Qualidade fisiológica e resistência do recobrimento de sementes de milho

Abstract

Este trabalho foi desenvolvido com o objetivo de avaliar a qualidade fisiológica de sementes de milho UENF 506-8 recobertas e a resistência do recobrimento utilizando diferentes proporções de cimentante. Foi utilizada no recobrimento das sementes uma mistura de calcário e meio de cultura. Como cimentante foi utilizada cola a base de acetato de polivinila (PVA). O recobrimento das sementes de milho foi realizado com uma mistura de 70% (p/p) de calcário, 10% (p/p) de meio de cultura semi-sólido JNFb e 20% (p/p) de água. Foram adicionadas a essa mistura diferentes proporções de cimentante: 0,5; 1; 2; 3; 4 e 5 % (p/p). Para avaliação da resistência do recobrimento foi simulado o transporte e a semeadura manual, e a semeadura mecânica das sementes recobertas. A avaliação da qualidade fisiológica das sementes foi realizada em sementes nuas (controle) e sementes recobertas com as proporções de cimentante: 0,5; 1; 2; 3; 4 e 5 %. O aumento da proporção de cimentante de 2 para 3% causou uma pequena redução na velocidade da germinação, na velocidade de emergência e na emergência, mas não afetou o número final de plântulas normais no teste de germinação e teste frio. Para a semeadura manual recomenda-se a utilização de 2% de cimentante e para a semeadura mecanizada 4 % de cimentante.

Physiological potential of stylosanthes cv. Campo Grande seeds coated with different materials

“…The assessments were performed at 4 and 10 days after the start of the test (first count (FCG) and final germination (G), respectively), computing the number of normal seedlings, abnormal seedlings (AS) and non-germinated seeds (NGS), according to the criteria established by Brasil (2009), and the results expressed as a percentage. Throughout the test, daily counts were performed to determine the germination speed index (GSI) by the formula proposed by Maguire (1962) and the mean germination time (MGT), according to Edmond and Drapala (1958).…”

“…Daily counts of the number of emerged plants were held for a period of 30 days. At the end, were determined the percentage of emergence (E), the emergence speed index (ESI), according to a formula by Maguire (1962), and the mean emergence time (MET), according to an adaptation by Edmond and Drapala (1958). At the end of 30 days, the plants were carefully removed from the trays and had their roots properly washed for measuring shoot length (SL) and root length (RL).…”

“…While improving the morphological characteristics of the seeds, the main obstacle to the use of coated seed is the delayed germination and emergence. Several studies indicate the occurrence of this delay in relation to uncoated seeds, as noted in coated seeds of lettuce (Silva et al, 2002), bell pepper (Oliveira et al, 2003a, supersweet maize (Mendonça et al, 2007), maize (Conceição and Vieira, 2008) and carrot (Nascimento et al, 2009). This delay is due to the arrangement of fine particles and the filling of the pores of the pellet by the cementing agent and water supplied during the procedure, which forms a barrier to the gaseous exchange between the seed and the environment external to the pellet (Silva and Nakagawa, 1998a).…”

“…(cultivated variety or cultivar) Campo Grande is a fodder Fabaceae, launched by EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária; Brazilian Corporation of Agricultural Research) in 2007, comprising the physical mixture of improved seeds of Stylosanthes capitata and Stylosanthes macrocephala, at the ratio of 80% e 20%, respectively (EMBRAPA Gado de Corte, 2007), and it is promising in providing good quality fodder. This legume is further characterized by having very small seeds (350-400 seeds/g) (EMBRAPA Gado de Corte, 2007), with color ranging from red to brown and black, features that hinder both its tillage as its sowing. In this context, the use of technologies such as coating the seeds, contributes to the solution of problems related to the size and shape of seeds, as it standardizes the seed size and shape, facilitating its distribution, whether manual or mechanical, providing greater precision in sowing Nascimento et al, 2009).…”

Germinative potential of encrusted seed of tropical forage species

“…Results have showed that, for corn and lettuce crop, variations in coating composition and thickness alter emergence speed index, and it is associated to the development of a physical barrier on the outside of seed making the direct absorption of water and oxygen difficult (CONCEIÇÃO & VIEIRA, 2008). That pre-treatment of seeds through scarification and film coating may restrict moistening seeds of B. brizantha cv.…”