Effect of Low Temperature and Moisture Stress on Seed Germination and Seedling Vigor of Wheat PDF Download

Author: Chaudhry Mohammad Ashraf
Publisher:
ISBN:
Category : Wheat
Languages : en
Pages : 146

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Author: Mya Than
Publisher:
ISBN:
Category : Wheat
Languages : en
Pages : 114

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Germinating seeds often encounter stress conditions of temperature, moisture and oxygen in the field. Germination tests conducted under these stress conditions in the laboratory might be methods of differentiating high and low vigor seeds. The objectives of this study were to (1) determine if these stress conditions reduce germination performance of low vigor seeds more than high vigor seeds, and (2) determine the potential for using one or more of these stress environmental conditions as the basis of a vigor test to predict relative field performance of wheat seed. Seed lots of varying levels of deterioration were produced by artificial aging of 'Malcolm' wheat (Triticum aestivum L.). Germination tests were conducted at temperatures of 5, 10, 15, 20, 25, and 30°C; water potentials of 0, -0.2, -0.4, -0.6, -0.8, -1.0, -1.2, and -1.4 MPa; and oxygen levels of 2, 4, 8, 12, 16% and air (21%). The water and oxygen stresses were applied at six temperatures. Laboratory germination results were compared to field emergence percentages of artificially and naturally aged seed lots. Germination percentage and rate of germination of low vigor seeds were depressed more than that of high vigor seeds at all water potentials and temperatures. At 20°C, for example, germination percentage of high, medium and low vigor seed lots at -0.6 MPa were 76, 48 and 29% respectively, compared to nearly 100% at 0, -0.2 and -0.4 MPa. Similar relationships existed at the other temperatures. Germination of low vigor seed generally declined with each reduction of oxygen level while that of high vigor seed remained nearly constant. The germination differential between high and low vigor seed lots widened to as much as 30% in 2% oxygen at 30°C. Twenty-four naturally-aged seed lots representing six varieties and four production years were evaluated for germination under water stress and field emergence. Correlation coefficients between germination at -0.6 MPa and field emergence were 0.61** and 0.59** for untreated and Arasan-treated seeds, respectively. It is clear from these studies that environmental stresses reduce the germination of low vigor seeds more than that of high vigor seeds. A vigor test based on one or more of these stresses has potential for being a practical and realistic method of predicting the relative field performance of wheat seed lots.

Author: Marcos Vinicius Assuncao
Publisher:
ISBN:
Category : Wheat
Languages : en
Pages : 216

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Two experiments were conducted to determine the effects of moisture stress on physiological changes that occur during the vegetative and reproductive stages of the wheat (Triticum aestivum L.) plant, and to relate these effects to seed yield, quality and performance. In a field experiment, different levels of moisture stress were obtained by establishing plots in two rainfall areas, and by planting on three different dates in the dryland area. Seed development and maturation occurred under extreme moisture stress in Moro (254mm annual rainfall), while stress at Corvallis (1020 mm annual rainfall) was low. Plants from the early fall planting were subjected to the most stress because of the greater fall growth which removed much of the soil moisture. Lowest seed yields occurred under the greatest moisture stress conditions, primarily because of a reduced number of seeds per spike. Seed size was the quality component most affected by moisture stress. Smaller seed size was associated with lower soil water potential, higher leaf area index during vegetative growth, and higher specific leaf weight and water soluble carbohydrate content of the plants after anthesis. Water soluble carbohydrate content was particularly high in the rachises of the most severely stressed plants, indicating a reduced rate of translocation to the developing seeds. Embryo weight was also reduced in the more stressed plants in proportioa to the reduction in seed weight. The protein contents of seeds from all three moisture stress levels at Moro were similar. Seeds developed under the most severe water stress had the highest respiratory quotient and lowest glutamic acid decarboxylase activity. The growth rate of seedlings produced by these seeds was 29% lower than that from seeds from the less stressed plots. A greenhouse experiment was conducted to study the effects of water stress under controlled conditions. Plants were grown under three moisture regimes (600, 300 and 150 ml water/pot/day) from the time awns were first visible on the main stem until maturity. Water-stressed plants had smaller leaf area and leaf dry weight, higher specific leaf weight, earlier leaf senescence, lower dry weight, and lower seed yield. On the other hand, water-stressed plants produced larger seeds, with heavier embryos, higher protein content, lower CO2 evolution and lower respiratory quotient. These seeds in turn produced seedlings with greater vigor in terms of seedling growth rate. Because of the compensation ability of the wheat plant, development of management practices to decrease certain yield components in favor of enhanced seed quality is worthy of further study.

Author: Mirza Hasanuzzaman
Publisher: Springer Nature
ISBN: 9811386250
Category : Science
Languages : en
Pages : 604

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This book introduces readers to both seed treatment and seedling pretreatments, taking into account various factors such as plant age, growing conditions and climate. Reflecting recent advances in seed priming and pretreatment techniques, it demonstrates how these approaches can be used to improve stress tolerance and enhance crop productivity. Covering the basic phenomena involved, mechanisms and recent innovations, the book offers a comprehensive guide for students, researchers and scientists alike, particularly Plant Physiologists, Agronomists, Environmental Scientists, Biotechnologists, and Botanists, who will find essential information on physiology and stress tolerance. The book also provides a valuable source of information for professionals at seed companies, seed technologists, food scientists, policymakers, and agricultural development officers around the world.

Author: Majid N. Fandi
Publisher:
ISBN:
Category :
Languages : en
Pages : 262

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Author: Susana Araújo
Publisher: BoD – Books on Demand
ISBN: 953512658X
Category : Technology & Engineering
Languages : en
Pages : 214

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New Challenges in Seed Biology - Basic and Translational Research Driving Seed Technology combines different aspects of basic and translational research in seed biology. A collection of eight chapters written by seed biology experts from the field of seed physiology, ecology, molecular biology, biochemistry, and seed technology was gathered. We hope that this book will attract the attention of researchers and technologists from academia and industry, providing points for interactive and fruitful discussion on this fascinating topic.

Author: Amal Faraj Ahmed Ehtaiwesh
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Increased ambient temperature and soil salinity seriously affect the productivity of wheat (Triticum aestivum L.) which is an important cereal second to rice as the main human food crop. However, wheat plant is most susceptible to high temperatures and salinity at booting and flowering stages. Several studies have documented the effects of individual stress like salinity and high temperature stress on wheat, nonetheless little is known about effects of combined salinity and high temperature at critical growth stages. Therefore, the objectives of this research were (i) to screen winter wheat germplasm for salinity tolerance at the germination stages and to determine seedling growth traits associated with salinity tolerance, (ii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the booting stages through growth, physiological, biochemical, and yield traits, and (iii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the flowering stages through growth, physiological, biochemical, and yield traits. In the first experiment, 292 winter wheat genotypes (winter wheat germplasm) was screened for salinity stress at germination stage under controlled environments. The seeds were subjected to three levels of salinity, 0, 60, and 120 mM NaCl to quantify the effects of salinity on seed germination and seedling growth. In the second experiment, controlled environment study was conducted to quantity the independent and combined high temperature and salinity stress effects on growth, physiological, biochemical, and yield traits of twelve winter wheat genotypes during booting stage. Plants were grown at 20/15 °C (daytime maximum/nighttime minimum) temperature with 16 h photoperiod. At booting stages, the plants were exposed to optimum (20/15 °C) or high temperature (35/20 °C) and without (0 mM NaCl) and with (60, and 120 mM) NaCl. In the third experiment, plants were exposed to optimum or high temperature and with and without NaCl levels at flowering stages. The temperature regime and salinity levels were same as experiment II. The duration of stress was 10 d and after the stress period the plants were brought to optimum temperature and irrigated with normal water (0 mM NaCl). The results indicated that, at 120 mM NaCl, the final germination percentage was decreased and the mean daily germination was delayed. Irrespective of the genotype, salinity stress significantly decreased the shoot and root length; seedling dry matter production, and seedling vigor. Based on the seedling vigor index, the genotype GAGE, OK04507, MTS0531, TASCOSA, ENDURANCE and GUYMON, were found to be most tolerant and CO04W320, 2174-05, CARSON, OK1070275, TX02A0252 and TX04M410211 were the most susceptible to salinity at germination stage. Combined stresses of high temperature and salinity decreased photosynthetic rate and grain yields. Based on grain yield, the genotype TASCOSA was found to be most tolerant (64 % decrease) to combined stresses, and AVALANCHE was the most susceptible to combined stresses (75 % decrease) at booting stages. Similarly, at flowering stage, TX04M410211 had greater tolerance to combined stresses (65 % decline) as compared to GAGE (83 % decline). In both experiments, tolerance was associated with higher spikelet number and seed set. In conclusion, there is genetic variability among winter wheat genotypes that can be used in breeding programs to improve winter wheat yield under combined high temperature and salinity stress conditions.

Author: Sergey Shabala
Publisher: CABI
ISBN: 1780647298
Category : Science
Languages : en
Pages : 378

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Completely updated from the successful first edition, this book provides a timely update on the recent progress in our knowledge of all aspects of plant perception, signalling and adaptation to a variety of environmental stresses. It covers in detail areas such as drought, salinity, waterlogging, oxidative stress, pathogens, and extremes of temperature and pH. This second edition presents detailed and up-to-date research on plant responses to a wide range of stresses Includes new full-colour figures to help illustrate the principles outlined in the text Is written in a clear and accessible format, with descriptive abstracts for each chapter. Written by an international team of experts, this book provides researchers with a better understanding of the major physiological and molecular mechanisms facilitating plant tolerance to adverse environmental factors. This new edition of Plant Stress Physiology is an essential resource for researchers and students of ecology, plant biology, agriculture, agronomy and plant breeding.

Author: Roberto Benech-Arnold
Publisher: CRC Press
ISBN: 1482277948
Category : Science
Languages : en
Pages : 501

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The latest findings in seed physiologydiscussed as they relate to agricultural problems! Presenting the latest findings in the area of seed physiology as well as the practical applications of that knowledge in the field, the Handbook of Seed Physiology: Applications to Agriculture provides a comprehensive view of seed biology and it

Author: Maya Muhieddine Bleik
Publisher:
ISBN:
Category : Soil moisture
Languages : en
Pages : 198

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Drought is the most common adverse environmental factor which limits crop productivity, especially in the Middle East area. Cultivating drought resistant wheat cultivars is therefore common sense to achieve stability in production. The objectives of this thesis were to determine the effect of various levels of osmotic stress on imbibition, germination and seedling growth of drought tolerant and drought susceptible wheat cultivars. Several parameters were recorded to evaluate cultivar response to osmotic stress including final moisture content {mg of H20 g"1 of dry seed) after imbibition, relative imbibition rate, percent germination, speed of germination index, percent elastic resistance, shoot length, root length, fresh and dry weight of shoots and roots, ratio of shoot to root, mean relative growth rate, leakage ratio of roots, and relative water loss of leaves. All cultivars showed similar patterns of imbibition regardless of the level of osmotic stress they were exposed to. Speed of germination was shown to be more sensitive to reduced osmotic potential than percent germination and thus is a more reliable parameter that can be used in selecting drought resistant cultivars. The relative tolerance of the five wheat cultivars to moisture stress at germination was Cham-6 > Salamouni > Najah > Mexipak > Memof. Cham-6 had also the best recovery from water stress while the other cultivars did not differ significantly. At the seedling stage, no cultivar differences in root and shoot lengths and fresh and dry weights of roots were observed. At that stage, Cham-6 had the lowest shoot to root ratio and Salamouni the lowest relative water loss ratio indicating once again their tolerance to drought. Parameters at which we had significant varietal differences corresponding to the actual drought rating of cultivars were the speed of germination index, percent elastic resistance, and ratio of shoot to root. Accordingly, these can be used as indicators of drought tolerance in wheat. As far as wheat is concerned, the general observation made from the screening results was that drought tolerance should not be treated as a single trait but rather as an accumulation of desirable drought tolerant traits.