Germination of palm seeds under periods of rehydration

Palm seeds are indicative of being recalcitrant species. Seeds germination for many species, is slow and uneven, even in favorable conditions, often due to the resistance of the woody endocarp that makes them impermeable to water. Most species also have the characteristic of not tolerating the drying process at low moisture levels, thus losing their viability. In view of these considerations, the objective was to evaluate the effect of different periods of rehydration on the germinative process of seeds of royal palm, dwarf palm and jeriva. Seeds were homogenized and immersed in water containing 3 times their volume, with daily replacement. The experimental design used was completely randomized, with 5 treatments (0, 3, 6, 9, and 12 days of rehydration), with 4 replications of 25 seeds. The seeds were placed in transparent “gerbox” plastic boxes containing medium vermiculite as substrate and placed in BOD with a photoperiod of 16-hour of light and their respective optimum temperatures for each species. The number of germinated seeds was counted every 2 days until germination stabilized. The variables analyzed were germination percentage, germination speed index (GSI), average germination time (AGT) and distribution of germination over the days. Rehydration for 3 days increased the germination rate of royal palm seeds. For dwarf and jeriva species, rehydration did not influence the analyzed variables. The GSI and AGT were negatively influenced by the rehydration periods for royal palm. Rehydration prolonged the peak of germination of the studied species.

Intraspecific Variation Along an Elevational Gradient Alters Seed Scarification Responses in the Polymorphic Tree Species Acacia koa

Physical dormancy in seeds can challenge restoration efforts where scarification conditions for optimal germination and seedling vigor are unknown. For species that occur along wide environmental gradients, optimal scarification conditions may also differ by seed source. We examined intraspecific variation in optimal scarification conditions for germination and seedling performance in koa (Acacia koa), which occurs across a wide range of environmental conditions. To evaluate scarification responses, we recorded imbibition percentage, germination percentage, germination time, seedling abnormalities, early mortality, seedling growth, and seedling survivorship. From these, we developed a scarification index (SI) that integrates these measures simultaneously. We hypothesized that seeds from lower elevation sources exposed to higher temperatures would have harder seed coats and would require more intense scarification treatments. To test this hypothesis, we repeatedly exposed seeds to hot water differing in temperature and time until seeds imbibed. Supporting the hypothesis, seeds from lower elevation sources generally required more intense scarification, although we found substantial variation among sources. Koa seeds germinated in about a week following imbibition. Boiling seeds (i.e., maintaining at 100°C) was effective for imbibing seeds but it also substantially reduced germination percentages. Repeated exposure to 90 to 100°C water did not reduce germination percentage but decreased seedling performance and increased early mortality. No seeds remained unimbibed after six attempts of boiling germinated whereas seeds remaining unimbibed after 15 attempts of exposure to 90 to 100°C water showed high germination percentages. Abnormalities in seedling development were rare but increased with treatment intensity. Exposure to 100°C water for 1 min overall generated the best SI values but the best treatment differed by elevation, and the treatment with the best SI was rarely predicted from the highest germination percentages. Seeds that imbibed without any treatment germinated at the same level as manually filed seeds but produced poor seedling quality. Variation in mother tree environments along an elevational gradient can lead to differences in seed coat characteristics, which may explain differing responses to treatments. Scarification treatments affected processes beyond imbibition and germination and using an index like SI may improve efficiency by identifying optimal scarification treatments while reducing seed waste.

Substrate and temperature on seed germination of Aspidosperma vargasii A. DC. (Apocynaceae)

The Amazon has a wide diversity, including forest species with timber and non-timber potential, which often have their use restricted due to a lack of silvicultural information. Thus, the present study aimed to evaluate the effect of substrates and temperatures on seed germination of Aspidosperma vagarsii. Therefore, the premise of a completely randomized design was followed, in a 3 x 3 factorial scheme, with three substrates (paper, sand and vermiculite) and three temperatures (20, 25 and 30 °C). The germination percentage, germination speed index and mean germination time were determined, as well as germination relative frequency graphs. In addition, the weight of a thousand seeds, the number of seeds per kilo, and the moisture content was determined. The weight of thousand seeds was equal to 276.4 g, with 3,618 seeds per kilo, and a moisture content of 9.5%. There was no interaction between the studied factors. The sand substrate and temperatures of 20 and 25 °C presented the best results for seed germination of A. vargasii.

Temperature and Light Effects on Germination Behaviour of African Eggplant (Solanum aethiopicum L.) Seeds

Background: A preliminary study of the African eggplant seeds obtained from farmers sources recorded a wide variation in percentage germination under ambient conditions (25±2°C). The germination percentage ranged from 0% to 25%, while fresh seeds ranged between 53% and 87%. As temperature and light are important factors of seed germination, the current study investigated the effect of temperature on the germination pattern and the influence of light interaction with temperature on seed germination of African eggplant (Solanum aethiopicum L.) under controlled conditions. Methods: Seeds of two cultivars of African eggplant were subjected to constant and alternating temperatures and under three light exposure regimes. Seed quality was accessed by per cent germination, mean germination time, time to reach 50% germination, germination index and mean daily germination. Result: The highest percentage germination under constant temperatures was recorded at 25°C (76%) and 20°C (74%). The maximum temperature and light conditions required for maximum seed germination quality (76-95%) at the shortest time (4-5 days) was 30/20°C under alternating 8/16 hours light and dark.

Seed germination responses to low-level narrow-band light spectra for 14 ornamental plant genotypes

To investigate whether low-level lighting is necessary and which narrow-band light spectra are effective in seeds germination, seeds of 14 genotypes from begonia, echinacea, gerbera, petunia, and vinca were germinated under ultraviolet-B (UVB), blue (B), green (G), red (R), far-red (FR) light, or darkness. Light-emitting diode (LED) fixtures provided all spectrum treatments except for UVB, which was provided by a narrow-band fluorescent light. The photon flux density at seed level was ≈18 µmol m-2 s-1 for B, G, R, and FR, and 0.4 µmol m-2 s-1 for UVB. Based on daily germination observations, final germination percentage, germination onset time, germination time spread, and germination speed were compared among different spectrum treatments for each of the plant genotypes. There were no promotive effects on final germination percentage, germination onset time, and germination time spread under the narrow-band lights compared to darkness. For all plant genotypes, B had a similar effect as darkness on seed germination. FR inhibited seed germination relative to darkness by reducing final germination percentage by 31–88%, delaying germination onset time by 30–40%, and decreasing germination speed by 11–48% in some genotypes. Under R, G, and UVB compared to darkness, germination speed was promoted for begonia ‘Apricot Shade’, a light-requiring genotype, and inhibited for vinca ‘Burgundy’, a light-inhibited genotype. Therefore, lighting at low levels used in our study is unnecessary for seed germination of the tested species except light-requiring genotypes, where R, G, and UVB are the most promotive among the tested narrow-band lights.

EFFECT OF DIFFERENT DRYING METHODS ON SEED GERMINATION OF TWO PEPPER VARIETIES

High seed germination is an important criteria in the seed industry, so the discovery of new processing processing methods that can improve percentage germination will be of great benefit for seed producers as well as for farmers. Seed germination tests of two pepper varieties (Bozok and pinar) that were dried using common (sun, shade, greenhouse) and novel (oven, microwave, liyofilization) drying methods were experimented. Two types of solid medium were used, one which was a mixture of peat and perlite (M1) and the other that contained only vermiculite (M2), a paper wet test in petridish (M3) was also performed, but was not replicated. There were no difference between both medium but a difference in viability in both varieties, Bozok was found to be more viable. Sun drying gave the highest emmergence rate 80% and 60% respectively in M2 and M1 for Bozok. Novel drying methods had no positive effect on seed germination.

Interactive Influence of Location and Variety on Physiological Quality of Cowpea Seeds (Vigna unguiculata (L) Walp.)

The production environment plays a significant role in the production of high-quality seeds. Therefore, the knowledge of the relative contributions of the different factors that impact seed quality will be important for the management of seed production. The objective of this study was to assess the relative contribution of location and variety to the physiological quality of the cowpea seeds. Seeds of two varieties of cowpea, IT97K-918-118 and 977K-1499-35 were produced at three locations: Ikenne, Ilora, and Ballah. Hundred seed weight, seed moisture content, standard germination, accelerated ageing germination and electrical conductivity tests were carried out on the seeds. The results indicated that the location effect was highly significant (P<0.05) for hundred seed weight, germination percentage, germination rate index, accelerated ageing germination percentage and accelerated ageing germination rate index, while the varietal effect was highly significant for only hundred seed weight. However, location alone contributed more than 50% to the observed variability in hundred seed weight, germination percentage, germination rate index and accelerated ageing germination percentage. Seeds from Ballah had the highest viability (germination percentage = 84.67%) but also the lowest vigour (accelerated ageing germination = 11%; electrical conductivity = 64.10µscm-1g-1). Thus, the modulating effect of the environment on the quality of cowpea seeds is not the same for the different components of quality and the choice of location for the production of cowpea seeds should be given a higher priority than a choice of variety per se.

Pengaruh Konsentrasi dan Lama Perendaman GA3 terhadap Perkecambahan Benih dan Pertumbuhan Bibit Johar (Cassia seamea)

Johar (<em>Cassia seamea</em>) is a medicinal plant with a cassiarin A compound to combat malaria and has a low Cassiarin A is an active compound in Johar (<em>Cassia seamea</em>) medicinal plant capable of combating malaria, despite showing a low seed production rate due to dormancy. This inactivity is severed using gibberellic acid (GA₃) treatments. This study aims to determine the effects of concentration and soaking period of GA₃ on seed germination and growth of Johar seedlings. A completely randomized design (CRD), consisting of 2 treatments was applied as the research method. The first treatment employed GA₃ concentrations of 0, 45, 90 and 135 ppm, while the second was based on the soaking interval at 6, 12, 18 and 24 hours. The results showed the capacity of GA₃ able to shatter the seed dormancy with percentage germination of 43.03% and a concentration of 50.28 ppm. Therefore, the interaction of the two treatments significantly influenced the growth of Johar seedlings. Consequently, the concentration of GA₃ at 79.89 ppm increased the root length to 52.19 cm, while 84.68 ppm produced a total of 20.91 roots, after a 6 hour soaking. In addition, the 96.67 ppm expanded the stem diameter by 0.93 cm.

THE ALLELOPATHICITY OF RED SPRANGLETOP (Leptochloa chinensis L.) AGAINST GERMINATION AND SEEDLING GROWTH OF RICE (Oryza sativa L.)

Red sprangletop (Leptochloa chinensis L.) is a problematic weed of aerobic rice (Oryza sativa L.) that greatly reduces in yield. The laboratory studies were undertaken to confirm allelopathicity of its plant leachates and soil-decomposition plant residues towards emergence and seedling growth of rice. In first experiment, aqueous extracts from various plant parts of red sprangletop (stem, root, leaves, flower and entire plant) at their 5% (w/v) concentration were applied to germinating rice seeds. In second experiment, soil-decomposed red sprangletop plant residues of variable concentrations (2, 4 and 6% w/w) were used as germination media for rice. Among plant parts, red sprangletop leaves showed maximum allelopathic effect by fully inhibiting the germination of rice while its stem could be positioned at second situation as it caused 60, 73, 84.13 and 86 % reductions in germination percentage, germination index, seedling length and seedling dry biomass of rice as compared with control, respectively. This treatment also resulted in maximum delays in mean germination time (up to 4.80 days) and days taken to 50% germination (up to 4.40 days) of rice. The highest concentrated (6%) soil-decomposed plant residue of red sprangletop significantly diminished the germination percentage, germination index, seedling length and seedling vigor index that were 35.13, 23.26 and 41.61% lower than control. It very well may be presumed that liquid concentrates of leave and stem soil-decomposed plant residues of 6% concentration had different kind of allelochemicals that inhibited the germination, seedling growth and development of rice.

Allelopathy of vegetable residues on the sowing properties of soft winter wheat grain

Aim. To study the allelopathy of vegetable residues on sowing properties of soft wheat grain. Methods. Laboratory, mathematical and statistical, physical. Results. The highest germination energy was obtained in the variant with water, corn and wheat stalks – 100%, percentage germination was 95%. Under conditions of germination in rye, rape and oat stalks, percentage germination was 15–30 % points lower compared to the control. Germination of soft wheat grain in the stalks of other crops provided percentage germination of 15–50 %. Obviously, soybeans, sunflowers, mustard, peas, barley, flax, safflower, buckwheat and sorghum show high allelopathy during the germination of soft wheat grain. The highest seedling vigor was obtained during germination in water and in corn stalks – 50 %. This figure in wheat and rye stalks was 33 and 28 %, respectively, or 17–22 points lower than the control. During the germination of soft wheat grain in the stalks of other crops, the seedling vigor was the lowest – 8–22 %. The average germination rate varied inversely proportional to seedling vigor. On average, wheat grain in corn stalks germinated for 29 minutes which was at the control level. During germination in wheat and rye stalks, it grew for up to 43–58 minutes. During germination in the stalks of other crops, the average speed increased to 72–288 minutes. Different germination substrates changed the parameters of soft wheat stalks. This indicator was at the level of control over grain germination in rye and corn stalks – 9.2–9.3 cm with fluctuations from 8.1 to 10.3–10.4 cm, and the variation coefficient was small (V = 12.0–12.5 %). The stalk length was significantly shorter during germination in wheat stalks, but the variation coefficient was insignificant (V = 5.2 %). During germination in the stalks of other crops, the stalk length decreased from 7.3 to 0.6 cm. Coclusions. Germination of wheat grain in corn and wheat stalks did not affect the deterioration of germination. The lowest allelopathy was shown by grain germination in rye stalks. The highest allelopathy was shown by germination in soybean and sunflower stalks. Crops, according to the influence on the length of soft wheat stalk, are arranged in the following order: sunflower, buckwheat, sorghum, safflower, soybean, mustard, flax, oats, rape, barley, peas, wheat. Grain germination in corn and rye stalks did not affect the length of soft wheat stalks