Abstract
Abstract Seminiferous propagation of Dietes bicolor is hindered by the probable physical and/or morphophysiological dormancy. The objective was to analyze the efficacy of different methods of overcoming dormancy in D. bicolor seeds to determine a possible pre-germination treatment for the species. Two experiments were conducted: (I) Evaluation of the breaking of physical dormancy, in which the treatments of mechanical scarification were carried using sandpaper #100; chemical scarification with sulfuric acid (H2SO4) for 5 and 10 minutes and immersion in hot water (70 ºC), also, for 5 and 10 minutes, were evaluated. The intact seed was considered a control. (II) Evaluation of morphophysiological dormancy, in which the seeds were submitted to combined treatments of stratification of hot temperature (20-35 °C) and/or cold temperature (9 ºC), distributed in periods of 0, 1, and 2 weeks, totalizing 9 treatments. In both experiments, germination percentage (G), germination speed index (GSI), and first count (FC) were determined, using a randomized block design, and evaluated by the Scott-Knott test at 1% and Dunnett’s test at 5%. The use of H2SO4 10 minutes induced 42% germination, 0.52 GSI, and 18% FC, but only FC was significantly different from the control. In the second trial, the treatment that spent only two weeks in hot temperatures (20-35 ºC) showed the highest germination (30%), compared to the control (G = 22%). These results provide relevant information for understanding the physiology of D. bicolor germination, in addition to contributing to the optimization of pre-germination practices for this important ornamental species.
Highlights
Floriculture has a growing impact on agriculture
Given our little knowledge on the process of germination of D. bicolor, this study aimed to identify the type of dormancy and evaluate the effects of pre-germination treatments in overcoming dormancy in seeds of this species
The mechanical and chemical scarification treatments used to overcome physical dormancy in D. bicolor seeds showed no differences compared to the control treatment regarding germination percentage and germination speed index (Table 2)
Summary
Floriculture has a growing impact on agriculture. The global production of ornamental plants has grown worldwide, showing potential for expansion (Van Rijswick, 2016). The distinction of the flower market occurs due to the continuous integration of production and logistics technologies as well as the introduction of new species and cultivars into the market (Junqueira and Peetz, 2017) In this context, the Iridaceae species have stood out due to the recognized ornamental importance of these species, because of the beauty of their flowers and leaves, and the large number of species cultivated for this purpose. Iridaceae is a family of perennial monocots, consisting of about 2,000 species mainly distributed in the Northern Hemisphere, Africa, and Central and South America (Goldblatt et al, 2008b) These species are usually propagated by clumps and have slow vegetative development and low germination rates (Hajyzadeh et al, 2019). These species are usually propagated by clumps and have slow vegetative development and low germination rates (Hajyzadeh et al, 2019). Kildisheva et al (2020) classify seed dormancy in Iridaceae as (I) physiological, in which the seeds absorb water and have embryos with low growth potential, sometimes in combination with a mechanical restriction of the seed; or (II) morphological, in which the seeds absorb water readily; the embryos are underdeveloped and require time to grow before germination
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