Process for bringing pregerminated seed in a sowable and for some time storable form, as well as pilled pregerminated seeds

The present invention relates to a process for bringing pregerminated seed n a sowable and for some time storable form. The invention further relates to pilled pregerminated seeds. According to the invention the pregerminated seed is pilled, whereas in the pilling mixture at least one compound which slows down the germinating process is included under formation of a moist pill in which a suitable micro-climate is secured until the time of sowing. This required micro-climate inside the moist pill is obtained by addition of compounds which have a retarding action to the germinating process, such as compounds having an osmotic effect, e.g. water soluble sugars and their derivatives, salts, or glycols and their polymers; or having a growth retarding action, e.g. absicine acid.

The present invention relates to a process for bringing pregerminated seed 
in a sowable and for some time storable form. The invention further 
relates to pilled pregerminated seeds. 
Such a process has already from early times been applied in agriculture and 
horticulture by the farmer who for obtaining a better and quicker 
germination soaks the seed in advance and admixes the presoaked seed with 
wet sand in order to be able to divide it better over the land. 
Nowadays slowly germinating seed varieties are often pregerminated besides 
the presoaking, whereby the growing process of the germ root is already 
started before the seed is sown. Hereby a still quicker emergence of the 
sowing-seed and together with it a smaller risk of damage by diseases, 
pests or weather conditions is attained. 
Recently in the United Kingdom the so-called "fluid drilling" technique has 
been developed for sowing such pregerminated seed having a visible germ 
root of about 2 mm. As described in an article by P.J. Salter in 
Horticulture Industry. March 1976, page 178-179, this pregerminated seed 
can readily be handled in water deposits the fragility of the germ root. 
After addition of a gel forming component the mixture of pregerminated 
seed and jelly may by means of a specially for this purpose developed 
machine through trunk-shaped conduits be sown in regular rows in which 
however the plants emerge at random interdistances. The jelly-like mass of 
pregerminated seed is however not suitable for application in the existing 
precision-sowing-machines by which individual seeds are brought in the 
soil with constant interdistances at the place at which also the later 
plant is desired. For the seeds which may be used in a 
precision-sowing-machine should have such a form that they may be put one 
by one in the soil either mechanically or pneumatically. 
Since for many plant varieties, such as for example celery and lettuce, a 
uniform interdistance is desirable, and the user has anyway already the 
standard precision-sowing-machine to his disposal for sowing quickly 
germinating seed varieties, a great need exists in the practice for the 
possibility of precision sowing pregerminated seed too. Moreover the 
aforementioned process has also the disadvantage that in a liquid medium 
the pregerminated seed may only be stored up to 14 days at a temperature 
of 0.degree.-1.degree. C. and that for that reason in fact the user 
himself will have to pregerminate the seed shortly before sowing. 
The invention aims to provide a process by which the disadvantages 
mentioned are eliminated in an effective manner. 
Therefore the process according to the invention is characterized in that 
the pregerminated seed is pilled, whereas in the pilling mixture at least 
one compound which slows down the germinating process is included under 
formation of a moist pill in which is suitable micro-climate is secured 
until the time of sowing. 
Surprisingly it appeared that the moist pills according to the invention 
are well sowable with the conventional precision-sowing-machines for dry 
seed or dry pills, whereas also after longer periods of storage of the 
moist pills an excellent emergence percentage of the sowing-seed was 
obtained. 
Although the pregerminated seed is only damaged in a slight degree at the 
application of the coating, it is preferred that the pregerminated seed is 
pilled before the germ root has broken through the seed-coat, in order to 
eliminate any chance that the vulnerable germ root can break. Such 
pregerminated seed in which the germ root is not yet visible, germinates 
quicker, better and more uniformly than normal, non-pregerminated seed, 
for instance: 
celery: 5-7 days quicker than normal, 
leek: 3-5 days quicker than normal, 
tomato: 2-3 days quicker than normal. 
The speed of germination is dependent of batch and variety, but also of the 
conditions at which germination takes place. As the conditions are more 
unfavourable, as when sowing on the outside land, the differences in speed 
between pregerminated and non-pregerminated seed are larger. 
Since the growing process of the new plant has already irreversibly been 
started in pregerminated seed, the micro-climate to be established inside 
the formed pill is of vital importance for the surviving chances of the 
germinating seed and for the emergence percentage upon later sowing. On 
the one hand the germ may not die off, but on the other the growth must be 
slowed down to such an extent that the germ root will not burst from the 
pill already before sowing and be damaged in the precision-sowing-machine. 
From the following table representing the percentage of visible germination 
in a certain time it appears that such a micro-climate is absent in dry 
pills prepared in a manner usual for non-pregerminated seeds. 
TABLE 
______________________________________ 
Celery Tall Utah 
52- 70 R Improved 
Leek Kilima 
______________________________________ 
germinating method: 
20 .degree. C., light, 
15 .degree. C., light 
filter paper filter paper 
non-pregerminated 
91% in 9 days 95% in 6 days 
seed: 
pregerminated seed: 
98% in 3 days 97% in 4 days 
pregerminated seed + 
95% in 3 days 97% in 4 days. 
normally pilled: 
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From this table it appears clearly that the conventional coating has no 
retarding influence on the germination of the seed which brings the 
disadvantage that the pilled seeds obtained in this way already sprout and 
break the pill, before sowing could have taken place. 
According to the invention the required micro-climate inside the moist pill 
is obtained by addition of compounds which have a retarding action to the 
germinating process, such as compounds having an osmotic and/or growth 
retarding action. Particularly suitable compounds having an osmotic action 
are water soluble sugars and their derivatives, salts and glycols and 
their polymers. Preferably a solution of sodium chloride having a strength 
of 0.001-1M is used. As compound having growth retarding action for 
obtaining the desired micro-climate absicine acid is preferred in a 
concentration of 10.sup.-6 -10.sup.-4 M. 
The micro-climate inside the moist pill thus obtained is maintained 
according to the invention by storing the pills at a temperature of 
0.degree.-10.degree. C. and/or under an adapted atmosphere, for example 
under reduced pressure, until the moment of sowing. In this way the seeds 
in pilled form are storable for 2-5 weeks, what is long enough to 
distribute the pills from a central point to the users. 
For an optimal sowability according to the invention the moist pills 
preferably are finished with a smooth mineral compound, preferably with 
talc. 
The pregerminated seed pilled to moist pills according to the invention 
gives also for slowly germinating seed varieties a quick emergence, a high 
emergence percentage and a uniform distribution of the emerging vegetation 
over the land to be cultivated.

The invention is further illustrated by the following non-restrictive 
examples. 
EXAMPLE I 
Celery Tall Utah 52-70 R Improved 
An amount of 3000 g of pregerminated seed, corresponding with about 1500 g 
of dry seed, was coated in a conventional pilling kettle (diameter: 1000 
mm, rotation speed: 22 rotations per minute) with a coating mixture 
according to the Netherlands Patent Specification No. 74,911. In order to 
raise the osmotic value the mixture was sprayed with a 0.2M aqueous 
solution of sodium chloride during the process. Per 3000 g pregerminated 
seed 18-43 kg of the coating mixture and about 2.5 l of the salt solution 
was used for pills of 2-2.5 mm depending of the fineness of the seed. 
After the pills had attained the desired size, they were coated with an 
amount of talc equal to 1.6 times the weight of the pregerminated seed. At 
the end of the pilling process the pills were sieved on 2-2.5 mm and 
further stored at 5.degree. C. 
Weight of 1000 pills: 11-13 g 
Add on weight: 10-18 x 
Time of the pilling: 4 h 
The pilled pregerminated seed thus obtained was sown by means of a 
precision-sowing-machine on press pots in the green house at 18.degree. C. 
and after 10 days an emergence percentage of 97% was observed. When the 
pilled pregerminated seed had been stored before sowing during 20 days at 
5.degree. C. under vacuum, the emergence percentage was 96% 9 days after 
sowing. 
EXAMPLE II 
Leek Alaska 
An amount of 5000 g of pregerminated seed, corresponding to about 3000 g of 
dry seed, was coated in a conventional pilling kettle (diameter: 1000 mm, 
rotation speed: 22 rotations per minute) with a coating mixture according 
to the Netherlands Patent Specification No. 72,576. 
In order to increase the osmotic value a 0.3M aqueous solution of sodium 
chloride was sprayed. Per 5000 g pregerminated seed 32-38 kg of the 
coating mixture and 1-1.5 l of salt solution was used for pills of 3-3.5 
mm depending of the fineness of the seed. 
For finishing the pills 5000 g of mineral compound was used. At the end of 
the pilling process the pills were sieved on 3-3.5 mm, directly 
transferred to a sealed tin under reduced pressure and stored at 5.degree. 
C. 
Weight of 1000 pills: 40-45 g 
Add on weight: 8.5-10 x 
Time of the pilling: 2.5-3 h 
Emergence percentage at sowing in the green house on press pots: 98% after 
7 days 
Emergence percentage at sowing after intermediate storage during 17 days at 
5.degree. C.: 96% after 7 days 
EXAMPLE III 
The Examples I and II were repeated applying the coating mixture according 
to the Netherlands Patent Specification No. 139,091. 
Instead of the salt solution 0.5-1M solutions of sugar or 1-20% by weight 
solutions of glycol were used for increasing the osmotic value. The pills 
obtained showed properties comparable with those of the preceding 
examples. 
EXAMPLE IV 
The Examples I and II were repeated applying the coating material according 
to the Netherlands Patent Specification No. 139,091. Instead of the salt 
solution for increasing the osmotic value in this case 10.sup.-5 M 
absicine acid was used as compound having growth retarding action. The 
pills obtained showed properties comparable with those of the preceding 
examples.