A review of dipterocarps - Center for International Forestry Research

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Seed Physiology 60 Table 2. Percentage moisture content and oil values for processed, dewinged whole seed and excised seed parts (Tompsett and Kemp 1996a, b). Species Whole-seed moisture content* (percentage) *: calculated on wet weight basis; **: calculated on dry weight basis; determined; in addition, declining moisture content, increasing germination and increasing weight of the seed were recorded. One theory proposed was that early desiccation of the seed coat may be connected with poor viability; this explanation appears unlikely since S. roxburghii has similar seed coat structures and is much longer-lived. An interaction of maturity with chilling damage has been noted. Increased resistance to such damage was observed as maturity approached for S. siamensis (Panochit et al. 1984); germination declined to zero and 25% for seed collected 4 and 2 weeks respectively before maturity after storage for 28 days at 2°C, but mature seed still gave about 60% germination after 56 days of similar storage. The same effect was noted for S. roxburghii (Panochit et al. 1986). Axis moisture content* (percentage) Embryo oil content ** (percentage) Dipterocarpus intricatus *** 8 n/a 16 Dipterocarpus alatus *** 11 n/a 7 Dipterocarpus tuberculatus *** 11 13 19 Shorea ferruginea 29 n/a 61 Shorea argentifolia 29 51 n/a Hopea ferrea 32 n/a 9 Shorea parvifolia 32 62 n/a Hopea foxworthyi 34 52 n/a Hopea odorata 36 54 20 Shorea gibbosa 37 64 n/a Dipterocarpus costatus 38 n/a 10 Shorea macrophylla 38 66 n/a Parashorea tomentella 40 63 n/a Shorea amplexicaulis 40 69 57 Dipterocarpus grandiflorus 40 70 n/a Anisoptera costata 42 n/a 33 Shorea fallax 42 70 n/a Shorea affinis 44 63 n/a Dipterocarpus chartaceus 47 n/a 8 Shorea leptoderma 47 61 n/a Parashorea malaanonan 48 66 n/a Dryobalanops keithii 50 56 n/a Stemonoporus canaliculatus 53 64 n/a Shorea macroptera 55 n/a n/a Dipterocarpus obtusifolius 56 74 n/a ***: seeds of OLDA (orthodox with limited desiccation ability) dried naturally in the field. Tang and Tamari (1973) were the first to report the post-harvest-maturation phenomenon for dipterocarp seeds. They found that Hopea helferi and H. odorata seeds blown down prematurely by a high wind increased in germination during storage. The effect was observed over a period of about one week for seeds held at 15 °C. Desiccation Studies Knowledge of its storage physiology category, which can be derived from desiccation studies, is the single most useful piece of physiological information about a seed. It is the key to correct seed handling procedures. Seed storage physiology categories Three storage category designations are recognised. Of these, the main two are:
Seed Physiology 61 § orthodox; and § recalcitrant. The orthodox type is capable of desiccation to a low moisture content (approximately 5%) and storage for several years at -20 o C with little loss of viability (Roberts 1973). By contrast, the recalcitrant type is not capable of desiccation to a low moisture content without loss of germination capacity and cannot be stored for long periods of time (Roberts 1973). A third category of seed storage physiology has been described. It was first defined in 1984 in relation to Araucaria columnaris seed (Tompsett 1984) and was termed ‘orthodox with limited desiccation ability’ (OLDA). A similar category was later defined for coffee seed and termed ‘intermediate’; the name denotes its partial tolerance of desiccation (Ellis et al. 1990, 1991). Some recent evidence (Tompsett, unpublished), however, confirms there may be little physiological difference between this third category of seed and the orthodox type. There are, however, important practical handling difficulties associated with this third category. These problems justify its retention as a distinct storage type. Some tropical seed is additionally subject to lowtemperature damage when stored in the moist condition (chilling damage, see pages 58-59). As a result, further categories could have been included. However, it was considered preferable, for the sake of simplicity, to employ only the three desiccation-damage-based categories described above. To date, all dipterocarp species examined have been found to be subject to chilling damage when moist. Desiccation physiology Curves of germination percentage against moisture content percentage can be plotted for the results from controlled desiccation studies. These curves illustrate whether the seed is recalcitrant or not and give parameters for the way the seed responds when it is dried. One parameter is the lowest-safe moisture content (LSMC), defined as the value below which viability is immediately lost on drying. The value for this parameter provides a guide to the moisture content below which seed should not be held during handling procedures. LSMC values were assessed under standard drying conditions and were found to vary between 26% and 50% (Table 3). In Table 4 further LSMC data are given; although these were assessed using various desiccation methods, the results are in broad agreement with those in Table 3. Slope and intercept parameters are presented for some species (Table 3); these define the relationship between germination and moisture content during desiccation. Desiccation rates It is possible that desiccation rate may influence viability; for example, seeds dried quickly might give lower germination than seeds dried more slowly and gently to the same moisture content. However, in the case of the ‘recalcitrant’ seed of Araucaria hunsteinii (Araucariaceae) no such differences were observed (Tompsett 1982). No intensive study of this sort has been carried out on dipterocarp seed. However, Amata-Archachai and Hellum (unpublished) found that immature fruits of Dipterocarpus alatus clearly dried quicker than mature fruits; they suggested that the difference could be because of the death on drying of the immature seeds. However, the faster loss of moisture by immature seeds could also be explained by their smaller size. Small seeds have a higher ratio of surface area to volume than large seeds, enabling quicker moisture loss. In this connection, Tamari (1976) found small seeds of S. parvifolia (0.3 g) gave low viability, whilst large seeds (0.5 g) gave higher viability. One explanation for the latter finding is that the smaller seeds had dried quicker and thus lost more viability than larger seeds prior to testing. Clear-cut differences in desiccation rates among seeds of species in the same genus have been reported by Tompsett (1986, 1987); rates for Dipterocarpus seeds varied greatly and depended on their size and structure. At the one extreme D. intricatus seed required only one week to dry to 7% moisture content; at the other extreme, seed of D. obtusifolius under identical conditions retained c. 30% moisture content even after 5 weeks. Likewise, Yap (1986) found S. parvifolia seeds dried quicker than those of two larger-seeded species of Shorea; he believed the difference in rates to be related to pericarp thickness. Differences in desiccation rates of the type discussed above may possibly affect both the initial post-desiccation viability and the subsequent storage life of the seed. Further studies are needed to assess these effects.
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A Review of Dipterocarps Taxonomy,
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ã 1998 by Center for International
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Authors S. Appanah Forest Research
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SPINs Species Improvement Network T
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Foreword The Center for Internation
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Introduction As a consequence, much
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Introduction each project that is m
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Biogeography and Evolutionary Syste
Page 17 and 18: Biogeography and Evolutionary Syste
Page 55 and 56: Conservation of Genetic Resources i
Page 65 and 66: Seed Physiology P.B. Tompsett Seed
Page 67: Seed Physiology 59 (Sasaki 1980, Ya
Page 71 and 72: Seed Physiology 63 Table 4. Lowest-
Page 73 and 74: Seed Physiology 65 Table 5. (contin
Page 75 and 76: Seed Physiology 67 Table 6. Viabili
Page 77 and 78: Seed Physiology 69 Dipterocarp seed
Page 79 and 80: Seed Physiology 71 Roberts, E.H. 19
Page 81 and 82: Seed Handling 74 viability of the s
Page 83 and 84: Seed Handling 76 the basic activiti
Page 85 and 86: Seed Handling 78 Table 2. Seed (fru
Page 87 and 88: Seed Handling 80 Table 3. Mean inse
Page 89 and 90: Seed Handling 82 Seedling storage u
Page 91 and 92: Seed Handling 84 air will ensure ra
Page 93 and 94: Seed Handling 86 ASEAN Forest Tree
Page 95 and 96: Seed Handling 88 Tompsett, P.B. and
Page 97 and 98: Seedling Ecology of Mixed-Dipteroca
Page 107 and 108: Root Symbiosis and Nutrition Table
Page 109 and 110: Root Symbiosis and Nutrition Table
Page 111 and 112: Root Symbiosis and Nutrition specie
Page 113 and 114: Root Symbiosis and Nutrition in Sab
Page 115 and 116: Root Symbiosis and Nutrition where
Page 117 and 118: Root Symbiosis and Nutrition 5. Lim
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Root Symbiosis and Nutrition Group
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Root Symbiosis and Nutrition Takaha
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Pests and Diseases of Dipterocarpac
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Management of Natural Forests S. Ap
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Management of Natural Forests about
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Management of Natural Forests 4. Cl
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Management of Natural Forests were
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Management of Natural Forests incre
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Management of Natural Forests 1. He
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Management of Natural Forests which
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Management of Natural Forests Cheng
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Management of Natural Forests Uebel
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Plantations 152 macrocarpa, V. indi
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Plantations 154 are: Dipterocarpus
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Plantations 156 and no longer in ne
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Plantations 158 able to store them
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Plantations 160 ‘Predictive Test
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Plantations 162 Qureshi et al. (196
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Plantations 164 Tomboc and Basada (
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Plantations 166 are removed. Anothe
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Plantations 168 intervention. Sange
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Plantations 170 mono-layered. The r
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Plantations 172 diameter of 46.3 m
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Plantations 174 Ang, L.H., Maruyama
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Plantations 176 Cheah, L.C. 1971. A
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Plantations 178 Kadambi, K. 1957. B
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Plantations 180 Moura-Costa, P. 199
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Plantations 182 Regional Workshop o
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Plantations 184 Conference on Dipte
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Non-Timber Forest Products from Dip
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Scientific Index BIXALES, 25 BOLETA
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Scientific Index EPHEMEROPTERA, 119
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Scientific Index Ovalis section, 8,
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Scientific Index Shorea leptoderma,
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Scientific Index VATERINAE sub-trib
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General Index barus kapur, 192-3 ba
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General Index endangered species, i
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General Index distribution, 15 enda
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General Index nurse crops, 161, 165
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General Index seed material, cryopr
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General Index TPI, 139 tractors, 15
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