Métodos de colheita e qualidade das sementes de capim colonião cultivar Mombaça

Abstract

RESUMOA produção de sementes, em gramíneas forrageiras tropicais como o capim colonião (Panicum maximum Jacq.), apresenta particularidades capazes de interferir na pureza física e na germinação das sementes. Por conseqüência, o método de colheita pode influenciar diretamente na qualidade das sementes produzidas. Buscando estudar o assunto, a presente pesquisa utilizou sementes de P. maximum cultivar Mombaça, colhidas pelos métodos (tratamentos) do cacho, de varredura e mecanizado, as quais, previamente analisadas quanto à pureza física, foram armazenadas sob condições não controladas de laboratório durante 15 meses. A avaliação da qualidade fisiológica das sementes, realizada trimestralmente em seis épocas, constou da realização dos testes de germinação, de primeira contagem de germinação, de envelhecimento acelerado e de condutividade elétrica. Os resultados indicaram que há influência do método de colheita na qualidade das sementes; o método de varredura permite a obtenção de sementes que, embora de menor pureza física, apresentam maior qualidade fisiológica do que as provenientes dos métodos do cacho e mecânico.Palavras chave: métodos de colheita, qualidade fisiológica, vigor, dormência. ABSTRACT EFFECTS OF HARVESTING METHODS ON SEED QUALITY OF PANICUM MAXIMUM (JACQ.) CULTIVAR MOMBAÇAThe production of higher quality seeds of tropical forage grasses such as guinea grass (Panicum maximum Jacq.) presents some details that are able to influence on seed purity and germination. As a consequence, harvest time and method have a direct influence on seed quality. This research was carried out with the main objective of evaluating the quality of guinea grass seeds, cv Mombaça, harvested by three methods: a) hand cutting the panicles followed by curing on the ground for three to five days; b) hand collecting the shattered seeds from the ground and c) mechanical. Seeds obtained from each harvesting procedure, were first evaluated for physical purity and then stored under uncontrolled conditions during 15 months. Germination, vigor (first count, accelerated aging, electrical conductivity) were determined at three-month intervals during storage. Seeds collected from the ground, in spite of lower physical purity, exhibited superior physiological quality than those harvested by the other two methods.

Seed production of 'Mombasa' grass subjected to different closing cut dates and nitrogen rates

“…The CCDs with greater growth durations and higher N rates caused compensations in the PTN and pure seeds per panicle, benefiting PSY. It must be highlighted, according to Maschietto et al (2003), that the high abscission of M. maximus seed decreases the seed yield estimates and makes them more inaccurate. In the present work, the proportion of seed abscised from panicles was not assessed.…”

Processing in the Quality of Tanzania Grass Seeds

“…Furthermore, because they are not domesticated plants, the forage grass have uneven maturation of spikelets in the bunch and, at harvest, the lot is heterogeneous, consisting of seeds of different sizes, density, germination and vigor (MASCHIETTO et al, 2003;MENDONÇA et al, 2015). Therefore, several characteristics need to be improved in the processing method to address the needs of the domestic and international markets aimed at commercialization and sowing (MASCHIETTO et al, 2003;HESSEL et al, 2012;QUADROS et al, 2012).…”

“…Therefore, several characteristics need to be improved in the processing method to address the needs of the domestic and international markets aimed at commercialization and sowing (MASCHIETTO et al, 2003;HESSEL et al, 2012;QUADROS et al, 2012).…”

Evaluation the physiological quality of Brachiaria brizantha cv. BRS ‘Piatã’ seeds

“…Although B. brizantha seeds are sometimes dormant (BRASIL, 2009) this has not been observed nowadays in commercial lots of seeds of this species, this being probably due to the fact that the harvested seeds are those which have naturally fallen from the plant and are swept to 575 Evaluation the physiological… SILVA, G. Z. et al be collected, or, in other words, only the physiologically mature seeds are harvested, that is, the seeds which have had the time to complete the maturation process (MASCHIETTO et al, 2003;GASPAR-OLIVEIRA et al, 2008;TOMAZ et al, 2015). Seedling emergence in the field data were used as a reference for the selection of the vigor tests.…”

“…The inefficiency of the electrical conductivity test is probably related to the seed harvesting method (seeds after naturally falling onto the ground are swept and gathered with the help of a broom) (MASCHIETTO et al, 2003) -the contact between the seeds and materials such as soil, fertilizers residues, and organic matter is likely to impregnate them with substances capable of interfering in the electrical conductivity test results.…”