What’s in a seed? A seed contains the blueprint or instructions to produce a new plant. Traditionally all seeds were open-pollinated. That is, the pollen from the anther (male part of the flower) entered the stigma and travelled to the ovary (female part of the flower). Fertilisation occurred and seeds were formed with or without fruit. There are many forms of fertilisation but this is the basic concept.
Over time we have seen desirable features in plants – its flowers or fruit, hardiness or appearance – and have sought to improve them to create more desirability. Different types of seed have been developed for many given plants. In this article we are seeking to explain what these differences are and what they mean for you.
Open Pollinated Seed
These are the traditional seeds produced by plants. They will produce plants that are basically identical to their parent plant. The seeds will form mainly from pollen from the plant itself. If seed is saved over generations it is often referred to as ‘heritage’ or ‘heirloom’ seed. The huge range of these seeds in tomatoes, for example, is because people have selected variations in these tomatoes that they want to keep and develop. This may be size, flavour, colour, hardiness, ripening time, growing time, etc. So the traditional Grosse Lisse tomato is the same plant as Roma but slight genetic variations in the original tomato have been selected or developed over time for their desirable features. Open pollinated seed can be saved and will produce plants true to type (the same as its parent).
Hybrid seed is seed from cross pollination of two plants from the same genus and species. It is very common. These hybrids may produce seed that will grow true to type or may have to be reproduced vegetatively i.e. from cuttings or roots. The desirable characteristics of one plant may be introduced to another with different features to hopefully produce a new plant combining the desired features of both parents. Seeds from the crossing will be grown on and any that produce unwanted features will be discarded. The apple ‘Pink Lady’ was developed from a crossing of ‘Golden Delicious’ and ‘Lady William’. Lady William is a very firm late apple that stores well and Golden Delicious is an earlier sweeter apple that does not store so well. Doubtless there were many new plants grown from the cross pollination and Pink Lady was the selected result. The botanical name for both of these varieties or cultivars is Malus pumila (originally M. domestica).
So the original wild apple (M. pumila) was grown and selected over some hundreds of years for desirable features and then completely different looking apples have been cross-pollinated to produce a new variety.
Brassica oleracae is the botanical name for many of the vegetables we eat. In the wild it is called “wild cabbage” and is native to southern and western Europe including England. It has been selected and developed by regional communities in Europe for hundreds of years and has resulted in us having cabbages, Brussels sprouts, cauliflower, broccoli, kale, collard greens, kohlrabi, Jersey Walking Stick cabbage and some Asian varieties. This potential was latent in one species of plant and has been enhanced to produce a wide spectrum of vegetable varieties.
Originally carrots were thin yellowish roots but consider the amazing variety of colours and forms that are currently available. Likewise tomatoes which originated in South America, where they still grow wild, have been developed and selected to give us a vast range of colour, form, flavour, growing times, etc.
F1 hybrid seed is the result of controlled pollination of two plants or breeding stock with desirable characteristics. This is a form of ‘inbreeding’ and displays the desirable features of both parents. A good analogy to understand this concept can be seen in humans. Two unrelated individuals from the same genus and species (Homo sapiens) produce offspring that will have characteristics from both parents.
Many seeds are available as F1 Hybrids. They will have the best features of both plants and have been selected for advantageous features e.g. vigour, taste or disease resistance. Seed is more expensive as this crossing must be repeated for every batch of seed. Tomatoes and sweet corn are two common ones.
It’s not worth saving seeds from F1 hybrids because the seeds will be either sterile or produce an assortment of plants with different characteristics. Most will probably be inferior but you could chance a good one. If you had the passion and the time you could grow and select seed from this good seedling over a number of years, dropping out the poor ones and end up with a new variety that will germinate true to type. For home gardeners this is hardly worth the effort.
F1 seeds are certainly OK to plant but new seed will need to be purchased for each new season.
GM Seed (genetically modified seed)
GM or GMO seeds are grown from plants that have had their DNA engineered or modified to introduce a new trait into a plant that currently doesn’t exist. Examples could be resistance to certain pests, diseases, environmental conditions, reduction of spoilage or resistance to chemicals such as herbicides. It is a laboratory-mediated variation of the natural selection process that led to the formation of the range of Brassicas and carrots referred to above.
GM seeds are expensive to produce and may contain ‘terminator’ genes so the seed from a crop will be sterile and cannot be saved for future planting.
Some common examples of GM crops grown around the world include: sweet corn, soy beans, cotton, potatoes, squash and canola. Some specific genetic modifications are:
- Potatoes are subject to attack by potato moth if not properly managed. A gene from bacteria has been inserted in GM potato seeds so that potato moth larvae eating the potato crop will die.
- Canola has had herbicide resistant genes inserted into it to enable farmers to control weeds by spraying with glyphosate (Roundup/Zero) rather than by cultivation.
- The gene for blue does not exist in roses although there are a number of lavender coloured varieties. Plant engineers are working to create the classic blue rose by inserting the gene for blue flowers from another unrelated plant to achieve this result.
This concept may have an upside for primary producers but this is far outweighed by the downsides. The trash from a crop of GM potatoes will kill soil life that consumes it as it contains the same bacteria. Canola is a distant relative of the cabbage family and GM canola was listed as Canada’s 13th worst weed some years ago. It has also hybridised with other plants in that country to create ‘super weeds’.