Active root distribution pattern of Hevea brasiliensis determined by radioassay of latex serum

George, Sherin; Suresh, P. R.; Wahid, P. A.; Nair, R. B.; Punnoose, K. I.

doi:10.1007/978-90-481-3365-9_2

Cited by 4 publications

(7 citation statements)

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“…() and George et al . () pointed out that rubber tree is a surface feeder, and in mature rubber trees, about 55–86% of the total active roots are confined to the top 0–20 cm of soil. The higher concentration of feeder roots near the soil surface may be attributed to the accumulation of organic matter through litter decomposition at the surface layer (Philip et al ., ), and the sharp decline in root density with increasing depths signals that increased inter‐tree competition would occur near the surface of the soil (George et al ., ).…”

Section: Discussionsupporting

confidence: 61%

“…Hevea brasiliensis (rubber tree), the single viable source of natural rubber, is a perennial crop that has economic and social importance in many tropical and subtropical areas in the world (George et al, 2009). As a tree native to the tropical rainforest of the Amazon Basin, its ideal habitat is characterized by small variations in air temperature (24-28°C) and precipitation (about 2000 mm) throughout the year and monthly rainfall of >100 mm (Vogel et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…and George et al (2009) pointed Mean root density (±1 standard error, n = 6) with depth for rubbers at the upslope and downslope positions. * indicates significant difference (P < 0·05), and Ns no significant (P > 0·05) between upslope and downslope.…”

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confidence: 99%

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Vertical patterns of soil water acquisition by non‐native rubber trees (Hevea brasiliensis) in Xishuangbanna, southwest China

Liu

Lü

et al. 2013

Ecohydrology

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The rubber tree (Hevea brasiliensis) has been extensively cultivated in Xishuangbanna, southwest (SW) China. It shows strong synchronicity for flushing and shedding, displaying a very different phenology to the native vegetation. However, little is known about the water‐use patterns of the plant in this area. We assessed seasonal water‐use strategies of rubber trees over the course of a rainy/dry season cycle. Stable isotope compositions of water in xylem, soil, rain and groundwater were sampled on seasonally distinct dates, and soil water content, root distribution and leaf water potential on sunny days were measured in order to determine the proportion of water derived from different soil layers. Midday leaf water potential of rubber trees was relatively stable throughout the year and did not drop significantly during the late dry season, displaying isohydric behaviour. Soil and stem water isotope signatures along with rooting distributional patterns revealed that rubber trees extracted their water mostly from the top 30 cm and less from below 70 cm of the soil profile during the late rainy season when soil water was plentiful. During the late dry season, as the moisture in the middle soil layers (30–70 cm) was gradually depleted, the depth of water uptake shifted to deeper soil levels. Model calculations showed that the proportion of water uptake from the shallow soil layer (<30 cm) increased markedly after the most recent rainfall in the late dry season and the early rainy season (varying between 65% and 71%), indicating significant plasticity in sources of water uptake in this dimorphic‐rooted species. This ability to take up a large proportion of shallow soil water after rainfall is likely the key feature enabling rubber trees to thrive through the period of greatest water demand. Our results suggest that rubber trees are able to adjust the allocation of resources and thus acclimate to the spatiotemporal changes to water conditions in the soil profile. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Discussionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

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Vertical patterns of soil water acquisition by non‐native rubber trees (Hevea brasiliensis) in Xishuangbanna, southwest China

Liu

Lü

et al. 2013

Ecohydrology

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“…In Kerala, George et al (2009) used the 32 P soil injection technique to determine active root distribution of mature (18-year-old) rubber trees (clone RRII 105). They based their observations on a radio assay of the latex serum after 45 days.…”

Section: Rootsmentioning

confidence: 99%

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

Carr

2011

Ex. Agric.

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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.

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“…The rubber tree ( Hevea brasiliensis ) is a perennial crop that is native to the tropical rainforest of the Amazon Basin; it has both economic and social importance in many developing countries 2 (particularly in tropical and subtropical areas). The ideal habitat for the rubber tree is characterized by low variation in air temperature (24–28 °C) and precipitation (monthly rainfall greater than 100 mm) throughout the year in areas of low latitude and elevation 3 4 5 .…”

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confidence: 99%

Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants

Jian

Liu

Chen

2016

Sci Rep

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Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ18O, and δ13C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ18O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ13C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer.

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Active root distribution pattern of Hevea brasiliensis determined by radioassay of latex serum

Cited by 4 publications

References 5 publications

Vertical patterns of soil water acquisition by non‐native rubber trees (Hevea brasiliensis) in Xishuangbanna, southwest China

Vertical patterns of soil water acquisition by non‐native rubber trees (Hevea brasiliensis) in Xishuangbanna, southwest China

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

Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants

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