Effects of chlorine deficiency in the field on leaf gas exchanges in the PB121 coconut hybrid

Braconnier, Serge; Bonneau, Xavier

doi:10.1051/agro:19980806

Cited by 12 publications

(6 citation statements)

References 4 publications

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“…Applying common salt (sodium chloride) at annual rates of up to 4.5 kg palm −1 reduced mortality, reduced defoliation, advanced recovery after the start of the rains and increased the yield of copra from 10 to 15 kg palm −1 (averaged over eight seasons). Previously, Braconnier and Bonneau (1998) had confirmed the important role that the chloride ion plays in maintaining gas exchange (net assimilation and transpiration) in dry weather through stomatal regulation. Indeed, sodium chloride is recommended as a cheaper alternative to potassium chloride as a fertilizer in Indonesia, particularly in dry areas, where it contributes to drought mitigation (Bonneau et al, 1997).…”

Section: Drought Mitigationmentioning

confidence: 93%

“…Chloride deficiency resulted in delayed stomatal opening at the start of the day, and a reduction in the capacity for osmoregulation when plants were stressed. Subsequently, Braconnier and Bonneau (1998) showed clearly in a field study in Sumatra (cv. PB-121) how stomatal conductance was reduced in chloride deficient palms, but only in the dry season not in the rains.…”

Section: Rootsmentioning

confidence: 94%

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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: Drought Mitigationmentioning

confidence: 93%

Section: Rootsmentioning

confidence: 94%

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

Carr

2011

Ex. Agric.

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“…Biochemical measurements were taken once a month during the rainy season and the frequency was increased to once a week during the drought. Leaf samples taken from the middle portion of the ninth leaf from top (Braconnier and Bonneau, 1998) were used for all biochemical assays. Total sugar (µg/g DW), starch (µg/g DW) (Dubois et al, 1956) and proline (mg/g DW) (Bates et al, 1973) content were assayed using oven dried, powdered leaf samples extracted in 80 per cent Ethanol.…”

Section: Introductionmentioning

confidence: 99%

Biochemical changes of four different coconut (Cocos nusifera L.) Forms under moisture stress conditions

2006

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Drought causes a substantial reduction in national yield of coconut and also a loss of coconut palms in severe droughts thus resulting in serious economic consequences to the coconut industry in Sri Lanka. Therefore, it is of prime importance to identify some putative drought tolerant forms to use in drought-prone areas. As the long generation and maturation periods of coconut restrict the selection of coconut forms based on yield, the knowledge on physiological and biochemical responses to water deficit conditions plays an important role in developing a rapid selection criterion. Therefore, the objectives of this research was to quantify the variations in drought tolerance in selected coconut forms, based on their biochemical responses to progressive soil moisture deficits in the field.Four coconut forms (Clovis, Dwarf Green, Dwarf Brown, Cameron Red Dwarf) were selected for the experiment. Palms were subjected to 80-day natural drought experienced in early 2005. Biochemicals namely leaf proline, total soluble sugar and starch contents were studied during the drought period along with the corresponding soil moisture contents at 50 and 100 cm depths. They showed slightly increasing trends with progressive water stress but not significantly different in between four forms. However, duration of natural drought that occurred during the experimental period was shorter than the dry spells which are commonly observed in the area. Therefore, further research under long dry spells is needed to reach a more comprehensive and repeatable results before coming to a final conclusion.

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“…All physiological measurements were conducted on the ninth leaf, counting from top. The ninth leaf has been identified as being representative of the middle whorl (leaf numbers 9-14), which is considered as the most active physiologically (Braconnier and Bonneau, 1998). The rate of photosynthesis (A, μmol m -2 s -1 ), stomatal conductance (g s , mol m -2 s -1 ), the rate of transpiration (E, mmol m -2 s -1 ) and intercellular CO 2 concentration (Ci, ppm) were measured using the gas exchange technique in a closed-system portable photosynthesis system (Li-6200, LI-COR Inc., USA); and the instantaneous water use efficiency (ω inst , μmol CO 2 mol -1 H 2 O) was calculated as the ratio of A/E.…”

Section: Physiological Parametersmentioning

confidence: 99%

A Case Study on Physiology-Based Drought Screening of Coconut with Selected Accessions

Nainanayake

Morison

2009

COCOS

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Recurrent droughts in Sri Lanka, now becoming increasingly frequent, cause substantial losses in coconut production. Consequently, the development of drought tolerant coconut varieties is an urgent need. Yield is the most reliable parameter to evaluate genotypes for drought tolerance but yieldbased evaluation is a complex and time consuming exercise with a perennial tree crop like coconut.With the objective of identifying drought tolerant varieties, 40 coconut forms or accessions (forms/acc) in the germplasm collection at Coconut Research Institute of Sri Lanka (CRISL) have been screened. This ongoing investigation gathered information on different types of parameters, and data on a wide range of physiological parameters of adult coconut palms, during an 81-day natural drought was available, along with soil moisture readings in the manure circle. Five contrasting forms/acc (Clovis, Kasagala, Dwarf Green, Cameroon Red Dwarf, and Dwarf x Tall hybrid DT), out of the forty screened, were selected for the present case study to explore the behaviour of some important physiological functions during a drought, their relationships, and the possibility of developing a method for rapid selection of putative drought tolerant coconut palms, based on easily measurable physiological parameters.The response to drought, in terms of physiological parameters, varied in the forms/acc selected for the case study. Clovis was identified as a putative drought tolerant form/acc as it maintained a high rate of photosynthesis and water use efficiency even at the end of the dry spell. Cameroon Red Dwarf was the most drought sensitive. Kasagala showed a degree of drought tolerance, oriented towards survival, with conservation and efficient use of available soil water. However, Kasagala is not likely to be viable as a commercial crop as its low photosynthetic rate due to low stomatal conductance is indicative of low potential productivity. Drought sensitivity 1 of DT was at an intermediate level. The assimilation rate of DT was 20% higher than the mean rate of other forms/acc up to mild levels of water stress, but declined sharply when soil moisture content decreased below 15%. However, it recovers very quickly on rewetting of the soil with the onset of rains, which enables it to maintain a high overall yield.The drop in coconut production when soil water is deficient is mainly due to limitations at the stomatal level rather than at the non-stomatal (biochemical) level of the assimilation process, especially in mild to moderate drought conditions. Screening for drought tolerance based on physiological parameters appears to be rapid and promising. Nevertheless, these procedures should be further verified with long-term yield data of more forms/acc before they are widely applied.

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Effects of chlorine deficiency in the field on leaf gas exchanges in the PB121 coconut hybrid

Abstract: -A study of leaf gas exchanges during the dry and rainy seasons confirmed the importance of the chloride ion in coconut. In the dry season, compared to a control, chloride deficiency led to lower stomatal conductance, hence a reduction in leaf gas exchanges. This

Cited by 12 publications

References 4 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

Biochemical changes of four different coconut (Cocos nusifera L.) Forms under moisture stress conditions

A Case Study on Physiology-Based Drought Screening of Coconut with Selected Accessions

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