Just a quickie to add an update on some new blooms. My Phalaenopsis Mini Pink has flowered again after 2 years without any flowers! This plant is a particularly fussy bloomer for some reason but this year there are tonnes of flowers. The first bloom opened this past Friday. The next plant to flower was a No ID Cymbidium that I have been baby-sitting for my wife's grandmother. It too had not flowered in several years but gratefully it produced two pendulous spikes of beautiful small green flowers this year. I have it in mind to get it identified because I have some Eulophia parviflora that are spiking now and I would like to hybridise these two. There are more blooms to come. My Aerangis hyaloides and Angraecum sesquipedale should be flowering very soon, followed by Aerangis modesta and some Oncidium species.
The laminar flow hood is arguably one of the most important pieces of equipment for flasking and re-plating orchid seeds and seedlings. It allows you to work in a sterile space provided by a steady stream of pre-filtered sterile air delivered by a blower through a HEPA filter (High Efficiency Particulate Air filter). Initially I used a sterile transfer hood to do all my flasking and re-plating and I have had good success with this chamber containing a germicidal UV lamp but contamination still creeps in from time to time and losses as a result could be avoided by upgrading to a full laminar flow hood. In addition, my existing sterile transfer chamber has a relatively short lifespan because of the degrading affect of UV on the acrylic walls.
Of course cost is always a factor and by no means are HEPA filters cheap, nor are they easy to find in Cape Town. HEPAs are classed according to their accuracy and ability to remove particles from the air. For flasking, a HEPA with an H14 class which is rated to remove 99.95% of all airborne microbiological contaminants is standard.
There are two main types of design for laminar flow hoods, a horizontal laminar flow which provides a horizontal flow of sterile air through the working chamber towards the operator, and a vertical laminar flow hood which delivers sterile air from the top of the chamber towards the base which usually has escape channels in it, or the air simply escapes through the front working access. I chose to design a horizontal laminar flow for my requirements. The concept of sterility is often not easy to grasp unless you have actually had experience working in a truly sterile area. I am fortunate enough to have been trained in molecular techniques in a DNA laboratory working with various techniques including PCR. Here, sterility is essential to avoid contamination and you begin to realise just how unsterile everything can be. Two of the most important contamination sources include the air and YOU. Imagine briefly how many suspended particles are in the air at any given point. Often some of these particles can be seen when the light from the sun shines through a window in the early morning. It is nearly impossible to avoid contamination in flasks when opening them or during transfer without first sterilising the air. The laminar flow hood provides this steady flow of sterile air into the working chamber at a higher pressure than ambient so no contaminated air can get into the working area when switched on. Of couse, all equipment must also be completely sterile when used in the working area and I also find that spraying the outside of flasks down with a sodium hypochlorite solution before placing them into the working area also reduced contamination risk when re-plating. I also get into the habbit of ensuring as few as possible movements for any single action or sets of actions. Everything is well timed and well planned. Anything that accidentally comes into contact with my tools during an operation is deemed to be a potential contamination risk and I either change my tool immediately or re-sterilise that tool by ethanol-flaming. After each completed action, tools are ethanol-flamed.
My laminar flow hood will be constructed from waterproof ply (12mm or 16mm thick depending on cost) and will be epoxy coted for longevity and for ease of cleaning with either ethanol or oxidising agents like sodium hypochlorite or hydrogen peroxide. The design is "L" shaped and will be free-standing. The HEPA chamber will have an access panel at the back for the initial HEPA installation and future replacement and a second chamber will house twin blowers delivering the required amount of air needed to produce a laminar flow of 0.5m/second filtered air. The HEPA I have ordered measures 610mm X 305mm (H14 class) and will be attached to the inner frame with a gasket secured with bolts and wing nuts for easy removal.
Another important feature of the laminar flow hood is the blower. These need to be able to deliver the correct flow of air through the HEPA at the required filter's static pressure. To avoid using a blower that is too powerful and that may damage the HEPA, I have chosen to use two smaller twin units mounted horizontally one above the other. A third blower is kept as a replacement unit in case one of the two fails during operation. Both blowers are easily accessible through the side chamber which will be fitted with a verically sliding and fully removable pre-filter.
Laminar flow plans
I will follow up with the progress on the laminar flow hood construction as I get there. The HEPA will take about 4 weeks to arrive from Germany so in the mean time I will start working on the case.
I have been wanting to do this blog for a while now. I had sent some Dendrobium crosses to David for flasking. I thought I would keep two pods and flask them my self in the kitchen. I thought it would be a good idea to check the progress of home flasking to flasks done in a laboratory environment.
It is not a difficult thing to flask orchids at home in the kitchen. All you need is a lot of Miltons sterilizing liquid a few glass jars, your growing medium and of coarse the seed. Once you have those things you are ready to start. Its even possible to make your own growing medium with agar and a few other ingredients. I will get into that in a second.
This is a flask I sowed on 24/11/2010. This is growing on home made Agar- Agar mix which consists of the following.
I was not trying to put the best growing medium together. I just used what I had in the kitchen. The seeds germinated a few weeks later on the 7/12/2010 and looked good. I had made 4 flasks and lost 2 two contamination in a very short time. Its been many months now and it is growing very slowly, but its growing. This is how they are looking right know.
David had sowed the seeds I sent him around the same time I had sowed mine. I got the flasks from him a few weeks later and was surprised at how much they had grown compared to the flasks I had done in the kitchen. Here they are.
These grew very quickly and started filling almost the whole bottom of the flask in a few weeks.
Once they had taken over the bottom of the flask they started growing the first "leaves".The real growing began and they started looking like little orchids.
After the leaves had developed nicely the roots started pushing out from the base of the little plants.
Once the roots started growing, the now proper seedlings grew even faster on Davids enhanced orchid medium. This is how the roots have developed in a space of about two months since they first started growing.
This is how they are looking at the moment.
I have already potted up two flasks that are doing well ! Root development and growth is a bit slower in the com pots, but plants are looking stronger .
Home flasking in the kitchen or in your own laminar hood can be rewarding in a way of accomplishment. The down side is contamination is a big issue and the growth can be much slower if you decide to make your own growing medium for flasking. The seedlings will take many more years to flower due to slow growth.
Sending your precious seed pods to a laboratory is much less of a risk and you can be sure that you are going to have strong seedlings for potting up when the time comes. Plants will also mature faster and flower sooner. We all want flowering plants after all.
This is a picture of both a home flask and a lab flask . Both these flasks are roughly seven months old.You can see there is a big difference.