WO2000052990A1

WO2000052990A1 - Method for determining properties of plant seeds

Info

Publication number: WO2000052990A1
Application number: PCT/NL2000/000166
Authority: WO
Inventors: Henricus Peter Martinus Van Laarhoven; Josephus Johannes Maria Groote Schaarsberg
Original assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
Priority date: 1999-03-11
Filing date: 2000-03-10
Publication date: 2000-09-14
Also published as: AU3335400A; NL1011537C2

Abstract

The invention provides a device and method whereby in a simple, fast and inexpensive manner, without any complicated pre-treatments, a number of important properties of plant seeds can be determined, in particular properties of barley which are revelant to the malting process. When an arrangement according to the invention is used in combination with a bandfilter for a wavelength in the range around 850 nm, the water uptake pattern of gelatinized barley grains can be rendered well-visible.

Description

Title: Method for determining prά^-tties of plant seeds.

The invention relates to a method for determining properties of plant seeds, in particular properties concerning the internal condition of plant seeds such as, for instance, the water uptake, steeliness, acrospiral length and root length. More in particular, the invention relates to a method for determining water uptake of barley during the malting process.

In the malting process, the procedure of steeping malting barley is considered to be a critical step. This water uptake is influenced by different factors; in this regard, very important factors are the barley variety, the grain size distribution, the nitrogen content, the initial moisture content, the water sensitivity of the barley and the manner of steeping. An incorrect performance of this part of the malting process cannot be corrected anymore during the germination phase or kiln-drying. In other words, the water uptake in the barley grains substantially determines the quality of the malt produced therefrom. In the current malting practice, the degree of steeping is the most important control and/or check parameter. This degree of steeping does not distinguish in water uptake between the different parts of the grain that are capable of absorbing water. Also, the degree of steeping does not yield any information about the mutual differences in water uptake between the grains of one batch. However, the water uptake of the grain is in particular determinative for the necessary enzymatic modification of reserve substances stored in the endosperm. For that reason, both the mean water uptake of the batch and the distribution in water uptake between the grains of the batch are of importance. For an improved control of the malting process, the mean water uptake in the endosperm and the distribution thereof can be used for regulation of the steeping time and the temperature of the steeping water. A known method for determining properties of plant seeds, such as barley, wheat, oats or rice, is detection of light in a transmission arrangement. For determining the quality of rice, this method is described in EP 0060493, where a light source is disposed on one side of a seed sample and the detector is arranged on the other side, opposite thereto. All the light detected by the detector passes through - or along - the seed sample. The light transmission through a dry seed sample is very low, for barley this is, for instance, to the order of 0.6 per mille. The direct result is that the light intensities and resolutions to be measured are very low. To obtain a light level that is acceptable in any way, this requires a strong light source and a high amplification and sensitivity of the detector.

If the light along the seed sample falls directly on the detector, the light intensity is much too high relative to that of the light through the seed sample. The solution of EP 0060493 is to cause a strong, narrow light beam to fall on only a small portion of the grain. Disposed opposite this light beam are two detectors for measuring a difference of light detected through the front side and the rear side of the grain. In the case of deviations in the light intensity, it can be determined whether the grain contains fractures. A drawback of this solution, however, is that much information of the internal structure of the grain cannot be detected in this manner. In particular, it is impossible to make camera recordings of the entire contents of the grain, whereby properties concerning the internal structure can be determined, like determining in which portions of the grain water uptake has taken place. Further, it is known to shield the surroundings of the seed sample with a mask. However, this requires an inconvenient and intensive preparatory operation, while the seed samples can only be tested piece by piece. A problem with these masks is further that they do not always fit perfectly, as a consequence of which recordings are often overexposed due to diffused light.

The object of the invention is to provide a method whereby in a simple, fast and inexpensive manner and without any complicated preparatory operations, a number of important properties of plant seeds can be determined, in particular properties concerning the internal condition of plant seeds, such as, for instance, steeliness, acrospiral length and root length, and more in particular properties of barley that are relevant to the malting process, such as the water uptake in the barley seed and water distribution of a batch of seeds, so that the above-mentioned problems are solved or reduced.

This object is realized by following the method for determining properties of plant seeds according to the invention, wherein a sample of plant seed is positioned in the light of a substantially parallel light beam; a camera captures the properties of the sample in a recording, by means of detection of diffused light passing through the sample and deflected at a particular angle to the beam, while the light of the beam going straight on along the sample is not detected; and the resulting recording of the camera is processed by means of image analysis, so that the properties can be determined.

In an arrangement according to the invention, the light that is not influenced by the seed sample goes straight on and will not be detected by the camera. Light that does pass through the seed sample is diffused in all directions. A large part of the amount of hght is lost, but a part thereof will be detected within the limited aperture angle of the camera which is arranged at an angle to the light beam behind the sample. Hence, the camera only detects the light coming through the sample; this light has a mutually comparable and relatively slight intensity. The invention has the advantage that properties of entire seeds, with or without pre-treatment, can be rendered visible by image analysis, while the components of the measuring arrangement consist of relatively simple and inexpensive parts. In particular, properties relating to the internal condition can be determined, such as acrospiral length, water uptake, root length or steeliness, but external properties such as soundness, thickness or circumference can be determined thereby as well. In addition, this method provides the possibility of measuring several seeds at the same time, without shielding of the individual seeds. Also, samples having a strong light barrier, such as chaff with barley, hard-coated and strongly colored or dark seeds, can be measured directly as well. The method also offers possibilities of judging the vitality of plant seeds at an early stage of germinating whole seeds and of following the germinating process of seed. Also, with this method, the moisture content of seeds can be determined.

In particular, it is possible to distinguish between seeds that have taken up little water, and seeds that have taken up much water, and to analyze the water distribution in the grain. When an arrangement according to the invention is used in combination with a bandfilter for a wavelength in the range around 850 nm, the water uptake pattern can be rendered well- visible for gelatinized barley grains. This is partly due to the fact that at this wavelength, chaff has a high transmission and, accordingly, has a relatively low influence on the image formation. Here, after an image analysis, the camera recording of a whole barley grain is evaluated in respect of its degree of water uptake. From the data, the mean water uptake and the distribution per batch are calculated. With this evaluation, an accurate control of the steeping procedure in the malting process can be realized. The water uptake properties of a batch can also be analyzed for variety testing or breeding purposes. At other wavelengths in the range of 400-1200 nm, this water uptake pattern can become visible as well, but in that case, the quality of the recording is less. The invention enables distinguishing between germinating and nongerminated seeds, because the roots are much more translucent than the seed. Thus, the homogeneity and rate of root development of germinating batches can be determined. This is an indication of the vitality of the seed. For barley, a maximum contrast is achieved with light of a wavelength around 450 nm, or 850 nm. The arrangement according to the invention further offers the possibility of determining properties such as acrospiral length and steeliness of plant seed. For barley, this can be achieved with light of a wavelength of around 600 nm.

Further advantages and particulars will become clear from a description with reference to the drawing, wherein: Fig. 1 shows an arrangement for a measurement in transmission; and Fig. 2 shows an arrangement according to the invention. In Fig. 1, reference numeral 1 designates a light source, for instance a halogen lamp; above this light source, a diffuser (2) of, for instance, teflon or milk glass may be provided. A transparent support (3), such as, for instance, a Petri dish, holds the sample (4). The sample is shielded with a mask (5). A filter (6) is positioned in front of an optic (7) such as a macro lens or an enlargement objective, for filtering out a particular wavelength. The arrangement is completed by a camera (8) positioned directly opposite the light source, with the sample to be analyzed disposed therebetween. In the arrangement, use is made of a strong light source with light from a wide-band spectrum and a camera having a high amplification and sensitivity. Thus, acceptable resolutions can be achieved if the sample is shielded to prevent the perception of diffused light and direct light which has not passed through the sample.

Fig. 2 shows an arrangement for a method according to the invention. This arrangement consists of a perfectly light-shielding box (not shown). In the box, a light source (1) is provided on one side. In a practical arrangement, this light source may be a Xenon light source, with an associated power supply, with or without a net voltage filter, providing the Xenon light source with a constant voltage. The light source may also be, for instance, a laser. The light of the light source is directed in a straight parallel beam (3) by an optic (2) of lenses. Positioned on the other side of the box is a camera (5), behind a holder for the sample of the barley grains (4), at a small angle outside the light beam, so that the sample (4) is positioned in the light beam (3) that goes straight on. The camera (5), having a sensitivity in the range of the wavelength emitted by the light source, is disposed adjacent this beam at an angle, so that the light passing under and above the sample is not detected. Due to the diffusion at the sample (4), light which actually passes on or through the sample is emitted in all directions. A substantial part of the amount of light is lost, but a part thereof is detected within the limited aperture angle of the camera as diffusion beam (6). This light has a mutually comparable and relatively slight intensity, so that it is not necessary to operate with a shielding mask, and a much larger sensitivity can be achieved. Hereinbelow, an example of a method according to the invention will be described, wherein in a simple manner, the water uptake behavior of the endosperm of barley grains can be determined.

For that purpose, barley is cultured according to a specific, fixed protocol, which boils down to swelling the seed in a fast and controlled manner, by alternately steeping it wet for a number of hours (steeping in) and subsequently causing it to rest dry again (steeping out), up to a total steeping period of about 30 hours.

From this, a fixed amount (about 30 g) is prepared as sample for recording according to the invention, by gelatinizing the seeds, with gelatinization of the portion of the endosperm of the seeds which has taken up water. This can be effected by boiling the seeds briefly (about 30 sec), subsequently cooling them strongly in ice water (about 30 sec), followed by immersing them in 70% EtOH for about 30 sec, whereby the water is driven off through a fast-evaporating component, and subsequently drying them in a strongly standardized air flow for 5 minutes.

A number of barley grains (max. 50) are subsequently placed in a Petri dish as samples; this can be carried out manually or by a special instrument rendered suitable for that purpose. The orientation of the seeds is of minor importance. The optical measuring arrangement consists of an arrangement according to Fig. 2.

The camera only detects the diffused light through the absorption and diffusing characteristics of the arranged preparation (the gelatinized barley seeds), against a black background. To enable arranging the seeds horizontally in the Petri dish, the light of the light beam is bent vertically upwards through an angle of 90° (not shown). -Arranged directly in front of the camera is one of the filters that can be used for this application, for instance a bandfilter of the type B850, for transmitting light of a wavelength of 850 nm ± 20 nm. The diaphragm and the enlargement can be set separately at the camera. The camera according to this exemplary embodiment is a CCD camera MX-5 with a macro-objective, a focal distance of 25 cm and a setting diaphragm having a maximum diameter of 8.5 cm.

The signal of the camera is converted into a digital image by means of a so-called "frame grabber". Next, the images are processed and analyzed with an image-processing program. The standard image size is 768 x 547 pixels, with 256 grey values. By selecting a proper threshold value in the grey values, a distinction can be made between the areas in the barley seeds where water uptake has taken place, and areas where water uptake has not taken place. In this manner, the water uptake pattern can be rendered properly visible. Next, an example of a method according to the invention will be described wherein the acrospiral length of barley grains can be determined in a simple manner. To that end, a number of barley grains are placed as samples in a Petri dish, like in the above-described example; the optical measuring arrangement again consists of an arrangement according to Fig. 2. Provided directly in front of the same camera as described earlier is a smallbandfilter of the type B600, for transmitting light of a wavelength of 600 nm ± 20 nm.

From the digital recording thus obtained, the acrospiral length can be determined. For determining the root length, the same method for determining the acrospiral length can be followed; however, the smallbandfilter now consists of the type B450, for transmitting light of a wavelength of 450 nm ± 20 nm, or of the type B850, for transmitting light of a wavelength of 850 nm ± 20 nm.

It is further observed that the exemplary embodiment chosen does not limit the invention in any way to the arrangement described with reference to the drawing and the preparations mentioned. The arrangement may also be designed with another type of CCD camera and common objectives, and, of course in so far as it falls within the protective scope of the claims, the method and device described are suitable for measuring numerous other properties, such as acrospiral length, water uptake, root .. length or steeliness, but also other properties such as soundness, thickness or circumference of numerous preparations, such as cereals, rice or other plant seeds such as carrot, tomato, paprika or lettuce.

Claims

1. A method for determining properties of plant seeds, in particular properties concerning the internal condition of plant seeds, such as, for instance, water uptake, steeliness, acrospiral length and root length, wherein:

I. a sample of plant seed is positioned in the light of a substantially parallel light beam;

II. a camera captures the properties of the sample in a recording, by means of detection of diffused light passing through the sample and deflected at a particular angle to the beam, while the light of the beam that passes straight on along the sample is not detected; and III. the resulting recording of the camera is processed by means of image analysis, whereby the properties can be determined.

2. A method according to claim 1, characterized in that the sample is composed of several plant seeds.

3. A method according to claim 1 or 2, characterized in that the sample is composed of whole plant seeds.

4. A method according to any one of claims 1-3, characterized in that the plant seed comes from, inter alia, barley, oats, rye, rice, carrot, tomato, paprika or lettuce.

5. A method according to any one of the preceding claims, characterized in that the seeds have been gelatinized.

6. A method according to any one of the preceding claims, characterized in that for determining the water uptake, the wavelength of the light lies in a wavelength range of between 800 and 900 nm, preferably between 830 and 870 nm.

7. A method according to any one of claims 1-5, characterized in that for determining the acrospiral length, the wavelength of the light lies in a wavelength range of between 550 and 650 nm, preferably between 580 and 620 nm.

8. A method according to any one of claims 1-5, characterized in that for determining the root length, the wavelength of the light lies in a wavelength range of between 400 and 500 nm, preferably between 430 and 470 nm, or that the wavelength of the light lies in a wavelength range of between 800 and 900 nm, preferably between 830 and 870 nm.

9. A device for determining properties of plant seeds according to the method of any one of claims 1-8, comprising a light source generating a parallel light beam, a sample of plant seed positioned in the light of the light beam and a camera positioned on the side of the sample remote from the incident light, characterized in that the camera is positioned so that the diffused hght that passes through the sample and is deflected at a particular angle to the beam, is detected by the camera and that the light of the beam that passes straight on along the sample is not detected.

10. A device according to claim 9, characterized in that additional provisions are present to prevent the light which passes straight on along the sample from wholly or partially illuminating as yet the side of the sample that faces the camera.