THE WATER RELATIONS OF RUBBER (HEVEA BRASILIENSIS): A REVIEW

2011 ◽  
Vol 48 (2) ◽  
pp. 176-193 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
East Asia ◽  
Water Relations ◽  
Leaf Growth ◽  
Water Productivity ◽  
Stomatal Closure ◽  
Rubber Tree ◽  
Background Information ◽  
South East Asia ◽  
Water Requirements ◽  
Water Potentials

SUMMARYThe results of research done on water relations of rubber are collated and summarised in an attempt to link fundamental studies on crop physiology to crop management practices. Background information is given on the centres of origin (Amazon Basin) and production of rubber (humid tropics; south-east Asia), but the crop is now being grown in drier regions. The effects of water stress on the development processes of the crop are summarised, followed by reviews of its water relations, water requirements and water productivity. The majority of the recent research published in the international literature has been conducted in south-east Asia. The rubber tree has a single straight trunk, the growth of which is restricted by ‘tapping’ for latex. Increase in stem height is discontinuous, a period of elongation being followed by a ‘rest’ period during which emergence of leaves takes place. Leaves are produced in tiers separated by lengths of bare stem. Trees older than three to four years shed senescent leaves (a process known as ‘wintering’). ‘Wintering’ is induced by dry, or less wet, weather; trees may remain (nearly) leafless for up to four weeks. The more pronounced the dry season the shorter the period of defoliation. Re-foliation begins before the rains start. The supply of latex is dependent on the pressure potential in the latex vessels, whereas the rate of flow is negatively correlated with the saturation deficit of the air. Radial growth of the stem declines in tapped trees relative to untapped trees within two weeks of the start of tapping. Roots can extend in depth to more than 4 m and laterally more than 9 m from the trunk. The majority of roots are found within 0.3 m of the soil surface. Root elongation is depressed during leaf growth, while root branching is enhanced. Stomata are only found on the lower surface of the leaf, at densities from 280 to 700 mm−2. The xylem vessels of rubber trees under drought stress are vulnerable to cavitation, particularly in the leaf petiole. By closing, the stomata play an essential role in limiting cavitation. Clones differ in their susceptibility to cavitation, which occurs at xylem water potentials in the range of −1.8 to −2.0 MPa. Clone RRII 105 is capable of maintaining higher leaf water potentials than other clones because of stomatal closure, supporting its reputation for drought tolerance. Clones differ in their photosynthetic rates. Light inhibition of photosynthesis can occur, particularly in young plants, when shade can be beneficial. Girth measurements have been used to identify drought-tolerant clones. Very little research on the water requirements of rubber has been reported, and it is difficult to judge the validity of the assumptions made in some of the methodologies described. The actual evapotranspiration rates reported are generally lower than might be expected for a tree crop growing in the tropics (<3 mm d−1). Virtually no research on the yield responses to water has been reported and, with the crop now being grown in drier regions, this is surprising. In these areas, irrigation can reduce the immaturity period from more than 10 years to six years. The important role that rubber plays in the livelihoods of smallholders, and in the integrated farming systems practised in south-east Asia, is summarized.

scholarly journals THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF SUGAR CANE (SACCHARUM OFFICINARUM): A REVIEW

2011 ◽  
Vol 47 (1) ◽  
pp. 1-25 ◽  
Author(s):  
M. K. V. CARR ◽  
J. W. KNOX
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Sugar Cane ◽  
Root Zone ◽  
Water Productivity ◽  
Crop Coefficient ◽  
Saccharum Officinarum ◽  
Irrigation Scheduling ◽  
Background Information ◽  
Technology Choice

SUMMARYThe results of research on the water relations and irrigation needs of sugar cane are collated and summarized in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the centres of production of sugar cane is followed by reviews of (1) crop development, including roots; (2) plant water relations; (3) crop water requirements; (4) water productivity; (5) irrigation systems and (6) irrigation scheduling. The majority of the recent research published in the international literature has been conducted in Australia and southern Africa. Leaf/stem extension is a more sensitive indicator of the onset of water stress than stomatal conductance or photosynthesis. Possible mechanisms by which cultivars differ in their responses to drought have been described. Roots extend in depth at rates of 5–18 mm d−1 reaching maximum depths of > 4 m in ca. 300 d providing there are no physical restrictions. The Penman-Monteith equation and the USWB Class A pan both give good estimates of reference crop evapotranspiration (ETo). The corresponding values for the crop coefficient (Kc) are 0.4 (initial stage), 1.25 (peak season) and 0.75 (drying off phase). On an annual basis, the total water-use (ETc) is in the range 1100–1800 mm, with peak daily rates of 6–15 mm d−1. There is a linear relationship between cane/sucrose yields and actual evapotranspiration (ETc) over the season, with slopes of about 100 (cane) and 13 (sugar) kg (ha mm)−1 (but variable). Water stress during tillering need not result in a loss in yield because of compensatory growth on re-watering. Water can be withheld prior to harvest for periods of time up to the equivalent of twice the depth of available water in the root zone. As alternatives to traditional furrow irrigation, drag-line sprinklers and centre pivots have several advantages, such as allowing the application of small quantities of water at frequent intervals. Drip irrigation should only be contemplated when there are well-organized management systems in place. Methods for scheduling irrigation are summarized and the reasons for their limited uptake considered. In conclusion, the ‘drivers for change’, including the need for improved environmental protection, influencing technology choice if irrigated sugar cane production is to be sustainable are summarized.

Water relations characteristics of Alnusrubra and Populustrichocarpa: responses to field drought

1988 ◽  
Vol 18 (9) ◽  
pp. 1159-1166 ◽  
Author(s):  
S. R. Pezeshki ◽  
T. M. Hinckley
Keyword(s):  
Water Relations ◽  
Root Development ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Age ◽  
Leaf Water ◽  
Black Cottonwood ◽  
Red Alder ◽  
Mature Leaves ◽  
Water Potentials

Water relations of red alder (AlnusrubraBong.) and black cottonwood (populustrichocarpa Torr. & Gray) were studied in the field during the 1980, 1981, and 1982 growing seasons. Stomatal closure in response to drought was noted in both species; however, the following major differences were noted between the 1980 observations and those of 1981 and 1982; (i) stomatal conductance was greater in black cottonwood than in red alder, whereas the reverse was noted in 1980, and (ii) even though 1981 and 1982 were warmer and drier than 1980, corresponding changes in predawn and minimum leaf water potentials were not observed. These differences were attributed to greater root development, particularly in black cottonwood, in the second (1981) and third (1982) years following establishment (1980) of these species. Leaf age and drought exposure were observed to influence osmotic potentials in both species. Values of the osmotic potential at saturation varied from −0.80 to −1.03 MPa in newly mature leaves of red alder and from −1.00 to −1.26 MPa in similarly aged leaves of black cottonwood. Values in mature leaves ranged from −0.84 to −1.27 MPa in red alder and from −1.37 to −1.75 MPa in black cottonwood. There appeared to be a continued decrease in osmotic potential in both species throughout the growing season, a response associated with leaf development and drought exposure. Throughout the study, significantly lower values of osmotic potential at saturation and at the turgor loss point were found in black cottonwood than in red alder. Consequently, black cottonwood had a potential adaptive advantage in comparison with red alder. Leaf shedding in response to drought was noted mainly in red alder. Generally, both of these riparian species exhibited slight to moderate capabilities of surviving exposure to low leaf water potentials and moderate to excellent capabilities of stomatal closure under conditions potentially leading to low water potentials. The role played by root development in the differences observed among the years and between black cottonwood and red alder is discussed.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF OIL PALM (ELAEIS GUINEENSIS): A REVIEW

2011 ◽  
Vol 47 (4) ◽  
pp. 629-652 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
West Africa ◽  
Soil Water ◽  
Water Use ◽  
Water Relations ◽  
Oil Palm ◽  
Water Productivity ◽  
Background Information ◽  
Flower Initiation ◽  
Irrigation Interval ◽  
Best Estimates

SUMMARYThe results of research on the water relations and irrigation need of oil palm are collated and summarized in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information is given on the centres of origin (West Africa) and of production of oil palm (Malaysia and Indonesia), but the crop is now moving into drier regions. The effects of water stress on the development processes of the crop are summarized followed by reviews of its water relations, water use and water productivity. The majority of the recent research published in the international literature has been conducted in Malaysia and in Francophone West Africa. The unique vegetative structure of the palm (stem and leaves) together with the long interval between flower initiation and the harvesting of the mature fruit (ca. three years) means that causal links between environmental factors (especially water) and yield are difficult to establish. The majority of roots are found in the 0–0.6 m soil horizons, but roots can reach depths greater than 5 m and spread laterally up to 25 m from the trunk. The stomata are a sensitive indicator of plant water status and play an important role in controlling water loss. Stomatal conductance and photosynthesis are negatively correlated with the saturation deficit of the air. It is not easy to measure the actual water use of oil palm, the best estimates for mature palms suggesting crop evapotranspiration (ETc) rates of 4–5 mm d−1 in the monsoon months (equivalent to 280–350 l palm−1 d−1). For well-watered mature palms, crop coefficient (Kc) values are in the range 0.8–1.0. Although the susceptibility of oil palm to drought is well recognized, there is a limited amount of reliable data on actual yield responses to irrigation. The best estimates are 20–25 kg fresh fruit bunches ha−1 mm−1 (or a yield loss of about 10% for every 100 mm increase in the soil water deficit). These increases are only realized in the third and subsequent years after the introduction of irrigation and follow an increase in the number of fruit bunches as a result of an improvement in the sex ratio (female/total inflorescence production) and a reduction in the abortion of immature inflorescences. There is no agreement on the allowable depletion of the available soil water, or on the associated optimum irrigation interval. Drip irrigation has been used successfully on oil palm.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF CITRUS (CITRUS SPP.): A REVIEW

2012 ◽  
Vol 48 (3) ◽  
pp. 347-377 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
Water Relations ◽  
Water Productivity ◽  
Rooting Depth ◽  
Yield Response ◽  
Growth Stages ◽  
Canopy Conductance ◽  
Crop Water ◽  
Water Requirements ◽  
Crop Water Requirements ◽  
General Terms

SUMMARYThe results of research on the water relations and irrigation need of Citrus spp. are collated and reviewed in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information is given on the centres of origin (south-east Asia) and of production of citrus (areas with subtropical Mediterranean-type climates). The effects of water stress on the development processes of the crop are summarised followed by reviews of the plant water relations, crop water requirements, water productivity and irrigation systems. The topic is complicated by the diversity of species and cultivars (including rootstocks) that are embraced within Citrus spp. The effects of water availability on vegetative growth are understood in general terms, but the relationships have not yet been quantified. Similarly, the need for a ‘rest period’ to induce flowering is understood, but its magnitude (in terms of a drought stress index or day-degrees) does not appear to have been specified with precision. Again, the effects of drought on flower and fruit formation and retention are understood in general terms, but the relationships have not been quantified in useful ways for specific cultivars. Rooting depth and distribution have only been described in a limited number of situations. Environmental factors influencing stomatal conductances are generally well described and relationships with some growth processes established. Compared with other crops, low stomatal/canopy conductance restricts water use of Citrus spp. Some (limited) progress has been made in quantifying crop water requirements in specific conditions. Despite many recent attempts to specify how little water can be applied at specific growth stages to optimise water productivity through regulated deficit irrigation, no consensus view has emerged. The yield response to ‘full’ irrigation is of the order 6–7 kg fresh fruit m−3 as a result of an increase in the number of fruit of marketable size. There are also improvements in fruit quality. The most effective way of irrigating a citrus orchard is with a microirrigation system (drip or microsprinklers), but both methods require answers to the question: what proportion of the root zone needs to be irrigated? Both methods, especially drip, allow water to be applied (with fertigation) at very frequent intervals (including several times a day), although formal evidence of the benefits to be obtained from this level of intensification is lacking.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF OLIVE (Olea europaea L.): A REVIEW

2013 ◽  
Vol 49 (4) ◽  
pp. 597-639 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
Water Relations ◽  
Deficit Irrigation ◽  
Root Zone ◽  
Eastern Mediterranean ◽  
Stomatal Closure ◽  
Irrigation Scheduling ◽  
Convincing Evidence ◽  
Background Information ◽  
Evaporative Demand ◽  
Biennial Bearing

SUMMARYThe results of research on the water relations and irrigation needs of olive are collated and summarised in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the ecology of the olive (it is native to the coastal areas of the eastern Mediterranean) and on crop development processes are presented, followed by reviews of the influence of water stress on gas exchange (stomatal conductance, photosynthesis and transpiration), crop water requirements, water productivities and irrigation systems. The olive has many attributes that help to protect it against drought, including the morphology of the leaf, and the capacity to conserve water under conditions of high evaporative demand through stomatal closure, osmotic regulation and resistance to cavitation. The concept of ‘deficit irrigation’ has been the subject of much research. Although vegetative growth is restricted, there is no convincing evidence that ‘sustained deficit irrigation’ or ‘regulated deficit irrigation’ or ‘partial root zone drying’ offer any advantages over conventional practices. Water productivities are very variable and difficult to reconcile due, in part, to biennial bearing, tree-to-tree variability and differences in tree population densities. Similarly, no clear consensus has emerged on how best to exploit the sensitivity of trunk expansion to water availability in irrigation scheduling. As production methods for this historical crop are intensified (high-density hedgerows, irrigated and mechanized orchards), so will the need to understand the role that water plays in the production processes become ever more critical.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCOA (THEOBROMA CACAO L.): A REVIEW

2011 ◽  
Vol 47 (4) ◽  
pp. 653-676 ◽  
Author(s):  
M. K. V. CARR ◽  
G. LOCKWOOD
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Use ◽  
Water Relations ◽  
Stomatal Closure ◽  
Dry Season ◽  
Leaf Water ◽  
Background Information ◽  
Published Data ◽  
Rhythmic Pattern

SUMMARYThe results of research into the water relations of cocoa are reviewed in the context of drought mitigation and irrigation need. Background information on the centres of production of the cocoa tree, and the role of water in crop development and growth processes, is followed by reviews of the effects of water stress on stomatal conductance, leaf water status and gas exchange, together with drought tolerance, crop water use and water productivity. Leaf and shoot growth occur in a series of flushes, which are synchronized by the start of the rains following a dry season (or an increase in temperature), alternating with periods of ‘dormancy’. Flowering is inhibited by water stress but synchronous flowering occurs soon after the dry season ends. Roots too grow in a rhythmic pattern similar to that of leaf flushes. Roots can reach depths of 1.5–2.0 m, but with a mass of roots in the top 0.2–0.4 m, and spread laterally >5 m from the stem. Stomata open in low light intensities and remain fully open in full sunlight in well-watered plants. Partial stomatal closure begins at a leaf water potential of about −1.5 MPa. Stomatal conductance is sensitive to dry air, declining as the saturation deficit increases from about 1.0 up to 3.5 kPa. Net photosynthesis and transpiration both consequently decline over a similar range of values. Little has been published on the actual water use of cocoa in the field. Measured ETc values equate to <2 mm d−1 only, whereas computed ETc rates of 3–6 mm d−1 in the rains and <2 mm d−1 in the dry season have also been reported. Despite its sensitivity to water stress, there is too a paucity of reliable, field-based published data of practical value on the yield responses of cocoa to drought or to irrigation. With the threat of climate change leading to less, or more erratic, rainfall in the tropics, uncertainty in yield forecasting as a result of water stress will increase. Social, technical and economic issues influencing the research agenda are discussed.

scholarly journals THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF LYCHEE (LITCHI CHINENSIS SONN.): A REVIEW

2013 ◽  
Vol 50 (4) ◽  
pp. 481-497 ◽  
Author(s):  
M. K. V. CARR ◽  
C. M. MENZEL
Keyword(s):  
South Africa ◽  
Water Deficit ◽  
Water Relations ◽  
Southern China ◽  
Water Status ◽  
Water Productivity ◽  
Water Requirements ◽  
Leaf Water Status ◽  
Supplementary Irrigation ◽  
Irrigation Requirements

SUMMARYThe results of research into the water relations and irrigation requirements of lychee are collated and reviewed. The stages of plant development are summarised, with an emphasis on factors influencing the flowering process. This is followed by reviews of plant water relations, water requirements, water productivity and, finally, irrigation systems. The lychee tree is native to the rainforests of southern China and northern Vietnam, and the main centres of production remain close to this area. In contrast, much of the research on the water relations of this crop has been conducted in South Africa, Australia and Israel where the tree is relatively new. Vegetative growth occurs in a series of flushes. Terminal inflorescences are borne on current shoot growth under cool (<15 °C), dry conditions. Trees generally do not produce fruit in the tropics at altitudes below 300 m. Poor and erratic flowering results in low and irregular fruit yields. Drought can enhance flowering in locations with dry winters. Roots can extract water from depths greater than 2 m. Diurnal trends in stomatal conductance closely match those of leaf water status. Both variables mirror changes in the saturation deficit of the air. Very little research on crop water requirements has been reported. Crop responses to irrigation are complex. In areas with low rainfall after harvest, a moderate water deficit before floral initiation can increase flowering and yield. In contrast, fruit set and yield can be reduced by a severe water deficit after flowering, and the risk of fruit splitting increased. Water productivity has not been quantified. Supplementary irrigation in South-east Asia is limited by topography and competition for water from the summer rice crop, but irrigation is practised in Israel, South Africa, Australia and some other places. Research is needed to determine the benefits of irrigation in different growing areas.

CIScoSI Study [Children Immunization Status and cases of Systemic Illness]

2018 ◽  
Vol 3 (3) ◽  
Keyword(s):  
Infectious Diseases ◽  
East Asia ◽  
Pediatric Patients ◽  
Severe Disease ◽  
Tertiary Care ◽  
Immunization Coverage ◽  
South East Asia ◽  
Immunization Status ◽  
Tertiary Care Hospitals ◽  
Total Coverage

To determine the immunization status of pediatric patients under age of 5 years visiting pediatric department of tertiary care hospitals in South East Asia. The aim of this study was to appreciate the awareness and implementation of vaccination in pediatric patients who came into pediatric outpatient Department with presenting complain other than routine vaccination. we can also know the count of patients who do not complete their vaccination after birth. we can differentiate between vaccinated and unvaccinated patients and incidence of severe disease in both groups. Immunization is a protective process which makes a person resistant to the harmful diseases prevailing in the community, typically by vaccine administration either orally or intravenously. It is proven for controlling and eliminating many threatening diseases from the community. WHO report that licensed vaccines are available for the prevention of many infectious diseases. After the implementation of effective immunization the rate of many infectious diseases have declined in many countries of the world. South-East Asia is far behind in the immunization coverage. An estimated total coverage is 56%-88% for a fully immunized child, which is variable between countries. Also the coverage is highest for BCG and lowest for Polio.

Maidstone's woodpecker – an unexpected bird specimen in the herbarium of Sir Hans Sloane

2014 ◽  
Vol 41 (2) ◽  
pp. 230-239 ◽  
Author(s):  
Charles E. Jarvis ◽  
Joanne H. Cooper
Keyword(s):  
Natural History ◽  
East Asia ◽  
East India Company ◽  
South East Asia

It had long been believed that none of the bird, egg or nest specimens that had been in the collection of Sir Hans Sloane at his death in 1753 had survived. However, a specimen of a rhinoceros hornbill, originally in Sloane's hands, was discovered in the Natural History Museum's collections in London in 2003, and three more Sloane hornbill specimens have subsequently come to light. In addition, we report here a most unexpected discovery, that of the head of a woodpecker among the pages of one of Sloane's bound volumes of pressed plants. The context suggests that the head, like its associated plant specimens, was probably collected in south-east Asia about 1698–1699 by Nathanael Maidstone, an East India Company trader, the material reaching Sloane via William Courten after the latter's death in 1702. A detailed description of the head is provided, along with observations on its identity and possible provenance.

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