Fotoblastismo e temperaturas na germinação de sementes de celosias

Janine Farias Menegaes,Geovana Facco Barbieri,Rogério Antônio Bellé,Ubirajara Russi Nunes

doi:10.14295/oh.v24i4.1233

Janine Farias Menegaes, Geovana Facco Barbieri + Show 2 more

Open Access

https://doi.org/10.14295/oh.v24i4.1233

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Abstract

Germination is the result of the triggering of various processes occurred in the seed, which are influenced by the environmental conditions, especially light and temperature. In this way, the objective of the present study was to evaluate the influence of different temperatures and photoblastic on the germination of cockscomb seeds. The experiment was carried out in a completely randomizeddesign, with a 2 x 5 factorial scheme (two lighting regimes and five temperatures), with four replicates of 50 seeds, for two species of cockscomb (Celosia argentea L. and C. cristata L.). The lighting regimes were with absence (dark continuous) and the presence of light (photoperiod of 24 h), and temperatures were constant at 15, 20, 25, 30 and 35 ºC. The seed lots of the two species of cockscomb were cultivated in 2012 and stored in a cold chamber (15 ºC and 40% RH), with an average moisture content of 11% and a mean germination of 98%. The results of the laboratory tests indicated that the two species of cockscomb presented fast germination in average 2.5 and 4.5 days for the regimes with presence and absence of illumination, respectively, characterizing as neutral photoblastic species. However, it was observed that the temperature is a limiting factor for the germination of the two species of cockscomb, having its optimal thermal range between 20 and 30 ºC.

Highlights

The species from Amaranthaceae family stands out by the exoticism of its inflorescences and the great seeds production per plant, on average of 1,580 kg ha-1 (BELLÉ and SPANNENBERG, 1997)
The germination is considered a critical phase because it is regulated by physiological processes of seed, besides the environmental conditions, and in relation to the extrinsic factors, each vegetal species requires certain conditions regarding the adequate supply of water, oxygen, temperature, light and depth of seeding for occurrence of germination (MONDO et al, 2010; MARCOS FILHO, 2015)
In relation to the germination of normal seedlings carried out on the 14th days after sowing (DAS), we verified that for the two lighting regimes, germinative percentage was above 70% for the temperatures of 20, 25 and 30 oC, demonstrating elevated physiological potential of these seeds (Table 1)

Summary

Introduction

The species from Amaranthaceae family stands out by the exoticism of its inflorescences and the great seeds production per plant, on average of 1,580 kg ha-1 (BELLÉ and SPANNENBERG, 1997). The two species of cockscomb (Celosia argentea L. and Celosia cristata L.), originating in Asia, have erect size and little branched, from 30 to 90 cm of height, green leaves and slightly reddish, ornamental inflorescences of several colors, among red, yellow and white (LORENZI, 2013). Their inflorescences, of summer cultivation in Rio Grande do Sul, are produced from seeds, which have their physiological and sanitary qualities affected by the adopted management, mainly, in germination (FERREIRA et al, 2012). Among the environmental factors determined for the germination the temperature and light deserve highlight (CARVALHO and NAKAGAWA, 2000; MARCOS FILHO, 2015)

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