Showing papers in "Seed Science and Technology in 2000"

Chemical stimulation of seed germination in Aconitum heterophyllum Wall. and A. balfourii Stapf.: important Himalayan species of medicinal value.

Abstract: Aconitum heterophyllum Wall, and A balfourii Stapf are important medicinal herbs of the Himalayan region The effect of plant growth substances (PGSs, namely, abscisic acid, 6-benzylaminopurine, gibberellic acid and zeatin riboside) and two nitrogenous compounds (thiourea and potassium nitrate) for enhancing and synchronising uniform germination was examined The tetrazolium (Tz) staining pattern indicated that freshly collected seeds had high viability which decreased following storage at 4°C for 6 and 12 months The treatments and time of seed germination were found to be significantly different (P <001) Gibberellic acid (GA 250 μM) significantly enhanced seed germination (425% compared to 275% in control) in A balfourii with in 15 weeks but was inhibitory in A heterohyllum, 6-Benzylaminopurine (BAP; 25 and 250 μM) and zeatin riboside (ZR; 25 and 250 μM) did not enhance germination in A balfourii; 250 μM ZR was actually inhibito ry In A hererophyllum the lower concentration of BAP was inhibitory (75% compared to 250% in control while 250 μM BAP enhanced germination (425% compared to 250% in control); the higher concentration of ZR was inhibitory The combined treatments of gibberellin and cytokinin in general resulted in reduced ger mination in both species Among the nitrogenous compounds, thiourea (CH 4 N 2 S) increased the rate and germination percentage in both species but potassium nitrate (KNO 3 ) enhanced germination in A baifourii only Seed germination was first detected in A balfourii in the 5th week (25%) Following treatment with 65 mM CH 4 N 2 S and this value increased to 225% in the 7th week and reached as high as 75% (compared to 275% in control) in the 15th week A higher dose of thiourea (130 mM) resulted in a rapid and high germination rate (40% compared to 0% in control) in the 7th week, reaching 75% in 10th and 12th weeks and a maximum 80% (compared to 275% in control) in the 15th week, In A heterophyllum, however, thiourea only marginally enhanced germination even up to the 15th week In A balfourii, KNO 3 (50 and 100 mM) significantly enhanced germination (62-70%) within 15 weeks

Imbibition behavior of soybean (Glycine max (L.) Merrill) accessions with different testa characteristics.

Abstract: The imbibition behavior of 18 soybean accessions with a wide range of seed size and testa color was examined. In two accessions, the presence of an intact testa did not reduce the rate of water uptake, and provided no protection against imbibition damage. In one black-seeded accession, seeds soaked with the testa intact had a higher rate of water uptake than embryos without testas due to the loose adherence of the testa, hence creating a wide gap that allowed free water to be trapped between embryos and testa. In the other black-seeded accession, a delayed-permeability testa characteristic was associated with low levels of imbibition damage. Wetting and drying of seeds increased the rate of the water uptake, but this effect could not be attributed entirely to a loosening of the seed coat to the embryo due to the presence of ruptures in the testa surface. Although adherence of the testa to the embryo could play an important role in controlling water uptake in soybeans, it appeared to be difficult to measure or quantify its role per se.

Phosphorus seed coating and soaking for improving seedling growth of Oryza sativa (rice) cv. IR66.

Abstract: In view of the large influence which phosphorus (P) can have on early seedling growth and the fact that many rice growing soils are P deficient, appropriate methods of P application to enhance the efficient use of P fertilizer for early plant growth need to be investigated. The objective of the study was to determine the effect of coating and of soaking rice (Oryza sativa) seed with various P fertilizers at increasing concentrations, on early plant growth. Treatments comprised: control; seed coated with single superphosphate (SSP), rock phosphate (RP), monoammonium phosphate (MAP) and potassium phosphate (PP); and seeds soaked in three levels of KH2PO4 (PP), or NaH2PO4.2H2O (SP) solutions (5, 10, 20% w/v), each with three replicates. Amounts of P applied to the seeds by coating or soaking were as follows (mg P seed-1): Control, 0; Coating-SSP, 3.8; Coating-RP, 1.2; Coating-MAP, 3.4; Coating-PP, 3.7; Soaking-PP (5-20%), 0.05-0.17; Soaking-SP (5-20%), 0.05-0.21. Seedling emergence was depressed by 40-60% when seeds were coated with SSP, MAP or PP or soaked in PP or SP solutions. By contrast, seed coating with RP did not affect final emergence compared to the untreated control although it delayed seedling emergence by 2-3 days. At 20 and 40 days after sowing (DAS), soaking in P solutions had no significant effect on plant growth. At 20 DAS, coating increased shoot dry weight but decreased root dry weight of plants. The effect of coating treatments persisted to 40 DAS and at this stage, seed coating increased root length and dry weight and increased shoot dry weight by 400-870%. Although plant growth responded to coating seeds with SSP, MAP or PP, these seed treatments initially depressed seed emergence and may therefore not be acceptable to farmers. Coating rice seeds with RP may be more promising for stimulating early rice growth on low P soils. Rock phosphate when applied at 1.2 mg P per seed or 0.5 kg RP per kg of seed was not harmful to final seedling emergence but quadrupled shoot and root growth of rice.

Pretreatments to overcome seed coat dormancy in Dimorphandra mollis.

Abstract: Dimorphandra mollis Benth. is a multipurpose tree species providing important subsistence and economic benefits to rural communities of the Brazilian cerrado. Seeds of D. mollis were collected to test for germination following one of 24 pretreatments intended to overcome seed coat impermeability. The tests were conducted for 21 days at 28°C under a 24-hour constant light regime. Seeds without a pretreatment resulted in only 4% germination while immersion in sulfuric acid for 45 min to 1 hours and mechanically scarifying the seeds with a file improved germination to over 90%. A sulfuric acid treatment for 1 hours followed by a 2 hour water soak was the most efficient method of accelerating germination rate. Seeds exposed to sulfuric acid for longer than 1 hours showed marked decreases in viability. Though several heat pretreatments with boiling water provided germination responses of over 50%, fire was not successful in eliciting germination significantly higher than the control. These results provide viable pretreatment options for both large and small-scale reforestation efforts.

Alleviation of innate and salinity-induced dormancy in Atriplex griffithii Moq. var. stocksii Boiss.

Abstract: Atriplex griffithii var. stocksii is a perennial salt-secreting halophyte that grows in the coastal and inland salt deserts of Karachi, Pakistan. Seeds are surrounded by bracts at maturity, and were inhibited from germinating. when they were enclosed by bracts or when naked seeds were germinated in the presence of their excised bracts but had 60% germination in the absence of bracls. The effect of dormancy relieving compounds (ethephon, fusicoccin, nitrate, thiourea, proline and betaine) in alleviating the effects of innate or salt-induced dormancy on seed germination of A, griffithii was mvestigated. Ethephon and fusicoccin failed to stimulate germination, whereas proline, betaine, nitrogen, and throurea partially alleviated the innate dormancy in seeds. Salinity-induced dormancy was partially alleviated by fusicoccin, proline, betaine, thiourea, and nirrate. The rate of germination in non-saline controls increased significantly when seeds were treated with proline, betaine, and thiourea. Proline, betaine, thioucea, and nitrate also were found to inerease the rate of germination under saline conditions.

Effects of desiccation on the lipid peroxidation and activities of peroxidase and polyphenoloxidase in seeds of Telfairia occidentalis

Abstract: Seeds of Telfairia occidentalis Hoof (fam. Cucurbitaceae) were examined for their desiccation tolerance at different temperatures (5°C, 30°C) and drying rates. Seeds were intolerant of desiccation and required fairly high moisture contents (about 40% or more) to remain viable. Limited desiccation stimulated germination of the seeds, adding support to the local practice of sun drying seeds before sowing. Activities of peroxidase and polyphenoloxidase were suppressed when seeds were dried to moisture contents less than 40%, identified as the eritical moisture content for survival. Significant negative correlations were found between hydroperoxide levels and germination (r = -0.98) and between hydroperoxide levels and moisture content (r = -0.82) in seeds dried over CaCl 2 at 5°C. Results suggest that an increase in hydroperoxide levels may be associatec with declining seed viability and that peroxidation may occur with desiccation in seeds of Telfairia occiden talis. Peroxidation was affected by the temperature and rate of desiccation.

Desiccation tolerance of four seedlots from Euterpe edulis Mart.

Abstract: In order to identify the desiccation tolerance of E. edulis seeds, four fruitlots were collected from the Campinas Agronomic Institute Palmae collection, located at Ubatuba, state of Sao Paulo, Brazil, and taken in moisture-proof containers to the College of Agriculture in Botucatu, state of Sao Paulo, There, the fruits were shelled and the seeds were dried, either under siliea gel conditions or in a drying chamber. The effects of dehydration were evaluated by measurements of the germination, embryo protrusion, germinative button plumule, speed of emergence, seedling length, seed dry matter and water content. Differences among seedlots and between harvest season for most of the traits were observed. Euterpe edulis seedlots seem to tolerate water content reductions until 39% without significant reduction in germination and vigor. Below this value, most of the evaluated traits were negatively affected. Total loss of germination was observed whenever seed water content was reduced to values below 21%.

Effects of initial quality, low temperature and ABA on the storage of seeds of Inga uruguensis, a tropical species with recalcitrant seeds.

Abstract: This research was carried out to identify harvest and storage conditions to increase seed storability of Inga uruguensis. Fruits were collected from trees on the banks of the River Oricanga (22°17'S; 47°03'WG), on 27/dec/95 (early harvest), 09/jan/96 (mid-harvest) and 23/jan/96 (late harvest). Fruits were obtained directly from the trees or from the ground. They were opened manually and their seeds removed. Seed dimensions, water content, dry weight, germination and vigour were evaluated. Then, the seeds were stored in cold chamber or laboratory, in three different forms: tray, wet vermiculite or vermiculite soaked in 10 -4 M abscisic acid. Every 20 days of storage, samples of seeds were taken out from each treatment and then their quality was evaluated. The results permit to conclude that seeds harvested directly from the trees at fruit maturity stage, stored in cold chamber and wet vermiculite, maintained 80% of germination and normal seedling growth up to 40 days after seed harvest. High quality seeds, stored in cold chamber in wet vermiculite, reached 80 days with germination. In contrast, low quality seeds, on the same conditions, did not reach 60 days. Abscisic acid improved the storage capability of high quality seeds.

Chemical induced prolongation of seed viability and stress tolerance capacity of mung bean seedlings.

Abstract: Mung bean (Vigna radiata L. Welczek cv. PS-16) seeds lost viability at a rapid rate under accelerated ageing condition at 99.5% relative humidity (RH) and 32 ± 2°C temperature for 30 days. Pretreatment of seeds with sodium dikegulac (Na-Dk, 2.3:4-6 di-0-isopropylidene-α-L-xylo-2 hexalofuranosate) for 8 hours and seed treatment with Eucalyptus oil throughout the ageing period of 30 days remarkably slowed the fall of germination and reduced the time (h) required for 50% germination (T 50 ). The chemicals also hardened the seeds under adverse storage environment by increasing percent germination and by decreasing T 50 hours after 7 days of PEG-induced water stress treatment (1.0 MPa) for 48 h. Speed of seed germination under stress treatment was significantly slowed down in control seed lots aged for 15 days and this was relieved by treatment with Na-Dk or Eucalyptus oil. The Na-Dk and Eucalyptus oil induced changes of germination behaviour of seeds were associated with parallel changes of seedling growth and metabolism under stress condition. Significan reduction of shoot and root length, epicotyl girth and leaf area of seedlings, raised from 15 day-aged seeds, as a result of stress treatment was diminished in Na-Dk and Eucalyptus oil treated samples. The chemicals checked the loss of seedling potential as evident from higher chlorophyll, protein and RNA levels as well as higher activity of catalase and lower activity of IAA-oxidase. Influence of the chemicals on stress tolerance capacity of mung bean seedlings in addition to their role on deferment of storage deterioration on seeds is discussed.

Physiological maturity effects on seed quality, seedling vigour and mature plant characteristics of maize in a tropical environment.

Abstract: Kernel dry matter accumulation, milk line and black layer formation which are regarded as indices of physiological maturity were compared and effect of maturity on viability and seedling vigour was investigated. Pattern of dry matter accumulation in the two hybrids used for the study was similar. The indices gave different estimates of the time physiological maturity was attained in the two hybrids. Cubic regression equations gave more realistic estimates than linear and quadratic ones, 41 and 48 days after silking in Oba Supa 1 and Oba Supa 2, respectively. Performance of seed of Oba Supa 1 harvested at 45 days after silking and with seed dry weight less than maximum, was better in laboratory and field investigations than that harvested before and after this time. There was no significant maturity-stage effect on viability of seeds. But seeds harvested before full maturity, irrespective of kernel dry weight, germinated faster, having significantly lower emergence indices than those harvested at full maturity. The rate at which seedlings accumulated dry matter during the first 30 days after planting in the field was closely related to seed dry weight.

Effects of different environmental stresses on seed germination.

Abstract: In this paper, the hypothesis was that different environmental stresses may show similar responses in a biological system, as exemplified by the kinetic of germination of Eucalyptus grandis W. Hill ex Maiden seeds. It was observed that the kinetic of germination depends on environmental factors, and different treatments induced similar germination responses. The treatments with PEG 6000 and NaCl suggest that germination depends on solute used, since NaCl exhibit both ionic and osmotic effects. The analysis of the results showed that different external disturbances may lead, perhaps through different physiological ways, to similar responses related to the germination process.

Drying during muskmelon (Cucumis melo L.) seed priming and its effects on seed germination and deterioration

Abstract: Effects of drying conditions during seed priming on muskmelon seed quality were investigated either immediately after seed priming or after twelve months of storage. Seeds of muskmelon, cv. Top Net SR were primed for 6 days in darkness at 25°C in KNO 3 (0.35 M) aerated solution. Seeds were rinsed in running tap water and redried at 18, 28, and 38°C during 24, 48, and 72 hours. Seeds were stored at 10°C, 45% RH for 12 months. The beneficial effects of seed priming were maintained after dehydration. Drying temperature did not affect seed germination after priming. An interaction effect on germination between temperature and drying duration was observed at low temperature. Seed germination and vigour of primed seeds decreased after 12 months of storage. Both temperature and duration of drying affected seed vigour after storage period. A better management of drying conditions during muskmelon seed priming should be focused in order to achieve the benefits of seed priming and to maintain seed quality, especially if primed seeds are to be stored.

Variability in seed coat dormancy in Dimorphandra mollis

Abstract: Information concerning the genetic diversity of most tropical tree species is lacking, causing many with economic potential to be overlooked for tree domestication and reforestation efforts. This study was conducted to determine whether variation in seed coat dormancy exists among seeds collected from 14 different maternal families of the native Brazilian tree species, Dimorphandra mollis Benth. Seed dormancy differences were found in germination capacity, rate, and viability. Families differed by pretreatment in their relative germination success. Variation in germination among families was eliminated with the filing pretreatment, while sulfuric acid pretreatment was the most effective method of reducing variation in germination rate. The resultant high uniform germination among all families from mechanically rupturing the seed coat suggests that the mechanism of dormancy lies in the seed coat. Repeatability measures suggest the presence of relatively high genetic control of germination capacity and a moderate genetic control of germination rate, though the differential microclimates in which seeds from different trees developed could also play a role in this variability. This study also demonstrated the benefits of maintaining seed samples from different families separate and the need for determining pretreatments that can elicit uniform germination across a number of families.

Improvement in seed germination of Myrica esculenta Buch.-Ham. ex D. Don - a high value tree species of Kumaun Himalaya, India.

Abstract: The paper describes various experiments carried out to break the dormancy, improve germination ability and reduce the mean germination time (MGT). Germination ability of seeds from different sources (population) were compared to determine the effect of source environment. However, results revealed no significant variation in germination among sources. Compared to control, most of the pretreatments improved percent germination. The imbibed seeds prechilled at 4°C for 20 days showed best (48.6%) response. Significant reduction of MGT and substantial improvement in germination (MGT 28.6 d; Germination 42.1%) was, however, observed for 100 ppm GA 3 (in scarified seeds) pretreatment. Considering practical feasibility and cost effectiveness, the mechanical scarification at micropyle end (MGT-31.6 d; mean germination 40.0%) was recommended as one of the best options especially for rural inhabitants. An attempt has been made to identify various attributes contributing toward seed germination responses in Myrica esculenta. The physical dormancy caused by an impermeable seed coat appears to be the main reason of poor germination.

Varietal discrimination of tomato (Lycopersicon esculentum L.) by ultrathin-layer isoelectric focusing of seed protein.

Abstract: Ultrathin-layer isoelectric focusing (UTLIEF) of seed proteins soluble in 4 mmol l -1 NaCl was used to discriminate tomato varieties. Eight polymorphic protein bands were found on the gel with a pH range of 4-8, of which six bands were reported for the first time. About 87% of pairwise comparisons of the 11 varieties tested showed at least one different protein band. Almost all varieties were found to be not homozygous genetically.

Time-course changes in organic metabolites and mineral nutrients in germinating maize seeds under salt (NaCl) stress.

Abstract: The kernels of maize (cv Sultan) were incubated for seven days in solution culture containing 0, 40, 80 or 120 mol m -3 NaCl. Data for seed germination and fresh and dry weights of plumule, radicle and germinating seed were recorded daily after the inception of germination. Fresh weights of seeds decreased significantly with increase in NaCl concentration of the growth medium whereas seed dry weights remained almost unaffected. However, fresh and dry weights of both shoot axis and radicle increased consistently with time but this increase was considerably higher in non-saline conditions than that in saline substrate. Na + concentrations in the germinating seeds increased with time in all salt treatments except the control treatment and the marked effect of time was observed at the highest salt regime (120 mol NaCl m -3 ). The same pattern of Na + transport was observed in the shoot axis whereas the reverse was true for radicle in which Na + concentrations decreased considerably with time. Saline medium caused a significant increase in Cl- concentration of the seeds, plumule and radicle and the time-course increase in Cl- was also significant in these plant parts. K + concentrations in the germinating seeds and shoot axis decreased with time and a significant reduction in K + level was observed on day 7 of germination in all treatments. Saline growth medium had no effect on K + concentrations of radicles but in contrast, there was a significant time-course reduction in radicle K + concentration regardless of NaCl treatment. Similar effect of salt and time was observed on Ca 2+ concentration of the germinating seeds. No significant effect of salt or time was observed on Ca 2+ concentrations in the radicles but in contrast, the time-course decrease in shoot axis Ca 2+ was observed only at the highest salt level. Soluble proteins of seeds, plumule and radicle decreased significantly with increase in time or external salt regimes whereas no effect of salt or time was observed on free amino acids of the germinating seeds. However, a slight time-course decrease in these biochemicals was found in both plumule and radicle. In contrast, a time-course increase in soluble sugars of seeds, plumule and radicle was significant. Total lipids decreased significantly in the germinating seeds with time but this decrease was more pronounced in the control treatment than that in the saline conditions. The time-course change in lipid content was negligible at the highest salt level. The salt sensitivity of maize at the germination stage was found to be associated with high transport of Na + and Cl - to the growing shoot axis and time-course decrease in K + and Ca 2+ concentration in the embryonic tissues. In addition, the adverse effect of salt on seed germination is partly due to impairment in breakdown of seed lipids so as to supply soluble sugars to the respiratory metabolism of the growing embryo.

Alternaria brassicae in seeds of rapeseed and mustard, its location in seeds, transmission from seeds to seedlings and control.

Abstract: Using the component plating technique, Alternaria brassicae was found predominantly in the seed coat and rarely in embryos of rapeseed (Brassica campestris L. var. toria) and mustard (Brassica juncea). The fungus sporulated profusely in the hilum region when tested by the deep-freeze blotter method. Field experiments conducted in 1991 and 1992 showed that the seed-borne inoculum of the fungus produced lesions on the cotyledonary leaves and then in first true leaves. In most cases A. brassicae sporulated within diseased tissues. The relationship between seed infection and disease transmission to seedlings was significant in the field trials of both years. Seed-borne inoculum of A. brassicae was controlled most effectively by sced treatment with iprodione (Rovral), thiram (Thiride), mancozeb (Dithane M-45) and captan also gave significant control. The paper discusses the implications of the survival of inoculum in stored seeds at low temperature and movement of infected seeds from gene banks to within a country or in other countries of the world.

Detection and evaluation of seed damage of cypress, Cupressus sempervirens L., in Italy.

Abstract: The damage to cypress seed caused by insects and tree pathogens was estimated in a plantation of a clone patented for resistance to cypress canker (Agrimed 1) and in a stand heavily attacked by the canker, which is caused by the fungus Seiridium cardinale. Five seed quality categories were identified based on X-ray analysis. Filled seeds were more abundant in the clonal plantation whereas empty seeds prevailed in the stand. Seed damage by insects, a seed bug (Orsillus maculatus) and a seed chalcid (Megastigmus wachtli), was higher in the stand whereas the brown degeneration of the gametophyte occurred more frequently in seed from the clonal plantation. Cones infected with S. cardinale produced fewer filled seeds and more empty seeds than healthy cones. An incubation experiment conducted with seed from healthy and fungus-infected cones allowed to detect the presence of pathogens and to evaluate the germination capacity of the seed for each of the five seed quality categories. In healthy cones the pathogens, mainly S. cardinale and Pestalotiopsis funerea, were associated with seed damage by insects. Seed germination occurred almost exclusively for filled seeds. These findings may support the suitability of X-ray analysis in the assessment of cypress seed quality and emphasize the role of seed insects in disseminating the fungus among cypress cones.

Differentiation between closely related lentil (Lens culinaris Medik.) cultivars using DNA markers

Abstract: The DNA polymorphism detected by analysis of variable number of tandem repeats (VNTR), (microsatellite and minisatellite DNA sequences), inter-simple sequence repeats (ISSR), and amplified fragment length polymorphism (AFLP) has been used to distinguish between commercial lentil cultivars (Lens culinaris MEDIK.) that are closely related or identical by pedigree and agronomical and morphological traits. The DNA marker systems used generated polymorphic DNA banding patterns and the lentil cultivars examined could all be differentiated from each other.

Germination of sugar beet (Beta vulgaris L.) seed submerged in hydrogen peroxide and water as a means to discriminate cultivar and seedlot vigor

Abstract: Adequate field emergence of sugar beet (Beta vulgaris L) seed is a major concern of sugar beet growers, particularly in rainfed systems such as the Great Lakes region of the United States Despite commercial requirements for high germinability (>92%), field emergence is much lower (50 - 60% on average), and the causes of this discrepancy are presumed to be stress related Many stress factors may be involved, and alternative stress-germination tests may help to identify some of the more important factors, particularly as related to breeding for better emergence We have begun to re-examine germination in the laboratory using rapid, non-conventional methods Here, we report results from germination in liquid media that (i) simulate optimal conditions for germination and (ii) differentiate cultivars and seedlots Using a range of germplasm, some known to be compromised in their germinability, incubation in dilute hydrogen peroxide solutions stimulated germination, but not generally beyond values obtained with standardized germination tests Incubation in water alone showed a range of germination values from 90% among seedlots with otherwise good germinability Different seedlots of the same cultivar often showed differences in water germination However, differences between cultivars were apparent This system may be of use as a sugarbeet seed quality and vigor test with further applications in selection and breeding

Effect of preplant seed conditioning treatment on the germination of switchgrass (Panicum virgatum L.).

Abstract: Switchgrass (Panicum virgatum L) is being developed and evaluated as summer forage and for biomass production in eastern Canada Uneven germination and slow seedling growth in spring are some of the factors limiting its cultivation A study was conducted to reduce seed dormancy and to improve germination at suboptimal temperatures in switchgrass cultivars Cave-in-Rock (CIR), Dakota (DK) and New Jersey 50 (NJ) Seeds of these cultivars were conditioned either with 02% potassium nitrate (KNO 3 ) or 1mM gibberellic acid or osmo-conditioned with polyethylene glycol 8000 (PEG) solution with or without 02% KNO 3 or 1 mM gibberellic acid (GA 3 ); or matriconditioned with Micro-Cel E (MC) with either water, 02% KNO 3 or 1 mM GA 3 The seeds were conditioned at 8 or 16°C for 4 days and then germinated at 8, 16 or 24°C Conditioning treatment and temperature influenced germination For CIR seeds germinated at 8°C, conditioning with PEG at 8°C increased germination from 0 (control) to 22% All the conditioning treatments germinated earlier and the proportion of seeds that eventually germinated was higher than for the unconditioned control In the cultivar NJ conditioning at 16°C with water or 1 mM GA 3 increased germination to 12 and 17% respectively (0 for the control) when seeds were germinated at 8°C When germinated at 16°C treatments containing 1 mM GA 3 germinated earlier Osmoconditioning in PEG with 1 mM GA 3 had the highest final germination at 56% (37% for control) Cultivar DK did not significantly respond to the various conditioning treatments Overall, both osmoconditioning and matriconditioning hastened germination and total germination in switchgrass cultivars CIR and NJ

Desiccation sensitivity and recalcitrant behavior of seeds of Aquilaria agallocha Roxb.

Abstract: Seeds of Aquilaria agallocha were dried at different drying conditions to detect the seed storage behavior. Moisture content, germination percentage and leachate conductivity were then determined at different intervals. Moisture content was rapidly decreased during first few hours/days and then slowly stabilized. Germination percentage declined after drying to certain level of moisture content i.e., lowest safe moisture content that was observed 20-30% depending on desiccation condition. Leachate conductivity of seeds was increased with the loss of viability and indicated a strong correlation with it.

Seed trait variation in Dalbergia sissoo Roxb.

Abstract: Twenty seed sources of Dalbergia sissoo Roxb scattered over the entire natural range in India were studied for pod, seed, germination and nursery characteristics Highly significant variations were observed among the seed sources for all the characters studied The extent of variation observed for germination characters was large compared to other characters studied Significant positive correlations were observed for seed length with seedling height (P<0001), final germination percent with seedling height and biomass (P<005) Pod length and number of seeds per pod showed a significant positive relationship with altitude and longitude respectively However, number of seeds per pod showed a significant negative relationship with altitude Significant negative correlation was observed between seed weight and rainfall at the source location indicating the existence of higher seed weights in drier areas The seed from locations Muzaffarnagar, Kanpur and Kotdwar were found to be more vigorous on the basis of germination characters and nursery performance and are recommended for meeting the immediate seed requirement for planting programs The study indicates the need for multi-trait selection in ranking the desired seed sources Seed length, seed weight and germination percent were observed to be important characters in selecting and delineating seed sources

Vigour of Welsh onion seeds in relation to storage temperature and seed moisture content.

Abstract: The effect of storage temperature and seed moisture content on the vigour of Welsh onion (Allium fistulosum L.) seeds was investigated in this study. After two years storage, several indices of seed vigour, including dehydrogenase activity, germination energy, vigour index and emergence percentage of the seeds, declined as storage temperature and seed moisture content increased. When the seeds were stored at room temperature or 6°C for two years, the indices were significantly influenced by the seed moisture content. The increase of seed moisture content resulted in the significant decrease of the indices, some of which were reduced to zero. The low temperature storage at -6°C reduced the effect of seed moisture content on seed vigour. Seedling emergence from seeds stored for two years was closely associated with the storage temperature and seed moisture content. The low temperature storage of the seeds with low moisture content maintained a high seed vigour. If seeds, in which the moisture content had been reduced to less than 6%, were stored at -6°C, the germination percentage was above 90% after three years storage. These results are important for seed storage and genetic resources conversation of Welsh onion.

Effects of ferulic and p-coumaric acids on canola (Brassica napus L. cv. Hyola 401) seed germination

Abstract: Soils contain substances such as cinnamic acid derivatives that, in sufficient concentration, affect seed germination, root elongation, biomass and, consequently, the seedling growth. A characteristic of these effects is the variability among species which does not have a defined rule that applies to all plants. Although plant physiological responses under the action of these compounds have been shown in several species, no attention has been given to their effects on canola (Brassica napus L. cv. Hyola 401) seed. The objective of this research was to investigate how ferulic (FA) and p-coumaric (p-CA) acids influence canola seed germination. Data showed that neither compounds affected germination percentage in concentrations up to 1.0 mM. Above this concentration, they affected seed germination and cotyledon and root weights by suppressing the primary root elongation with the more significant effect caused by p-CA.

Variation in germination response among local populations of Scotch thistle, Onopordum acanthium L.

Abstract: Cypselas of Scotch thistle, Onopordum acanthium L., collected from four populations in or near London, Ontario in September 1996, were incubated under seven diurnal light and temperature regimes (35/20, 25/10 and 10/5°C, both under alternating light and darkness and continuous dark conditions, plus a 20°C dark treatment). Although all populations originated on gravel soil of similar pH near the Thames River, there were large differences among populations in both germination rates and final percentages in several treatments. At 25/10°C, cypselas from all populations had 3.5 to 13 times as much germination in alternating light and dark as in continuous darkness. At 35/20°C three of the populations had higher germination percentages in continuous darkness than under alternating light and dark. Under both 10/5°C treatments, as well as at 20°C in darkness, less than 8% germination was recorded for any population. Under alternating light and dark, cypselas of all populations germinated fastest in the 25/10°C treatment. Variation in germination response among local populations gives a species a greater range of responses and a better chance of surviving changeable environmental conditions.

Temperature requirements for seed germination in four annual clovers grown under two irrigation treatments.

Abstract: Annual clovers are very popular fodder crop species in the Mediterranean basin, however poor and slow seed germination, due to unfavourable temperatures, can cause somewhat erratic seedling emergence. Our objectives were to (i) evaluate the influence of two irrigation treatments during seed maturation on subsequent germination ability of seed and (ii) to determine the temperature requirements for seed germination in four annual clovers: berseem (Trifolium alexandrinum L.), crimson (Trifolium incarnatum L.), Persian (Trifolium resupinatum: L.) and squarrosum (Trifolium squarrosum L.). Seeds of each species were germinated in the dark in a germinator at constant temperatures of 5, 10, 15, 20, 25, 30 or 35°C. Germination counts were recorded daily for 14 d and percent germination at 7th and 14th days, median germination time (MGT), rate of germination (GR) and the base temperature for germination (T g G) were determined. In all species the percent germination was not affected by the irrigation treatment during seed production, Percent germination and MGT showed a curvilinear relationship with temperature, a temperature of 20°C was optimum for berseem, crimson, and squarrosum elovers and 25°C for Persian clover. The four annual clovers had different sensitivity to temperature. Persian clover appeared to be the most macrothermic species with the T b G at 1.5°C, the optinum temperature for good germination at 23°C and a slight increment in MGT at 30-35°C. Berseem and squarrosum clover showed a very slow germination under cool temperatures. Results indicated that to reduce the risk of pour stand establishment in cold soils, particular attention should be used to program the time of autumn sowing for these species.

Effects of different salt (NaCl), nitrate (KNO3) and acid (H2SO4) concentrations on the germination of some Salvia species seeds.

Abstract: In this study, the seed germination characteristics of six Salvia species [ (S. cryptantha, S. cyanescens, S. dichroantha, S. tchihatcheffii, S. aethiopis, S. virgata)], and the effects of various concentrations of salt (NaCl), nitrate (KNO 3 ) and acid (H 2 SO 4 ) on germination rates of these species were examined. It was observed that, although all salt concentrations reduced germination percentage, low salt concentrations (0.5-1%) had no effect on germination speed while high concentrations (1-3%) had an inhibiting effect. Increasing concentration of potassium nitrate reduced germination percentage for all six Salvia species but two species (S. cyanescens and S. dichroantha) gave higher germination speed. Sulfuric acid inhibited both germination percentage and speed, inhibiting or preventing germination altogether. Significant differences in sensitivity to salt and acid were also determined among the six Salvia species.

Germination-enhancing techniques for Pinus monticola seeds and speculation on seed dormancy

Abstract: A papery-layer in seeds of Pinus monticola Dougl. ex D. Don delays germination and reduces efficient use of seeds in nurseries. Six experiments were used to improve the understanding of environmental effects on seed germination. I conclude most germination-enhancing treatments alleviate atmospheric paradormancy.

Incidence of bean common mosaic virus and bean common mosaic necrosis virus in bean (Phaseolus vulgaris L.) and wild legume seedlots in Tanzania.

Abstract: Nearly 10,300 seeds representing 341 bean (Phaseolus valgaris L.) and 30 wild legume seedllots from bear growing areas of Tanzania were screened for infection by bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) by using enzymc linked immunosorbent assay (ELISA). Wild legume species were included in the test to estimate the possible role of these species in the ecology of bean viruses. Virus isolates were grouped into serotypes by ELISA and into pathogroups by their pathogenecity reaction on differential bean cultivars. Thirty of the 341 P. vulgaris secdlots tested had virus infected seeds. No virus was detected in the wild legume seeds. A total of 122 isolates were obtained from bean seeds which had a positive reaction by ELISA. The isolates were differentiated into two serotypes, A and B, and three pathogenicity groups (PGs) (sensu Drijfhout, 1978). (PG I, PG JU and PG JV). Thirteen isolates comprised new pathotypes. Ninety of the 122 isolates were BCMNV and 32 were BCMV. The results of this study indicate that BCMV and BCMNV are widely distributed in seeds originating from research stations but scarce in farmers landraces. The results also showed that the main pathotypes of BCMNV and BCMV in Tanzania are NL1, NL3, and NLS. Two pathotypes TN2 and TN3 are reported for the first time, Implicatious are discussed for bean improvement research in Tanzania.