Báo cáo lâm nghiệp: Influence of the moisture content of forest tree its response to different viability tests pollen on

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Báo cáo lâm nghiệp: "Influence of the moisture content of forest tree its response to different viability tests pollen on"Influence of the moisture content of forest tree pollen onits response to different viability tests M. Bonnet-Masimbert 2J. Webber1 Research Branch, British Columbia Ministry of Forests, Victoria, Canada, and2 INRA, Station dAm6lioration des Arbres Forestiers, Ardon, 45160 Olivet, FranceIntroduction atmosphere (humidity, temperature and exposure time) on in vitro viability shown. are response,Pollen management has become anintegral part of intensive tree impro-vement, especially for facilitating breedingprograms and improving both orchard Materials and Methodsyields and genetic efficiency. To handlepollen successfully, particularly its storage,drying to moisture contents of less than Procedures for testing in vitro viability have10% is required (Webber, 1987; and been described by Charpentier and Bonnet-unpublished data). However, in certain Masimbert (1983) and Webber (1987). Theangiosperms, dehydration can have a effect of 2 relative humidities (70 and 100% RH)detrimental effect on pollen germination and 3 temperatures (10, 20 and 30°C) onand vigor which is only restored by rehy- rehydration of Douglas fir (Pseudotsuga men- ziesii) pollen and their effects on germinationdration (Shivanna and Heslop-Harrison, and conductivity over 9 exposure times (0, 3, 6,1981 ). 16, 24, 48, 72, 96 and 120 h) were tested. The The of reduction this 70% RH was generated by controlling wet- in cause bulb/dry-bulb temperatures using a water bathgermination and viability with dehydration (T1) and an incubator (T2). The 100% RH wasis not fully understood but loss of created by saturating air in a closed containermembrane integrity may be involved maintained at the incubator temperature T2.(Shivanna and Heslop-Harrison, 1981).. ) Germination of Douglas fir pollen wasCertainly, it is a principal factor in the loss assessed for class 1 grains (defined as elon-of vigor in corn (Kerhoas, et al., 1987). gation more than twice the original diameter of the grain) after 48 h of incubation and In this paper, data from previous expressed as a percentage of the total numberexperiments are summarized to show the of pollen grains observed. Conductivity wasfactors affecting reactivation of pollen determined using 25 mg of pollen in 7.5 ml ofvigor, and data from recent tests, which ultra-pure H and measured after 1 h at 25°C 0 2 (cold leachate).demonstrate the effect of rehydrationResults at 30°C), suggesting that mem- ticularly brane reorganization was incomplete. RH, membranes ap- at 100% However,Correlation analysis for Douglas fir pollen early and conductivity to stabilize peared values remained relatively stable, at least up to 72 h, after which deteriorationTableI summarizes the correlation coef- apparent (again, more prominent at wasficients between 3 in vitro assays (res- 30°C).piration, conductivity and germination) and Of particular interest was the differentialpercent filled seeds per cone (% Fspc) for response by pollen lots (data not shown).Douglas fir pollen. It is apparent that Our best lot, determined by assay re-respiration is less sensitive to the moisture sponse, remained stable and showed the However, hydrationcontent ...