Archive Article: 1997/09/06
IT IS still some way from being foolproof but it wont be long before scientists working on a joint ADAS/Nottingham University project, for the HGCA, will be able to predict by computer the likely lodging risk for virtually any standard variety.
Thanks to spring predictions, it should be possible to say whether individual crops need one or more growth regulators to keep them standing – or whether they will need any extra help at all.
The prototype model has predicted 50-70% of summer lodging in the two years of experiments so far, according to Pete Berry of Nottingham University, who is carrying out the experiments at ADAS Rosemaund in Herefordshire.
Predictions are made by combining information on site characteristics such as wind speed, rainfall and soil type with known variety characteristics, including stem strength, height at the centre of gravity, root development, and the stems natural frequency.
Much of the experiment has focussed on gathering basic information about varieties, by making a number of spring measurements, including plant populations, canopy size, shoot and leaf number, stem development and structural root depth.
This has highlighted factors influencing the lodging susceptibility of individual varieties such as Spark, which has a good root spread helping it stand better than Cadenza with a weaker root cone.
Root plate spread will vary with variety, says Dr Berry, but can also be manipulated by seed rate. Lower seed rates give greater root spread and increased lodging protection.
"You dont need a big difference in seed rate to get a change in the diameter of the root, but a small increase in diameter can have a big effect on lodging," he adds.
Drill at 100kg/ha, instead of the standard 160kg/ha, and root spread can be increased by 50%. Tiller numbers are likely to be increased in many varieties but the extra root spread easily copes with the additional leverage and yield is likely to stay the same.
Earlier sowing is more conducive to reduced seed rates but the project is continuing to work on drilling dates.
This year has provided excellent test beds for the project. Extensive lodging occurs on average every four or five years during wet summers. The last severe lodging year of 1992 is thought to have cost growers up to £130m in lost yields. In 1996, growers spent £16m on plant growth regulators.
By being able to predict lodging by GS30, growers may be able to save on inputs on the less at-risk crops.
Other trials at Rosemaund are showing the effects of PGRs. Rhone-Poulenc found that the PGR ethephon has a particular effect in shortening the second node in wheat. This lowers plant centre of gravity and has the greatest effect on lodging.