A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
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Seed Physiology 60<br />
Table 2. Percentage moisture content and oil values <strong>for</strong> processed, dewinged whole seed and excised<br />
seed parts (Tompsett and Kemp 1996a, b).<br />
Species Whole-seed moisture<br />
content* (percentage)<br />
*: calculated on wet weight basis;<br />
**: calculated on dry weight basis;<br />
determined; in addition, declining moisture content,<br />
increasing germination and increasing weight <strong>of</strong> the seed<br />
were recorded. One theory proposed was that early<br />
desiccation <strong>of</strong> the seed coat may be connected with poor<br />
viability; this explanation appears unlikely since S.<br />
roxburghii has similar seed coat structures and is much<br />
longer-lived.<br />
An interaction <strong>of</strong> maturity with chilling damage has<br />
been noted. Increased resistance to such damage was<br />
observed as maturity approached <strong>for</strong> S. siamensis<br />
(Panochit et al. 1984); germination declined to zero and<br />
25% <strong>for</strong> seed collected 4 and 2 weeks respectively<br />
be<strong>for</strong>e maturity after storage <strong>for</strong> 28 days at 2°C, but<br />
mature seed still gave about 60% germination after 56<br />
days <strong>of</strong> similar storage. The same effect was noted <strong>for</strong><br />
S. roxburghii (Panochit et al. 1986).<br />
Axis moisture<br />
content*<br />
(percentage)<br />
Embryo oil content<br />
** (percentage)<br />
Dipterocarpus intricatus *** 8 n/a 16<br />
Dipterocarpus alatus *** 11 n/a 7<br />
Dipterocarpus tuberculatus *** 11 13 19<br />
Shorea ferruginea 29 n/a 61<br />
Shorea argentifolia 29 51 n/a<br />
Hopea ferrea 32 n/a 9<br />
Shorea parvifolia 32 62 n/a<br />
Hopea foxworthyi 34 52 n/a<br />
Hopea odorata 36 54 20<br />
Shorea gibbosa 37 64 n/a<br />
Dipterocarpus costatus 38 n/a 10<br />
Shorea macrophylla 38 66 n/a<br />
Parashorea tomentella 40 63 n/a<br />
Shorea amplexicaulis 40 69 57<br />
Dipterocarpus grandiflorus 40 70 n/a<br />
Anisoptera costata 42 n/a 33<br />
Shorea fallax 42 70 n/a<br />
Shorea affinis 44 63 n/a<br />
Dipterocarpus chartaceus 47 n/a 8<br />
Shorea leptoderma 47 61 n/a<br />
Parashorea malaanonan 48 66 n/a<br />
Dryobalanops keithii 50 56 n/a<br />
Stemonoporus canaliculatus 53 64 n/a<br />
Shorea macroptera 55 n/a n/a<br />
Dipterocarpus obtusifolius 56 74 n/a<br />
***: seeds <strong>of</strong> OLDA (orthodox with limited desiccation<br />
ability) dried naturally in the field.<br />
Tang and Tamari (1973) were the first to report the<br />
post-harvest-maturation phenomenon <strong>for</strong> dipterocarp<br />
seeds. They found that Hopea helferi and H. odorata<br />
seeds blown down prematurely by a high wind increased<br />
in germination during storage. The effect was observed<br />
over a period <strong>of</strong> about one week <strong>for</strong> seeds held at 15 °C.<br />
Desiccation Studies<br />
Knowledge <strong>of</strong> its storage physiology category, which can<br />
be derived from desiccation studies, is the single most<br />
useful piece <strong>of</strong> physiological in<strong>for</strong>mation about a seed.<br />
It is the key to correct seed handling procedures.<br />
Seed storage physiology categories<br />
Three storage category designations are recognised. Of<br />
these, the main two are: