(pp. 87-95)
Seed Vigor and Uniformity of Seedling Emergence in Soybean
D.B. Egli*, Brigitte Hamman and Marcy Rucker
ABSTRACT:
Seed vigor is defined as those “seed properties that determine the potential for rapid, uniform emergence and development of seedlings under a wide range of field conditions.” The relationship between seed vigor and soybean [Glycine max (L.) Merr.] seedling emergence is well documented, but much less is known about the effect of seed vigor on the uniformity of emergence.
Emergence of seedlings from seed lots with standard germination > 80% and seed vigor levels (accelerated-aging germination) from 5 to 94% was determined in greenhouse experiments that included variation in planting depth (2.5 to 8.9 cm), low temperatures, and sterile and pathogeninfected soil. Emergence (growth stage VE) was counted at 4- to 8-h intervals and the Gompertz model was used to describe cumulative emergence vs. time. The uniformity index (UI) (time from 10 to 90% of maximum emergence) varied from~15 to 160 h and increased as the time to 50% emergence (T50) increased. Seed vigor had no effect on UI when the seedlings emerged rapidly, but the UI for high-vigor seed was smaller (emergence was more uniform) than for low vigor seed when T50 was large (less than ideal conditions for emergence). The largest UI (~160 h) occurred when lowvigor seed was planted deep in pathogen-infested soil. Seed size (sized vs. unsized or large vs. small) had no effect on UI. Uniformity was related to seed vigor, but only when conditions for emergence were less than ideal.
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(pp. 96-107)
Effects of Salinity and Temperature on Germination and Seedling Growth of Nine Medicinal Plant Species
F. Nadjafi*, J. Shabahang and A.M.Mahdavi Damghani
ABSTRACT:
Salinity stress is a major environmental constraint in arid and semi-arid regions such as Iran. Excessive amounts of salt in soil severely reduce seed germination and seedling growth of crops in agricultural systems. The purpose of this research was to study the effect of temperature, salinity and their interaction on the germination and seedling growth of nine medicinal plant species.
Treatments included three temperatures (15, 25 and 35 °C) and four NaCl concentrations (0, 5.3, 8.48 and 10.6 g L-1). Results showed that salinity treatments significantly reduced germination percentage, germination rate, seedling growth and seedling vigor in all nine medicinal plant species. Germination percentage and germination rate of all medicinal plant species gradually declined as the concentration of NaCl increased. Ocimum basilicum was the only species among the nine medicinal plants in this study that germinated in salinity concentration of 8.48 g L-1. Germination rate and germination percentage of all species, except O. basilicum were adversely affected by increasing temperature to 35 °C. The highest seedling vigor in most species was observed in a temperature range of 15 to 25 °C and increasing temperature up to 35 °C strongly decreased it. The interaction effect of temperature and NaCl concentration on final germination in all species was significant, indicating that germination response to salinity depended on temperature. The inhibitory effect of high salinity on final germination, germination rate, seedling growth and seedling vigor was greater at 35 °C than at 15 °C.
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(pp. 108-116)
Pretreatments Influence Germination of Myrica esculenta Buch-Ham. Ex. D. Don., a Multipurpose Tree Species of the Subtropical-Temperate Himalayan Region
Shruti Shah* and Ashish Tewari
ABSTRACT:
Myrica esculenta is well-known for its edible fruit and other by-products and has emerged as a potential income generating species. The species is generally propagated via seeds but physical dormancy caused by an impermeable seed coat results in unreliable germination.
Fruits of M. esculenta were collected from nine sites varying from low, mid and high range of the species’ distribution (900–2100 masl) and used to study the influence of eight pretreatments on germination. Seeds treated with different concentrations and durations of sulfuric acid (H2SO4) failed to germinate. Seeds treated with hot water gave maximum germination ranging between 33% and 57%. Seeds treated with cold water showed 13% to 26% higher germination compared to the control, whereas germination following hot water treatment was 10% to 26% higher than germination following cold water treatment.
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(pp. 117-127)
Cryopreservation Criteria of Podophyllum hexandrum and Aconitum heterophyllum Seeds Based on Storage Behavior
Rekha Kushwaha, Sanjoy Chanda, R.K. Ogra and Amita Bhattacharya*
ABSTRACT:
The storage method to preserve seed quality is highly dependent on the recalcitrant, orthodox and intermediate nature of seeds. Storage behavior of Aconitumheterophyllum and Podophyllumhexandrum, two endangered medicinal plants of western Himalaya, is unknown, preventing cryopreservation of these species. To develop seed cryopreservation protocols for these highly valued medicinal species, moisture content and temperature effects on storability were evaluated by seed germination and viability.
While seeds did not maintain high germination percentages when stored at 25 °C, irrespective of moisture content, seeds of both species desiccated to 5% moisture content could withstand temperatures as low as −20 °C. The critical storage temperature and moisture content of these seeds were 4 °C and 5%, respectively, based on germination (100 and 75%) recorded after 12 and 24 months. This seed storage behavior characterized the seeds of both species as “orthodox”. Following newly established moisture and temperature criteria, 14 accessions of P. hexandrumand two accessions of A. heterophyllum were successfully cryopreserved for future germplasm availability.
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(pp. 131-137)
SNP Induced Improvement in Seed Germinability Characteristics in Brassica napus Under Simulated Drought Conditions
Shalini Pahwa*, R.C. Setia and Neelam Setia
ABSTRACT:
The present investigation was carried out to evaluate the carryover effects of foliar applications of nitric oxide (NO) using sodium nitroprusside (SNP) as a donor at 50, 100, 200 and 400 μg mL-1 on seed quality in terms of seed germinability characteristics of Brassica napus L. (cv. GSL-1) under simulated drought conditions.
Seeds harvested from SNP treated plants showed higher germination percentage, seedling length, seedling dry weight and seedling vigor as compared to controls when germinated at different PEG induced osmotic potentials (0, −0.2, −0.4 and −0.6 MPa). Seed imbibition, electrolyte leakage and relative water content of seedlings were also favorably altered following SNP treatments when seeds were germinated under simulated drought conditions. Thus, seeds from SNP treated plants performed better under all PEG levels indicating the improved quality of seeds in terms of germinability characteristics. Among different SNP foliar treatments, 100 μg mL-1 SNP showed better germinability and seedling responses.
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(pp. 138-144)
Pretreatment Effects on Germination of Mimusops elengi L.
Bharat Gami*,Minoo Parabia and I.L. Kothari
ABSTRACT:
Seed germination of Mimusops elengi L. is hindered by a hard seed coat making natural revegetation through seeds very difficult. This study was conducted to establish a method of seed germination for M. elengi.
Treatments included subjecting seeds treated to hot water and sulfuric acid (H2SO4) for 20 and 40min, withering of viable seeds in cow and buffalo manure for 45 d and in vitro propagation on MS media fortified with plant growth regulators including IBA, 2,4-D, IAA, Kn, BA and GA at concentrations of 0.2 mg L-1. Well-developed seedlings were transferred to sterilized soil-sand mixtures and subsequently transferred to containers with soil and compost fertilizer for further growth. Sulfuric acid and hot water did not promote germination, while withering with manure improved germination. Seed germination was observed in media fortified with IBA, Kn, BA and GA while 2,4-D did not promote germination. In vitro developed seedlings were successfully transplanted to the field with a 100% survival rate. In vitro techniques proved superior to conventional techniques for seed propagation of M. elengi.
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