Reproductive biology and characterization of ... - Springer Link

Genet Resour Crop Evol (2009) 56:1037–1044 DOI 10.1007/s10722-009-9475-6

NOTES ON NEGLECTED AND UNDERUTILIZED CROPS

Reproductive biology and characterization of Allanblackia parviflora A. Chev. in Ghana T. Peprah • D. A. Ofori • D. E. K. A. Siaw S. D. Addo-Danso • J. R. Cobbinah • A. J. Simons • R. Jamnadass

•

Received: 9 September 2008 / Accepted: 19 August 2009 / Published online: 13 October 2009 Ó Springer Science+Business Media B.V. 2009

Abstract Allanblackia parviflora A. Chev. (Clusiaceae Lindley) is an indigenous tree species which is found in the rain forest regions of Ghana. It is a potential candidate fruit tree species being introduced in agroforestry systems. Information on genetic diversity, reproductive biology and fruit yield are not known. Field expeditions to seven populations of Allanblackia parviflora in Ghana were undertaken in 2003–2006 during which fruits were collected from 109 trees for characterization. The species was found to be dioecious. The colour of flowers varied from whitish to reddish. No ecological differences in number of fruits per tree, fruit shape and seed health were observed. However, large variations in fruit size and shape were observed among individual trees sampled. A high heritability (h2 = 0.822) in fruit size and genetic gain (G = 20.1%) in fruit size for selection of trees with above average fruit size were observed. A positive significant correlation was observed between fruit size and seed weight (R = 0.54, P \ 0.05; Fig. 6). The results suggest

T. Peprah D. A. Ofori (&) D. E. K. A. Siaw S. D. Addo-Danso J. R. Cobbinah Forestry Research Institute of Ghana, Council for Scientific and Industrial Research, P. O. Box 63, KNUST, Kumasi, Ghana e-mail: [email protected] A. J. Simons R. Jamnadass World Agroforestry Centre (ICRAF), United Nations Avenue, Gigiri, P. O. Box 30677-00100, Nairobi, Kenya

that selection and cloning of trees with large fruits could lead to higher yield of seeds for oil production. Keywords Allanblackia parviflora Characterization Domestication Flowering Fruiting Genetic variation

Introduction Traditional food crop farming systems in the humid tropics of Africa often exclude tree crops in the landscape. This practice has immensely contributed to deforestation and biodiversity loss. Stabilization of the fragile small-holder food crop farming systems through integration of high value indigenous fruit trees could lead to sustained productivity. Allanblackia parviflora A. Chev. of the family Clusiaceae is a potential candidate fruit tree species that could be introduced into agroforestry systems. Allanblackia parviflora (known locally in Ghana as Sonkyi, Kusiadwe etc.) is an indigenous tree species which is found in the rain forest regions of Ghana. It is a medium-sized tree (Fig. 1) that grows to a height of about 40 m. The bole is cylindrical or slightly fluted, rarely greater than 50 cm diameter at breast height (DBH) with narrow crown of horizontal branches with large leaves, which have shiny surfaces and numerous lateral nerves forked near the margins. The bark is reddish-brown with small rectangular or

123

1038

Genet Resour Crop Evol (2009) 56:1037–1044

Allanblackia seed oil is being developed as a new agri-business in Ghana, Nigeria, Cameroon and Tanzania (Shrestha and Akangaamkum 2008). This rural based enterprise would not only increase livelihood opportunities for farmers but also ensures retention of trees on farms for environmental sustainability. Early in the Allanblackia initiative, the need for planting rather than reliance on sourcing oil solely from natural stands was identified as a crucial task (Siaw et al. 2003; Shrestha and Akangaamkum 2008). The age at which the tree flowers and fruits is not known. Ecological influence on seed yield is also not known. Furthermore, genetic diversity and morphological markers associated with high yielding is not known. Knowledge on these coupled with understanding of the reproductive biology could lead to high and quicker genetic gain. The objectives of the study were therefore to; (1) determine the flowering and fruiting patterns as well as the variability among fruit yield and (2) identify indicators for high fruit yield and device appropriate measures for selection of elite genotypes for domestication.

Methodology Site selection and marking of trees Fig. 1 A typical tree of Allanblackia parviflora growing at Gwira Banso (N 05° 07.5451, W 002° 15.1101) in the Western region of Ghana. This falls within the Wet evergreen forest zone with average rainfall [1,750 mm per annum. Tree height and diameter are 24.5 and 40 cm, respectively

circular scales over small red pits (Hawthorne 1990; Hawthorne and Gyakari 2006). Allanblackia has several uses including shade, timber, medicine and seed oil. The kernel when dried contains about 67–73% of solid white fat (Siaw et al. 2003; Sefah 2006). Traditionally oil extracted from the seed has been used locally for cooking and soap making (Ofori et al. 2006; Irvine 1961). Recently new uses at industrial scale have been discovered by Unilever N. V. (Rotterdam) for its application in the manufacture of margarine (Shrestha and Akangaamkum 2008). The high melting point of the Allanblackia seed oil among other things make it superior to other alternatives like palm oil (Siaw et al. 2003; Sefah 2006). Despite the numerous uses of Allanblackia parviflora at both subsistence and industrial levels, it has been neglected and underutilised for far too long. Currently, the

123

In order to capture the total diversity reposed in the entire population in the distribution range of Ghana, germplasm collection had to be undertaken throughout the distribution range in Ghana. Based on an inventory study of Allanblackia in Ghana to establish the distribution range and population density (Siaw et al. 2003), collection zones and expedition routes were established. Seven populations, ranging from Wet evergreen through Moist Evergreen to Moist semi-deciduous forest zones where the species occurs were sampled (Table 1). The selected trees were marked, labelled and assigned accession names. The passport information recorded included location, ecological zone, contact person, latitude and longitude determined by GPS 76 (Garmin, USA). Flowering and fruiting Three populations (Dwirabanso, Daboase and Mankranso), each from the different ecological zones were selected for this study (Table 1). Flowering and fruiting patterns were determined by observing five

Genet Resour Crop Evol (2009) 56:1037–1044 Table 1 Ecological zones, number of trees sampled per population and their rainfall regimes

1039

Ecological zone

Code

Populations sampled

Number of trees per population

Rainfall (mm)

Wet evergreen forest zone

WE

Dwirabanso

14

[1,750

Moist evergreen forest zone

ME

Sefwi Wiawso

4

1,500–1,750

Daboase Samreboi

6 24

Benso

13

Mankranso

38

Moist semi-deciduous forest zone

trees each from the three populations. The marked trees were observed for onset of flowering and fruiting. Variability in flowering and fruiting among and within populations were also noted. The number of fruits per tree was determined by counting the number of fruits on the selected trees. Genetic variation Fruit collection for evaluation of phenotypic variation was undertaken within all the seven populations (Table 1) between January 2003 and April 2006. Since the species is alternate fruiter and also fruits mature once in a year (January to April), three collections were made from each tree within the four fruit collection years. Only mature fruits were collected and these were fruits that had dropped from the tree on their own. In total, fruits were collected from 109 trees (Table 1). The fruits collected from each tree were kept separately in labeled sacks before transporting to Forestry Research Institute of Ghana (FORIG), Kumasi for characterization. Fifteen fruits were randomly sampled from each tree for characterization. The fruit weight, length and circumference were recorded followed by the estimation of fruit volume. The number of seeds and seed weight per fruit were recorded. Unhealthy seeds floated on water during processing and were separated from the healthy seeds. The proportions of unhealthy and healthy seeds were also recorded.

MSD

Afosu/Apapam

10

Total

109

1,250–1,500

each year were used as one replicate. Radius (r) of fruit was estimated as r = C/2p, where C represents the circumference of the fruit. This was followed by estimation of fruit volume (V) as V = pr2L/2, where ‘L’ represents fruit length. Fruit weight, fruit volume, number of fruits per tree, number of seeds per fruit and weight of fresh seeds were analysed using one-way analysis of variance. Family heritability (h2 = proportion of the total phenotypic variance in a population that may be accounted for by genetic factors) for fruit volume was estimated based on variance components obtained from analysis of variance as described by Zobel and Talbert (1991). The mean values were transformed to percentage deviation from the overall mean fruit volume and were further multiplied by the heritability to provide the predicted family value also known as genetic gain (G) as: G = h2S, where S is selection differential or deviation from overall mean fruit volume. Correlation between fruit volume and seed weight was estimated. Multivariate analysis based on fruit length, diameter, volume and seed weight using PC-Ordination programme (McCune and Mefford 1997) was performed to examine the relationships among fruits from different trees.

Results Flowering and fruiting patterns of Allanblackia parviflora trees

Data analysis All fruits collected were sent to FORIG for characterization. Within the four fruit collection periods, fruits were collected 3 times (once in a year) from each of the 109 trees which had been marked. Collections made

Development of flower buds and flowering coincided with the fruit maturity period (January to April) with a high concentration at the tips of the branchlets. The colour of flowers ranged from white/cream through pink to red (Fig. 2a, b, c). Twenty eight percent of the

123

1040


Fig. 2 Allanblackia parviflora flowers showing different colours and sexes. a White/cream female flower with a developing fruit. b Pink/red female flower. c Pink/red male flower (Color figure online)

the Wet Evergreen forest zone were more prolific and decreased through Moist Evergreen to Moist Semideciduous forest (Fig. 3), although the difference was not significant (P [ 0.05). The mean fruit weight, varied, with the highest recorded in Wet evergreen, but this was also not significant (P [ 0.05; Fig. 4).

250

Number of fruits per tree

trees encountered during fruit collection had flowers with white/cream background while 72% had flowers with pink/red background. Flowering synchrony among the three ecological zones was observed. Twenty seven percent of the mature trees encountered were found flowering profusely and had longer periods of flower production but all the flowers later dropped and did not produce any fruits while the others (78%) produced plentiful number of fruits after flowering. The trees that flowered but did not produce fruits were identified as male trees and the others with fruits were identified as female tree. A. parviflora has imperfect flowers with the male flowers (Fig. 2c) consisting of five sepals, five petals and five thick and fleshy filaments, each possessing many anthers but lack the carpel (stigma, style and ovary). The female flowers (Fig. 2a, b) also possess five sepals, five petals and the carpel but without the stamen (anther and filament). It was however, difficult to differentiate between male and female trees morphologically off flowering and fruiting seasons.

200

150

100

50

0 WE

ME

MSD

Ecological zones

Fruit and seed characteristics The mean number of fruits per tree varied for the different ecological zones. Generally trees found in

123

Fig. 3 Mean number of fruits per A. parviflora tree as observed in different ecological zones (WE, Wet evergreen; ME, Moist evergreen; MSD, Moist semi-deciduous forest zones). Error bars represent standard errors


1041

Fig. 5 Variation in shape and size of A. parviflora fruits. Fruits were collected from Wassa Akropong and its environs in the Western region of Ghana. This falls within the Moist Semi-

deciduous forest zone with rainfall ranging between 1,500 and 1,750 mm. Fruit length ranges between 20 and 40 cm and circumference between 25.3 and 41 cm

Mean fruit weight (kg)

Significant differences (P \ 0.05) were, however, observed among some of the individual trees. Furthermore significant differences were observed in the number of seeds per fruit among individual tress but this was not significantly different among provenances. Generally, the number of seeds per fruit

ranged between 18 and 48 with a mean of 26.5 (±1.18 SE). Fruit shape varied substantially ranging from round to oblong (Fig. 5) but shapes were not site specific. Some fruits were elongated with low diameter: length ratio while others were on the contrary. Significant differences (P \ 0.05) in fruit volume were observed among the various accessions collected. The average fruit volume was 1545.22 cm3 with a range of 528.3–2793.52 cm3. A high heritability (h2 = 0.822) in fruit size and genetic gain (G = 20.1%) in fruit size for selection of trees with above average fruit size were observed. A significant positive correlation was observed between fruit volume and seed weight (R = 0.54, P \ 0.05; Fig. 6). Differences in fruit size were not population structured as shown in the scatter diagram (Fig. 7). Principal component analysis defined by axis 1 and 2 (Fig. 7, accounting for 99.25% of the total variation) provides a clear view of the relationships among the accessions. This suggests that differences in fruit size

2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 WE

ME

MS

Ecological zones Fig. 4 Mean fruit weight per ecological zone (WE, Wet evergreen; ME, Moist evergreen; MSD, Moist semi-deciduous forest zones). Error bars represent standard errors

123

Seed weight per fruit (kg)

1042


0.6 y = 0.1424Ln(x) - 0.8302 0.5 0.4 0.3 0.2 0.1 0 0

500

1000

1500 2000

2500 3000

3500 4000

Fruit volume (cm3) Fig. 6 Relationship between seed weight [kg] and fruit size

were not population structured. Ranking of fruit volume was comparable with the partitioning based on principal component analysis using the four variables (fruit volume, fruit length, diameter and seed weight). Trees on the negative side of the X-axis had large fruits (above average) while those on the positive side of the X-axis had small fruits (below average). The proportion of healthy seeds ranged between 89% (Wet evergreen) and 92% (Moist evergreen) but these not significantly different (P [ 0.05).

Discussions and conclusion Allanblackia parviflora was found to be a dioecious species with male and female flowers occurring on different trees. Field observation indicates that there are more female trees than male trees with a ratio of about 3:1 (F:M) respectively. This sex ratio should, however, be used with care since trees that did not flower and fruit during the study period could not be sexed. Flowering occurs in February to April coinciding with the fruit maturity period. Trees growing in the Wet Evergreen had the highest mean number of fruits per tree and this decreased from wet zones towards dry zones (Fig. 3), however, the differences were not significant (P [ 0.05). The mean fruit weight, health of fruits and number of seeds per fruit did not follow any trend and were also not ecologically influenced. The colour of flowers ranges from white to grey to pink to reddish. Suggesting the possible occurrence of different varieties and/or species in Ghana,

123

although only A. parviflora has been reported to exist in Ghana (Hawthorne 1990; Hawthorne and Gyakari 2006). Hence more work needs to be done on species identification. Qualitative and quantitative analyses demonstrated the existence of a high degree of polymorphism in the fruit shape. Unlike Atriplex halimus (Hcini et al. 2007), no clear morphological differences in fruit size and shape were observed among the different populations. The observed variations, however, occurred both within and among different populations (Fig. 7). This suggests that the observed variability may have little to do with environmental factors but rather has a genetic basis that may be reflected in molecular DNA analysis currently in progress. This is supported by the high heritability estimate (h2 = 0.822) in fruit size. Based on this, selection of elite trees for domestication was not based on average population characteristics but rather on individual trees. In order to avoid erroneous conclusions, the choice of trait to be used for selection was quite difficult. It was realised that no single trait (fruit length, diameter, circumference or weight) was ideal to be used for selection. This is because fruit shape varied with some being elongated but with small diameter and vice versa. Fruit weight was also not considered suitable because some fruits lost bits and pieces of the pods when they drop from the tree. The ideal method was therefore the use of fruit length, diameter, volume and seed weight in the construction of the cluster analysis. Nonetheless, for the sake of simplicity and the quest for best indicators for selection, fruit volume was found to be a suitable indicator since it is a function of the diameter and length but independent of weight. Seed yield is also considered as one of the most important characters to be considered in the selection and improvement programme of Allanblackia parviflora. Interestingly, total seed weight per fruit was found to be positively correlated with fruit size, hence, selections based on fruit size suggest a substantial potential for high seed yield. Selection of 58 elite trees with above average fruit size resulted in 20.1% genetic gain in fruit size. The results of this study therefore suggest that a large proportion of the fruit morphology observed in A. parviflora might be genetically controlled. Individual selection based on fruit size could be a

1043

Axis 2


NEN 4

NEN 6 NK 2 TIA 14 MH 3

WA 4 WAMK 5

GB 10

TIA 7 NEN 16

NB 3 DB 2 NEN 21 TIA 3 TIA 17

NK 9

AK 2

K5

DB 4 TIA 6 TIA 2 NK 7 LAHO 2 NEN 22 NK 6 MH 1 MN 3 WAMK 14 WR 11 AY 1 TIA 4 B 21 WAMK 1 NZA 40 NB 1 SA 1 SA 48 NZA 24 DB 9 B 4 NZA 1 B 22 K 2 B 17 WAMK 8 MA 4 NZA 3 NEN 19 ASN 11 WAMK 3 MH 4 NEN 18 MN 4 LAHO 4 NEN 27 MN 1 2 NEN 14 DM 4 LAHO 3 WAMK 15 KW 2 GBMH TIA 9 34 NZA 11 B1 LAHO 5 NEN 20 NEN 29 AK 1 OT 7 WH 1 N2 AFS 3 KW 1 DM ASN 12 WAMK 4 NEN 30 NZA 26 2 GB 11 NEN 25 BMK 13 DM 1 TIA 13 B 13 NB 1 B 19 BS 1 SA 2 WA 6 B 11 DB 12 NEN 28 WAMK 2 WAMK 7 MA 1 OT 3 NEN 23

GB 12

NEN 9

LAHO 1 ATB 1

WAMK 6

TIA 1

NEN 11

AWA 2 OT 1

B 23 WAMK 9

AFS 1

B 10

WA 2

B 20 B6

MH 5

NZA 12

B 24

B9

NZA 2

Axis 1

D6

NEN 24

NZA 31

OT 5

NEN 26

Fig. 7 Genetic relationships among fruit size (fruit length, diameter, fruit volume) and seed weight per fruit. Letters in the accession names represent codes of localities within the populations where they were sampled as shown below

Key Population

Codes

Mankranso

AK, KW, AY, NEN, MH, OT, MN, NB, WH, AWA

Samreboi

LAHO, NK, WAMK, WA, MA, BS

Sefwi Wiawso

SA, WR

Benso

B, K

Daboase

ATB, DB, DM

Dwirabanso

AS, ASN, BMK, GB, NZA, OB

Afosu/Apapam

TIA, AFS

fast and efficient way for capturing higher genetic gains in A. parviflora. Accurate estimate of the sex ratio and estimation of oil content and quality from seeds of the selected trees should, however, be made for better deployment of clones in agroforestry systems.

Acknowledgments We thank Unilever International and MARS for supporting this study financially. We are also grateful to the staff of the Forestry Research Institute of Ghana, World Agroforestry Centre, Novel Development-Ghana and International Tree Seed Centre for their assistance and encouragement. Support provided by our field guides and farmers from whose farms samples were collected is also acknowledged.

123

1044

References Hawthorne W (1990) Field guide to forest trees in Ghana. Chatham: Natural resources institute for overseas development administration, London. Ghana Forestry Series 1, pp 278 Hawthorne W, Gyakari N (2006) Photoguide for forest tree of Ghana. A tree spotters guide for identification of large trees. Oxford Forestry Institute, UK, p 432 Hcini K, Farhat MB, Harzallah H, Bouzid S (2007) Diversity in natural populations of Atriplex halimus L. in Tunisia. Plant Genet Resour Newsl 149:34–38 Irvine FR (1961) Woody plants of Ghana with special reference to their uses. Oxford University Press, Oxford, pp 143–144 McCune B, Mefford MJ (1997) Multivariate analysis of ecological data, version 3.04, MjM software. Gleneden Beach, Oregon Ofori DA, Peprah T, Siaw D, Cobbinah JR (2006) Domestication of Allanblackia in Ghana. In: Muasya S, Rutatina

123

Genet Resour Crop Evol (2009) 56:1037–1044 F, Munjuga M, Simons AJ (eds) Status and prospects for Allanblackia domestication in Tanzania. CD-ROM compilation. ICRAF, Nairobi. ISBN 92 9059 196 X Sefah W (2006) Extraction and characterisation of vegetable fat from Allanblackia floribunda. Thesis submitted to the department of Biochemistry and Biotechnology in partial fulfilment of the requirement for the award of the Master of Science (M.Sc.) degree in food science and technology. Kwame Nkumah University of Science and Technology, pp 146 Shrestha RB, Akangaamkum AD (2008) Novella partnership, a partnership for poverty reduction through sustainable enterprise development based on Allanblackia, SNV Ghana, pp 20 Siaw DEKA, Cobbinah JR, Kankam BO, Derkyi SA, Oduro KA, Agyili J, Peprah T (2003) Allanblackia floribunda, final report submitted to Unilever Ghana Limited by Forestry Research Institute of Ghana, pp 69 Zobel B, Talbert J (1991) Applied forest tree improvement. Waveland Press Inc, Illinois, p 505