Massa das sementes de Tecoma stans L. Juss. ex Kunth (Bignoniaceae): efeitos na emergência e desenvolvimento de suas plântulas no sol e na sombra

Abstract

The aim of this study was to evaluate the effect of Tecoma stans L. Juss. ex Kunth seeds mass on initial emergence, growth and, seedling development under different light conditions. The seeds were separated in four mass classes and sowed in four replicates of 24 seeds for each class, under full sun and canopy shade. Under sun environment was observed a greater percentage of emergence. Heavy seeds presented the greater percentage of emergence under both environments, but a greater rate was observed under canopy shade. One month after the start of experiments, the seedlings at the shade environment presented 100% of mortality. The growth and development seedlings under full sun were noticed for five months. In this period, only in the first three months was possible to observe the effects of Tecoma stans seeds mass on capacity of seedlings to acquire dry mass. The seedlings biomass partitions were similar among the tested mass class. The seedlings of smaller mass tended to a high specific leaf area in relation to the seedlings from large seeds, mainly in the first three months, resulting in a great acquisition of dry mass by these seedlings. In the fourth month, the specific leaf area did not present any tendency. Because the biggest seeds to give rise seedlings with best initial development than smallest seeds can be considered as species reproductive strategy. To produce seeds of different sizes also can be considered as way of species to spread in many microhabitats. Resumo: Este estudo teve como objetivo avaliar o efeito da massa das sementes de Tecoma stans L. Juss. ex Kunth na emergência, no crescimento e no desenvolvimento inicial de suas plântulas sob diferentes condições de luminosidade. As sementes foram separadas em quatro classes de massa e semeadas em quatro réplicas de 24 sementes para cada classe, no sol e na sombra. No ambiente de sol ocorreu a maior porcentagem de emergência. Dentre as classes de massa, sementes maiores apresentaram maior porcentagem de emergência em ambos os ambientes, porém a maior velocidade foi observada na sombra. Após um mês do início do experimento as plântulas da sombra apresentaram 100% de mortalidade. O crescimento e desenvolvimento das plântulas no sol foram acompanhados mensalmente por um período de cinco meses. Neste período, foi possível observar os efeitos da massa das sementes de Tecoma stans no ganho de massa seca das plântulas nos três primeiros meses; a partir deste, a massa das sementes não teve efeito no ganho de matéria seca pelas plântulas. A partição da biomassa das plântulas não diferiu entre as classes de massa testadas. As plântulas de menor massa apresentaram uma tendência a uma maior área foliar específica em relação às plântulas originárias de sementes mais pesadas, principalmente nos três primeiros meses, resultando em um ganho maior de matéria seca das plântulas de menor classe de massa. Já no quarto mês, a área foliar específica não apresentou qualquer

The role of historical and ecological factors on initial survival of Copaifera langsdorffii Desf. (Fabaceae)

“…However, this pattern can be maintained until plant maturity or this initial size advantage of seedlings from large seeds may disappear with time (Cordazzo 2002;Socolowski et al 2011). In addition, the results of interaction between seed size and seedling development can also be affected by light intensity (Socolowski et al 2011), water stress (Kaydan & Yagmur 2008) & Bullock 2003). In general, the results of the present study reveal that Copaifera langsdorffii seedlings originating from larger seeds presented greater development of shoots and roots (only root length was unaffected by seed size).…”

Anti-oxidant activity of seedlings from rice seeds stored in different temperatures over 10 years

“…BRS Pelota demonstrated better response for seedlings from seeds stored at -15 and 18 ºC, which differed significantly from the storage at 1 ºC ( Table 2). Length evaluation takes into account the measurement of physical quantities, which is justified by the fact that seed lots with high germination percentage not always result in seedlings with higher growth, since these characteristics depend on the size of seeds, initial stage of cell division as well as constitution of reserve tissue of seeds (Vanzolini et al, 2007;Guedes et al, 2009;Socolowski et al, 2011) The dry matter of root (DMR) of the cultivar BRS Pelota was significantly higher only in the storage at -15 ºC. According to Patané et al (2006), depending on the storage conditions, seeds may undergo severe stress, leading to a fast uptake of their reserves just as the beginning of the germination process and a fast growth, fact that may explain the higher shoot length and root dry matter of seedlings of cv.…”

Weight is a key factor in the physiological quality of Parapiptadenia rigida seeds

“…Extensive natural variation within species is observed for this trait (Gnan et al, 2014). Studies conducted with Gmelina arborea (Owoh et al, 2011), Tecoma stans (Socolowski et al, 2011b), Pterocarpus marsupium (Mishra et al, 2014), Sapindus mukorossi (Attri et al, 2015) and Tamarindus indica (Ghaffaripour et al, 2017) showed a direct relationship between seed weight or size and seedling vigor. However this should not be considered as a rule, as germination and seedlings growth of Tectona grandis (Khera et al, 2004) and Schizolobium parahyba (Freire et al, 2015) were not affected by seed size.…”