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 Enquiries SEED News - nov/dec 2006
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This section is coordinated by the professors from the Federal University of Pelotas-Brazil, with the objective of answering the inquiries sent by the readers.
Send your question to e-mail: silmar@seednews.inf.br
The other day I heard someone saying that the State of Rio Grande do Sul - Brazil has only 70% of the seed demand for the soy crop year of 2006/07. In this direction, I would like to know what is meant by seed demand?
In the State of Rio Grande do Sul some four million ha are sown with soybean, which, considering a sowing density of 60kg/ha, is equivalent to a potential demand of 240.000t of soybean seeds. However, there is a percentage of farmers who use their own seeds (farm saved seeds). In the case of RS, in the last 20 years, the maximum value was of 5%. This percentage, for seeds of self pollinated varieties, as soybean, wheat and rice, is normal, therefore for tradition or other factors, some farmers use their saved seeds. Thus, in order to have the right quantity of seed to be produced we must consider the sowing density and the commercial seed usage, so in our case it would be of 65% (100-35) on the maximum, or 156,000 t of seeds. Summarizing, the state of the RS possesses enough seed to take care of the real demand of soybean seeds for the crop year 2006/07.
Please, could you comment on some tips as to minimize mechanical damage on soybean seeds. Last year many seed lots were lost after some months of storage and, as someone told me, one of the causes could be mechanical damage.
All seed possess three essential parts: the embryo, to originate the new plant, one part as reserve for feeding, and the physical protection, ordinary known as seed coat. Any part that does not function will cause serious problems to the seed. In the case of mechanical damage, the natural protection of the seeds is lost and, depending on the degree, the seed can die immediately or speed up the deterioration process, in such a way that in a few weeks it will lose its capacity to originate a new plant. In your case, it was probably the latter.
I have harvested soybean seeds with temperatures higher than 30oC and this is causing me concern. I know that temperature is one of the factors that affect the physiological quality of seeds. I would like to know what can be done to minimize the negative effect of high temperatures on seeds.
The high temperature is, really, one of the main factors that affect the physiological quality of the seeds, and in accordance with a practical rule, for each 5oC increases in temperature, seed storage potential is reduced by 50%. As the soy seeds possess a low storage potential (eight months under conventional storage conditions), we must reduce the temperature of the seed mass as fast as possible. That, in your case, must be carried out no later than one week post harvest.
Seed piracy is a global concern that causes extended damage to the seed business. Could you please comment on the main problems?
In fact, piracy is global and we have to use all tools to minimize it. The main problem is that it directly affects breeding programs to obtain and develop new and better varieties. As it is known since the time of our grandfathers, the success of a crop is centered in the use of suitable varieties. Many other inconveniences could be cited, as lack of quality guarantee of the seeds and dissemination of plagues.
The seed production fields of our company are more than 100 km from the Seed Conditioning Unit (SCU), and this year we harvested wheat seed with high moisture content and seems that some loads over heated. Would it be possible to have a comment on it?
Seed with high moisture must be dried as fast as possible. In the case of wheat with 18% of moisture, the drying process must begin in a 24-hour period. In your case some seed were warm, in wich case the seed moisture was probably higher than 15% and the drying process was delayed, caused by any factor and one of them could be the distance from production field to the SCU
Is it true that to possess a seed laboratory is not enough to start carrying out services to evaluate seed quality?
To have a physical structure and the minimum equipment to evaluate seed quality, is not enough to start to operate a seed laboratory. The laboratory also needs to be accredited by an agency or entity (like ISTA), to show its competence and the ability to adopt a recognized quality system.
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