Seed germination and substrates for seedlings cultivation of Melocactus zehntneri

Abstract

The populations of Melocactus zehntneri 'chapéu-de-frade' have shown an alarming decline due to the constant withdrawal of individuals from their natural areas. The low percentage of germination of M. zehntneri seeds, added to the slow growth, requires a system for commercial propagation of this species. This study aimed to test the influence of water, hydrochloric acid or acetic acid pre-treatments on seed germination and the influence of different substrates on the initial development of M. zehntneri seedlings. The seeds were immersed in deionized water, hydrochloric acid (5N) or glacial acetic acid (100%) for 10, 20, 30, 40 and 50 minutes and placed to germinate in a Petri dish containing filter paper moistened with 5 mL deionized water. The seedlings obtained from this germination (≡ 0.4 cm diameter) were cultivated on Carolina Soil® and vermiculite [2:1] substrates; Carolina Soil® and vermiculite [2:1] + drainage; medium-grained sand; medium-grained sand + drainage; medium-grained sand and organic compost [1:1]; medium-grained sand and organic compost [1:1] + drainage; and Carolina Soil® and medium-grained sand [1:1]. The highest percentage of germination was obtained with the pre-treatment by immersion in water, in the times of 10 and 30 minutes, totaling 55% of germinated seeds. Treatments with hydrochloric acid did not increase the percentage of germinated seeds, which were also close to 50%. In the test with the substrates, in Carolina Soil® there were the best rates of seedling survival after transplanting (87.5%) and seedling development performance. Treatments containing organic compost resulted in lower survival (69%) and seedling development. Seed germination and seedling development in Carolina Soil® substrate and sand proved to be an excellent alternative for the production of M. zehntneri seedlings.

Effect of Shading, Substrate, and Container Size on Argania spinosa Growth and Cost–Benefit Analysis

“…However, this is not the only reason, since the soil microbiological status may affect it as well, such as the case of fusarium attack of seeds. Our results agreed with several studies which report that the composition and granulometry of the substrate are detrimental to the germination rate difference [42,43]. According to Willmensen [44], it is advisable to use a loose substrate, such as in S1 and S6, rather than a compressed substrate, as in the case of S2, for improving the germination rate.…”

Light and Ethephon Overcoming Seed Dormancy in Friar’s Crown (Melocactus zehntneri, Cactaceae), a Brazilian Cactus

“…Successful in vitro germination was reported for M. glaucescens (68.1%), M. sergipensis (64%), M. zehntneri (58.7%), and M. violaceus (59.3%) [ 14 ]. Additionally, previous results obtained by our group have demonstrated similar percentages of seeds germinated in Petri dishes (50–55% on average) for M. zehntneri [ 15 ]. Thus, the results obtained with different species of Melocactus showed that a substantial part of the seeds (40–80%) continues with some unknown type of dormancy, with no germination.…”

“…Interestingly, even after a short period of darkness (10 days), seeds did not germinate even after up to 12 months under the same light conditions that promote germination, with the probable acquisition of secondary dormancy due to the absence of light. Under light conditions, the percentage of germinated seeds of M. zehntneri was, on average, 40–60% [ 15 ], showing their photoblastic positive response.…”

“…Interestingly, the in vitro seeding and germination increased the germination percentage of seeds (76% in control) of M. zehntneri compared to the previous experiments in filter paper (≡60% germination) and showed that in vitro conditions can be used for this cactus species. The main differences between these two experiments explain that these differences are the result of the use of a culture media (nutrients, sucrose, and other components) instead of deionized water under filter paper conditions, as well as the use of pre-treatment with water for 24 h before seeding instead of only 10 min, which was used for the experiment with filter paper and previously reported in another study [ 15 ].…”