in a preferred form , the present invention is generally a multi - step process for ex vitro sowing and germination of plant somatic embryos using conventional horticultural equipment and facilities , comprised of but not necessarily restricted to the following sequential steps : 1 . sowing the plant somatic embryos into nursery containers containing a three - phase substrate , said three phases comprising solids , liquids and air . 2 . placing the nursery containers sown with plant somatic embryos , into a conventional plant propagation environment in which light , temperature , atmospheric humidity , and moisture content of the rooting substrate can be controlled and manipulated to enable and facilitate germination of the somatic embryos and their further development into complete seedlings . 3 . supplying an aerosol to the surface of the nursery containers sown with somatic embryos , said aerosol containing the necessary carbohydrate compounds required to initiate and sustain the germination processes of the somatic embryos . 4 . supplying , in the forms of an aerosol and / or a liquid suspension and / or a liquid solution , the micro - and macro - mineral and other nutrative elements required to sustain the germination of somatic embryos and their subsequent development into seedlings . 5 . adjusting as required during the somatic embryo germination period , the ambient light intensity and diurnal photoperiod , temperature and atmospheric humidity to maintain the development of germinated somatic embryos into complete seedlings . a particular advantage of this novel process , at least in preferred forms , is that special hygienic and / or aseptic and / or sterile handling methods and / or equipment and / or facilities are not required to successfully handle , sow and germinate plant somatic embryos . it is preferable that the present invention be practiced with plant somatic embryos that have been dried to moisture contents that approximate those of their corresponding zygotic seeds , i . e ., in the range of 5 - 20 % and , more specifically , in the range of 10 - 15 %. however , it is possible to practice the present invention with somatic embryos containing higher moisture contents in the range of 20 - 78 % with the only limitation on the upper limit being the highest level of moisture content that the somatic embryos can be singulated , handled and sown with conventional seeding equipment . although the present invention can be practiced with all conventional seeding equipment used for sowing zygotic seeds , it is preferred to use equipment that dispenses seed into multi - chambered nursery containers , commonly referred to as miniplug trays , flats or cell - packs , said containers commonly used to produce plant plugs which can be mechanically transplanted into larger containers or into field - growing environments . an important advantage of the present invention , at least in preferred forms , is that it can be practiced with a wide variety of non - sterilized growing substrates commonly used in conventional plant propagation . the preferred growing substrate is peat - based and formulated specifically for germination of zygotic seed , and is exemplified by mixtures such as ( a ) 15 . 2 cu . ft of peat , 8 cu . ft . of vermiculite , 680 grams of dolomite lime , and 300 grams of micromax ® ( a commercial fertilizer composition comprised of microelements such as , but not limited to , sulfur , boron , manganese , magnesium , cobalt and iron ), and ( b ) 16 . 2 cu . ft . of peat , 6 . 75 cu . ft . perlite , 4 cu . ft . vermiculite , 6 kilograms of dolomite lime , 1 . 5 kilograms of gypsum , 375 grams of potassium phosphate , 250 grams micromax , and 35 grams of wetting agent . alternatively , commercially formulated mixes such as pro - mix - g ® or pro - mix - pgx ® ( premier peat moss ltd . montreal , pq , canada — a commercial soilless plant growing media containing , but not limited to , peat , perlite , vermiculite and / or pumice ), sunshine mix # 3 ( sun - gro horticulture inc ., hubbard , oreg ., usa ), and redi - earth ® ( the scotts co ., marysville , ohio , usa — a commercial soilless plant growing media containing , but not limited to , peat , perlite , vermiculite and / or pumice ), can also be used with the present invention . it is preferred that the peat - based growing substrate is moistened to a moisture content in the range of 50 - 80 % and then dispensed into multi - chambered trays commonly used for commercial production of plant plugs . although examples of such trays include styrofoam # 252 or # 448 miniplug trays manufactured by beaver plastics inc . ( edmonton , ab , canada ) and hard plastic # 288 or # 512 miniplug trays manufactured by tlc polyform inc ( plymouth minn ., usa , 55441 ), the present invention can be practiced with other types of multi - chambered trays , or alternatively , with individual pots . it should be noted that the practice of the present invention is not restricted to peat - based mixtures , but also includes other substrates such as jiffy - 7 peat plugs , composted or shredded or unprocessed coconut husk fibres commonly referred to as “ cor ” or “ coir ” ( 1993 crystal co ., st . louis , mo ., usa ), polymerized substrates ( grow tech inc ., san juan bautista , calif . usa ; preforma inc ., oberlin , ohio usa ), extruded foams such as oasis ® ( smithers - oasis ltd ., kent , ohio , usa — a commercial expanded foam product comprising urea formaldehyde ), rock wool ( rockwool international a / s , hovedgaden 584 , dk - 2640 , denmark ) and the like . regardless of the rooting substrate chosen , its physical characteristics should enable development and maintenance of a high relative humidity i . e ., in excess of 75 % rh , in the gaseous phase within the substrate while minimizing saturation of the substrate with the liquid phase . after the somatic embryos are sown onto the surfaces of the rooting substrates , if desired , the embryos may be covered with a thin layer of additional rooting substrate that may be comprised of the same material underneath the embryos or , alternatively , with a different type of material . one non - limiting example is sowing embryos onto pro - mix - pgx medium , then overlaying the embryos with a thin layer of coir , i . e ., composted coconut husk fibres . nursery containers sown with somatic embryos are preferentially placed into a conventional plant propagation environment wherein the conditions are within but not limited to the ranges of temperatures of 15 - 35 ° c ., relative humidities of 75 - 100 %, light intensities of 10 - 500 foot candles , and diurnal cycles of 6 h day / 18 h night to 22 h day / 2 h night . it is preferable to maintain a very high level of atmospheric humidity around the nursery containers sown with somatic embryos , i . e ., greater than 90 % rh , for the first 2 - 10 days after sowing to facilitate somatic embryo imbibition and germination . a number of methods can be used to maintain the atmospheric humidity at these levels including but not restricted to placing the containers in a greenhouse environment with misting or fogging equipment which is deployed at controlled intervals , placing the containers in a fogging or misting tent or chamber , placing clear plastic domes over the nursery containers and then removing domes periodically to mist or fog the sown embryos and replacing the domes immediately thereafter . another non - limiting method is to provide a space ranging between 2 mm and 10 mm above the surface of the rooting substrate onto which the embryos are sown and the top of the container , and then covering the top of the nursery container with a plastic film which is removed to enable misting or fogging of the sown embryos and then immediately replaced . after somatic embryo germination is established as evidenced by development of shoot and root structures , the germinants can be weaned from the high relative humidity environments by gradually reducing the amount of misting / fogging applied and / or by extending the periods of time between the misting or fogging steps . it is preferable to maintain the sown embryos in a high relative humidity environment , i . e ., greater than 90 % rh , for a period of , but not restricted to , 3 - 7 days after sowing to facilitate embryo imbibition , prior to supplying exogenous nutrients required for embryo germination . another advantage of the present invention , at least in its preferred forms , is that the exogenous nutrients , including but not restricted to carbohydrates , minerals , vitamins and hormones which are required for successful somatic embryo germination and subsequent growth and development can be applied as aerosols . the nutrient solutions can be applied with , but not restricted to , conventional misting and / or fogging equipment . although , the nutrients can be applied individually or combined into one solution , it is preferred to supply the carbohydrates as one solution and the remaining nutrients as a separate solution . a non - limiting example of how this can be practiced is by applying a solution containing a sugar source such as but not limited to sucrose in a concentration selected from the non - limiting range of 1 . 5 - 9 %, preferably in the range of 3 - 6 %, as a mist to the surface of the growing substrate containing a sown embryo , and then applying as a mist at a later time , a solution containing a mixture of mineral nutrients formulated to deliver but not restricted to 454 mg / l nitrogen , 81 mg / l phosphorus , 704 mg / l potassium , 50 mg / l calcium , 39 mg / l magnesium , 193 mg / l sulfur , 3 mg / l manganese , 0 . 5 mg / l zinc , 89 mg / l chlorine , 3 mg / l iron , 0 . 7 mg / l iodine , 0 . 6 mg / l boron , 0 . 01 mg / l molybdenum , 0 . 01 mg / l cobalt , and 0 . 01 mg / l copper . alternatively , the macronutrients can be supplied as a commercial formulation such as but not restricted to plantprod ® plant starter fertilizer 10 - 52 - 10 ( nitrogen - phosphate - potassium ) or plantprod ® forestry seedling starter 11 - 41 - 8 ( nitrogen - phosphate - potassium ) ( plant products ltd ., brampton , on , canada ). the plantprod ® products are commercial water - soluble fertilizers containing mineral nutrients such as nitrogen , phosphorus and potassium , and a dye . an alternative non - limited means of supplying exogenous nutrients to somatic embryos sown onto three - phase growing media within nursery containers is to irrigate or “ drench ” the media with nutrient solutions formulated as previously described . this is preferably done just before the embryos are sown onto the three - phase growing media . since microorganisms such as fungi , bacteria , yeast , and algae , are ubiquitous in conventional plant propagation substrates , equipment , containers and growing environments , a wide variety of chemical and biological pesticide products are available to control and eradicate plant pathogens . the inventors of the present invention , however , have surprisingly found that aseptic handling procedures and sterilized growing substrates , nursery containers and environments are not required to successfully germinate and grow plant somatic embryos . indeed , the present invention can be practiced in conventional plant propagation environments using only the standard commercial methods of hygiene . furthermore , we have surprisingly found that pesticides such as benlate ® ( a commercial fungicide composition containing a chemical active ingredient ), rovral ® ( a commercial fungicide composition containing a chemical active ingredient ), trumpet ® ( a commercial insecticide composition containing a chemical active ingredient ), and the like , which are registered for pest control in plant crops , can be used on somatic . embryos sown with the novel multi - step procedure of the present invention , without any debilitating effects on germination . the following examples are provided to further illustrate the present invention , but are not to be construed as limiting the invention in any manner . somatic embryos ( se ) of interior spruce ( picea glauca engelmannii complex ) line 23 - 2672 were produced according to the methods of roberts et al . ( 1990a ; 1990b ) and webster et al . ( 1990 ). after harvesting , the se ( somatic embryos ) received two drying treatments , the first being hrht ( high - relative humidity treatment ) while the second hrht followed by further drying for 3 days at a relative humidity of 85 % ( the relative humidity was provided in a sealed chamber containing a saturated kcl solution ). the moisture content of se produced for treatment 1 ( hrht only ) was 69 . 7 %, while the moisture content of se produced for treatment 2 ( hrht followed by rh 85 %) was 14 . 8 %. se from the two drying treatments were hand - sown into phytatrays containing agar comprised of 0 . 55 % difco noble agar , ½ gmd nutrients ( webster et al ., 1990 ), and 2 % sucrose . three phytatrays , each containing 30 se , were sown with each set of se ( i . e ., drying treatments 1 & amp ; 2 ), and then incubated for three weeks at 23 ° c . with a diurnal cycle of 20 h light and 4 h dark . a custom - formulated seedling growing mix comprised of 16 . 2 cu . ft . of peat , 6 . 75 cu . ft . perlite , 4 cu . ft . vermiculite , 6 kilograms of dolomite lime , 1 . 5 kilograms of gypsum , 375 grams of potassium phosphate , 250 grams micromax , and 35 grams of wetting agent ( westcreek farms , fort langley , b . c ), was prewetted with benlate suspension ( 0 . 5 g / l ), then dispensed into a beaver plastics styrofoam miniplug trays containing 252 cells ( 10 ml / cavity ). after the miniplug cells were filled with growing mix , they were dibbled to produce a ¼ ″- ½ ″ head space between the top of the growing mix and the top of the miniplug tray . se from the two drying treatments were sown into the miniplug trays ( 60 se / treatment / tray ). the se were immediately misted with 2 % sucrose and then the miniplug trays were immediately tightly covered with plastic wrap ( saran wrap ). the trays were maintained in a commercial greenhouse environment kept at 20 °- 25 ° c . with a 20 h light / 4 hr dark diurnal cycle . the se were misted each morning with 2 % sucrose and each afternoon with “ plant starter fertilizer formulation at 100 ppm n ( plantprod 10 - 52 - 0 ). the miniplug trays were misted with a benlate suspension ( 0 . 5 g / l ) as necessary to prevent fungal growth . the miniplug trays were tightly covered with saran wrap after each misting . two weeks after sowing , the misting regime was modified to include a commercial rooting hormone formulation ( dip &# 39 ; n grow ®, astoria - pacific inc ., portland oreg ., usa ). diluted to deliver 20 ng iba and 10 ng naa , data collected three weeks after sowing , are summarized in table 1 . these data demonstrate that se produced from interior spruce line 23 - 2672 germinated ex vitro in a non - sterile peat - based growing mix supplemented with exogenous nutrient applications via aerosols , when propagated in a conventional commercial greenhouse facility . somatic embryos ( se ) of interior spruce ( picea glauca engelmannii complex ) line 107 - 1979 were produced according to the methods of roberts et al . ( 1990a ; 1990b ) and webster et al . ( 1990 ). after harvesting , the se received two drying treatments , the first being hrht ( high - relative humidity treatment ) while the second treatment received hrht followed by further drying for 3 days in a chamber wherein the atmospheric relative humidity was maintained at 85 %. the moisture content of se produced for treatment 1 ( hrht only ) was 64 . 8 %, while the moisture content of se produced for treatment 2 ( hrht followed by rh 85 %) was 42 . 6 %. beaver plastics styrofoam # 252 miniplug trays were filled to within ¼ ″- ½ ″” of the top of the trays with one of the following soil - less growth substrates : ( 1 ) a custom formulated peat - substrate comprised of 16 . 2 cu . ft . of peat , 6 . 75 cu . ft . perlite , 4 cu . ft . vermiculite , 6 kilograms of dolomite lime , 1 . 5 kilograms of gypsum , 375 grams of potassium phosphate , 250 grams micromax , and 35 grams of wetting agent ( westcreek farms , fort langley , bc , canada ), prewetted with benlate suspension ( 0 . 5 g / l ), ( 2 ) oasis foam ( smithers - oasis ltd ., kent , ohio ), and ( 3 ) rock wool ( rockwool international a / s ). prior to sowing with se , all substrates were prewetted with a solution containing 2 % sucrose , 0 . 5 g / l benlate and ½ - strength gmd ( per webster et al ., 1990 ). after sowing , the miniplug trays were tightly covered with plastic wrap ( saran wrap ), and misted 3 - 5 times daily with a solution comprised of 4 . 5 % sucrose and plantprod forestry seedling starter fertilizer 11 - 41 - 8 at 50 ppm n . the miniplug trays were also misted every 2 - 3 days with a rotation of benlate , thiram and rovral . data collected two weeks after sowing , are summarized in table 2 . these data demonstrate that se produced from interior spruce line 107 - 1917 germinated ex vitro in different types of non - sterile growing substrates including a peat - based formulation , an extruded foam ( i . e ., oasis ) and rock wool when supplemented with exogenous nutrient applications via aerosols , and propagated in a conventional commercial greenhouse facility , somatic embryos ( se ) of interior spruce ( picea glauca engelmannii complex ) lines 1 - 1281 and 107 - 1917 were produced according to the methods of roberts et al . ( 1990a ; 1990b ) and webster et al . ( 1990 ). after harvesting , the se were dried using the hrht method . beaver plastics styrofoam # 252 miniplug trays were completely filled with of the following three soil - less growth substrates : ( 1 ) a custom formulated peat - substrate comprised of 16 . 2 cu . ft . of peat , 6 . 75 cu . ft . perlite , 4 cu . ft . vermiculite , 6 kilograms of dolomite lime , 1 . 5 kilograms of gypsum , 375 grams of potassium phosphate , 250 grams micromax , and 35 grams of wetting agent , prewetted with a benlate suspension ( 0 . 5 g / l ), ( 2 ) oasis foam , and ( 3 ) rock wool . prior to sowing with se , all substrates were prewetted with a solution containing 2 % sucrose , 0 . 5g / l benlate and ½ - strength gmd ( per webster et al ., 1990 ). after sowing , the miniplug trays were placed into a fogging / misting tent constructed on a greenhouse bench within a commercial greenhouse facility . the miniplug trays were fogged through misting nozzles with a 1 - mm orifice ( dramm co ., manitowoc , wisc ., usa ) for 15 secs at 2 - hr intervals for 2 weeks . the miniplug trays fogged four times daily through the misting system with a solution comprised of 4 . 5 % sucrose and plantprod forestry seedling starter fertilizer 11 - 41 - 8 at 50 ppm n . the miniplug trays were also misted every 2 - 3 days with a rotation of benlate , thiram and rovral . data were collected two weeks after sowing , and are summarized in table 3 . these data demonstrate that se produced from interior spruce lines 1 - 1281 and 107 - 1917 germinated ex vitro in different types of non - sterile growing substrates including a peat - based formulation , an extruded foam ( i . e ., oasis ) and rock wool when placed into a conventional misting / fogging tent , and supplemented with exogenous nutrient applications via fogging , and propagated in a conventional commercial greenhouse facility somatic embryos ( se ) of interior spruce ( picea glauca engelmannii complex ) lines 1 - 1281 , 4 - 2809 , 5 - 1702 , 10 - 1995 , 23 - 2672 , 119 - 2560 were produced according to the methods of roberts et al . ( 1990a ; 1990b ) and webster et al . ( 1990 ). after harvesting , the se were dried using the hrht method . a custom - formulated seedling growing mix comprised of 16 . 2 cu . ft . of peat , 6 . 75 cu . ft . perlite , 4 cu . ft . vermiculite , 6 kilograms of dolomite lime , 1 . 5 kilograms of gypsum , 375 grams of potassium phosphate , 250 grams micromax , and 35 grams of wetting agent 5 ( westcreek farms , fort langley , b . c ), was prewetted with a suspension comprised of 3 % sucrose , plant products forestry seedling starter fertilizer 11 - 41 - 8 at a concentration of 50 ppm n , then dispensed into styrofoam miniplug trays containing 252 cells ( beaver plastic ltd .). the miniplug trays were sown with se ( 1 line / tray ), then covered with a thin layer of coir ( fine fibres of composted coconut husks ) and misted with water . the miniplug trays were then placed into a fogging / misting tent constructed on a greenhouse bench within a commercial greenhouse facility . the miniplug trays were fogged through misting nozzles with a 1 - mm orifice ( dramm co ., manitowoc , wisc ., usa ) for 30 sec at 4 - hr intervals for 1 week . the miniplug trays were also misted by hand three times daily with a solution comprised of 4 . 5 % sucrose and forestry seedling starter fertilizer 11 - 41 - 8 at 50 ppm n . data collected indicated that average daily temperature within the misting / fogging tent was 25 ° c . while the average atmospheric relative humidity was 92 %. data collected one week after sowing , are summarized in table 4 . these data demonstrate that se produced from six interior spruce lines sown onto a peat - based growing substrate and covered with a thin layer of coir , germinated ex vitro when placed into a conventional misting / fogging tent , and supplemented with exogenous nutrient applications via fogging , and propagated in a conventional commercial greenhouse facility . somatic embryos ( se ) of interior spruce ( picea glauca engelmannii complex ) line 23 - 2672 were produced according to the methods of roberts et al . ( 1990a ; 1990b ) and webster et al . ( 1990 ). after harvesting , the se were dried for three weeks using the hrht method and then , dried further for 20 h at 23 ° c . in a sealed chamber containing a rh of 88 . 5 % which was maintained with an unsaturated nacl solution placed in the chamber . water contents of embryos were determined immediately after the hrht treatment , and after the further desiccation at 88 . 5 .% rh . desiccated embryos were imbibed for 18 h in an environment with a rh of 100 %, and then sown into 400 - cavity miniplug trays containing a non - sterile peat - based soil - less growing substrate that was gelled with a polymer ( grow tech inc ., san juan bautista , calif . usa ). after sowing was completed , the miniplug trays were placed into a humidified germination chamber for 1 week with the following environmental conditions : 95 - 98 % rh ; 25 °/ 20 ° c . day / night temperatures ; a diurnal period of 18 h light / 6 h dark ; light intensity of 30 - 40 μm m − 2 s − 1 photosynthetic photon flux . the blocks were then moved into a misting chamber with similar environmental conditions except for an increase in light intensity to 120 - 150 μmol m − 2 s − 1 . after two more weeks of growth , germination success was recorded and the results summarized in table 5 . these data demonstrate that spruce somatic embryos which were desiccated to water contents approximating those of zygotic spruce seed , germinated when sown directly onto the surface of a non - sterile peat - based growing substrate which had been gelled with a polymer . mature somatic embryos of ( 1 ) pinus patula scheide et deppe , and ( 2 ) western white pine ( pinus monticola doug1 . ex d . don ) were directly sown into non - sterile soilless seedling mixes comprised of 50 % screened peat and 50 % fine perlite ( mix b2 ) in tlc polyform 288 / ml miniplug trays ( 10 ml / cavity ). after sowing , the trays were placed in a humidified growth chamber with an environmental condition of 95 - 98 % rh , day / night air temperatures of 25 / 20 ° c ., and an 18 hour photoperiod of 90 - 120 μmol m − 2 s − 1 photosynthetic photon flux . for the first three days since sowing , a modified gmd nutrient solution containing 3 % sucrose was sprayed onto the trays twice a day . thereafter , nutrient solution application was reduced to only once a day . after 3 weeks , the experiments were terminated and germination successes tabulated . the results are summarized in table 6 . mature somatic embryos of ( 1 ) pinus patula scheide et deppe , and ( 2 ) western white pine ( pinus monticola doug1 . ex d . don ) were directly sown into 400 - cavity miniplug trays containing a non - sterile peat - based soil - less growing substrate that was gelled with a polymer ( grow tech inc ., san juan bautista , calif . usa ). after sowing , the trays were placed in a humidified growth chamber with environmental conditions comprised of 95 - 98 % rh , day / night air temperatures of 25 / 20 ° c ., light intensity of 90 - 120 μmol m − 2 s − 1 photosynthetic photon flux and an 18 - hour photoperiod . for the first three days since sowing , a modified gmd nutrient solution containing 3 % sucrose was sprayed onto the trays twice a day . thereafter , nutrient solution application was reduced to only once a day . after 3 weeks , the experiments were terminated and germination successes tabulated . the results are summarized in table 7 . these data demonstrate that patula pine ( pinus patula ) and western white pine ( pinus moticola ) somatic embryos can be germinated ex vitro in a non - sterile peat - based growing substrate which had been gelled with a polymer . mature somatic embryos of pinus patula scheide et deppe and pinus patula were further desiccated for 20 h at 23 ° c . in a sealed chamber containing a rh of 88 . 5 % which was maintained with an unsaturated nacl solution placed in the chamber . western white pine ( pinus monticola doug1 . ex d . don ) embryos were desiccated for 72 h in the same environment , i . e ., with a rh of 88 . 5 %. water contents of the embryos were determined immediately after the hrht treatments , and after the further desiccations at 88 . 5 .% rh . desiccated embryos were imbibed for 18 h in an environment with a rh of 100 %, and then sown into 400 - cavity miniplug trays containing a non - sterile peat - based soil - less growing substrate that was gelled with a polymer ( grow tech inc ., san juan bautista , calif . usa ). after the sowings were completed , the miniplug trays were placed into a humidified germination chamber for 1 week with the following environmental conditions : 95 - 98 % rh ; 25 °/ 20 ° c . day / night temperatures ; a diurnal period of 18 h light / 6 h dark ; light intensity of 30 - 40 μmol m − 2 s − 1 photosynthetic photon flux . the blocks were then moved into a misting chamber with similar environmental conditions except for an increase in light intensity to 120 - 150 μmol m − 2 s − 1 . after two more weeks of growth , germination successes were recorded and the results summarized in table 8 . these data demonstrate that desiccated somatic embryos from various pine species can germinate when sown directly onto the surface of a non - sterile peat - based growing substrate which had been gelled with a polymer . mature somatic embryos of pinuspatula scheide et deppe and pinus patula were desiccated for 24 h at 23 ° c . in a sealed chamber containing a rh of 92 . 4 % which was maintained with an unsaturated nacl solution placed in the chamber . the embryos were then transferred to a sealed chamber maintained at a rh of 88 . 5 % and further desiccated at 5 ° c . for 42 h . water contents of the embryos were determined immediately after the hrht treatments , and after the further desiccations at 88 . 5 .% rh . desiccated embryos were imbibed for 18 h in an environment with a rh of 100 %, and then sown into 400 - cavity miniplug trays containing a non - sterile peat - based soil - less growing substrate that was gelled with a polymer ( grow tech inc ., san juan bautista , calif . usa ). after the sowings were completed , the miniplug trays were placed into a humidified germination chamber for 1 week with the following environmental conditions : 95 - 98 % rh ; 25 °/ 20 ° c . day / night temperatures ; a diurnal period of 18 h light / 6 h dark ; light intensity of 30 - 40 μmol m − 2 s − 1 photosynthetic photon flux . the blocks were then moved into a misting chamber with similar environmental conditions except for an increase in light intensity to 120 - 150 μmol m − 2 s − 1 . after two more weeks of growth , germination successes were recorded and the results summarized in table 9 . these data demonstrate that desiccated somatic embryos from various pine species can germinate , regardless of how they were processed during desiccation , when sown directly onto the surface of a non - sterile peat - based growing substrate which had been gelled with a polymer . hrht - treated loblolly pine ( pinus taeda l ) somatic embryos were directly sown into tlc polyform 288 - cavity miniplug trays containing soilless mixes comprised of screened peat and fine perlite . after sowings were completed , the trays were placed in a humidified growth chamber with an environmental condition of 95 - 98 % rh , day / night air temperatures of 26 / 20 ° c ., and an 18 hour photoperiod with a light intensity of 90 - 120 μmol m − 2 s − 1 photosynthetic photon flux . a modified gmd nutrient solution containing 3 % sucrose was sprayed onto the trays once a day . germination successes were assessed after 2 weeks . the results are summarized in table 10 . matured canola ( brassica napus l .) somatic embryos were harvested and conditioned in nln - 13 liquid medium ( lichter , 1982 ) for one week as follows . embryos were placed in 250 - ml baffled erlenmeyer flasks containing 100 ml of medium . the flasks were then placed onto a shaker ( 60 rpm ) under constant ( 24 h / day ) illumination at 20 - 30 μmol m − 2 s − 1 of photosynthetic photon flux . the conditioned embryos were then sown into 288 - cavity miniplug trays containing non - sterile soilless peat - based seedling mixes . after sowing , the miniplug trays were placed into a high - humidity ( 95 - 98 % rh ) chamber . photosynthetic photon flux ( i . e ., light intensity ) in the chamber was 30 μmol m − 2 s − 1 at the surface height of the trays . a modified gmd solution containing 3 % sucrose was sprayed onto the embryos once every weekday during the length of the experiment . germination success was recorded after 3 weeks . the shoot lengths of the canola somatic seedlings ranged between 0 . 5 to 4 . 0 cm tall and their root systems were well developed . the results are summarized in table 11 . matured canola ( brassica napus l .) somatic embryos were harvested and conditioned in nln - 13 liquid medium ( lichter , 1982 ) for one week as follows . embryos were placed in 250 - ml baffled erlenmeyer flasks containing 100 ml of medium . the flasks were then placed onto a shaker ( 60 rpm ) under constant ( 24 h / day ) illumination at 20 - 30 μmol m − 2 s − 1 of photosynthetic photon flux . the conditioned embryos then received a three - day hrht treatment after which , they were sown into 288 - cavity miniplug trays containing non - sterile soilless peat - based seedling mixes . after sowing , the miniplug trays were placed into a high - humidity ( 95 - 98 % rh ) chamber . photosynthetic photon flux ( i . e ., light intensity ) in the chamber was 30 μmol m − 2 s − 1 at the surface height of the trays . a modified gmd solution containing 3 % sucrose was sprayed onto the embryos once every weekday during the length of the experiment . germination success was recorded after 3 weeks . the results are summarized in table 12 . these data demonstrate that somatic embryos from an angiosperm species , brassica napus l ., processed with an hrht treatment , can be germinated ex vitro in various compositions of non - sterile soilless growing mixes . matured canola ( brassica napus l .) somatic embryos were harvested and conditioned in nln - 13 liquid medium ( lichter , 1982 ) for one week as follows . embryos were placed in 250 - ml baffled erlenmeyer flasks containing 100 ml of medium . the flasks were then placed onto a shaker ( 60 rpm ) under constant ( 24 h / day ) illumination at 20 - 30 μmol m − 2 s − 1 of photosynthetic photon flux . the conditioned embryos then received a three - day hrht treatment after which , they were further desiccated at 23 ° c . in one of the following desiccation environments , 84 . 2 % rh ; 85 % rh ; 92 . 4 % rh ; 96 . 7 % rh . water contents of the embryos were determined immediately after the hrht treatments , and after the further desiccations at 88 . 5 .% rh . desiccated embryos were imbibed for 18 h in an environment with a rh of 100 %, and then sown into 288 - cavity miniplug trays containing non - sterile soilless peat - based seedling mixes . after sowing , the miniplug trays were placed into a high - humidity ( 95 - 98 % rh ) chamber . photosynthetic photon flux ( i . e ., light intensity ) in the chamber was 30 μmol m − 2 s − 1 at the surface height of the trays . a modified gmd solution containing 3 % sucrose was sprayed onto the embryos once every weekday during the length of the experiment . germination success was recorded after 3 weeks . the results are summarized in table 13 .
a multi - step process by which plant somatic embryos can be sown and germinated ex vitro using conventional seeding equipment , growing mixes , and plant propagation environments . the process most preferably comprises the steps of : placing a somatic embryo on or within a three - phase substrate , the phases comprising solid , liquid and gas phases , placing the substrate containing a somatic embryo into an environmentally - controlled plant - growing environment in which at least one environmental factor may be controlled and manipulated , manipulating at least one of the environmental factors to enable and facilitate germination of the somatic embryo , and applying water and / or nutrient solutions at regular intervals , the intervals preferably ranging from 1 minute - 24 hours , to the surface of the substrate in the form of microdroplets , preferably for a period of time ranging between 3 to eight weeks , such that somatic embryo imbibition , germination , growth and development occur . the process can be practiced in non - sterile conditions with “ naked ” fresh and / or hrht - treated and / or desiccated embryos , i . e ., non - encapsulated or otherwise uncoated embryos , and does not require the use of aseptic techniques or sterilized media or equipment .