This section is coordinated by the professors from the Federal University of Pelotas-Brazil, with the objective to answer the inquiries sent by the readers
know that seeds need special conditions to germinate, among them, is the appropriate moisture of the soil. In the last soybean sowing, I verified that, even with a relative moisture of 100%, and in spite of absorbing humidity, the seed didn't unchain the germination process. Could you explain what was happening?
Indeed, moisture is one of the essential conditions for the seed to germinate, and the quantity varies among soil types and seed species. For instance, the soybean seed needs to be with 50% of moisture to unchain the germination process. In your case, the soybean seeds must have entered in hygroscopic balance with moisture between 25 and 30%, therefore, way below the necessary for the germination process. For the seeds to reach the necessary moisture to germinate, they need water in liquid form, because only with the steam (the relative moisture indicates the steam saturation in the air) they don't reach the necessary level, and that is for all the species.
A ponta negra em sementes de milho indica maturidade Fisiológica
I liked the article about research, presented in the last edition of the SEEDnews magazine. In fact, the research requests, besides knowledge, creativity, perseverance, reliability, a lot of work and many times high financial resources. In this sense, I would like
to know, concisely, what is the work involved to know the corn seed moisture at the physiologic maturity point?
The physiologic maturity point of the seeds is the stage of maximum energy, viability and dry weight. To determine this point, cornears are marked so that they are at the same maturation point in the moment of harvest, which begins few days after the stigma (beard) changes of color and it is prolonged for a period of two months. Hereby, several harvests are accomplished with three to four replications an each period, and in each one is determined the energy, viability, dry matter and the moisture of the seeds. In the end, the moisture degree of the seed is related to the point of maxims, to be able to inform that the physiologic maturity point of the corn seed is when the moisture is 35%.
Hybrid seeds usually produce more than varieties, therefore why don't seed companies produce only this type of material, hereby would the farmers produce more in smaller area and would the piracy problem be minimized?
The well developed and adapted hybrids produce more and they possess a natural protection for piracy. However, in some species the cost to obtain a hybrid one is so high that it doesn't compensate its production. In corn, the process involves the castration, in that the feminine and masculine parts are in different points in the plant, so the work is relatively easy. But for other species, such as rice, the castration becomes unviable, requesting that one of the parts be male sterile, whose mechanism is very complex, depending on the environmental conditions for manifestation. In some vegetables, the hybrid is obtained by manual castration, burdening a lot the process, however the seeds are sold by unit, it could even reach US$0,50/unit.
I am in the grass seed business willing to offer to my customers a product of superior quality. With this goal at, I am planning to cover the seeds and to put them in a plastic package. Could you comment about it?
To offer high quality seeds is a strategy to obtain new customers and to satisfy the conquered ones. The coating with protectors, nutrients and facilitators for sowing is an excellent idea. There are companies of specialized coating in the process and with good products. In relation to the plastic package, you must be careful with the seed moisture. For storage of up to six months, the seed moisture should be inferior to 12%,insofar for one year it should be inferior to 11%.
I am technical responsible of a company that commercializes annually around of 6 000t of soybean seeds. This year we had a very big incidence of the Asian rust in our production fields, lowering a lot the income. I would like to know if the quality of the soybean seed will be affected by the attack of this disease.
On this agricultural year of 2003/04, the production of soybean seeds was affected or by the drought in one region area or by the rain in other areas, favoring the disease. The attack of the Asian rust reduces the production, because it affects the process of seed filling and, in more serious cases, because it kills the plant. The plant protects itself to perpetuate its species and, in case problems occur, some seeds will be normal and others in initial phase will be sacrificed. So, seed lots descendent of fields attacked by the rust will present more immature seeds that are easy to separate during conditioning. The disease is not transmitted by the seeds.