Germination studies on seed of fruit trees indigenous to Malawi

Forest Ecology and Management ELSEVIER

ForestEcolo~ and Management64 (1994) 1! 1-125

Germination studies on seed of fruit trees indigenous to Malawi H. Prins, J.A. Maghembe* ,~.a.DCCIICRAFAgroforestryProject,P.O.box 134, Zomba,Malawi

Abstract

Indigenous fruit trees play an important role in rural areas in Malawi. However, information on propagation techniques for these species is scantily available. Freshly obtained seed of 16 indigenous fruit trees and one exotic species were therefore collected and tested for germination after applying eight different seed pretreatments. The pretreatments included direct sowing, washing, soaking, hot water treatment and different degrees of removal of the seedcoat. The objective was to find a simple technique to germinate seed of each species so that such a technique can be applied under village conditions in Malawi. More than 80% germination was achieved for Bridelia cathartica, Bridelia micrantha, Diospyros mespiliformis, Parkia filicoidea, Piliostigma thonningii, Strychnos spinosa, Syzygium cordatum, Tamarindus indica, Uapaca Mr. kiana, Ziziphus abyssinica and Ziziphus mauritiana by simply cleaning and soaking the seeds. Quicker germination could be achieved by partial removal of the seedcont for some species. Azanza garckeana and Parinari cura. tellifolia, however, required partial or complete removal of the seedcoat to achieve some germination. Flacourtia indica and Parinari curatellifolia had very poor germination of 20% and 17%, respectively. Key words:Germination;Seedtreatment;Indigenousfruit tree

1. Introduction In June 1989 an ethnobotanical survey was conducted in Malawi to identify the range and uses of trees in farmers' fields and around their homesteads. One of the outcomes of this survey was the realization that farmers greatly value indigenous fruit trees and manage over 30 species on their farms (Maghembe and Seyani, 1991 ). In addition to food and cash, farmers obtain fodder, fuel wood, shade, building materials and medicine from these fruit tree species (Palgrave, 1984; Williamson, 1974; Campbell, 1987). Available data on the nutritional value of several indigenous fruits (Wehmeyer, 1966; Saka et *Correspondingauthor.

al., 1988) show many to be rich in sugars, essential vitamins and minerals while some are high in vegetable oils and proteins. In a study by Campbell (1987), over 95% of respondents stated that members of the family and especially children eat wild fruit for taste, nutrition, disease and hunger prevention. This is important in view of the findings of Welnneyer (1966) who showed that some local fruits tend to have a higher vitamin C content than exotic species, while other constituents are comparable. Further, because ot better storage properties of certain indigenous fruits, they can be made available as food at any time of the year (Gumbo et al., 1990). Wild fruits have received httle attention in research and development when compared with

0378-1127/94/$07.00 © 1994ElsevierScienceB.V. All rightsreserved SSD10378-1127 (93)06042-4

112

H. Prins,J.A.Maghembe/ForestEcolo3yandManagement64 (1994)111-125

exotic varieties because of perceived slow growth rates and long periods between germination and fruiting, a low ratio of edible to non-edible parts and irregular fruiting. Cultivation, selection and improvement of these wild fruits is desirable to explore their potential and conserve a valuable genetic pool. Mwamba (1989) found, for instance, a great natural variation in fruit size and pulp volume for Uapaca kirkiana. This process of cultivation, selection and improvement requires the understanding of propagation techniques, including appropriate seed germination methods. Some work on a few species has been reported earlier (Maghembe and Msanga, 1989; Msanga and Maghembe, 1989; Ngulube and Kananji, 1989; Okafor, 1980) but more remains to be done. This report summarizes results of tests on germination of indigenous fruit tree species of which relatively little is known. Emphasis is made on techniques that can be adopted at village level in Malawi and elsewhere in the Miombo ecozone of Southern Africa. 2. Materials and methods

2.1. Seed pretreatments and experimental design Seeds of 17 species of fruit tree (Table 1 ) were collected and subjected to up to eight treatments under conditions that can be repeated at village level: no sterilized soil, no chemical treatments and grown in the open. Seed of most species has collected in August 1989. Because of different times of fruiting, seeds of Bridelia micrantha, Parkia filicoidea, Syzyglum cordatum and Uapaca kirkiana were collected in December 1989 while those of Vangueria infausta were collected in April 1990. All seeds originated from an area between Namadzi (15°34'S, 35°13'E) and Mangochi (14°28'S, 35 ° 16'E) in Malawi. The study was carried out at the SADCC/ICRAF nursery, Makoka Agricultural Research Station, Thondwe, Malawi, which is within the seed collection area. For each treatment, 30 seeds were used in a randomized complete block design, replicated three

times. The following treatments were included: T1---direct sowing of seeds after removing the fruit pulp. T2--soaking seeds in cold water for 24 h after removing the fruit pulp. T3---cleaning seeds thoroughly, i.e. removing all mesocarp carefully, and soaking for 24 h. T4--cleaning seeds and placing in 0.51 ofwarm water at 65°C, then leave to cool for 24 h. T5--cleaning seeds and placing in 0.51 of hot water at 100°C, then leave to cool for 24 h. T6---cleaning seeds and placing in 0.51 of hot water at 100°C, allow to boil for I min then leave to cool for 24 h. T7--nicking seeds, i.e. making a hole in the seedcoat through abrading or cutting. T8---complete removal of the seed coat. For T2, the mesocarp was removed, leaving behind some pulp on the seed as would normally be left behind when eating the fruit. For T3, however, all m e ~ a r p was carefully removed with a brush ~md tapwater. T2 and T3 are different in that some mesocarp still covering the seed may inhibit germination. Table 2 lists the treatments applied to each species. In certain cases the limited number of seeds available restricted the number of treatments applied to those species. In cases where seeds were limited, selection of treatments was made based on seed morphology and our experience. For each seed, quality was visually checked, and rotten, damaged or otherwise infected seeds were discarded. Plastic containers (20 c m × 10 cm×7.5 cm) were filled with sieved river sand up to 2 cm below the rim. The sand was moistened and the treated seeds were pressed into the medium such that only the was visible and then some sand was sprinkled on top. The containers were covered with transparent plastic and placed in the open, under shade so that no direct sunlight reached the seeds. The medium in the container was kept moist at all times. During experimentation, the temperature ranged from 19°C at night to 31 °C during the day with a minimum of 15.5 °C and a maximum of 37°C. The number of germinated seeds was recorded daily. Germinants were removed and

H. Prins,J.A. Maghembe l Forest Ecology and Management 64(1994) 111-125 Table ! ~ome informatioh on ee~,~nce, di~ibution, tree form and fruits of the tree ~

tt3

tested at Makoka, Malawi

Species

Family

Occurrence

Tres form

F~,~

Aranza ~,ckeana

Malvaesae

All types of woodland,

Bushyshrub to m e d i ~ tree, 3-10 m hallht

Feb.-Sep.+ + Sl~erifal, 2-4 cm. Sweet ~ime ~ em w h a dL'wed ~ + I cm, e ~ e

seslevelm 1700 m

Brideliacathartica

Euphorbiacese

Bridelia micrantha

Euphorbiacese

Canthiumfoetidum

Rubiacesc

Stream bank& riverine fringe thicket and fittoral m ~ b Rb~rine forest, relic f o r ~ and open woodland

M ~ tree, 4-6 m

shrub or

Medium altitude,

Small tree, 3-$ m

Small to m e d i ~ tree, 7-15 m

op~woodland Diospyrosmesoiliformis Ebenacese

Flacourtiai n d i c a

Flacourtiacese

Jan.-Maxch+ + ~ilmoidai, 0..%-1cm. Ta~e ~ b l a c k ~ July-Oct. +

lc~E4i~but~/~ asU~

Low to medium altitudes, weedlaa~ ale~ riven, m ~ y on rocky hill slopes Woodland, from sea leval to 1600m

Medium*sizedtree, 10.15 m, with desN, roeaded crown givi~ excellent ~tdo

~d'p.+ 4- + Ovoid, ~ , 2.5 ~ ~ma f t ~ m d ~

Thorny shrub or small

Parinaricumteil(fol~a

Chrysobalanacesc

Open deciduous woodlands on umdy soils, S00.1200 m

Las~ tree, up to 2 ! m, with a heav~, monded crown, ~

Parkiafilicoide~

I.eguminoses (mimmoidese)

Riparian for~ts, 500.1200 m

Large tree, up to 25 m with spresdin& umbrella*shaped crown

AWIl-Sgp,+ + B c n ' y ~ fleshy,up to 2.5 an. Sweet/acid Oct.-Jan. + + Oval, 5 aa, with flbm~ aad sweet but aslrialNm 1 ~ al~! tlm:e ed~t~emeds Nov.-Feb. + + Pods (15-30 cm) contin ~eet, onmSe ~ p~

Piliostigm~thonningii

Leguminmes

Woodland and wooded

Small m rae~um.sized

J~me-Sep.+

(Caesalpinioidese)

grassland,medium to low altitude, 300.1200 m From ses level to 1500 m, open woodland lind riveriae f i i n ~ Medium to high altitude, riverine thicke~ mui forests, alwaysnear water or a l o n s w a ~ Low altitude woodland, wooded lp'asslandand bush, alon4 rivers, Introduced from Middle East, low altitude

Uee, 3-5 m height

Dry pods (pulp) ami seeds m famine food. 10.2~ cm ~Aeg.+ + ~ with weedy ~ I L Edible lmlp. 8-15 cm Nov.-Mind:h+ + Ovoid, I.$ cm lon~ Fn~hy, slightly~veet/acid

Medium altitude, 5001300 ra, open woodland, dominant on Bravely soil Medium altitude, wooded grLu~acb, amon8 rocks and sand dunes Medium to low altitudes, open woodlami, wooded srastland and alon$ river banks Medium to low altitudes, open weedlaad, weeded ,n.~and

Medium to small tree, 3-10 n~ with open, rounded crown

Strychnosspinosa

Logania¢~ae

Syz3~ium cordatum

Myrta¢~ae

Tamanndus indica

Leiponinosae (Caesalpinioidese)

Tevminaliacataopa

Combretaceae

Ualmcakirkiana

Euphorbiacese

Vangueriainfausta

Rubia~ae

Ziziphtts abysfinica

Rhamnaceae

Zizii~uS raalffitiana

Rham~tcese

tree, 3-5 m

Shreb or medium-sized tree, 1-9 m in height Medium-sizedtree, 8-15 m in height Medium to ~ ~v~lt~ll tree, 20-24 m, with a denae mown Medium to large evergreen trce, 8-15 m

Smalldeciduous tree, 3-7 m with open crown Shrub or small tree, uptoTm Small tree, 7-12 m

• +, fruits occasionallyesten; + +, fruits generally liked; + + +, fruits held in high esteem.

Julle-Jttly + 4""4" Pods with sticky, edible p~lp, acid. Mmy mcs Jely-Sep. + + String, edible Imlp with edible UUL10-15 cm lm~ Oct-Dec. + + + Sphc~'iesl,2-3.$ CnL Sweet, edible flesh Feb.-April ( A ~ ) + + + Spherical, 2-3.5 era. Swee~ e~ibk ~ p Jone-Sep.+ Sl~'ri~, ! - 3 ~ ~Uble, ~ishey acid Juee-Sep.+ + + Also tm:d for distiUi~ spirit, l-3cm

114

H. Prins, ZA. Maghembe / Forest Ecology and Management 64 (1994) 111-125

Table 2 Treatments applied to seeds of indigenous fruit trees to induce germination at Makoka, Malawi

1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17

Species

Vernacular*

Treatments

Azanza garckeana Brideliacathartica Bridelia micrantha Canthiumfoetidum Diospyros mespiliformis Flacourtia indica Parinari curatellifolia Parkiafilicoidea Piliostigma thonningii Strychnos spinosa Syzygium cordatum Tamarindus indica Terminalia catappab Uapacakirkiana Vangueriainfausta Ziziphus abyssinica Ziziphus mauritiana

Matowo Mtundi Msopa Chisukunthu Msumwa Nthudza Muula Nkhundi Chitimbe Mteme Nyowe Bwemba Mkunsu Masuku Mbulukutuku Kankande Masao

1, 2, 3, 4, 5, 6, 7 1, 2, 4, 5, 6, 7 1, 2, 4, 8 1,2,3,4,5,6,7,8 1, 2, 4, 5, 6, 7 1, 2, 3, 7, 8 1, 7, 8 1, 2, 3, 7, S I, 2, 4, 5, 6 3, 7, 8 I, 3, 4, 8 1, 2, 7 1, 2, 4 2, 3, 7, 8 7 1, 2, 4, 5, 6 1, 2, 4, 5, 6

aBinnsand Logah(1972).Shorter(1989). bT.catappahas beenincludedin this studyalthoughthe species hasbeenintroducedto Malawi. transplanted into polythene tubes for further growth. A seed was considered as germinated when the cotyledons had emerged above the soil surface. Observations were terminated after 30 days except for Canthium foetidum (45 days), Diospyros mespiliformis (43 days), Flacourtia indica (42 days), Piliostigma thonningii (33 days) and Terminalia catappa (36 days).

2.2. Data analysis For statistical analysis the cumulative number of seeds that had germinated was expressed as a percentage of the total number of seeds sown in each treatment. All cumulative germination data were subjected to arcsine transformation (Freese, 1967) before analysis of variance (ANOVA) using Genstat 5 (Payne et al., 1987). Leas'L significant difference was used to separate significant means. 3. Results and discussion

The simplest treatments such as direct sowing

(T1), soaking (T2) and cleaning plus soaking (T3) resulted in good germination in most species (Table 3, Figs. 1-3). More than 80% germination was achieved with at least one of these treatments for all species except Azanza gar-

ckeana, Canthium foetidum, Flacourtia indica and Parinari curatellifolia, Vangueria infausta was not tested for these treatments because of lack of seed, thus only T7 was tested (see also Msanga and Maghembe, 1989). For Azanza garckeana and Canthium foetidum, good germination (100% and 93%, respectively) was achieved with scarification by nicking (T7). Complete removal of the seed coat (T8) on the other hand achieved a germination percentage of 63% in A. garckeana and 87% in Canthium foetidum. Flacourtia indica and Parinari curatellifolia gave poor germination results in all treatments. F. indica gave a maximum of 20% with T1 and P. curatellifolia 17% with T7. In the case of F. indica, the small seeds have a very hard seedcoat which makes imbibition difficult. Nicking and complete removal of the seedcoat should have had a marked positive effect on germination. However, the small size of the seed and the hard seedcoat often resulted in embryos being damaged during pretreatment, resulting in low germination in T7 and T8. On the other hand, imbibition, after removal of the seedcoat (T8), may in fact have damaged the internal seed structures by unimpeded swelling (PoweU and Matthews, 1978). When applying treatment T8, it became evident that very few seeds of F. indica were viable; this could not be determined while applying treatments T 1, T2 and T3. After the germination tests it was found that the larger seeds in a fruit were viable whereas the smaller seeds appeared to have no embryo at all. The difficulty with P. curatellifolia is that seeds are recalcitrant and the oily seeds deteriorate quickly at higher temperatures. Furthermore, the endocarp is very hard making it difficult to extract the seed without damage. Although relatively simple methods are sufficient to obtain good germination for most species, rapid germination, which may not be conferred by the simpler methods, may be preferred under rural conditions. Quickly germinated seed

H. Prins,J.d. MaghembeI ForestEcologyand Management 64 (1994) 111-125

A z an, z a mean

cumulative

g arck Matowo

Il

e area

germination

10

-

:4

;~

):

,~" .-~

×

8 6 4 2 0 5

10

15

20

~5

30

days since sowing ~"

tl

--4-- t~ & t3

~

t4

--e-- t5 & t6

~

t7

~

t8

B r i d e lia cath.arti, e a Mtundi mean

cumulative

germination

10

5

I0

15

20

25

days since sowing tl

---4--- t 2

*

t4

~

t5 & t6

--~-- t 7

Fig, 1. Mean cumulative germination per treatment for some fruit trees indigenous to Malawi.

30

H. Prins, J.A. Maghembe I Forest Ecology and Management 64 (1994) 111-125

! !6

Bride lia ,~icrantha Msopa mean

cumulative

germination

,

/ I

T

[

I

[

5

I

I

I

I

l

l

I

|

I

I

I

I

15

I0

I

I

I

I

I

I

20

|

I

I

[

30

25

dayssineesowing tl

--4-- t2

Canthiurn

-~

t4

--e- t8

f o e tid, um~

Chisukunthu m e a n cumulative germination 10

5

10

15

20

25

30

35

40

days since sowing tl

--4-- t2

--~

t3

-~-

Fig. I. Continued.

t4

~

t7

--~

t8

45

H. Prins,Y.4. MaghembeI ForestEcologyand Management 64 (I 994) 111-125

117

Diospyros m.espilif orvnis Msumwa mean

cumulative germination

I0

5

I0

15

20

25

30

35

40

days since sowing -'--

tl

--+- t2

~

t4

--e-- t5

~

t6

F l a c o'~crtia 'i,i~.dic Nthudza, mean

~

t7

a

Nthema

cumulative germination

I0

~~rTT:':TTT s

~o

TTT:TT!'II, [i TTiTTiiTTT

2o

~5 days tl

--~

25

since t2

3o

as

sowing -~-

t3

Fig. 1. C o n t i n u e d .

~

t7

.~o

118

H. Prins, ZA. Maghembe I Forest Ecology and Management 64 (1994) 111-125

Parinari curatellifolia Muula mean

cumulative

germination

10

i

~

i

[

i

?

i

i

i

5

i

?

i

i

i

10

i

i

i

i

i

15

i

i

i

f

f "1---/

20

~

i ' ~

25

30

days since sowing ~--tl

--+-" t 7

~

t8

Parkia fiticoidea Nkhundi mean

cumulative

germination

i:iiiiiiiiiiiiiiiiiiiiiiii

10 8 6 4

t

i

I

I

'"1

'T

i

5

i

i

I

i

I

I

10

i

i

i

I

i

15

i

I

I

I

~0

I

I

t

i

s

25

days since sowing tl

---+-- t 2

~

t3

~

t7

~

t8

Fig. 2. Mean cumulative germination per treatment for some fruit trees indigenous to Malawi.

i

30

H. Prins, J.A. Maghembe / Forest Ecology and Management 64 (! 994) 111-125

I|9

P'il,ios t i g m a t h o n n i n g i i Chitimbe mean

cumulative

germination

I0,

/-

i-

¢-

i

T

T

r

¢

"r

T

I

5

T

I'

I"

I"

10

'I"

r

'r

T

I"

15

r

T

I"

I"

"I" T

20

'r

"r

25

'r

~

r

I"

'r

'I"

30

days since sowing --+-- t 2

tl

---*-- t 4

-e--

t5

~

t6

S t'rg c h;no s spino s a Mteme mean

cumulative

germination

10 /

,j-

°

~

=

:

I I I0

I

I

/ ~

;

i

i 5

i~-f

I

l

L

i t-I 15

I

I

I ; 20

days since sowing t3

~

t7

Fig. 2. Continued.

& t8

=

i

I

i ; -h--t 25

I 30

H. IVins, ZA. Maghembe / Forest Ecology and Management 64 (1994) 111-125

120

Syzygium

cordatum

Nyowe mean

cumulative germination

5

I0

15

20

25

30

days since sowing tl

~

t3

~

t4

Tamarindus

- - ~ t8

indica

Bwemba mean

cumulative germination

lO

1

5

I0

15

20

days since sowing ~tl

--+-t2

'--~--t7

Fig. 2. Continued.

25

30

H. Prins,J.A. MaghembeI ForestEcolobwand Management 64 (1994) 111-125

121

Uapaea k i r k i a n a Masuku m e a n cumulative germination

i

i

i

i

i

5

i

i

i

i

i

I0

i

i

t

i

15

i

t

i

i

i

i

20

i

t

i

i

~5

30

days since sowing --+--t3

t~

Va

~

t7

-e-

t8

gueTi.a il faus't,a Mbulukutuku

m e a n cumulative germination I0

r _

_

~I"

_

I _

~TI

~

_

l

l

5

_

l

/

l

l

l

~

10

l

l

l

i

15

l

l

l

l

l 20

l

i

l

l

l

i

i

~5

30

days since sowing t7

Fig. 3. Mean cumulative

germination

per treatment

for some fruit trees indigenous

to Malawi.

H. Prins, ZA. Maghembe ~ForestEcology and Management 64 (1994) 111-125

122

Kankande cumulative g e r m i n a t i o n

mean 10

~ .- ) - - - ~ - - - - ~ - ~ - .%__+_~ ,'..~---~-+-+--

4 7

/

/ 7 _-'~ 4.. ~

..#"

?"

~"

I.// , ~ ....,,---.....~ / ,/ J 2 1

5

10

15

20

25

,30

days since sowing tl

--+-- t~

~

t4

--~-

t5

Z i z i,p b u s

~

i6

t.i.co Masawo

mean

cumulative

germination

10 -q--+---b

t

8 /

i

6 4

2: 0 5

l0

15

~0

25

days since sowing ----

tl

-q--

t2

--t--

t4

Fig. 3. Continued.

-~-

t5 & t6

30

H. Prins. ZA. Maghembe / Forest Ecology and Management 64 (1994) 111-125

123

Mkungu mean

cumulative

germination

lO

8

o~: ~ r = ~ - - r z ~ 1

r-~

5

t ~ ~ .....

10

7,

15

.............

20

25

30

3,5

days since sowing ....

tl

----4--- t 2

--*-- t4

Fig. 3. C o n t i n u e d . Table 3 M e a n c u m u l a t i v e g e r m i n a t i o n ( % p e r t r e a t m e n t ) , F probability a n d least significant difference b e t w e e n t r e a t m e n t s f o r e a c h species Species

TI

T2

T3

Azanzagarckeana Brideliacathartica Bridelia micrantha Canthiumfoetidum Diospyros mesplliformis Flacourtta indica Parinari curatellifolia Parkiafilicoidea Piliostigma thonningii Strychnos spinosa Syzygium cordatum Tamarindus indica Terminalia catappa Uapaca kirkiana Vangueria infausta Ziziphusabyssinica Ziziphus mauritania

17 93 0 10 80 20 0 100 50

40 75 93 47 60 0 . 77 90

43 43 7

0

-

100 70 -

93 97 43

.

T4

. 3 80 93 93

-

-

-

100 100

80 87

-

NS, n o t significant; L S D , least significant difference.

23 73 60 13 60 . 77 27 17 87 100

T5

T6

T7

T8

F probability

LSD ( t 0.05 )

0 0 0 0 -

0 0 0 3 -

10 -

0 -

100 90 93 87 13 17 13 0 87 87

63 73 87 3 13 97 0 27 100

0.001 0.001 0.001 0.001 0.001 0.026 0.290 0.001 0.001 0.001 0.007 0.444 0.008 0.021

17 25 20 39 22 19 NS 42 31 13 44 NS 37 34

-

-

40

-

-

20 0

0 0

-

-

0.001 0.001

.

36 16

124

H. Prins,J.A. Maghembe/ ForestEcologyand Management 64 (1994) 111-125

Table 4 Best seed pretreatments to achieve best or quickest germination Species

Treatment

Azanza garckeana Bridelia cathartica Bridelia micrantha Canthiumfoetidum Diospyrosmespiliformis Flacourtiaindica Parinaricuratellifolia Parkiafilicoidea Piliostigma thonningii Sto,chnos spinosa Syzygium cordatum Tamarindus indica Terminalia catappa Uapacakirkiana Vangueriainfausta Ziziphus abyssinica Ziziphus mauritiana

T7 or T8 TI or T7 T2 TI or T7 Tl or T7 TI or T7 T7 T1 T2 T3 T3 TI or T7 T2 T3, T7 or T8 T7 TI or T4 TI or T4

may have a greater chance of producing seedlings than seeds that take longer to germinate. This is because of the likelihood of funsal, insect or rodent attack. In practical terms, this will also tie nursery beds for prolonged periods increasing nursery costs and reducing seedling vigour. Figures 1-3 demonstrate that A. garckeana, Bridelia cathartica, C. foetidum, D. mespiliformis, F. indica, Tamarindus indica and U. kirkiana respond quickly to T8 or T7, whereas Ziziphus abyssinica and Ziziphus mauritiana germinate faster by applying T4. It must be emphasized that conclusions made in these studies are based on the use of mostly fresh seeds, i.e. seeds stored not longer than 3 weeks. With U. kirkiana completely different results can be experienced when using older seeds. A closer look at the seed reveals that at ripening fully developed green leaves, in fact a small seedling, are contained within the seed which makes storage of the seeds virtually impossible because of quick deterioration of the embryo. In nature, the fruits of U. kirkiana ripen towards the beginning of the rainy season, facilitating germination soon after the fruits have fallen from the tree. Seeds stored for long periods in cold room conditions show poor germination, and studies in

Malawi (Ngulube and Kananji, 1989) revealed that viability of carefully stored seeds of U. kirkiana was lost within a month of collection. Strychnos spinosa is known to be a species difficult to germinate (Ngulube and Kananji, 1989). The seed coat may contain a germination inhibitor which is only deactivated by proper washing. Such a strategy would allow germination only after heavy rains when enough moisture is available to secure suitable growing conditions. Alternatively, the fruit pulp may protect the seed from deterioration. The results from this experiment indicate that the seed pretreatments can be applied as in Table 4 to achieve satisfactory germination.

4. References Binns, B. and Logah,J.P., 1972. Dictionaryof Plant Names in Malawi.GovernmentPrint, Zomba,Malawi. Campbell, B.M., 1987. The use of wild fruits in Zimbabwe. Econ.Bot.,41: 375-385. Freese, F., 1967. ElementaryStatistical Methodsfor Foresters. US Department of Agriculture Forest Service, Agricultural Handbook317.US GovernmentPrint, Washington, DC. Gumbo,D.J., Mukamuri,B.B.,Muzondo,M.I.and Scoones, I.C., 1990.Indigenousand exoticfruit trees, whydo people want to growthem. In: R.T. Princely (Editor), Agroforestry for Sustainable Production: EconomicImplications. Enda, Harare, Zimbabwe,pp. 185-214. Maghembe,J.A. and Msanga, H.P., 1989. Effectof physical scarification and gibberelic acid treatments on the germination of Trichilia emetica. Int. Tree CropsJ., 5: 163177. Maghembe,J.A. and Seyani,J.H., 1991.MultipurposeTrees Used by Smallholder Farmers in Malawi: Results of an Ethnobotanical Survey. International Council for Research in AgroForestry,Nairobi,Kenya. Msanga, H.P. and Maghembe,J.A., 1989.Physicalscarification and hydrogenperoxide treatment improvesgermination of Vangueriainfausta seed. For. Ecol.Manage.,28: 301-308. Mwamba, C.K., 1989.Natural variation in fruits in Uapaca kirkiana in Zambia. For. Ecol.Manage.,26: 299-303. Nguhbe, M.R. and Kananji, B., 1989.SeedProblemsof Edible IndigenousFruits in Malawi.ForestryResearchInstitute of Malawi, Zomba, 16 pp. Okafor, J.C., 1980. Edible indigenous woodyplants in the rural economyof the Nigerian forest zone. For. Ecol. Manage., 3: 45-55. Palgrave, C.K., 1984. Trees of Southern Africa. C. Struik, CapeTown,959 pp. Payne,R.W.,Lane,P.W.,Ainsley,A.E.,Bicknell,ICE.,Digby,

H. Prins, J,A. Maghembe / Forest Ecology and Management 64 (1994) 111-125 P.G.N., Harding, S.A., Leech, P.IC, Simpson, H.R., Todd, A.D., Verrier, P.J., White, R.P., Gower, J.C., Tunni¢liffe Wilson, G. and Paterson, L.J., 1987. Genstat 5. Clarendon Press, Oxford, 749 pp. Powell, A.A. and Matthews, S., 1978. The damaging effect of water on dry pea embryos during imbibition. J. Exp. Bot., 29:1215-1219. Saka, J.D.K., Msonthi, J.D. and Sambo, E.Y., 1988. Chemical composition of some edible wild fruits of Malawi. Proceedings of Workshop on Utilization and Exploitation of Indigenous and Often Neglected Plants and Fruits

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ofF.astern and Southern Africa, 21-27 Aeipu~, Malawi. Shorter, C., 1989. An introduction to the common trees of Malawi. Wildlife Society of Malawi, ~ i ~ L~ onL,we, Malawi, 126 pp. Wehmeyer, A.S., 1966. The nutrient composition of same edible wild fruits in the T ~ . S. Aft. Med~ J., 40:. 1102-1104. Williamson, J., 1974. Useful Plants of Malawi. Momfort Press, IAmbe, Malawi, 336 pp.