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 Consults SEED News - nov/dec 2003
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This section is coordinated by the professors from the Federal University of Pelotas -
www.ufpelsementes.com.br
Send your question to e-mail: silmar@seednews.inf.br
Would it be possible to explain why soybean seed when planted in the afternoon, in case it receives a strong rain at night, doesn't emerge?
Soybean seed, when put in the soil, possesses around 12% moisture content and with four or five hours of imbibition, it will increase to 16-18%. Therefore, in case it is exposed to a strong rain, the absorption of water will be very intense, damaging the internal membranes of the seed, which provokes leaching of essential materials to germination and emergence. Soybean seed protected with hydrophobic product prevents leaching damage by slowing down the process, which gives time for the membranes to organize themselves.
I have curiosity in knowing the reason for which popcorn explodes and the corn doesn't?
Actually, both corn and popcorn explode. What happens is that popcorn, due to its composition of starch, possesses a larger expansion capacity, provoking a really big explosion. Yet about materials that explode, there is a moisture determinator for rice that is called "popcorn maker" because some rice seeds when exposed to high temperatures also explode.
I have observed that corn that come from the field, is already affected by weevils attack and some seeds are deteriorated. How can I solve that?
Corn reaches physiologic maturity with 35% moisture content, and in order to be dried until 13%, it takes an average of 45 days. Therefore, it is normal to detect the low quality of corn when dried in the field until the13% referred. The solution is to harvest the corn in the ear when it has about 30-35% moisture and to dry it in the sun or using an artificial dryer. It is possible to detect when corn had reached the physiologic maturity point by checking the black layer in the extremity of the seed.
Please, comment about the reasons of the use of brachiaria (forage) seed with 40% purity, since there are seeds with purity above 99%?
The main reason of finding in the market seeds with low purity is due to the fact that consumers are not aware of the value of a high quality seed. And, as always it is possible to lower the price of a product lowering its quality, with the brachiaria happens the same.
They are offering me sorghum seeds that have been stored since last season. What precaution should I take?
Sorghum seeds possess high storage potential. In case they have high quality and are stored appropriately (low temperature and moisture), they can have quality after 18 months of storage. It's suggested to make a germination test moments before planting and, if possible, also a field emergence test.
I would like to know how long a soybean seed could remain in a dry soil before losing its emergence capacity.
First of all, in case the soil doesn't have moisture, it is not advisable to plant. However, it is known that a soybean seed treated with fungicide can stay up to five days in a very dry soil, waiting the right moment to germinate and to emerge.
I understood that the insect attack in soybean seed production is more harmful in the final phase of the maturation. Could you comment on it?
The insect attack in the initial phases of the seed formation will make the seed remain small and deformed, being relatively easier to separate it from the others in the conditioning process. On the other hand, insect attack in the final phase of maturation practically won't alter the size and the form of the seed, being very difficult to separate that material in the conditioning machines. So, it is advisable to control the insect in the field.
What calculation is used to determine the seed multiplication index for soybean, for instance, from the basic class to the certified one?
In normal circumstances, for a cultivar that it is already in the market for some time, the calculation is 1:20, in other words, for each kilogram of planted seed it is used 20 kilograms of seed to be commercialized. Actually, the multiplication index is larger, but with the losses in the field, the conditioning and in the handling, the index turns out to be relatively low. Seed producers that are able to get index higher than 1:20 obtain larger benefits.
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