Water Relations of Coconut Palms Affected With Root (Wilt) Disease

Rajagopal, V.; Sumathykuttyamma, B.; Patil, K. D.

doi:10.1111/j.1469-8137.1987.tb00866.x

Cited by 11 publications

(11 citation statements)

References 5 publications

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“…By contrast, stomata of palms suffering from root (wilt) disease remained open throughout the day regardless of the season (Rajagopal et al ., 1986). Leaf water potentials were also less in diseased plants (down to −1.99 MPa) leading to flaccidity (Rajagopal et al ., 1987). Progressive stomatal closure (from 10:00 to 12:00 hours) was also observed by Kasturi Bai et al .…”

Section: Plant Water Relationsmentioning

confidence: 99%

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW

Carr

2011

Ex. Agric.

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SUMMARYThe results of research on the water relations and irrigation needs of coconut are collated and summarized in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information on the centres of origin and production of coconut and on crop development processes is followed by reviews of plant water relations, crop water use and water productivity, including drought mitigation. The majority of the recent research published in the international literature has been conducted in Brazil, Kerala (South India) and Sri Lanka, and by CIRAD (France) in association with local research organizations in a number of countries, including the Ivory Coast. 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 (44 months) mean that causal links between environmental factors (especially water) are difficult to establish. The stomata play an important role in controlling water loss, whilst the leaf water potential is a sensitive indicator of plant water status. Both stomatal conductance and leaf water potential are negatively correlated with the saturation deficit of the air. Although roots extend to depths >2 m and laterally >3 m, the density of roots is greatest in the top 0–1.0 m soil, and laterally within 1.0–1.5 m of the trunk. In general, dwarf cultivars are more susceptible to drought than tall ones. Methods of screening for drought tolerance based on physiological traits have been proposed. The best estimates of the actual water use (ETc) of mature palms indicate representative rates of about 3 mm d−1. Reported values for the crop coefficient (Kc) are variable but suggest that 0.7 is a reasonable estimate. Although the sensitivity of coconut to drought is well recognized, there is a limited amount of reliable data on actual yield responses to irrigation although annual yield increases (50%) of 20–40 nuts palm−1 (4–12 kg copra, cultivar dependent) have been reported. These are only realized in the third and subsequent years after the introduction of irrigation applied at a rate equivalent to about 2 mm d−1 (or 100 l palm−1 d−1) at intervals of up to one week. Irrigation increases female flower production and reduces premature nut fall. Basin irrigation, micro-sprinklers and drip irrigation are all suitable methods of applying water. Recommended methods of drought mitigation include the burial of husks in trenches adjacent to the plant, mulching and the application of common salt (chloride ions). An international approach to addressing the need for more information on water productivity is recommended.

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Section: Plant Water Relationsmentioning

confidence: 99%

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW

Carr

2011

Ex. Agric.

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“…Application of balanced dose of fertilizer along with organic manure application and irrigation has favoured the growth and development of the palms and reduced intensity of root (wilt) symptoms. Rajagopal et al (1986a and1987b) have reported that, leaves of diseased palms had lower stomatal resistance (with relatively high transpiration rates) and leaf water potentials than apparently healthy palms. Diseased palms also indicated that dysfunction of stomatal regulation and there was abnormally wide stomatal opening.…”

Section: Nut Yield and Copra Contentmentioning

confidence: 99%

Influence of integrated nutrient management and high density multi-species cropping system on soil properties, plant nutrition and yield in root (wilt) affected coconut palms

Maheswarappa¹,

Kumari²,

Kamalakshiamma³

et al. 2005

CORD

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A field experiment was conducted at Central Plantation Crops Research Institute (Regional Station), Kayamkulam, Kerala, India to study the effect of integrated nutrient management and high density multi-species cropping system in root (wilt) affected garden on root (wilt) index, yield of coconut palms and soil properties. The experimental results indicated that, there was improvement in soil properties like water holding capacity, organic carbon, major and micronutrient status of the soil due to adoption of integrated nutrient management practices and high density multi-species cropping system. There was improvement in the yield of the palms under different root (wilt) diseased palms coupled with reduction in root (wilt) indices due to reduction in root (wilt) symptoms especially yellowing. The increase in nut yield (five years average) was to the tune of 54.5%, 52%, 48.3% and 40.9% under apparently healthy, disease early, disease middle and disease advanced palms in comparison with pre-experimental yield.

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“…Wilt, scorch, blight, and other diseases associated with xylem dysfunction disrupt water transport capacity, causing substantial morbidity and mortality of plants (Beckman et al 1962; Rajagopal et al 1987; Denny et al 1990; Aguirreolea et al 1995; Lorenzini et al 1997). Denny et al (1990) determined that transpiration decreased as wilt symptoms appeared by weighing mock-inoculated and Ralstonia -infected tomato plants to measure water loss and estimate whole-plant transpiration rates.…”

Section: Discussionmentioning

confidence: 99%

Revisiting the source of wilt symptoms: X-ray microcomputed tomography provides direct evidence thatRalstoniabiomass clogs xylem vessels

Ingel

Caldwell

Duong

et al. 2021

Preprint

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Plant pathogenic Ralstonia cause wilt diseases by colonizing xylem vessels and disrupting water transport. Due to the abundance of Ralstonia cells in vessels, the dogma is that bacterial biomass clogs vessels and reduces the flow of xylem sap. However, the physiological mechanism of xylem disruption during bacterial wilt disease is untested. Using a tomato and Ralstonia pseudosolanacearum GMI1000 model, we visualized and quantified the spatiotemporal dynamics of xylem disruption during bacterial wilt disease. First, we measured stomatal conductance of leaflets on mock-inoculated and wilt-symptomatic plants. Wilted leaflets had reduced stomatal conductance, as did turgid leaflets located on the same petiole as wilted leaflets. Next, we used X-ray microcomputed tomography (X-ray microCT) and light microscopy to differentiate between mechanisms of xylem disruption: blockage by bacterial biomass, blockage by vascular tyloses, or sap displacement by gas embolisms. We imaged stems on plants with intact roots and leaves to quantify embolized vessels. Embolized vessels were rare, but there was a slight trend of increased vessel embolisms in infected plants with low bacterial population sizes. To test the hypothesis that vessels are clogged during bacterial wilt, we imaged excised stems after allowing the sap to evaporate during a brief dehydration. Most xylem vessels in mock-infected plants emptied their contents after excision, but non-conductive clogged vessels were abundant in infected plants by 2 days post infection. At wilt onset when bacterial populations exceeded 5x108 cfu/g stem tissue, approximately half of the xylem vessels were clogged with electron-dense bacterial biomass. We found no evidence of tyloses in the X-ray microCT reconstructions or light microscopy on the preserved stems. Bacterial blockage of vessels appears to be the principal cause of vascular disruption during Ralstonia wilt.

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Water Relations of Coconut Palms Affected With Root (Wilt) Disease

Cited by 11 publications

References 5 publications

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW

Influence of integrated nutrient management and high density multi-species cropping system on soil properties, plant nutrition and yield in root (wilt) affected coconut palms

Revisiting the source of wilt symptoms: X-ray microcomputed tomography provides direct evidence thatRalstoniabiomass clogs xylem vessels

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