Seed germination of Pilosocereus arrabidae (Cactaceae) from a semiarid region of south‐east Brazil

Abstract

We evaluated the effect of temperature regimes (six constant and four alternating temperatures), light qualities (five red : far red ratios) and water potentials (YW; seven NaCl and polyethylene glycol 6000 [PEG] solutions) on the percentage and germination rate, as well as the post-seminal development morphology, that allow Pilosocereus arrabidae seeds to germinate in a hot semiarid climate on the south-eastern Brazilian coast. The results showed that seeds germinated similarly between constant and alternating temperatures, with an optimal germination at 25/20°C and 20°C. Pilosocereus arrabidae seeds were photoblastic positive and the final germination percentage was inhibited at low red : far red ratios. Maximum germination was obtained in distilled water (0 MPa) and decreases of YW in the solutions reduced the germination, which was lower in NaCl than in iso-osmotic PEG solutions. Germination inhibition appears to be osmotic because the recovery response was high when non-germinated seeds from both iso-osmotic solutions were transferred to water. Seeds of P. arrabidae are small and germination is phaneroepigeal. Despite the slow growth typically seen in seedlings and adults of Cactaceae, germination in this species depends on the ability of the seeds to appropriately sense and react to environmental cues that correlate with times and places under low-risk growth conditions.

Seed germination of three endangered subspecies of Discocactus Pfeiff. (Cactaceae) in response to environmental factors

“…Although some studies have demonstrated that the requirement of alternating temperatures is common among species in arid and semiarid ecosystems (Meiado et al, 2012b), Martins et al (2012) found that a constant temperature was more favorable to the germination of seeds from Pilosocereus arrabidae (Lem.) Byles and Rowley.…”

Ecological longevity of Polaskia chende (Cactaceae) seeds in the soil seed bank, seedling emergence and survival

“…), Pilosocereus arrabidae (Martins et al . ), Opuntia tomentosa (Olvera‐Carrillo et al . ), Trichocereus terscheckii (Ortega‐Baes & Rojas‐Aréchiga ) , Echinocactus platyacanthus and Ferocactus flavovirens (Rojas‐Aréchiga et al .…”

Experimental assessment of factors mediating the naturalization of a globally invasive tree on sandy coastal plains: a case study from Brazil

“…The osmotic potentials used were: 0.0, −0.25, −0.5, −0.75, −1.0, −1.25 and −1.5 MPa. These different potentials were found in the restinga ( Martins et al 2012 ). PEG 8000 and NaCl solutions were prepared according to Villela and Beckert (2001) and Salisbury and Ross (1992) , respectively.…”

“…Casuarina equisetifolia seeds had a fast physiological response when in contact with water, and germination started in 3–4 days after water uptake in optimal germination temperatures (30 and 35 °C). For small-seeded species, high germination rate is crucial for the recruitment of new individuals, mainly in environments with water restrictions, as is the case in the restingas ( Martins et al 2012 ). The capacity to germinate under a wide range of temperature conditions, including low (15 °C) and high alternating temperatures (40/20 °C), although with decrease in the germination rate, is also an important factor for a population to become naturalized in the restinga, where the temperatures can range from 21 to 31 °C (mean of 25 °C) inside the patches, and from 19 to 44 °C (mean of 30 °C) in open areas ( Matos 2014 ).…”