Temperature and substrate on Plukenetia volubilis L. seed germination

Abstract

A B S T R A C TThe objective of this work was to evaluate the effect of temperature and substrate on the germination of P. volubilis seeds. Seeds harvested from 25 matrix plants were submitted, in two studies, to conditions of (i) sowing in rolled paper towel at the temperatures of 10, 15, 20, 25, 30, 35, 40, and 45 °C, for the evaluation of germination, first count of germination, germination speed index and mean time for germination, and (ii) sowing in the substrates paper towel, sand, Bioplant®, Bioplant® and micron, superfine, fine, medium and coarse vermiculite. The same evaluations mentioned in the first study were conducted at the temperature of 30 o C, as well as plant growth. The treatment replicates were distributed in a completely randomized block design and the effects of temperature were compared by polynomial regression analysis. The substrates were compared by the Scott-Knott test at 0.05 probability level. The data show that the ideal range of temperature for the germination of P. volubilis is between 25 and 30 °C. The temperature of 20 °C is the minimum for germination and those above 35 °C are lethal to these seeds. The most favorable substrate for P. volubilis seed germination is micron or fine vermiculite.Temperatura e substrato na germinação de sementes de Plukenetia volubilis L. R E S U M OObjetivou-se, neste trabalho, avaliar o efeito de temperaturas e substratos na germinação de sementes de P. volubilis. Sementes colhidas em 25 plantas matrizes foram avaliadas em dois estudos: (i) semeadura em rolo de papel nas temperaturas 10, 15, 20, 25, 30, 35, 40 e 45 ºC, avaliando-se a germinação, primeira contagem, índice de velocidade de germinação e tempo médio de germinação; e (ii) semeadura nos substratos rolo de papel, entre areia, entre Basaplant®, entre Bioplant® e entre vermiculita mícron, superfina, fina, média e grossa; conduzindo-se a 30 ºC os mesmos testes descritos no primeiro estudo e também o crescimento de plântulas. Os dados foram analisados em delineamento inteiramente casualizado com análise de regressão polinomial para a avaliação das temperaturas. Para a comparação entre os substratos utilizou-se o teste de Scott Knott, a 0,05 de probabilidade. Conclui-se que a germinação de sementes de P. volubilis deve ser conduzida nas temperaturas de 25 a 30 o C. A temperatura de 20 o C é a mínima para a germinação e as acima de 35 o C são letais para essas sementes. O substrato mais favorável à germinação de sementes de P. volubilis é a vermiculita mícron ou fina.

Substrates and Temperatures in the Germination of Hibiscus sabdariffa L. Seeds

“…The results obtained in this study agree with those reported by Silva et al (2016), who also evaluated germination of oleaginous seeds, such as Plukenetia volubilis L., where the maximum germination percentage occurred after sowing on paper roll at 25 ºC. However, Jeromini et al (2018) reported that the maximum germination rate of P. volubilis seeds, as occurred with those of H. sabdariffa L. var.…”

“…Lighter substrates, such as sand and vermiculite, allow greater gas exchange and better drainage, reducing the physical barrier to initial seedling development (Jeromini et al, 2018), as observed for P. volubilis by Silva et al (2016). It is noteworthy that the plantmax ® substrate has macro and micronutrients in its composition, as well as suitable particle quality, these led to favorable results for all H. sabdariffa seed evaluated variables, because just after the H. sabdariffa seed germination and emission of the primary roots, immediately began the process of absorption of the nutrients present in this substrate and its mobilization to the seedling structures, promoting their development and dry mass accumulation.…”

“…Based on these results, it can be inferred that the substrate and the temperature influence in the seed germination, because, to start this process, seeds undergo metabolic reactions that involve the activation of enzymes, hydrolysis, assimilation and mobilization of the reserves, and cell division (Melo et al, 2017). Thus, in addition to the physiological activities that vary according to the initial seed quality (Mbofung et al, 2013), the substrate structure, its water retention capacity, aeration and temperature adequacy also contribute to a higher germination percentage (Silva et al, 2016).…”

“…There are substrates that are used to standardize the seed germination test and others favor seedling production, all with some advantages and disadvantages. For example, some substrates can easily dry, particularly at higher temperatures (Melo et al, 2016). Paper rolls are indicated in germination tests by the rules of the Brazilian seed analysis (MAPA, 2009), because they remain moist for a longer period of time.…”

EFFECTS OF SUBSTRATE AND WATER AVAILABILITY ON THE INITIAL GROWTH OF Alibertia edulis RICH.

“…The results of emergence rate are consistent with those from Scalon and Jeromini (2013), who evaluated the emergence velocity of Eugenia pyriformis and found the highest values for substrate latosol + Bioplant® at 75% of WRC. The presence of organic matter and sand in the substrates may have improved emergence velocity, since they both might enable greater gas exchange and better drainage, as well as reduce the physical barrier to initial development of the seedling (SILVA et al, 2016).…”