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: Michael Patrick Conway
Publisher:
ISBN:
Category : Wheat
Languages : en
Pages : 288

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Laboratory studies were conducted under different temperature and moisture regimes to evaluate the effects of temperature and moisture on stand establishment and seedling characteristics associated with stand establishment. Percent stand and days to 25% emergence were used as indexes of stand establishment. Seedling characteristics analyzed were: shoot length, coleoptile length, seedling dry weight, and Adenosine Triphosphate (ATP) content. Each of these characteristics were tested with regards to predicting stand establishment over a wide range of temperature and moisture conditions. Experiments on stand establishment were also conducted under field conditions at the Sherman Experiment Station in north-central Oregon. The degree of association between stand establishment estimates obtained in the field and estimates of stand establishments obtained in the laboratory was determined. Attempts were also made to determine the mode of inheritance of coleoptile length and Adenosine Triphosphate and the association of these characteristics with stand establishment in early generations. Seven soft white winter wheat cultivars (Yamhill, Moro, Stephens, McDermid, Hyslop, Luke, and Daws) were used in the laboratory and field experiments. Parents, F1 s, and F2s from crosses among four of the cultivars (Yamhill, Moro, McDermid, and Daws) were utilized in the inheritance studies of coleoptile length and ATP. Broad sense heritability estimates for coleoptile length were computed using the parental and F2 variances. Frequency distribution of coleoptile length were tested for their fit to normality by use of the chi square test. Narrow sense heritability estimates for coleoptile length and Adenosine Triphosphate were computed using the standard unit (correlation) and regression methods. Three temperatures levels 8, 15, and 22°C) and three soil moisture levels ( -2, -4, and -6 bars) were used to study the effects of temperature and moisture on stand establishment and stand establishment characteristics of the seven cultivars in the laboratory. Different temperature and moisture levels exhibited significant effects on percent stand, days to 25% emergence, shoot length, coleoptile length, seedling dry weight, and ATP. Increasing temperature from 8 to 22°C resulted in decreases in percent stand, days to 25% emergence, and coleoptile length. Shoot length, seedling dry weight, and ATP increased as temperature was increased from 8 to 22°C. Increasing moisture stress from -2 to -6 bars had a significant negative effect on percent stand, emergence rate, and each of the seedling characteristics studied. Coleoptile length was found to be the best predictor of percent stand over the entire range of temperature and moisture combinations utilized in the laboratory. Percent stand was observed to decrease whenever coleoptile length was less than the depth of planting. Shoot length was found to be the best predictor of days to 25% emergence over the entire range of temperature and moisture levels. Semi-dwarf cultivars produced poorer stands than tall cultivars due to their coleoptile length. This difference in stand establishment capability was most pronounced under the warmest temperature (22°C) and the greatest moisture stress ( -6 bars). Estimates of minimum gene number together with data obtained from frequency distribution indicated that the inheritance of coleoptile length was controlled by one to three major genes and possibly some modifier genes. The close agreement between broad and narrow sense heritability estimates indicated that the expression of coleoptile length is controlled primarily by additive gene action. This suggests that selection for coleoptile length in early generations should give reliable estimates of coleoptile length expression in later generations. The heritability of Adenosine Triphosphate (ATP) was found to be subject to cytoplasmic influence. Maternal effects in the F1 generation, the occurrence of considerable inbreeding depression in the F2 generation, and relatively low narrow sense heritability estimates suggest that ATP can not be used as a selection character for seedling vigor in early generations of wheat in a conventional breeding program. Several characteristics (coleoptile length, ATP, plant height, and seed weight) were tested for their association with percent stand in the F 1 and F2 populations. None of these characteristics were significantly correlated with percent stand. Of these characteristics, coleoptile length produced the highest correlations with percent stand in the F 1 and F2 generations. The use of coleoptile length as a selection character for percent stand in early generations appears promising.

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