Leaf Drying Research Articles

Effect of the Leaf Drying and Geographic Sources on the Essential Oil Composition of Juniperus thurifera L. var. Africana Maire from the Tensift—Al Haouz, Marrakech Region

Essential oils of Moroccan Juniperus thurifera var. africana from three provenances (Forêt Islane, Ait Lkak and Plateau of Matat) in the Tensift-Al Haouz, Marrakech region, were analyzed by combined capillary gas chromatography/mass spectrometry. The oil yields from fresh leaves showed on differences among geographical sources. Air dried leaves appeared to yield more oil at the highest elevation (1.03%, Ait Lkak, 2900 m) than lower sites (0.67%, Plateau of Matat, 2200 m; 0.57%, Forêt Islane, 2000 m). The essential oils from each geographic site had very similar composition in fresh versus air dried leaves. The essential oils from provenance Ait Lkak and Plateau of Matat were very similar and characterized by a high sabinene content (21.2, 35.9%), in contrast to 10.% sabinene from the provenance Forêt Islane. The oil from Foret Islane had a high δ-cadinene content with 12.7%, whereas Aik Akak and Plateau of Matat contained only 0.6 and 0.8%. The Moroccan oils (J. thurifera var. africana) were compared to European J. thurifera var. thurifera (Spain) oil. Moroccan oils were found to be higher sabinene and limonene than the European oil

Breeding for drought tolerance: Direct selection for yield, response to selection and use of drought-tolerant donors in upland and lowland-adapted populations

Drought is the most important constraint reducing rice yield in rainfed areas. Earlier efforts to improve rice yield under drought mainly focused on improving secondary traits because the broad-sense heritability (H) of grain yield under drought stress was assumed to be low, however gains in yield by selecting for secondary traits have not been clearly demonstrated in rice. In present study, the effectiveness of direct selection for grain yield was assessed under lowland reproductive stage stress at Raipur in eastern India and under upland reproductive stage drought stress at IRRI. The selection under severe stress (in both upland and lowland trials) resulted in greater gains under similar stress levels (yield reduction of 65% or greater under stress) in evaluation experiments than did selection under non-stress conditions, with no yield reduction under non-stress conditions. We observed similar H of grain yield under stress and non-stress conditions, indicating direct selection for yield under drought will be effective under both lowland and upland drought stresses. None of the secondary traits (panicle exsertion, harvest index, leaf rolling, leaf drying) included in our study showed a higher estimate for H than grain yield under stress. Secondary traits as well as indirect selection for grain yield under non-stress situation were predicted to be less effective in improving yield under drought in both lowland and upland ecosystem than direct selection for grain yield under the respective stress situations. The low, but positive values observed for genetic correlation ( r G) between yield under stress and non-stress indicated that it is possible to combine drought tolerance with high-yield potential but low values also indicated that selection for grain yield needs to be carried under stress environments. The study also indicated that under lowland drought stress, the use of highly drought-tolerant donors, as parents in crosses to high yielding but susceptible varieties resulted in a much higher frequency of genotypes combining high-yield potential with tolerance than did crosses among elite lines with high-yield potential but poor tolerance. Breeding strategies that use drought-tolerant donors and that combine screening for yield under managed drought stress with screening for yield potential are likely to result in the development of improved cultivars for drought-prone rainfed rice producing areas.

Drought tolerance in rice: morphological and molecular genetic consideration

Rice is one of the most important food crop drastically affected by drought in lowland rice ecosystem. Dissecting out the traits of importance and genomic regions influencing the response of drought tolerance and yield traits on grain yield will aid the breeders to know the genetic mechanism of drought tolerance of rice leads to the development of drought tolerant varieties. Grain yield and its components on drought situation of recombinant inbred population (IR 58821/IR 52561) were investigated under lowland managed stress situation in 2003 and 2004 by given importance to the relative water content. Water deficit resulted in significant effect on phenology and grain yield. Best lines were selected for further varietal development programme. Variability studies showed the traits viz., days to 70% relative water content, leaf rolling, leaf drying, harvest index, biomass yield and grain yield offer high scope for improvement for drought tolerance by way of simple selection technique. Correlation and path analysis indicated that, to harness high yielding combined with drought tolerance breeders should give selection pressure on relative water content, panicle length, grains per panicle, harvest index, biomass yield, root/shoot ratio and root length in positive direction, and low scores of leaf rolling, leaf drying and drought recovery rate. Analysis of quantitative trait loci for drought tolerance, yield and its components allowed the identification of 38 regions associated with both drought tolerant and yield traits. Out of these, 18 were closely linked with DNA markers could be used for marker assisted selection in breeding for drought tolerance in rice. Pleiotropism and G × E effects interaction were noticed in some of the traits. Parent IR 58821 contributed favorable alleles for the entire drought related and most of the yield component traits. Identification of traits of importance and their nature of relationship by morphological and molecular level under lowland condition will be useful to improve drought tolerance of rice.

Mapping QTLs Linked to Physio-Morphological and Plant Production Traits under Drought Stress in Rice (Oryza sativa L.) in the Target Environment

Drought stress is a major constraint for rice (Oryza sativa L.) production and yield stability in rainfed ecosystems. Identifying genomic regions (QTLs) contributing in drought resistance will help to develop rice cultivars suitable for water-limiting environments through marker-assisted breeding. QTLs linked to physio-morphological and plant production traits under drought stress in the field were mapped by evaluating 177 F6 recombinant inbred (RI) lines of Bala × Azucena under rainfed conditions in the target environment (TE). The rice lines were subjected to severe drought stress during reproductive phase due to a natural rainfall failure event. The RI lines showed significant variation in physio-morphological and plant production traits under stress. A total of 24 QTLs were identified for various traits under stress, which individually explained 4.6 to 22.3% phenotypic variation. Composite interval mapping detected three markers viz., RM3894, RG409 and G1073 on chromosomes 3 and 8 linked to grain yield under drought stress in TE, respectively explaining 22..3, 17.1 and 10.9% of phenotypic variation. QTLs for leaf drying, days to 50% flowering and number of productive tillers under drought stress co-located at certain of these regions. Further, QTLs for several root traits overlapped with QTLs for grain yield under stress in these RI lines, indicating the pleiotropic effects of root trait QTLs on rice performance under stress. Correlation coefficients between potential root traits determined in another study and plant production under stress in this study were not significant in these RI lines. Consistent QTLs for drought resistance traits and yield under drought stress in TE were detected and might be useful for rainfed rice improvement.

Septoria antirrhini . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Septoria antirrhini . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot, leaf drying, defoliation. HOSTS: Antirrhinum antirrhiniflorum , A. majus, A. siculum ( Scrophulariaceae ). GEOGRAPHICAL DISTRIBUTION: AFRICA: South Africa. NORTH AMERICA: Canada, USA. SOUTH AMERICA: Chile, Colombia. ASIA: Armenia, Azerbaijan, China, Iran, Israel. AUSTRALASIA: Australia, New Zealand. EUROPE: Bulgaria, Czech Republic, Estonia, France, Germany, Great Britain, Hungary, Ireland, Italy, Netherlands, Portugal, Romania, Ukraine, former Yugoslavia. TRANSMISSION: Not reported, but almost certainly by airborne, splash-dispersed conidia from infected plant debris and seed stocks. The disease is significantly more severe under wet weather conditions (SINADSKIY et al. , 1985).

Septoria verbascicola . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Septoria verbascicola . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot, leaf drying. HOSTS: Verbascum blattaria, V. blattaria var. albiflorum, V. nigrum, V. orientale, V. songaricum, V. thapsus ( Scrophulariaceae ). GEOGRAPHICAL DISTRIBUTION: NORTH AMERICA: Canada, USA. ASIA: Turkmenistan. EUROPE: Czech Republic, Germany, Romania, Russia, Ukraine. TRANSMISSION: Water-drops (BEACH, 1919).

Septoria geranii . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Septoria geranii . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot; necrotic spots, leading to leaf drying. HOSTS: Geranium carolinianum, G. collinum, G. columbinum, G. depilatum, G. dissectum, G. divaricatum, G. graveolens, G. lucidum, G. molle, G. nodosum, G. palustre, G. pratense, G. purpureum, G. pusillum, G. pyrenaicum, G. rectum, G. robertianum, G. sanguineum, G. sylvaticum, G. versicolor ( Geraniaceae ). GEOGRAPHICAL DISTRIBUTION: AFRICA: Canary Is, Kenya. NORTH AMERICA: USA. ASIA: Azerbaijan, Republic of Georgia [ www.cybertruffle.org.uk/gruzmaps/index.htm ], India, Kazakhstan, Kirgizstan, Russia, Turkmenistan, Uzbekistan. EUROPE: Belarus, Bulgaria, Estonia, France, Germany, Great Britain, Greece, Hungary, Italy, Lithuania, Norway, Poland, Portugal, Romania, Russia, Spain. TRANSMISSION: Not reported, but almost certainly by airborne or splash-dispersed conidia.

How manufacturing processes affect the level of pesticide residues in tea

AbstractTea (both green and black) is consumed throughout the world, both for pleasure and therapeutic purposes. Most people will be unaware of their involuntary exposure to residues of pesticides lingering in processed tea and so possibly transferring into infusions of tea. The purpose of this work was to study the effect of green tea and orthodox black tea manufacturing processes on the fate of pesticides sprayed onto tea bushes (Camellia sinensis). The fates of residues of dimethoate, quinalphos, dicofol and deltamethrin in these two different types of tea manufacturing processes were compared. For black tea, the manufacturing process involves leaf harvesting, withering, rolling, fermentation and drying; and for green tea, leaf harvesting, microwave heating, rolling and drying. The two processes resulted in the same concentration factor of plant material into the dried commodity, while the decreases in residue levels were different for different pesticides. Initial microwave heating and dehydration in the green tea manufacturing process resulted in greater loss of pesticide residues than did withering and dehydration in black tea; no significant reduction in residue level resulted from the rolling and fermentation steps in black tea. Residue levels in both green and black teas were reduced during final drying. Copyright © 2004 Society of Chemical Industry

Yield response to water deficit in an upland rice mapping population: associations among traits and genetic markers

A population of recombinant inbred rice lines from a cross between the upland japonica cultivar Azucena and the upland indica cultivar Bala was evaluated in a series of upland field experiments. Water stress was imposed during the reproductive stage by managed irrigation during the dry season, while control treatments were maintained in aerobic, well-irrigated conditions. Water deficit resulted in a yield reduction of 17 to 50%. The genetic correlation between stress and control yields was quite high when stress was mild, and the heritability of yield was similar in stress and control treatments across both years of this study. Genetic correlations between secondary traits such as leaf rolling and drying and yield under stress varied from high (leaf drying) to insignificant (leaf rolling). Lines with superior yield tended to have fewer panicles and larger grain size than the high-yielding parent, Bala, even though the panicle number was positively correlated with yield and the thousand-grain weight was not associated with yield for the population as a whole. Analysis of quantitative trait loci (QTLs) for yield and yield components allowed the identification of 31 regions associated with growth or yield components. Superior alleles came from either parent. Several of the regions identified had also been reported for root mass at depth or maximum root length in this population in other studies made under controlled environments, and for leaf drying (LD) in field studies. However, the direction of the effect of QTLs was not consistent, which indicates that there was not necessarily a causal relationship between these secondary traits and performance. We conclude that mapping populations can provide novel insights on the actual relationships between yield components and secondary traits in stress and control environments and can allow identification of significant QTLs for yield components under drought stress.

Susceptibility of clover species to fungal infection: the interaction of leaf surface traits and environment

Many foliar pathogens require free water to germinate; therefore, disease pressure should favor plants that are able to repel water. For a suite of 18 sympatric clover species (Trifolium and Medicago, Fabaceae), we evaluated leaf traits affecting leaf wetness and susceptibility to infection by the fungal pathogen Stemphylium sp., causal agent of Stemphylium leaf spot. Spore germination increased with time in free water, and the relative susceptibility of host plants to infection was proportional to the duration of water retention on leaves. Larger leaves captured more water and retained it longer. Unexpectedly, trichomes and leaf wettability did not affect water capture. For clovers planted within natural clover populations at two sites, infection was threefold greater at the wetter site. At the drier site, water retention on the leaf surface was an important predictor of infection rates across host species, but persistent fog and dew at the wetter site reduced the importance of rapid leaf drying. Our results suggest that plant adaptations that reduce water retention on leaves may also reduce disease incidence, but the selective advantage of these traits will vary among habitats.

Biogenic C5 VOCs: release from leaves after freeze–thaw wounding and occurrence in air at a high mountain observatory

During investigations of the formation of volatile organic compounds (VOCs) in leaves, we observed C5 VOCs during leaf drying, senescence, and following freeze–thaw damage. VOCs were quantified by proton-transfer-reaction mass spectrometry (PTR-MS). In freeze-damaged leaves, VOC products were verified with a gas chromatography PTR-MS system, showing that a variety of plants produced 1-penten-3-ol and 1-penten-3-one with smaller amounts of 2(Z)-penten-1-ol and pentenals; similar VOCs have been detected in soybean seed homogenates (Gardner et al., J. Agric. Food Chem. 44 (1996) 882). Most plants wounded in this way also released hexenals and hexanal, and clover also released methylbutanals. The formation of the C5 products was oxygen–dependent, consistent with the involvement of the enzyme lipoxygenase, and pentenone appeared to form independent of an alcohol dehydrogenase reaction; the latter is apparently disrupted by the freeze–thaw treatment. In parallel with these laboratory experiments, on-line PTR-MS measurements of ambient air were conducted at the Sonnblick Observatory in the Austrian Alps (3106 m a.s.l.). Following a hard freeze in central Austria, substantial amounts of C5 VOCs, ranging from 300 pptv to 6 ppbv and including 1-penten-3-ol, methylbutanals and probably pentenone, were detected at this site for several days peaking after midnight. Factor analysis supported their biogenic origin. We speculate that these VOCs were derived from freeze-damaged local vegetation by processes similar to those seen in laboratory freezing studies. If confirmed, these results suggest that leaf-freezing events in forests will give rise to the release of substantial levels of reactive C5 and C6 VOCs that can contribute to regional tropospheric chemistry.

Designing pest-suppressive multistrata perennial crop systems: shade-grown coffee in Central America

During most of its cultivation in Central America, coffee (Coffea arabica L.) suffered few serious pest problems. However, over the past three decades, three factors contributed to significantly increase pest levels and losses: the recent introduction of new pests; more favorable conditions for existing pests, diseases, and weeds due to lower shade levels; and secondary pest problems caused by pesticide use. The strategy of maximizing coffee production with pest control dominated by synthetic pesticides has not only increased yields substantially, but also production costs, pesticide resistance, and both human health and environmental risks. An analysis of the response of the food web in coffee plantations to varying levels of light and humidity associated with different shade levels provides the basis for identifying the optimum shade conditions which minimize the entire pest complex and maximize the effects of beneficial microflora and fauna acting against it. These optimum shade conditions for pest suppression differ with climate, altitude, and soils. The selection of tree species and associations, density and spatial arrangement, as well as shade management regimes are critical decisions for shade strata design. Site-specific knowledge of the seasonal food web dynamics permits growers to determine the appropriate seasonal shade management in order to further suppress pest levels. For example in a low-elevation dry coffee zone, 35 to 65% shade promotes leaf retention in the dry season and reduces Cercospora coffeicola, weeds, and Planococcus citri; at the same time, it increases the effectiveness of microbial and parasitic organisms without contributing to increased Hemileia vastatrix levels or reducing yields. In these conditions, shade should be at a maximum early in the dry season and at a minimum by the middle of the rainy season. Further research is needed on: the effects of individual tree species on the food web; the role of canopy architecture for coffee vigor, photosynthesis, leaf drying, pest susceptibility, and pruning regimes; and on simple observation methods and decision criteria for farmer management of tree-coffee-food web interactions.

Mapping QTLs associated with drought avoidance in upland rice

The identification of molecular markers linked to genes controlling drought resistance factors in rice is a necessary step to improve breeding efficiency for this complex trait. QTLs controlling drought avoidance mechanisms were analyzed in a doubled-haploid population of rice. Three trials with different drought stress intensities were carried out in two sites. Leaf rolling, leaf drying, relative water content of leaves and relative growth rate under water stress were measured on 105 doubled haploid lines in two trials and on a sub-sample of 85 lines in the third one. Using composite interval mapping with a LOD threshold of 2.5, the total number of QTLs detected in all trials combined was 11 for leaf rolling, 10 for leaf drying, 11 for relative water content and 10 for relative growth rate under stress. Some of these QTLs were common across traits. Among the eleven possible QTLs for leaf rolling, three QTLs (on chromosomes 1, 5 and 9) were common across the three trials and four additional QTLs (on chromosomes 3, 4 and 9) were common across two trials. One QTL on chromosome 4 for leaf drying and one QTL on chromosome 1 for relative water content were common across two trials while no common QTL was identified for relative growth rate under stress. Some of the QTLs detected for leaf rolling, leaf drying and relative water content mapped in the same places as QTLs controlling root morphology, which were identified in a previous study involving the same population. Some QTL identified here were also located similarly with other QTLs for leaf rolling as reported from other populations. This study may help to chose the best segments for introgression into rice varieties and improvement of their drought resistance.

Septoria chelidonii . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Septoria chelidonii . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot, leaf mortality, leaf drying. HOSTS: Chelidonium majus, C. majus var. asiaticum (Papaveraceae). [Type host- Chelidonium majus .] GEOGRAPHICAL DISTRIBUTION: Asia: Armenia, Azerbaijan, Republic of Georgia, Iran, Kazakhstan, Kirghizistan, Korea, Russia (Siberia), Turkmenistan, Uzbekistan. Europe: Belarus, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, France, Germany, Ireland, Italy, Hungary, Latvia, Lithuania, Moldova, Netherlands, Norway, Poland, Romania, Russia, UK, Ukraine. North America: Canada, USA (Texas). TRANSMISSION: Not reported, but almost certainly by air-borne or splash dispersed conidia.

Effects of air humidity, lighting period and lamp type on growth and vase life of roses

The rose cv. Souvenir was grown at two air humidities (65% and 90% relative humidity, RH) combined with three lighting periods (16, 20 and 24 h day −1 at a photosynthetic photon flux of 170 μmol m −2 s −1) using high-pressure sodium lamps (HPS). In addition, fluorescent tubes were included at the two air humidities at 20 h day −1. It was found that raising the humidity generally slightly increased the shoot length, while time until flowering was slightly reduced at the longest lighting period and increased at the two shorter lighting periods. Time until flowering and shoot length were slightly reduced but shoot fresh weight was unaffected by an increase in the lighting period. Fluorescent light gave shorter and lighter shoots as compared with HPS light. Increasing the air humidity reduced the vase life of the roses from 8–13 to 2–5 days, while increasing the lighting period from 16 to 24 h day −1 at 65% RH reduced the vase life from 13 to 8 days. Shortening of vase life was caused by the early development of bent necks and leaf drying. Measurements of leaf diffusion resistance showed that the stomata did not close during the dark period when the roses were grown at high air humidity, and this was particularly the case when grown under a lighting period of 20 h day −1. The water-loss curves of detached leaves from shoots grown at 65% RH showed slight differences between the different lighting periods. The rate of weight loss of leaves from shoots grown at 90% RH was much greater than that at 65% RH, and increased with increasing lighting period.

Contents of sugars in leaves of drying desiccation tolerant flowering plants, particularly grasses

Sugar complements were analysed in extracts from leaves of desiccation tolerant species in the angiosperm families Cyperaceae, Gesneriaceae, Liliaceae, Poaceae and Velloziaceae. Total sugar content was higher in live air-dry leaves of all desiccation tolerant species (except the grass Eragrostiella nardoides; 22 µmoles/g dw) than in the dead air-dry leaves of the desiccation sensitive grass Sporobolus pyramidalis (36 µmoles/g dw). Sucrose contents rose to high levels (40–98 µmoles/g dw) in live air-dry leaves of all species (except the grass Eragrostiella nardoides in which it rose to only 11 µmoles/g dw) to become the predominant sugar. Glucose and/or fructose contents frequently were lower after leaf drying but usually these were the sugars of next highest contents in live air-dry leaves. Contents of raffinose (that has been postulated to reduce sucrose crystallization) rose to c. 10% of sucrose contents in air-dry leaves of most desiccation tolerant species (but only c. 4% in Tripogon jacquemontii) compared with c. 2% of sucrose contents in the sensitive grass S. pyramidalis. Trehalose (a rare sugar in seed-plants) was present in all but one desiccation tolerant species (Xerophyta villosa) but only in minor amounts. The results are consistent with the views that sugars play a protective role during drying of desiccation tolerant plants in general but that other factors are also involved indesiccation tolerance, that in desiccation tolerant angiospermae sucrose is generally the predominant protective sugar and that raffinose and trehalose may supplement the role of sucrose.

Effects of combined NaCl and CaCl2 salinity on photosynthetic parameters of barley grown in nutrient solution

The changes caused by NaCl− and CaCl2‐induced salinity on several leaf parameters have been measured in two cultivars of barley (Hordeum vulgare L.) growing in a growth chamber in nutrient solution. Salinity was induced by adding to the nutrient solution equal weights of NaCl and CaCl2, to obtain conductivities of 2, 6, 12, 19 and 26 dS m−1. Salinity induced decreases in the leaf water potential and in the osmotic potential. Salinity did not induce significant changes in the relative photosynthetic pigment composition of barley leaves, the photosynthetic pigment stoichiometry for neoxanthin:violaxanthin cycle pigments:lutein:β‐carotene:Chl b:Chl a being close to 3:6:14:12:25:100 (mol:mol). Salinity per se did not induce interconversions in the carotenoids within the violaxanthin cycle in most barley leaves. The PSII photochemistry of most barley leaves was unchanged by salinity. However, some apparently healthy leaves growing in high salinity exhibited sudden decreases in PSII photochemistry and increases in zeaxanthin (at the expense of violaxanthin), that preceded rapid leaf drying. Salinity induced significant changes in the slow part of the chlorophyll fluorescence induction curve from barley leaves.

Leaf Loss and Drying Rate of Alfalfa as Affected by Conditioning Roll Type

Field tests of seven mower-conditioners which utilized four different conditioning roll types were conducted. Resulting leaf loss and drying rate of alfalfa were determined. Average leaf loss for different roll types ranged from 5.2 to 5.9% of total dry matter. Intermeshing rubber rolls had the lowest average leaf loss, although loss was more dependent upon crop maturity or machine adjustment than roll type. Drying rate was not affected by roll type or machine.

Driptips, Drop Size and Leaf Drying

Driptips, Drop Size and Leaf Drying

Kansas Phytopathological Notes: 1963

Leaf rust overwintered (1962-1963) in abundance in most of the state. However, drought during the early spring, particularly during April, caused leaf drying and unusually early maturity of wheat in the southern half of the state. Even though environmental conditions were favorable for rust development in most of eastern Kansas from May 20 through early June, the crop matured before an epidemic stage was reached. Severities (as determined by the Cobb scale) of 5 to 20 percent were common in central and north central Kansas at harvest time. Loss to wheat leaf rust was estimated as a trace.