A psyllid was then identified as the causal agent, and in mid-June samples
were sent to the Oxford Forestry Institute and the cause of the disease was identified as
Heteropsylla cubana, with the fungal attack being a secondary effect. A pyrethrum-based
insecticide (CYMBUSH) was applied at approximately 10-day intervals at a concentration of
5 cc per 10 liters, and the plants recovered. The attack of H. cubana in an area where there are
no known local Leucaena populations demonstrates the mobility of the psyllid.
The Leucaena taxa showed varying degrees of susceptibility to H. cubana. Mortalities were only
recorded in four species; L. diversifolia ssp. stenocarpa (53/88), L. diversifolia ssp. diversifolia
(45/87), and L. diversifolia ssp. diversifolia K156 x L . pallida K376 (KX1) had a 4% mortality
among all the plants. L. greggii (82/87) had a 58% mortality rate. The majority of the
remaining taxa suffered varying degrees of defoliation, but the following eight taxa showed no
symptoms of psyllid attack: L. esculenta ssp. matudae (49/87), L. esculenta ssp. paniculata
(52/87), L. lanceolata (50/87), L. esculenta ssp. esculenta (47/87), L. esculenta ssp. esculenta
(48/87), L. leucocephala ssp. glabrata x L. pallida K376 (KX2 88-1), L. diversifolia ssp.
diversifolia (K156), and L. diversifolia ssp. stenocarpa (35/88).
Results and conclusions. The germination percentages (see Table 2) were high in comparison
to the results of the 16 seedlots tested by Hawkins and Ochoa (op. cit.) and those supplied by
the British Forestry Commission’s Research Station at Alice Holt, where the majority of the
Leucaena seed is stored. The appropriate comparison of results is between the nursery results
and those provided by Hawkins and Ochoa (op. cit.), because the seed had been stored under
identical conditions. Half the Leucaena seedlots in the nursery had germination percentages
which were lower than the laboratory results and the other half had higher germination
percentages. Only two seedlots in the nursery had germination percentages which were more
than 15% lower than those from the laboratory. The high germination results from the nursery
perhaps indicate that when the seeds were sown the laborers tended to select the better quality
ones. The results also show the success of the manual scarification pretreatment used.
One of the most striking observations is the superiority in height growth of L. esculenta ssp.
paniculata (52/87). This species, however, had the lowest r.c.d./height ratio of all the 39
Leucaena seedlots. The three seedlots of L. collinsii ssp. zacapana showed exceptional height
growth and this is of interest because the taxon is little known and it has performed well in the
project’s Leucaena species-cum-provenance trial (Stewart et al. op. cit.). L. salvadorensis,
another poorly known species native to Honduras and Nicaragua, also showed good height
growth.
With the exception ofL. esculenta ssp.paniculata (52/87), L. esculenta ssp. esculenta (47/87 and
48-87) and L. trichodes (61/88), the 13 seedlots that grew tallest in the nursery came from
Honduras and Guatemala (latitude 13°15’ N to 15°07’ N). The five smallest seedlots were
those that came from northern Mexico and the southern USA. (north of latitude 22°46’ N).
The taxa that are not found naturally in Central America are not adapted to the climate in
Honduras, and this can partially explain their generally poor performance in the nursery.
Despite the enormous variation in the size of the plants produced in the nursery, all the plants
were considered to be suitable planting stock at 84 days after sowing, and the Leucaena trial
was successfully established in the Comayagua valley at 112 days after sowing. CONSEFORH
has a lower altitude nursery in Choluteca in Honduras (latitude 13 18 N, longitude 87°11 ^W,
and 47 meters above sea level). The mean temperature in Choluteca is approximately 6° C
higher than that in Siguatepeque, and nursery results from the former suggest that the growing
period for Leucaena planting stock can be reduced by a third at this lower altitude nursery,
where performance of low-elevation species will be more typical of that observed throughout
the tropics.
A count of the number of nodules per seedlot was made, before the plants left the nursery. The
Comayagua valley, from where the nursery soil came, is associated with Acacia and mixed
Leguminosae scrub, and although L. shannonii ssp. shannonii (26/84) is the only taxon native
to the Comayagua valley, the plants of all 39 seedlots showed varying degrees of nodulation.
The total number of nodules per plant varied from 70 in the cases of L. collinsii ssp. zacapana
(56/88 and 18/84) to six in the case of L. esculenta ssp. matudae (49/87). The degree of
nodulation was calculated by a visual analysis, and this did not allow the confirmation or
otherwise of different strains of Rhizobium bacteria.
Acknowledgements. The assistance of all the staff of CONSEFORH, and in particular Thomas
Hawkins, is gratefully acknowledged. The CONSEFORH Project is jointly funded by the
Corporation Hondurena de Desarrollo Forestal (COHDEFOR) and the U.K. Overseas
Development Administration (ODA).
Table 1. Nursery results 84 days after sowing in order of height superiority.
Species
L. esculenta paniculata
L. esculenta esculenta
L. collinsii zacapana
L. collinsii zacapana
L. shannonii shannonii
L. trichodes
L. salvadorensis
L. collinsii zacapana
L. diversifolia stenocarpa
L. diversifolia stenocarpa
L. salvadorensis
L. esculenta esculenta
L. shannonii magnifica
L. diversifolia diversifolia (K156)
KX1 (hybrid)
L. trichodes
L. esculenta matudae
L. collinsii collinsii
L. collinsii collinsii
L. macrophylla macrophylla
L. shannonii magnifica
L. shannonii shannonii
KX3 (hybrid)
L. lanceolata
L. diversifolia diversifolia
KX3C (hybrid)
L. leucocephala glabrata (K636)
L. lanceolata
L. lanceolata
L. diversifolia diversifolia
L. macrophylla nelsonii
L. leucocephala glabrata (K8)
L. multicapitulata
KX2 88-1 (hybrid)
L. lanceolata
L. pulverulenta
L. pulverulenta
L. retusa
L- greggii
Germ. %
14 days
81
90
48
82
93
72
95
89
50
70
69
93
63
78
85
91
86
83
91
90
40
70
84
72
94
92
94
81
74
63
89
50
93
92
75
62
93
95
84
Height
(cm)
25.8 ± 1.7
17.8 ± 1.1
17.1 ± 1.2
16.8 ± 1.3
16.5 ± 1.3
16.0 ± 1.1
15.5 ± 1.7
15.4 ± 1.7
15.0 ± 1.4
14.7 ± 2.0
14.4 ± 1.5
14.4 ± 1.3
14.3 ± 1.0
13.6 ± 1.0
13.4 ± 1.6
13.2 ± 0.9
13.0 ± 0.9
12.6 ± 1.1
12.5 ± 0.9
12.1 ± 1.1
11.7 ± 0.9
11.6 ± 0.8
11.0 ± 1.2
10.8 ± 0.7
10.6 ± 0.7
10.6 ± 0.7
10.4 ± 0.8
9.9 ± 0.9
9.3 ± 1.0
9.3 ± 0.9
9.0 ± 0.5
8.6 ± 0.6
7.9 ± 0.8
7.8 ± 1.0
6.6 ± 0.7
6.2 ± 0.3
5.7 ± 0.4
4.1 ± 0.2
4.0 ± 0.5
r.c.d.
(cm)
0.32
0.38
0.28
0.30
0.27
0.30
0.31
0.29
0.24
0.22
0.30
0.33
0.27
0.29
0.31
0.27
0.35
0.27
0.27
0.28
0.27
0.27
0.29
0.29
0.22
0.30
0.34
0.33
0.26
0.27
0.25
0.33
0.26
0.31
0.21
0.20
0.23
0.25
0.20
* The r.c.d. / height ratio is calculated using the following equation:
ratio = root collar diameter in millimeters
shoot height in centimeters
r.c.d./
Project
height ratio* ID No.
0.12
0.21
0.16
0.18
0.16
0.19
0.20
0.19
0.16
0.15
0.21
0.23
0.19
0.21
0.23
0.20
0.27
0.21
0.21
0.23
0.23
0.16
0.26
0.27
0.21
0.28
0.33
0.33
0.28
0.29
0.28
0.38
0.33
0.40
0.32
0.32
0.40
0.61
0.50
43/89
36/89
52/89
56/89
29/89
48/89
26/89
46/89
54/89
44/89
30/89
38/89
27/89
99/89
88/89
25/89
39/89
33/89
42/89
53/89
47/89
45/89
84/89
40/89
35/89
86/89
82/89
31/89
41/89
34/89
37/89
55/89
49/89
87/89
32/89
58/89
51/89
28/89
50/89