Articles
SEEDBED CONDITIONS AND SEEDLING ESTABLISHMENT
Seed vigour is not the subject of this paper, but it must be realised that the effect of soil conditions on seeds often depends upon, the vigour level of the seed stock used, and the results described in this paper should be viewed in that context.
When 100 seeds are sown in the field, it is almost certain that emergence will be less than 100%. This may be because a proportion of the seeds at sowing is dead or abnormal (up to .35% of this category is permissable in commercial seed in a crop such as carrot), some may be dormant or dormancy may be induced after sowing, and the remainder (with a range of possible vigour levels) must face the rigours of the seedbed environment.
Although the requirements for seeds to germinate are relatively simple – air and a sufficient but not excessive supply of water at a moderate temperature, and freedom for the shoot to escape from the soil – the conditions in the seed zone of the soil can be far from optimal.
Establishment problems are often explained away in ill-defined terms (e.g. it was ‘the seed’, or cold/wet conditions, hot/dry conditions, pests/diseases, or capping, perhaps) yet the precise causes of seed or seedling losses seem rarely to have been accurately identified or quantified.
It is important, though, that this should be done, because only through this can sensible ways around the various problems be suggested.