SEED COATED WITH THIN LAYER HAVING PIGMENT

Abstract: A coated seed for use in agriculture, afforestation, and re-vegetation is provided. The coated seed (10) includes a seed (12) such as positive photoblastic seed and a thin layer (16) coated on the seed. The thin layer (16) further includes a pigment (14) which selectively allows light rays having wavelengths of about 570 to about 700 nm to pass therethrough. In another aspect of the invention, the thin layer includes a pigment which selectively reflects light rays having wavelengths of about 420 to about 520 nm.

Description: D E S C R I P T I O N SEED COATED WITH THIN LAYER HAVING PIGMENT FIELD OF THE INVENTION The present invention relates to a seed, in particular positive photoblastic seed, coated with pigment, for preferably use in agriculture, afforestation, and re- vegetation. BACKGROUND OF THE INVENTION Typically, seeds primarily for use in agriculture, afforestation and re-vegetation are provided for a cultivated soil such as ploughing and mounding of upland fields. Such seeds are significantly affected by a lightness of the environment and therefore classified into seeds which tend to bud in light and the seeds which tend to bud in the dark (hereinafter referred to as "positive photoblastic seeds" and "negative photoblastic seeds", respectively) . Generally, there are far more positive photoblastic seeds than negative photoblastic seeds. In the meantime, most of weed seeds are positive photoblastic seeds, and the weed seeds having been in the soil are sometimes moved upward to a surface of the soil as it is ploughed, so that they are stimulated to bud earlier than the seeds of crops and then run wild. Also, soil treatment type herbicides applied to the soil before sowing seeds in the soil may cause environmental problems . Further, light rays having wavelengths of about 420 to about 520 nm may inhibit some positive photoblastic seeds from being budding. Furthermore, a thick soil cover or sprayed adhesive materials by hydroseeding may prevent light from reaching the underlying positive photoblastic seeds from budding. SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems, a first embodiment of a coated seed according to the present invention is a positive photoblastic seed coated with a thin layer having a pigment which allows light rays having wavelengths of about 570 to about 700 nm to transmit therethrough, which accelerates budding of the positive photoblastic seed. Also, a second embodiment of a coated seed of the present invention is a positive photoblastic seed coated with a thin layer having a pigment which reflects light rays having wavelengths of about 420 to about 520 nm that inhibit the budding of the positive photoblastic seed. Preferably, the thin layer may include nitric acid compounds. With the first embodiment, the coated seed effectively absorbs the light rays having wavelength of about 570 to about 700 nm and then buds quickly. On the other hand, with the second embodiment, the coated seed reflects the light rays having wavelengths of about 420 to about 520 nm, which eliminates factors hindering the budding of the seed. Therefore, due to the thin layers, the coated seeds of the present invention overcome weeds and bud before the weed seeds germinate. This results in that the application of the soil treating agents becomes unnecessary, so that there is no danger of polluting the environment by the soil treating agents. Furthermore, the positive photoblastic seed coated with a thin layer containing a nitric acid compound can be accelerated in budding even in the dark, and therefore, such a seed can quickly bud even under a soil cover and sprayed adhesive and fibrous materials. BRIEF DESCRPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of a coated seed according to the present invention. PREFEERED EMBODIMENTS OF THE INVENTION Referring to the accompanying drawing, embodiments of the present invention will be described hereinafter. Fig. 1 illustrates a coated seed generally indicated by reference numeral (10). The coated seed (10) includes a seed (12) which is coated on its whole outer surface with a thin layer (16) having a pigment (14). The seed (12) used in the coated seed (10) is a positive photoblastic seed which tends to bud in light. Examples of the positive photoblastic seed include Poa pratensis, Poa nemoralis and the like for use as pasture grass and lawn. Crops of positive photoblastic seeds are, for example, Nicotiana tabacum, Petroselinum crispum, Lactuca sativa and the like. Trees of positive photoblastic seeds are, for example, a family of Alnus spp. including Alnus fir a and Pinus Virginia. It has been known in the art that budding of the positive photoblastic seeds are accelerated by, generally, visible light rays having wavelengths of about 570 to about 700 nm, particularly, red light rays having wavelengths of about 610 to about 700 nm. For example, the seed of Pinus Virginia does not tend to bud in the dark, but it is stimulated to bud when irradiated with red light rays. The budding of the seed of Lactuca sativa is accelerated by light rays having wavelengths of about 640 to about 670 nm. As mentioned above, although the wavelengths of light rays effective to the budding of the seeds vary depending on seeds, most of the seeds are o accelerated in budding by light rays having wavelengths of about 570 to about 700 nm. Accordingly, in the first embodiment of the present invention, the thin layer (16) coating the positive photoblastic seed (12) includes a pigment (14) which transmits light rays having wavelengths of about 570 to about 700 nm. Due to this, the positive photoblastic seed ( 12 ) quickly buds when it would receive light rays having wavelengths of about 570 to about 700 nm. Some positive photoblastic seeds, however, are inhibited from budding when they absorb light rays having specified wavelengths. For example, the seed of Lactuca sativa is inhibited from budding by light rays of blue- green, blue and blue-purple having wavelengths of about 420 to about 520 nm. Further, the seeds of the Alnus spp. family never bud when they would receive light rays of green and blue as in the dark. To cope with this, the coated seeds in the second embodiment of the present invention employ specific positive photoblastic seeds (12) which are inhibited from budding by light rays having wavelengths of about 420 to about 520 nm (for example, the seeds of Lactuca sativa and the Alnus spp. family as listed above) . The thin layers (16) coating such positive photoblastic seeds (12) include pigments (14) which reflect the budding inhibiting light rays having wavelengths of about 420 to about 520 nm. In this instance, the light rays having wavelengths of about 420 to about 520 nm are effectively reflected by the pigments (14) and do not reach the seeds (12), so that the seeds ( 12 ) are not inhibited from budding by such light rays. The coating of the seeds is not limited to a specific coating technique, and various known coating techniques disclosed in, for example, U.S.P No.5,443,637 may be utilized in applying the pigments (14) to the seeds. It should be noted that the thin layer (16) may include not only the pigments (14) but also other components. For example, the thin layer (16) may have a nitric acid compound such as potassium nitride (KN0 3 ), ammonium nitride (NH 4 N0 3 ) or the like for use in compensating for the loss of proteins in the seed under the light irradiating conditions. In this instance, the budding of the positive photoblastic seed is further accelerated. That is, even under a thick soil cover or sprayed adhesive and fibrous materials (under a dark condition), the budding is accelerated with an aid of the nitric acid compound analogous to that of a plant hormone. The thin layer (16) may include other material for accelerating the growth of the seed plants. For example, when using leguminosae seeds, it is preferable for the layer to include leguminous bacteria, Rhyzobium spp. The thin layer (16) may further contain a fertilizer suitable for the growth of each of the plants. EXPERIMETNS Two kinds of positive photoblastic seeds (white clover and tall fescue) were coated with layers having pigments which reflect red, blue and green light rays, respectively, and their budding was observed. The experiment for budding each seed was conducted three times. In each experiment, a Petri dish having a diameter of 15 cm and a depth of 55 mm was filled with a certain amount of distilled water and then with soil. After that, 100 seeds were planted per dish and allowed to bud under the following ambient conditions: the atmospheric temperature was maintained at 25°C in the daytime and 20°C in the nighttime, and the illuminance was maintained at 2,500 lux in the daytime. After fourteen days had passed since the planting, the number of buds in each dish was counted. As the pigments which reflect red, blue and green light rays (pigments R, B and G) , the following were mainly used. Pigment R = C. I. Pigment Red 57.1 Pigment B = Acid Blue 9 Pigment G = a mixture of Acid Blue 9 and Acid Yellow 23 The budding ratio of each seed is shown in the following table: BUDDING RATIO (%) PIGMENT AFTER 14 DAYS (REFLECTING WAVELENGTH) WHITE TALL CLOVER FESCUE R(app. 600 to app. 700nm) 34.67 85.67 B(app. 400 to app. 500nm) 52.67 86.00 G(app. 500 to app. 570nm) 79.67 87.33 As can be seen from the above table, different budding ratios resulted from the application of the pigments which reflect light rays having different wavelengths. The budding ratios of the seeds coated with the layers having pigment R which is shielded from (or reflects) the budding accelerating light rays for positive photoblastic seeds were the lowest in both cases of white clover and tall fescue, as compared with those of seeds coated with the layers containing pigments B and G which transmit the budding accelerating light rays. The same tendency was observed in the seeds enveloped with caryopsis like the seed of tall fescue as that of the seed without caryopsis (the seed of white clover) . As described above, the seeds coated with thin layers containing pigments which transmit light rays having wavelengths of about 570 to about 700 nm, once planted in the soil, efficiently absorb light rays within the above range from the sun light to increase plant hormones and vitamin C, so that the growth of the radicles and plumules are accelerated. As a result, such seeds rapidly bud, and the plants growing from such seeds overcome weeds. On the other hand, the seeds coated with thin layers containing pigments which reflect light rays having wavelengths of about 420 to about 520 nm are shielded from (or reflect) the budding inhibiting light and also selectively absorb only the budding accelerating light, so that the budding of the seeds are further accelerated. Furthermore, the seeds coated with thin layers containing nitric acid compounds can compensate for the loss of proteins when budding, and therefore can be accelerated in their budding. Still furthermore, the seeds coated with the thin layers containing the nitric acid compounds can rapidly bud owing to the hormone-like actions even under the dark condition when covered with the soil, and thus contribute to efficient achievement of the purpose of re- vegetation. The invention has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the sprit and scope of the invention.

Claims: C L A I M S 1. A coated seed for use in agriculture, afforestation, or re-vegetation, comprising: a seed; and a thin layer coated on said seed, said thin layer including a pigment which selectively allows light rays having wavelengths of about 570 to about 700 nm to pass therethrough. 2. A coated seed in accordance with claim 1, wherein said seed is a positive photoblastic seed. 3. A coated seed in accordance with claim 1, wherein said thin layer includes a nitric acid compound. 4. A coated seed for use in agriculture, afforestation, or re-vegetation, comprising: a seed; and a thin layer coated on said seed, said thin layer including a pigment which selectively reflects light rays having wavelengths of about 420 to about 520 nm. 5. A coated seed in accordance with claim 4, wherein said seed is a positive photoblastic seed. 6. A coated seed in accordance with claim 4, wherein said thin layer includes a nitric acid compound.

Inventors: NAKAGAWA TARO, SAOTOME ATUNOBU, YAMADA REN, NAKAGAWA, TARO, SAOTOME, ATUNOBU, YAMADA, REN
Applicants: NAKAGAWA TARO, RONTAI CO LTD, SAOTOME ATUNOBU, YAMADA REN, NAKAGAWA, TARO, RONTAI CO., LTD., SAOTOME, ATUNOBU, YAMADA, REN
Application year: 1999
Main classification: A01C1
IPC codes: A01C1