Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Patent
1999-01-08
2000-06-27
Walsh, Donald P.
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
209576, 209587, 2503418, 2503413, B07C 500
Patent
active
060809507
DESCRIPTION:
BRIEF SUMMARY
The present invention refers to a method for determining the maturity and quality of seeds by irradiation with electromagnetic radiation. Due to this irradiation the chlorophyll present in the seeds will show prompt fluorescence. Furthermore, the invention refers to an apparatus for sorting the seeds essentially consisting of a feeder for the seeds, a part for the irradiation of the seeds with electromagnetic radiation, a part for measuring the signal reemitted from the seeds, and a separation part that works on basis of the signal reemitted from the seeds. Seeds being defined as the reproductive unit of the plant after sexual or non-sexual fertilization of the ovule. By chlorophyll all appearances of the chlorophyll molecule are meant, such as the known leafgreen chlorophyll, protochlorophyll, and all other possible configurations.
BACKGROUND OF THE INVENTION
Measuring the amount of chlorophyll fluorescence of the seed envelope is a good method for the assessment of the maturity and quality of seeds. It appeared that simultaneously with the maturation of the seed, the chlorophyll which is present in the seeds is broken down. Therefore, during the maturation process the amount of chlorophyll in the seed envelope decreases. Coincidently the colour changes from green (among others due to the presence of chlorophyll in the immature seeds) to a colour which is depending on the species being investigated. It also appeared that seeds with cracks in the seed envelope showed higher chlorophyll fluorescent signals. Due to these cracks in the seed envelope, the underlying chlorophyll containing tissue (cotyledons, endosperm or embryo) is uncovered. With equipment known and used for sorting seeds on colour, seeds can be sorted in green classes. However, the discrimination of maturity based on colour is not satisfactory: only large differences in maturity can be measured by colour sorting equipment. Therefore, the amount of chlorophyll of the seed envelope is a better basis to discriminate between seeds which differ in maturity.
With the assessment of the amount of chlorophyll fluorescence according to the invention, high certainty can be obtained on the maturity state of the seeds and whether cracks in the seed envelope are present. This makes it possible to sort the seeds with respect to their maturity and on the appearance of cracks in the seed envelope as described in the examples. The border of a class depends on the species and on the seedlot and is calculated on basis of the distribution of the measured fluorescence of a sample taken at random of the particular seedlot. The quality of the seeds in a class depends among others on the choice of the borders of the class. Generally speaking, regarding seeds which after maturation are located in a dry fruit (like seed of cabbage and carrot) the quality of mature seeds is higher compared to less mature or immature seeds. Seeds which maturate in a moist fruit (like seeds of pepper and tomato) have an optimum in their maturity. Immature seeds, but also seeds which are over-mature, have a lower quality compared to seeds of the optimal maturity. Quality being defined as the seed maturation stage, number and size of cracks in the seed envelope, germination percentage, speed of germination, uniformity of germination, vigour, percentage normal seedlings, health and storability. Seeds with an optimal and uniform maturity and without cracks germinate more uniform and give less abnormal seedlings. Seed treatments like priming have a greater effect (faster and more uniform germination) when the seeds have a certain maturity. Moreover, mature seeds have a better storability than less mature or immature seeds. Immature seeds and seeds with cracks are also more sensitive to infection by diseases. Furthermore, a negative health condition during the development of the seed can disturb the maturation process. This will result in unhealthy seeds with a lower degree of maturity than for healthy seeds.
A method to determine the amount of chlorophyll in seeds is known from the article
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References B-M show the state of the art.
Centrum Voor Plantenveredelings
Jones David A.
Walsh Donald P.
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