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.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF CASHEW (ANACARDIUM OCCIDENTALE L.): A REVIEW

2013 ◽  
Vol 50 (1) ◽  
pp. 24-39 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
Water Relations ◽  
Large Scale ◽  
Water Status ◽  
Water Productivity ◽  
Irrigation Schedule ◽  
Leaf Water Status ◽  
Flow Measurements ◽  
Centre Of Origin ◽  
Cashew Nut ◽  
Dry Conditions

SUMMARYThe centre of origin of cashew is believed to be Brazil, from where it has spread since the 16th century throughout the tropics. In recent years, Vietnam has surpassed India to become the world's largest producer of cashew nut. Most of the research on the water relations of cashew has been done in Brazil, where it is both a large-scale commercial and a smallholder crop, and in Australia, where cashew is a possible emerging new crop. There are two ‘types’ of cashew: ‘talls’ and ‘dwarfs’. Both are evergreen trees in which vegetative growth occurs in a series of flushes. Flowers form annually on the end of branches in the dry season, and flowering continues for two to four months. It then takes about two months from pollination for the nut to mature. Roots can extend to great depths (>5 m), while cashew's wide-spreading rooting habit is critical to its successful adaptation to semi-arid/dry conditions. The optimum temperature for CO2 assimilation is in the range 25–35 °C. Progressive closure of the stomata occurs at saturation deficits of the air >1.5 kPa. In the field, differences in rates of gas exchange between irrigated and unirrigated cashew trees only become apparent three or four months after the end of the rains, the stomata playing an important role in maintaining a favourable leaf water status in dry conditions. Sap flow measurements indicate transpiration rates of 20–28 L d−1 tree−1. Irrigation can be beneficial during the period from flowering to the start of harvest, but reliable estimates of water productivity have yet to be established. The best/only estimate is 0.26 kg (nut in shell) m−3 (irrigation water). There is a continuing need to develop a method to estimate the water requirements of cashew, to identify where and when irrigation of cashew is likely to be justified and to develop a practical irrigation schedule.

Effect of irrigation on leaf gas exchange and yield of cashew in northern Australia

1996 ◽  
Vol 36 (7) ◽  
pp. 861 ◽  
Author(s):  
H Schaper ◽  
EK Chacko ◽  
SJ Blaikie
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Water Deficit ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Northern Australia ◽  
Wet Season ◽  
Leaf Water Status ◽  
Continuous Irrigation ◽  
Tropical Regions

Gas exchange, leaf water status, soil water use and nut yield of cashew trees were monitored during the reproductive phase in 2 consecutive years (1988 and 1989). Treatment 1 comprised continuous irrigation from the end of the wet season in April until harvest in October; T2, irrigation between flowering (mid June) and harvest; and T3, no irrigation. Irrigation was applied by under-tree sprinkler at 43 mm/week in 1988 and 64 mm/week in 1989. Measurement of leaf gas exchange, chlorophyll content and nut production showed that trees in T2 were as productive as those in T1 (>1.3 kg kernel/tree). In T3, water deficit caused a 4-fold reduction in leaf photosynthesis and reduced leaf chlorophyll content from about 600 to 400 mg/m2 during fruit development. There was no effect on the number of hermaphrodite flowers produced (both ranging from 0 to 15 hermaphrodite flowers/panicle) but the water deficit was associated with a lower kernel yield (1.16 kg kernel/tree). Commercial yields (kg kernel/tree) in irrigated treatments were 20% greater than in the non-irrigated treatment and the kernels from irrigated trees were of a higher grade (kernel recovery >32% in T1 and T2 compared with 27.4% in T3). These results suggest that irrigation of established cashew plantations in the tropical regions of northern Australia can be restricted to the period between flowering and harvest without reducing yield.

Abscisic Acid Levels in Nacl-Treated Barley, Cotton and Saltbush

1991 ◽  
Vol 18 (1) ◽  
pp. 17 ◽  
Author(s):  
Z Kefu ◽  
R Munns ◽  
RW King
Keyword(s):  
Abscisic Acid ◽  
Water Deficit ◽  
Water Status ◽  
Xylem Sap ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Cotton Plants ◽  
Presence And Absence ◽  
Leaf Water Deficit

Exposing barley and cotton plants to 75 mol m-3 NaCl reduced transpiration and increased abscisic acid (ABA) levels in leaves, roots and xylem sap. Exposing saltbush (Atriplex spongiosa) plants to 75 mol m-3 NaCI, at which concentration they grow best, did not affect transpiration or ABA levels but when the NaCl was increased to 150 mol m-3 transpiration fell and ABA levels rose. ABA levels in leaves were high in salt-treated barley and saltbush even when the leaf water status was raised by pressurising the roots. These responses indicate that an increased leaf ABA level was not triggered by leaf water deficit, but by the root's response to the salinity. The flux of ABA in the xylem sap of the three species was more than enough to account for the amount of ABA in leaves, in the presence and absence of salinity. This suggests that the roots may be the source of at least part of the ABA found in leaves.

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.

Response to terminal water deficit stress of cowpea, pigeonpea, and soybean in pure stand and in competition

2008 ◽  
Vol 59 (1) ◽  
pp. 27 ◽  
Author(s):  
A. A. Likoswe ◽  
R. J. Lawn
Keyword(s):  
Water Deficit ◽  
Water Status ◽  
Leaf Water ◽  
Water Deficit Stress ◽  
Pure Stand ◽  
Leaf Water Status ◽  
Test Species ◽  
Dehydration Tolerance ◽  
Dehydration Avoidance ◽  
Leaf Survival

The response to terminal water deficit stress of three grain legumes, soybean, cowpea and pigeonpea, was evaluated in plants grown in large tubes, in competition with either the same species or one of the other two species. The aim was to explore how species differences in drought response affected water use, growth and survival of plants in pure stand and in competition. Two plants, comprising the test species and its competitor, were grown in each tube. Water was withheld 26 days after sowing by which time each plant had at least three fully expanded trifoliolate leaves. Leaf water status and plant growth were measured through destructive samples when 80% and 90% of the estimated plant available water (PAW) was depleted and at plant death, while PAW depletion, node growth and leaf survival were monitored at 2–3 day intervals until the last plants died (61 days after water was withheld). In pure stand, the rate of PAW depletion was initially slowest in cowpea despite its much larger leaf area, and fastest in soybean. Node growth was most sensitive in cowpea, ceasing at 65% PAW depletion compared with 85% PAW depletion in pigeonpea and soybean, so that the latter two species produced relatively more nodes after water was withheld. However, senescence of the lower leaves was most rapid in soybean and slowest in cowpea. Cowpea and pigeonpea extracted almost all PAW and died an average 18 days and 14 days, respectively, after maximum PAW depletion. In contrast, soybean died before 90% of PAW was depleted and so in pure stand used less water. There were otherwise only minor differences between the species combinations in the timing and maximum level of PAW depletion. The ability of cowpea and pigeonpea to maintain leaf water status above lethal levels for longer was achieved through different means. Cowpea relied primarily on dehydration avoidance and maintained tissue water status higher for longer, whereas pigeonpea demonstrated greater dehydration tolerance. While significant levels of osmotic adjustment (OA) were identified in soybean and pigeonpea, OA appeared to be of limited benefit to leaf survival in soybean. Pigeonpea invested significantly more total dry matter (TDM) in roots than either cowpea or soybean. Cowpea survived longest in pure stand whereas pigeonpea and soybean survived shortest in pure stand, suggesting that the dehydration avoidance response of cowpea was more effective in competition with like plants whereas the dehydration tolerance strategies of pigeonpea and soybean were least effective when competing against like plants. On average, TDM per plant ranked in the order cowpea > soybean > pigeonpea, largely reflecting initial differences in plant size when water was withheld. However, there was an inverse relation between TDM of a species and that of its competitor, so that in effect, water not used by a given plant to produce TDM was used by its competitor and there were no differences in TDM production per tube.

Development and use of a variable-speed lateral boom irrigation system to define water requirements of 11 turfgrass genotypes under field conditions

2007 ◽  
Vol 47 (1) ◽  
pp. 86 ◽  
Author(s):  
D. C. Short ◽  
T. D. Colmer
Keyword(s):  
Water Conservation ◽  
Irrigation System ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Variable Speed ◽  
Leaf Water Status ◽  
Area Index ◽  
Class A ◽  
Irrigation Requirements ◽  
Class A Pan

Improved irrigation scheduling is one strategy by which water management can be improved in turfgrass systems. The development and testing of a variable-speed lateral boom irrigation system for use in field-based irrigation trials is reported. Christiansen’s coefficient of uniformity was greater than 92% and the efficiency of irrigator discharge was greater than 90% for application depths (mm/unit land area) of 0.5–13 mm. The minimum irrigation requirements were determined for 11 turfgrass genotypes from a summer irrigation dose–response field trial that applied daily treatments of 100 (control), 80, 60, 40 and 20% of the previous day’s net evaporation measured using a US Class A pan. Responses of several shoot parameters, including clipping production, green leaf area index, leaf chlorophyll and leaf water status were evaluated to define minimum irrigation requirements for the turfgrasses. Minimum irrigation requirements (as defined by declines of 10% in several shoot responses) for C3 and C4 turfgrasses were 64–94% and 32–78% of US Class A pan, respectively. Variability in irrigation requirements within C3 or C4 types was due mainly to variations in estimates based on the different shoot parameters. The results demonstrate the opportunity for water conservation by using C4 rather than C3 turfgrasses in locations with hot dry summers (and mild winters) typical of a Mediterranean-type climate.

scholarly journals FAO CROPWAT Model-Based Irrigation Requirements for Coconut to Improve Crop and Water Productivity in Kerala, India

2019 ◽  
Vol 11 (18) ◽  
pp. 5132 ◽  
Author(s):  
U. Surendran ◽  
C. M. Sushanth ◽  
E. J. Joseph ◽  
Nadhir Al-Ansari ◽  
Zaher Mundher Yaseen
Keyword(s):  
Crop Production ◽  
Water Productivity ◽  
The State ◽  
Coconut Palm ◽  
Current Recommendation ◽  
Water Requirements ◽  
Ecological Zones ◽  
Kerala State ◽  
Irrigation Requirements ◽  
Agro Ecological Zones

The irrigation requirements for coconut in Kerala are general in nature. This study determined the irrigation requirements for coconut, using CROPWAT based on agro-ecological zones (AEZs) for proposing the recommendations. The irrigation recommendations are generated based on the climatic, soil, and crop characteristics. The results showed that the irrigation requirements varied with the locations. Overall, for the state of Kerala, the irrigation requirements varied from 350 to 900 L of water per coconut palm, with the irrigation intervals ranging from three to nine days based on the AEZs. Moreover, this study also confirmed the variation of the water requirements observed within the districts. The quantity of water required per palm varied between 115 to 200 liters per day (LPD) per palm, which is lower than the existing recommendations of 175 to 300 LPD per palm. The proposed irrigation requirements appraised with the presently followed recommendations of the Kerala state, and its advantages discussed for improving the crop and water productivity. In nutshell, if the current recommendation is adopted, 30% of the water used for irrigation can be saved, as well as leading to an improvement in crop production.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF AVOCADO (Persea americana Mill.): A REVIEW

2013 ◽  
Vol 49 (2) ◽  
pp. 256-278 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
South Africa ◽  
Water Stress ◽  
Water Use ◽  
Water Relations ◽  
Water Productivity ◽  
Chloride Ions ◽  
Persea Americana ◽  
Mature Trees ◽  
Water Deficits ◽  
Eastern Australia

SUMMARYThe results of research on the water relations and irrigation need of avocado are collated and reviewed in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information is given on the centre of origin (Mexico and Central America) and the three distinct ecological areas where avocados are grown commercially: (1) Cool, semi-arid climates with winter-dominant rainfall (e.g. Southern California, Chile, Israel); (2) Humid, subtropical climates with summer-dominant rainfall (e.g. eastern Australia, Mexico, South Africa); and (3) Tropical or semi-tropical climates also with summer-dominant rainfall (e.g. Brazil, Florida and Indonesia). Most of the research reported has been done in Australia, California, Israel and South Africa. There are three ecological races that are given varietal status within the species: Persea americana var. drymifolia (Mexican race), P. americana var. guatemalensis (Guatemalan race) and P. americana var. americana (Antillean, West Indian or Lowland race). Interracial crossing has taken place. This paper summarises the effects of water deficits on the development processes of the crop and then reviews plant–water relations, crop water requirements, water productivity and irrigation systems. Shoot growth in mature trees is synchronised into flushes. Flower initiation occurs in the autumn, with flowering in late winter and spring. Flowers form on the ends of the branches. A large heavily flowering tree may have over a million flowers, but only produce 200–300 fruits. Fruit load adjustment occurs by shedding during the first three to four weeks after fruit set and again in early summer. Water deficits during critical stages of fruit ontogeny have been linked to fruit disorders such as ring-neck. Reproductive growth is very resistant to water stress (compared with vegetative growth). Avocado is conventionally considered to be shallow rooted, although roots extend to depths greater than 1.5 m. The majority of feeder roots are found in the top 0.60 m of soil and root extension can continue throughout the year. Leaves develop a waxy cuticle on both surfaces, which is interrupted by stomata on the abaxial surface (350–510 mm−2), many of which are blocked by wax. Stomata are also present on the sepals and petals at low densities (and on young fruit). During flowering, the canopy surface area available for water loss is considerably increased. Stomatal closure is an early indicator of water stress, which together with associated changes in leaf anatomy, restricts CO2 diffusion. There have only been a few attempts to measure the actual water use of avocado trees. In Mediterranean-type climates, peak rates of water use (in summer) appear to be between 3 and 5 mm d−1. For mature trees, the crop coefficient (Kc) is usually within the range 0.4–0.6. The best estimate of water productivity is between 1 and 2 kg fruit m−3. Soil flooding and the resultant reduction in oxygen level can damage roots even in the absence of root rot. Avocado is particularly sensitive to salinity, notably that caused by chloride ions. Rootstocks vary in their sensitivity. Both drip and under-tree microsprinklers have been/are successfully used to irrigate avocado trees. Mulching of young trees is a recommended water conservation measure and has other benefits. A large proportion of the research reviewed has been published in the ‘grey’ literature as conference papers and annual reports. Sometimes, this is at the expense of reporting the science on which the recommendations are based in peer-reviewed papers. The pressures on irrigators to improve water productivity are considered.

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