scholarly journals Quantification of Germination Response of Millet (Panicum miliaceum L.) Seeds to Water Potential and Priming using Hydrotime Model

2019 ◽  
Vol 52 (2) ◽  
pp. 178-185
Author(s):  
S.A. Tabatabaei ◽  
N. Bayatian ◽  
S. Nikoumaram ◽  
O. Ansari
Keyword(s):  
Water Potential ◽  
Arid Regions ◽  
Biological Process ◽  
Physical Factors ◽  
Panicum Miliaceum ◽  
Germination Response ◽  
Complex Biological Process ◽  
Hydrotime Model ◽  
Short Time ◽  
Temperature Water

Abstract Seed germination is a complex biological process that is influenced by different environmental physical factors including temperature, water potential, salinity, pH and light, as well as intrinsic genetic factors. In such environments, the water needed for germination is available for only a short time, and consequently, successful crop establishment depends not only on rapid and uniform germination of the seedlot, but also on its ability to germinate under low water availability. All of these attributes can be analyzed through the hydrotime model (HT). Millet (Panicum miliaceum L.) is cultivated in arid and semi-arid regions of Iran. Therefore, in this study, using the hydrotime modeling approach, germination response of millet to priming (water and gibberellin 50 ppm at 15°C for 24 h) and water potential (0, -0.3, -0.6, -0.9, and -1.2 Mpa) was studied. Hydrotime (HT) model were fitted to cumulative germination of seeds and recorded in germination tests carried out at different water potentials (0, -0.3, -0.6, -0.9 and -1.2 MPa) and priming treatments (control, hydropriming and hormone priming). Results showed that, germination of millet decreased significantly with reduction of osmotic potential. Results indicated that the hydro-time constant (θH) for control, hydro-priming and hormone priming were 0.89, 0.79 and 0.67 MPa d, the water potential (Ψb(50)) for control, hydropriming and hormone priming were -0.89, -0.94 and -1.11 MPa, respectively. Results indicated that the use of hydrotime model in germination prediction could be useful to provide more accurate estimates for the timing of sowing and management of millet.

Hydropriming accelerates seed germination of Medicago sativa under stressful conditions: A thermal and hydrotime model approach

2017 ◽  
Author(s):  
Rong Li ◽  
Dandan Min ◽  
Lijun Chen ◽  
Chunyang Chen ◽  
Xiaowen Hu
Keyword(s):  
Water Potential ◽  
Germination Rate ◽  
High Water ◽  
Nacl Stress ◽  
Base Temperature ◽  
Severe Water Stress ◽  
Hydrotime Model ◽  
Response To Temperature ◽  
Base Water Potential ◽  
Temperature Water

This study determined the effects of priming on germination in response to temperature, water potential and NaCl. Thermal and hydrotime models were utilized to evaluate changes in parameters of the model after priming. Priming reduced the amount of thermal time in both cultivars, but slightly increased the base temperature for germination from 1.0 to 3.5°C in “Longdong”. Priming significantly increased germination rate at high water potential but had no effect at low water potential. Further, priming reduced the hydrotime constant but made the median base water potential value slightly more positive in both cultivars. Thus, priming increased germination rate in water but decrease it under severe water stress. Germination rate was significantly increased in both cultivars under salinity (NaCl) stress. Moreover, priming improved seedling growth in response to temperature, water and salinity stress in both cultivars.

The Factors Affecting the Stem Water Potential of Tamarix ramosissima Lbd. in the Extremely Arid Regions

2013 ◽  
Vol 800 ◽  
pp. 143-148 ◽  
Author(s):  
Ai Hong Fu ◽  
Wei Hong Li ◽  
Ya Ning Chen
Keyword(s):  
Soil Moisture ◽  
Environmental Factors ◽  
Water Potential ◽  
Arid Regions ◽  
Normal Growth ◽  
Tamarix Ramosissima ◽  
Tarim River ◽  
Stem Water Potential ◽  
Factors Affecting ◽  
Stem Water

Using Tamarix ramosissima Lbd. growing in the extremely arid regions along the lower reaches of Tarim River, Xinjiang, we preformed a series of investigations on the effects of weather, soil moisture and salt on the stem water potential (ψs) of T. ramosissima. We identified the leading environmental factors affecting ψs of T. ramosissima and detected the thresholds of the environmental factors. First, the soil moisture was the most important factor affecting ψs of T. ramosissima among all the environmental factors. While there was no minimum threshold of the soil moisture for T. ramosissima to absorb moisture from soil, the highest threshold of the soil moisture was 36%. When the soil moisture was higher than 36%, there was a significant change on ψs of T. ramosissima. Our study provides crucial empirical data for keeping the normal growth of T. ramosissima.

scholarly journals The Boyd Orr Lecture: Nutrition interventions in aging and age-associated disease

2002 ◽  
Vol 61 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Mohsen Meydani
Keyword(s):  
Oxidative Stress ◽  
Cardiovascular Disease ◽  
Vitamin E ◽  
Biological Process ◽  
Sedentary Lifestyle ◽  
The Elderly ◽  
Energy Restriction ◽  
Cell Junction ◽  
Nutrition Interventions ◽  
Complex Biological Process

Aging is a complex biological process, which usually is accompanied by changes in socioeconomic status, which may have a great impact on the physical and nutritional status of the elderly. Decreased food intake and a sedentary lifestyle in the growing numbers of the elderly increase their risk for malnutrition, decline of bodily functions and developing chronic diseases. Oxidative stress is believed to be an important factor in aging and many age-associated degenerative diseases. Modulation of oxidative stress by energy restriction in animals has been shown to be one of the mechanisms for retarding the aging process. Dietary antioxidants are regarded as being important in modulating oxidative stress of aging and age-associated diseases. Supplementation of the elderly with vitamin E has been shown to enhance immune response, delay onset of Alzheimer's disease, and increase resistance to oxidative injury associated with exercise. Vitamin E, in comparison with other antioxidants, is also effective in reducing viral titres, but not the longevity of middle-aged mice. Our studies have indicated that polyphenols or vitamin E may assist in preventing cardiovascular disease, in part by decreasing expression by endothelial cells of proinflammatory cytokines, adhesion molecules, and monocyte adhesion. Most recently, we have found that some of these antioxidants may prevent tumour growth by inhibiting angiogenesis via suppression of interleukin 8 and modulation of the cell junction molecule, VE-cadherin. These findings provide further support for the consumption of fruit and vegetables, which contain several forms of phytochemicals with antioxidant activity, in order to reduce the risk of cardiovascular disease and cancer, the leading causes of morbidity and mortality among the elderly.

Hydrothermal time analysis of tomato seed germination at suboptimal temperature and reduced water potential

1994 ◽  
Vol 4 (2) ◽  
pp. 71-80 ◽  
Author(s):  
Peetambar Dahal ◽  
Kent J. Bradford
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Time Course ◽  
Hydrothermal Time ◽  
Tomato Seed ◽  
Time Model ◽  
Germination Time ◽  
Radicle Emergence ◽  
Time Courses ◽  
Hydrotime Model

AbstractBoth temperature (T) and water potential (ψ) have consistent and quantifiable effects on the rate and extent of seed germination (radicle emergence). Germination at suboptimal T can be characterized on the basis of thermal time, or the T in excess of a base (Tb) multiplied by the time to a given percentage germination (tg). Similarly, germination at reduced ψ can be characterized on a hydrotime basis, or the ψ in excess of a base (ψb) multiplied by tg. Within a seed population, the variation in thermal times to germination for a specific percentage (g) is based upon the normal distribution of ψb values among seeds (ψb(g)). Germination responses across a range of suboptimal T and ψ might be accounted for by a general hydrothermal time model incorporating both T and ψ components. We tested this hypothesis for tomato (Lycopersicon esculentum Mill.) seeds of two genotypes differing in germination rates and tolerance of suboptimal T and ψ. For combinations of T (10−25°C) and ψ (0 to −0.9 MPa), a general hydrothermal time model accounted for approximately 75% of the variation in times to germination within the seed populations of both genotypes, and over 96% of the variation in median germination rates. However, ψb(g) distributions were sensitive to both the T and ψ of imbibition, resulting in a poor fit of the model to specific time course data. Analysis of germination timing separately for low and high ψ ranges within a given T resulted in specific models accounting for 88−99% of the variation in individual germination times and >99% of the variation in madian germination rates. Thus, for a given T and ψ range, the hydrotime model closely matched tomato seed germination time courses. Accumulated hydrothermal time accounted well for germination rates at ψ> −0.5 MPa across suboptimal T if ψb(g) was allowed to vary with T. Germination did not show a consistent response to T at ψ < −0.5 MPa, and estimated Tb values varied over different T ranges. Generalization of the hydrothermal time model across the entire range of suboptimal T and ψ was limited by physiological adjustments of the seeds to their current environment. The hydrothermal time model detected and quantified these adjustment processes that would otherwise not be evident from inspection of germination time courses. Temperature and water potential influence the time to germination via physiological mechanisms that reciprocally interact.

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