Sunken Seeds Research Articles

Seed soak-sorting prior to sowing affects the size and quality of 1.5-year-old containerized <i>Picea abies</i> seedlings

We studied the effect of soak-sorting Norway spruce ( (L.) H. Karst.) seeds on emergence, development and quality of container seedlings in two commercial seed lots. The seeds, separated by soaking into bottom and surface fractions, were sown in June, and the seedlings were grown during two growing seasons under typical Finnish nursery conditions. The first summer seedlings were grown in a greenhouse and outdoors for the second, full growing season. All sunken seeds were full and viable according to radiography, whereas the floating seeds contained 2% and 13% larvae-filled and 8% and 11% anatomically immature seeds, depending on the seed lot. Seedlings grown from the bottom fraction seed emerged 2.5–3.5 days earlier than seedlings of storage dry (i.e. control) seed. Height, diameter, and shoot and root dry mass of the seedlings were affected by soaking after both the first and second growing seasons. The largest seedlings originated from the bottom fraction. The proportion of saleable seedlings was four percentage points higher in the bottom fraction than in the other seedlings. The effects of soaking found in this study are more notable than as previously reported for Norway spruce seedlings. This suggests that soaking and soak-sorting may be most useful when the growing conditions are stressful, i.e. when seeds are sown in summer rather than 1-year-old seedling crops sown in spring under the climate conditions typical of Finland.Picea abies

Quality Seed: An Innovative Sorting Technique to Sustainable, Uniform and Effective Seedling Establishment in Nursery for System of Rice Intensification

One of the major problems of adapting the System of Rice Intensification (SRI) techniques is knowledge shortfall on the technical skills for processing quality seeds to achieve uniform seedling establishment in the nursery and quick seedling recovery in the puddled field. Therefore, this study aimed to create suitably seed sorting technique leading to vigorous and quality seedlings to improve potentiality of SRI nursery and reduce seedlings transplanting shock. It involved sorting of MR219 rice seeds the most popular grown variety in Malaysia in NaCl solutions of 0 g/L(water alone), 40 g/L, 60 g/L, 80 g/L, 100 g/L and 120 g/L, respectively. The experiment revealed that 100% germination after ten days was obtained from the sunken MR219 seeds collected in 80 g/L of NaCl solution. These values reported a decrease in germination (85%) with increasing NaCl concentration (120 g/L), with least germination vigor of 42% in water alone (0 g/L) 3 days. The percentage of sprouting proved to be high from the sunken seeds obtained in 80 g/L with 100% sprouting success rate. A decrease in percentage (70%) has been revealed with increasing NaCl concentration from the seeds obtained in 120 g/L and also when it was reduced to 40 g/L which reported 65% of the sprouting rate. Therefore, this technical information serves as benchmark to practicing farmers that high concentration in NaCl not only reduces the percentage of viable seeds but also increases seedling preparation cost as well as the entire production cost.

Effects of seed pre-soaking on the emergence and early growth of containerized Norway spruce seedlings

To study the effects of seed soaking on seedling emergence and development in Norway spruce [Picea abies (L.) Karst.] two commercial seed lots were soaked for 15 h in aerated water. After soaking, floating and sunken seeds were separated and analyzed prior to being sown in peat-filled containers. Seedling development was followed for one growing season. All sunken seeds were viable according to radiography whereas the floating seeds contained a considerable number of larvae filled and empty seeds. Mean time of emergence of the sunken seeds was approximately 1.5 days shorter than control (i.e. dry) seeds and floating seeds. Soaking had no effect on the time taken for most germinants to emerge in both seed lots, thus failing to synchronize seedling emergence. The later a seedling would emerge, the more likely it was for it to die during the growing season or to be culled at the end of the growing season. Soaking had an inconsistent effect on stem diameter at the end of the growing season and no effect on stem or root biomass. Seedling size uniformity was equal in all treatments. This study suggests that soaking and seed sorting does not guarantee a more uniform seedling crop, but this technique may be useful in upgrading poor quality seed lots of Norway spruce containing a high number of empty or larva infested seeds.

Storing cowpea ( Vigna unguiculata ) seeds in active cattle kraals for suppression of Callosobruchus maculates

Post-harvest seed damage of cowpeas ( Vigna unguiculata ) by cowpea weevils ( Callosobruchus maculates ) is increasingly becoming a threat to food security among marginal communities. Effects of storing cowpea seeds in active cattle kraals (ACK) as an alternative to pesticide for suppression of C. maculates and improving seed quality were studied in three marginal communities of South Africa. A set of 500 seeds in 10 containers were infested with 20 C. maculates and inserted in 30-cm-deep holes within the ACK, while similar containers served as controls at the farmer level. At 120 days, relative to controls, ACK had reduced the final weevil population density by 76 to 82%, floating seeds by 86 to 98% and damaged sunken seeds by 36 to 53%, but increased undamaged sunken seeds by 358 to 572%. The treatment increased seedling emergence by 14 to 32%. In conclusion, suppression of weevil numbers and improvement of seed quality suggested that ACK may serve as alternative to pesticides in storage of cowpea seeds for planting in marginal communities and therefore, ensuring continued food security of this important crop. Keywords: Active cattle kraal, Callosobruchus maculates , seed quality, Vigna unguiculata

Using flotation in ethanol to separate filled and empty seeds of Pinus nigra ssp. pallasiana.

In this study, the separation of filled and empty seeds of Crimean pine (Pinus nigraArn. ssp. pallasiana (Lamb.) Holmboe) by flotation in ethanol and the effect of this treatment on seed germination were investigated. Flotation tests in 96% ethanol by the density method and then germination tests were made on the seeds from three Crimean pine provenances of southern Turkey. In the flotation tests, 97.92% of the filled seeds sank in ethanol and 98.73% of the sunken seeds were filled seeds as the general mean values of all the provenances. Germination percentages of the flotation in ethanol and control treatments were 98.03 and 98.62%, and germination energies were 82.12 and 79.45%, respectively, in the general mean. While there was no statistically significant difference (p > 0.05) between the flotation and control treatments in terms of germination percentage for all three provenances, there was no significant difference (p > 0.05) for two provenances; however, there was a significant difference (p < 0.05) for one provenance in favour of the flotation treatment in terms of germination energy. The results of the study indicated that filled seeds of Crimean pine could be separated from empty seeds at a very high proportion by flotation in ethanol and this treatment did not affect negatively the germination percentage and germination energy of the seeds. Key words: Crimean pine, filled seed, flotation method, ethanol, germination.

Petroleum Ether Separation and Seedcoat Removal Enhance Seed Germination of a Casuarina equisetifolia L. × C. glauca Sieb. ex Spreng Hybrid

Casuarina cunninghamiana Miq. is an introduced species to Florida that has potential as a windbreak plant to help manage canker in citrus groves; however, only Florida sources can be used for that purpose. Local sources of Casuarina are generally adequate seed producers, but germination percentages are frequently poor. Thus, the causes of low seed germination and methods to improve germination were investigated using C. cunninghamiana and a local hybrid (C. equisetifolia L. × C. glauca Sieb. ex Spreng.). Seeds of the hybrid were larger and heavier (88 mg/100 seeds) than those of C. cunninghamiana (mean wt. 67 mg/100 seeds). Shrunken, insect-damaged, and empty seeds, present in all unsorted seed lots, were responsible for poor seed germination of the four seed sources studied. Petroleum ether separation improved germination by dividing seeds into floaters and sinkers. The floater fraction consisted of 47.5% to 93% insect-damaged seeds compared with 9.0% to 43.5% among sinkers. More than 50% of the sinkers were filled seeds and less than 21% in floaters. No empty seeds were sinkers except for one source of C. cunninghamiana. In sorted hybrid seeds, petroleum ether separation eliminated a large proportion of ungerminable seeds (floaters) and seed germination among sinkers was faster with a higher germination percentage than floaters. Cumulative germination of hybrid seeds in a trial involving two temperatures was 23.0% for sunken seeds at 30 °C at the end of 8 weeks compared with 1% of unsorted seeds. Temperature had no significant effect on seed germination. The germination percentage of hybrid seeds with seedcoats removed was 91.0% in the first week of culture compared with only 1.2% in the first week and 12.6% seed germination at the end of 8 weeks' culture of intact seeds.

Petroleum flotation technique upgrades the germinability of Casuarina equisetifolia seed lots

The germination of Casuarina equisetifolia Forst seed lots is low (40–50%) even when freshly collected. This study aimed at upgrading the germination performance by removing non-germinable seeds using petroleum flotation technique. Seeds collected from 19 individual trees in seedling seed orchards in India were assessed using X-ray to determine the proportion of different seed lot fractions. The feasibility of petroleum ether as a separation medium was tested. Morphological characters of floating and sunken seeds were further studied using image analysis technique to examine their effects on the separation efficiency. The X-ray analysis revealed a large quantity of shrivelled, empty and insect-damaged seeds, altogether accounting 50%, which were the causes of low percentage germination of un-graded seed lots (48%). Petroleum flotation resulted in 90% germination in the sunken fraction and 4% in the floating fraction. The separation was distinct for most seed lots, except few seed lots that had relatively low germination in the sunken fractions and more than 10% germination in the floating fractions. As a whole, petroleum flotation appears to be a feasible technique to upgrade the germination of C. equisetifolia seed lots, and its efficacy is influenced by wing surface area, seed density and wing quotient of filled and empty seeds.

FARKLI YÜZDÜRME TEKNİĞİ VE SÜRESİ İLE KAVUN VE KARPUZDA DOLU TOHUMLARIN AYRILABİLMESİ ÜZERİNE BİR ARAŞTIRMA

In this study, effects of flotation technique and time on separating filled seeds of watermelon and melon by flotation in water were investigated. Three different flotation techniques and times were used for each seeds. As a result of the tests, the flotation technique in which the seeds were mixed in vertical direction in water, for 1 minute flotation time gave better results than the other used techniques and times. When this technique and 1 minute time were applied, it was determined for watermelon that 84.21% of the filled seeds sank and 95.52% of the sunken seeds were filled seeds. In this technique and time, in spite of 15.79% loss of the filled seeds, seed quality increased at a proportion of 19.52%. In melon that 77.77% of the filled seeds sank and 94.92% of the sunken seeds were filled seeds. In this technique and time, in spite of 22.23% loss of the filled seeds, seed quality increased at a proportion of 22.22%.

Enhancing germinability of Schinus molle L. seed lot from Ethiopia with specific gravity and IDS techniques

The IDS (Incubation, Drying and Separation) method was tested on Schinus molle L. seeds collected from Ethiopia in an attempt to sort non-viable from viable seeds. Seeds were incubated for 24 h followed by one, three, four, five, six, nine and twelve hours of drying and then separated in water. All IDS treatments gave 80.5–93.5% germination in the sunken fraction compared with 61% for untreated seeds. The mean germination time of sunken seeds reduced from 11.2 (control) to 8.9–9.2 days (IDS-treated). Specific gravity separation in water of untreated seeds was also tested, and the germination capacity of sunken fraction was 83.5% with a mean germination time of 9.3 days. IDS method can, therefore, be used to enhance both percentage and rate of germination of a seed lot of Schinus molle, which is desirable to produce uniform and vigorous seedlings in the nursery or out in the field.

Germination and water dispersal of seeds from a threatened plant species Penthorum chinense

To conserve a threatened plant species (Penthorum chinense Pursh) in Japan, seed germination responses to pretreatment (imbibition and/or chilled), temperature and light, and seed dispersal by water were examined. The seeds collected from abandoned paddy fields in a warm temperate region, central Japan, germinated in light (14 h photoperiod; light 22°C, dark 21°C) after a moist‐chilled treatment. After this pretreatment, the seeds germinated well at 10–25°C (optimum temperature 15°C), but did not germinate in darkness even at the optimum temperature. Most of the seeds floated on distilled water, but 20–60% of the seeds that were collected from several populations sank in distilled water, indicating dimorphism in seed dispersal by water. The floating and sunken seeds did not show significant differences in weight and germination rate within a population. The addition of a surface‐active agent in distilled water submerged the seeds, indicating that the buoyancy of the seeds is attributable to an oil coating on the seed surface that enhances the interfacial tension on the seeds. Three times the number of seeds sank in river water collected from a rural area than in distilled water. A greater number of seeds also sank in water that had increasing concentrations of linear alkylbenzenesulfonate, which is a major component of synthetic detergents. This suggests that the water dispersal of this species is suppressed by surface‐active agents, including detergents, in river water.

The Influence of Seed-Dispersal Mechanisms on the Dispersion of Anastatica Hierochuntica (Cruciferae) in the Negev Desert, Israel

SUMMARY (1) The annual plant Anastatica hierochuntica L. has two contrasting dispersal strategies in the Negev Desert: 'dispersal on the spot' and dispersal to a distance. The former results in regeneration in the close vicinity of the parent plant, and the latter in regeneration further away from the parental sites. (2) The dry, hardened, and curled-up skeletons of the dead parent plants serve to protect the seeds, which are released gradually. 'Dispersal on the spot' is achieved by opening of the skeletons after rainfall, followed by detachment of the seeds by falling raindrops. Dispersal to a distance occurs only when runoff carries floating and sunken seeds downstream in the wadis and runnels. (3) The numbers of plants derived from seeds falling close to the parent and from seeds dispersed to a distance in a particular area and year will be dependent upon the balance between rainfall and runoff. (4) The role of seed-eating rodents and birds in the dispersal of A. hierochuntica is discussed.