Growth And Water Potential Of Root Crops As Influenced By Salinity And Relative Humidity1 Pdf
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- Evapotranspiration and the Water Cycle
- Host genotype and age shape the leaf and root microbiomes of a wild perennial plant
- Influence of Soil Water Potential and Environment on the Internal Water Status of Grasses
Deficit irrigation of a landscape halophyte for reuse of saline waste water in a desert city. Saline waste waters from industrial and water treatment processes are an under-utilized resource in desert urban environments. Management practices to safely use these water sources are still in development. We used a deeprooted native halophyte, Atriplex lentiformis quailbush , to absorb mildly saline effluent mg l-1 total dissolved solids, mainly sodium sulfate from a water treatment plant in the desert community of Twentynine Palms, California.
Evapotranspiration and the Water Cycle
Suma, Kalyani Sreenivasan, A. Singh, J. The role of relative humidity RH while processing and storing seeds of Brassica spp. The variability in seed storage behaviour of different species of Brassica was also evaluated. The samples were stored at in sealed containers and various physiological parameters were assessed at different intervals up to three months. The seed viability and seedling vigour parameters were considerably reduced in all accessions at high relative humidity irrespective of the species.
Storage at intermediate relative humidities caused minimal decline in viability. On analyzing the variability in storage behaviour, B. The Brassica species have been cultivated in India since Vedic times. They are being used for many purposes, that is, edible oil, vegetable, fodder preparation and seasoning of food articles, and so forth.
They have also been used as medicine and condiments. The Brassica species complex is generally referred to as rapeseed mustard, which is the second most important edible oilseed crop of India after groundnut. The cultivation of rapeseed mustard, which was earlier confined to the northern belt, has now spread to nontraditional areas in western and southern regions of the country.
Eruca sativa , a member of Brassicaceae family, is an underutilized oilseed crop. Availability of genetic diversity in the gene pool of cultivated species is key for a planned genetic improvement and variety development programme.
In Brassica , availability of genetic diversity has been one of the major constraints. This is because the sizable collection available in the country does not represent the total spectrum of variability and because of the fact that, despite recognition to the importance of genetic diversity, it is being eroded because of poor conservation efforts.
Appropriate conditions have to be identified to restrict the deterioration of seed during processing and to prolong the life of the seed in storage. Therefore, considerable interest has been shown to investigate most suitable seed characteristics and storage conditions for prolonged germplasm conservation [ 1 — 3 ], as long term storage may adversely affect the regeneration capabilities of the seed.
The moisture content of the harvested seed is influenced by the surrounding relative humidity and the temperature conditions, the two major factors that control the longevity of the seed in processing and storage.
Therefore, the seed processing and storage problems are common in tropical countries like India, which has predominantly hot and humid tropical and subtropical conditions with great variation in relative humidities and temperatures throughout the year as per the season: summer, winter, and rainy , including biennial variation. Frequent fluctuation and relative humidity make the processing and storage of seeds difficult to minimize the loss of viability and change in genetic integrity of the seed and thereby conservation of genetic resources.
Research on the seed storage has corroborated that high temperature and relative humidity conditions accelerate the deterioration of the seed and thereby cause ageing. Therefore, exposure of seed to high temperature and high moisture conditions will cause ageing and has been commonly used for accelerated ageing of seeds in the laboratory. Such treatments to seeds prior to germination may yield useful information concerning the loss of seed viability, vigour, and longevity of viability [ 4 ] and may be used as a tool for predicting the relative seed-longevity.
Thus deterioration would occur relatively slowly at low moisture and temperature. Hence, seed drying in case of orthodox seeds is an important step in seed processing. The seeds absorb or lose moisture till the vapor pressure of seed moisture and atmospheric moisture reach equilibrium [ 5 ]. However, experiments have shown that there are limits to the beneficial effects of drying and that drying below a critical level of moisture content will not improve longevity [ 6 ] and may even have detrimental effect on seed survival during processing and storage [ 7 ].
The type of storage component in the seed also influences the equilibration of seed moisture content. Nutrients stored in the seeds are mainly sugar, starch, protein, and fat oil. The four components differ in their water affinity, sugar being the most hygroscopic binding most water followed by protein, starch, and oil. For fully hygroscopic seeds, oil content is a major factor that determines the attainment of final equilibrium seed moisture content.
The role of oil is passive, acting as a constant, but it is hydrophobic element of the seed weight; consequently seeds with high oil contents equilibrate to lower moisture contents faster under the same conditions than seeds with lower oil contents.
Because of the differences in anatomical structure and storage components of seeds, the equilibrium moisture content differs between species. Recognizing the value of critical moisture level, an insufficient drying may result in less than maximum longevity potential, while overdrying may result in waste of energy without any positive effect. Therefore, there is a need to investigate the effect of temperature and relative humidity for equilibration of seed moisture content to desirable levels.
In addition species as Brassica are rich in oil contents, it could also be understood how the composition of oil content in the seed effects the drying of seed during processing and seed-viability during storage.
In the present investigation an effort was made to investigate the role of relative humidity while processing and storaging Brassica seeds and to assess and analyze the variability in seed storage capacity of various species of Brassica and Eruca sativa under different relative humidities. The seed materials used in the present study include three accessions each of Brassica spp. In order to investigate the role of ambient relative humidity during seed drying and transit storage, seeds were stored over saturated solutions of various salts for maintaining different levels of relative humidity.
The relative humidities were established based on the method of Winston and Bates [ 8 ] using specific standard salt solutions while the temperature was maintained using incubators set at the required temperature and relative humidities were monitored with the help of hygrothermograph.
The samples were stored in the respective humidity in sealed containers, which were then transferred to an incubator, maintained at. Various physiological parameters were estimated to assess the effect of relative humidity on seed drying and transit storage. Germination tests were conducted using 25 seeds in three replications.
Seeds were plated in petri plates with wet filter paper and kept in germinator maintaining adequate humidity and temperature of [ 9 ]. Germination count was taken every day up to the seventh day. Germinated seeds were removed every day. Germination percentage was recorded on the basis of normal seedlings. Speed of germination was estimated along with standard germination test.
The humidity and temperature of germinator where samples were kept for speed of germination were the same as those of normal germination test. The seedling vigour and vigour index were calculated by plating the seeds on germination paper of dimension. The seeds were arranged on the paper and kept vertically on the template placed over water in a tray and covered with another tray to prevent entry of light.
Observations were taken on the seventh day of sowing. Three replications of 10 seeds each were sown. The length of roots and shoots was measured in centimeter and calculated on the basis of total number of seeds plated [ 11 ].
Vigour index was computed adopting method of Abdul-Baki and Anderson [ 12 ]. The most common method of determination of seed moisture is oven drying method. The principle underlying this method is the elimination of water from the seed by drying precisely for prescribed duration and temperature. The moisture content is expressed as the percentage of the seed dry weight. Each empty moisture bottle was weighed including its lid. Samples were added to these bottles.
The weight of the moisture bottle with sample was taken. Samples in moisture bottles with their lids open were placed in oven for drying. The moisture contents were calculated using the formula.
The data recorded as percentage were transformed to the respective angular arc sin values before subjecting them to statistical scrutiny. Moisture content is the primary factor influencing the storability of seeds. The seeds acquired the mean equilibration moisture content after 30 days after treatment and thereafter stabilized in this moisture.
When the seed lots of different accessions of Brassica spp. The accessions of B. Even small increments in moisture content are expected to influence the storability of seed at elevated temperature significantly and hence the observed differences in the germination percentage of the accessions of various species of Brassica and Eruca sativa.
The variability in seed viability could also be attributed to genotype differences between Eruca sativa and Brassica spp. This clearly indicates that rapeseed storage even for a short period under high relative humidity conditions should be avoided in the tropical region where such high temperature and RH conditions may occur.
The equilibrium moisture content of the seeds of various accessions was in the range of 0—0. Storage studies for longer duration are required to brief out the differences between storability of species under such circumstances.
The maintenance of germination capacity of various accessions of Brassica and Eruca sativa may be purely due to their genetic makeup, which also controls the proximate composition of the seeds. Many kinds of seed do not withstand drying to such low levels of moisture [ 17 ]. Rapeseeds being oil seeds and hydrophobic in nature probably caused tolerating drying to such low moisture content. Similar work on storage behaviour of Pongamia pinnata seeds also revealed comparable results of decline in germination percentage and vigour parameters and also increased time needed for germination [ 18 ].
The seed moisture contents to which the seeds equilibrated at these relative humidities were 3, 4, and 5 percent, respectively. Although the differences are less significant, there is an optimum water content for seed storage and for seeds with high oil content.
There is also undisputed evidence that the value of the critical water content varies among species and has an inverse relationship with the lipid content of seed [ 2 , 6 ]. Nakamura [ 17 ] has listed B. Halder and Gupta [ 21 ] studied the deterioration patterns of sunflower seeds stored at low and high relative humidities. They observed that the germinability changed very little during storage but observed reduced level of dehydrogenase enzymes in the embryonal axis of seeds at both low and high RH which indicates that changes in macromolecules occurred even when no observable changes could be seen at low relative humidity level.
Accelerated rate of production of lipid peroxidation products and decline in phospholipids have been cited as reason for faster rate of deterioration of seed stored at lower relative humidities at elevated temperature. MGT was significantly different among the species but not among accessions within the species. Delayed germination is one of the earliest responses exhibited by crop seeds, when they deteriorate.
The increase in MGT was significantly higher for B. Even though germination percentage was maintained high at all the three intermediate RH levels, time taken for germination MGT was high in all the accessions compared to the control. According to Bailly et al.
It was stated that the rate at which the seed ageing process takes place depends on the ability of the seeds to resist degradation changes and protection mechanisms, which are specific for each plant species [ 24 — 26 ] and also differ among varieties of the same species [ 27 ]. Increased rates of deterioration at elevated temperature and higher moisture contents have been reported, for corn seeds aged under similar conditions by Tang et al. The decline in shoot length was more remarkable at higher RH treatment.
In the table, the shoot length of control seeds ranged from 5. The differences are significant but not drastic. Minimum shoot length was observed for the Eruca sativa accessions followed by B. Differences among the different accessions of a species were not significant although difference between accessions of different species was highly significant.
Similar to shoot length root length declined with the passage of time, both under high and low RH Tables 4 a and 4 b.
Host genotype and age shape the leaf and root microbiomes of a wild perennial plant
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Suma, Kalyani Sreenivasan, A. Singh, J. The role of relative humidity RH while processing and storing seeds of Brassica spp. The variability in seed storage behaviour of different species of Brassica was also evaluated. The samples were stored at in sealed containers and various physiological parameters were assessed at different intervals up to three months.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Brown Published Environmental Science. Herman H. Wiebe Department: Biology The water relations of two grass species, smooth brome Bromus inermis Leyss. View PDF. Save to Library.
Abstract Crop salt tolerance is not absolute but depends on influence of atmospheric relative humidity on plant growth and how it interacts with salinity different osmotic potentials (s Ψo), the range depending on the crop's salt tolerance. With a nonsaline root medium, increasing the RH from 45 to 90%.
Influence of Soil Water Potential and Environment on the Internal Water Status of Grasses
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Salinity and sodicity are soil conditions that occur mainly in arid and semiarid regions. Rainfall leaches salts out of soils in humid regions, and salt problems are rare and transitory.
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