Effects of Visible Light Wavelengths on Seed Germinability in Stevia Rebaudiana Bertoni

Abstract

Stevia rebaudiana Bertoni is one of 154 members of the genus Stevia and it produces sweet steviol glycosides .It originated from Paraguay. The leaves were used as general sweetening agent. Seed germination in Stevia is generally very low and constituted major obstacle to large scale production of the crop. Different wavelengths from visible light were tested on germination of Stevia seeds. The two lights used were (i) white light -400 to 700nm, and (ii) red light -660nm. Parameters evaluated include (i) Mean time germination, (ii) mean daily germination, (iii) germination rate, (iv) daily germination speed and (v) germination value. Multivariate tests at probability level <.05 revealed that daily germination speed and number of germinated seeds were significantly higher at (< .001) and (< .014) respectively with the effect of red light on seed germination. Red light (660nm) had better influence on germination in Stevia seeds than white light (400-700nm) and control experiment.

Heritability and genetic variance estimates for agronomic traits and glycoside yield in four elite stevia breeding populations

“…The cultigens differed for stem height, branch width, and leaf area in June and August (rated subjectively as well as measured objectively for the 30‐plant plot), with the only exception being branch width measured in August (Table S2). We were able to support previous research that stevia cultigens vary in plant height, branch width, and leaf area (Abdullateef & Osman, 2011; Gaurav et al., 2008; Othman et al., 2015, 2018). Cultigens also differed for percent survival, yield (fresh wt.…”

<i>Stevia rebaudiana</i> (Bert) Bertoni: regression models with mixed effects for investigating seed germination data

“…The increased odds of abnormal seedlings result from the effects of light in chemical reactions of seeds damaged by rain water and insect attacks. Therefore, light is an essential fixed factor for investigating the germination of Stevia rebaudiana seeds under controlled conditions, which corroborates the findings reported in the literature (Abdullateef & Osman, 2011;Simlat et al, 2016;Uçar et al, 2016). Random effects from seed lots, otherwise, will be significant when the next lots will detain the estimates of variability with a high probability of being found within the confidence intervals indicated in Table 2.…”

“…Seed lots produced under field conditions have lower percentage of seed germination than seed lots harvested under glasshouse conditions (Carneiro & Guedes, 1995;Takahashi et al, 1996) when pollination was controlled by bees and where recent estimates have frequently exceeded 80%. The current estimates were in part higher than reported in the literature (Abdullateef & Osman, 2011;Abdullateef et al, 2015;Simlat et al, 2016;Özyğit et al, 2015;Uçar et al, 2016), where the influence of sources of light was studied, but lower than responses from our laboratory recorded soon after 1990, where the seeds had been produced under the protected environment of the glasshouse (Carneiro & Guedes, 1992;Carneiro, 1996). In fact, the germination of fruit-like seeds in the current experiment also explains our lower results, but they were necessary to exclude factors like physical damage to the seed embryo when the pappus is mechanically removed, although this method does not filter out seeds with immature embryos, which also reduces the estimates from the seed lots.…”

“…The responses also reinforce the influence of seed lots as a random effect on the botanical traits of germinating seeds. Seed production of Stevia rebaudiana under field conditions have the percentage of normal seedlings reduces to less than fifty percent -and this figure is still supported in the literature (Abdullateef & Osman, 2011;Abdullateef et al, 2015;Simlat et al, 2016;Özyğit, Esra, & Turgut, 2015) -compared to seed lots harvested under protected conditions when the pappus is eliminated (Carneiro & Guedes, 1992;Carneiro & Guedes, 1995;Takahashi, Melges, & Carneiro, 1996;Carneiro, 1996). The alternative use of plastic trays with hydrophilic cotton fibres made it necessary to investigate the germinative responses because the plastic trays reduce the illuminance in the lowest shelves.…”

“…Otherwise, the literature discriminating treatments based on the germination of Stevia rebaudiana seeds suggests descriptive methods using multivariate tests (Abdullateef & Osman, 2011), the analysis of variance (Abdullateef, Osman, & Zainuddin; or the analysis of variance with the multiple Duncan test (Simlat et al, 2016;Özyğit, Uçar, & Turgut 2015;Uçar, Özyğit, & Turgut, 2016). However, all these analyses in seed technology have investigated seed lots as fixed effects, thereby making it difficult to make inferences about the estimates.…”