Kaolin Treatments Research Articles

Minor Variety of Campania Olive Germplasm (“Racioppella”): Effects of Kaolin on Production and Bioactive Components of Drupes and Oil

The effects of climate change have a great impact on the Mediterranean regions which are experiencing an increase in drought periods with extreme temperatures. Among the various solutions reported to reduce the damage caused by extreme environmental conditions on olive plants, the application of anti-transpirant products is widespread. In an increasingly current scenario of climate change, this study was designed to evaluate the effect of kaolin on the quantitative and qualitative parameters of drupes and oil in a little-known olive cultivar known as "Racioppella", belonging to the autochthonous germplasm of Campania (Southern Italy). To this purpose, the determination of maturation index, olive yield/plant, and bioactive components analysis (anthocyanins, carotenoids, total polyphenols, antioxidant activity, and fatty acids) were carried out. Kaolin applications showed no statistically significant differences in terms of production/plant while a significant increase in the drupe oil content was observed. Kaolin treatments resulted in increased anthocyanins (+24%) and total polyphenols (+60%) content and at the same time a significant increase in the antioxidant activity (+41%) of drupes was recorded. As far as oil is concerned, the results showed an increase in monounsaturated fatty acids, oleic and linoleic acids, and total polyphenols (+11%). On the basis of the results obtained, we can conclude that kaolin treatment can be considered as a sustainable solution to improve qualitative parameters in olive drupes and oil.

Kaolin foliar-application improves the photosynthetic performance and fruit quality of Verdejo grapevines

Currently there is an urgent need to adapt vineyards to climate change in order to maintain and improve the quality of wines. In this context, it has been shown that the creation of a film of mineral particles, such as kaolin, on the vegetation can reduce stress caused by high temperatures in plants. The present study evaluated the effects of kaolin foliar-applications, from fruit set to veraison, on the physiological and agronomic behavior of a Verdejo white variety vineyard located in DOP Rueda (Spain). Compared to the controls, treated plants showed an increase in the photosynthetic performance, registering higher values of chlorophyll fluorescence parameters such as Fv/Fm, ΦPSII and ETR, and lower values of F0. Without affecting vigor and yield, grapes from treated vines produced musts with lower pH and phenolic content and greater color luminosity than those of untreated vines. The presented results suggest that kaolin treatments could be an effective tool to minimize the negative effects of climate change on the quality potential of white grape varieties grown in continental areas.

White and red-dyed kaolin particle films reduce Asian citrus psyllid populations, delay huanglongbing infection, and increase citrus growth

Florida citrus production has declined severely due to huanglongbing (HLB; “citrus greening disease”) caused by Candidatus Liberibacter asiaticus (CLas), a phloem-limited bacterium transmitted by the Asian citrus psyllid (ACP; Diaphorina citri Kuwayama). Kaolin particle films are a tool used to repel insect pests and improve growth. The film covers the natural color of the leaves, which attracts ACP. Kaolin, naturally white in color, has been found to reduce ACP in citrus plantings. Previous research suggests adding a red dye might lead to further ACP reductions by reducing ultraviolet and blue light that attract ACP. We implemented a field experiment to test the effects of white and red-dyed particle films on ACP pressure, CLas infection, and citrus growth over the course of a two-year field study. In this study, white and red-dyed kaolin particle films were applied in young, non-bearing ‘Hamlin’ sweet orange (Citrus x sinensis) trees. The white and red-dyed kaolin treatments reduced ACP pressure and delayed HLB infection, and the red-dyed kaolin particle film was more effective in reducing ACP and in delaying CLas infection. Trees in both the white and red kaolin treatments had greater relative growth rate of trunk cross-sectional area (TCSA) than controls. This effect was observed regardless of CLas infection. Both particle film treatments resulted in greater final TCSA. Our results suggest particle films are an effective alternative to insecticide-based management of ACP and have the added benefit of increasing citrus tree growth under HLB pressure.

Effect of surround WP (a Kaolin-based particle film) on Ceratitis capitata infestation, quality and postharvest behavior of cactus pear fruit cv Gialla

• Medfly can cause high preharvest and postharvest losses to cactus pear • Preharvest kaolin treatments effectively prevented medfly damage • Kaolin treatments reduced postharvest losses from decay caused by fungi or bacteria • Kaolin did not negatively affect the ripening process of cactus pear • Kaolin increased the postharvest level of betaxantins and polyphenols in cactus pear A Kaolin-particle film (Surround WP) was applied at 3% to cactus pear (Opuntia ficus-indica cv Gialla) to assess its capacity to Control medfly (Ceratitis capitata Wiedemann) infestation and to evaluate its effects on the quality and postharvest behavior of treated fruit. In the first trial, Kaolin was applied at the end of July when fruit were green and about two weeks later, at color breakage. Its efficacy was compared with a standard organophosphate insecticide (Phosmet). The experiment was conducted in two locations in 2014 and 2015. Kaolin application was very effective in preventing medfly attacks until natural fruit drop in November. Kaolin treated fruit were harvested at the commercial maturity stage and stored 2 weeks at 8 °C plus 1 week at 20 °C, or 3 weeks at 2 °C plus 1 week at 20 °C. The incidence of decay in the presence of medfly larvae or only due to molds was 2 -13%. Phosmet was ineffective in preventing medfly attacks. The second study of Kaolin on fruit quality and postharvest behavior demonstrated that Kaolin slightly delayed fruit coloration when fruit was once or twice before harvest. Respiratory activity, ethylene rates, juice chemical composition and color at harvest time and after 1 or 2 weeks of storage at 8 °C plus 4 d at 20 °C demonstrated slight differences between Control fruit and Kaolin. Vitamin C, betaxantins levels and the antioxidant capacity of Kaolin treatments were lower or not different than Control fruit at harvest but increased at a higher rate than in Control fruit over storage. Total phenols decreased in all treatments during storage but at a slower rate in Kaolin treatments. Overall results show that Kaolin treatments are effective to prevent medfly attacks in cactus pears with no negative effect on fruit quality and shelf life.

Metabolomics of Photosynthetically Active Tissues in White Grapes: Effects of Light Microclimate and Stress Mitigation Strategies.

The effects of climate change are becoming a real concern for the viticulture sector, with impacts on both grapevine physiology and the quality of the fresh berries and wine. Short-term mitigation strategies, like foliar kaolin application and smart irrigation regimes, have been implemented to overcome these problems. We previously showed that these strategies also influence the photosynthetic activity of the berries themselves, specifically in the exocarp and seed. In the present work, we assessed the modulating effects of both canopy-light microclimate, kaolin and irrigation treatments on the metabolic profiles of the exocarp and seed, as well as the potential role of berry photosynthesis herein. Berries from the white variety Alvarinho were collected at two contrasting light microclimate positions within the vine canopy (HL—high light and LL—low light) from both irrigated and kaolin-treated plants, and their respective controls, at three fruit developmental stages (green, véraison and mature). Untargeted liquid chromatography mass spectrometry (LCMS) profiling of semi-polar extracts followed by multivariate statistical analysis indicate that both the light microclimate and irrigation influenced the level of a series of phenolic compounds, depending on the ripening stage of the berries. Moreover, untargeted gas chromatography mass spectrometry (GCMS) profiling of polar extracts show that amino acid and sugar levels were influenced mainly by the interaction of irrigation and kaolin treatments. The results reveal that both photosynthetically active berry tissues had a distinct metabolic profile in response to the local light microclimate, which suggests a specific role of photosynthesis in these tissues. A higher light intensity within the canopy mainly increased the supply of carbon precursors to the phenylpropanoid/flavonoid pathway, resulting in increased levels of phenolic compounds in the exocarp, while in seeds, light mostly influenced compounds related to carbon storage and seed development. In addition, our work provides new insights into the influence of abiotic stress mitigation strategies on the composition of exocarps and seeds, which are both important tissues for the quality of grape-derived products.

Influence of kaolin application on most important fruit and leaf characteristics of two apple cultivars under sustained deficit irrigation

BackgroundApple is one of the oldest and most valuable fruits. Water restriction is one of the major problems in the production of this fruit in some planting areas.MethodsEffects of kaolin spray treatments were studied on two early apple cultivars of Golab and Shafi-Abadi under sustained deficit irrigation (SDI) in Alborz province, Iran during 2017 and 2018. Irrigation treatments were 100%, 85%, and 70% ETc and kaolin application were concentrations of 0, 3 and 6% in 2017 and 0, 1.5 and 3% in 2018.ResultsResults showed that 85% ETc treatment compared to other irrigation treatments improved apple tree crown volume in 2017. Deficit irrigation treatments significantly reduced fruit weight in both years. Application with 6% kaolin resulted in 33.3% increase in apple fruit weight compared to non-kaolin treatment at 100% ETc irrigation in the first year. Severe deficit irrigation (70% ETc) significantly reduced apple fruit length in both years, but 6% kaolin increased fruit length in both apple cultivars in 2017. Severe deficit irrigation treatment increased the firmness of apple fruit compared to control and mild deficit irrigation (85% ETc) in the first year of experiment. There was no significant difference between irrigation treatments for apple fruit firmness in the second year of experiment. Kaolin treatments of 1.5% and 3% at full irrigation increased the soluble solids content of apple fruit by 36.6% and 44.1% in 2018, respectively. Deficit irrigation treatments significantly increased leaf proline content compared to control in both years. In the first year, kaolin treatments increased leaf proline but in the second year, leaf proline was not significant. Deficit irrigation treatment of 70% ETc and 6% kaolin had the highest amount of glycine betaine content, malondialdehyde and hydrogen peroxide in apple leaf in the first year of experiment.ConclusionsSevere deficit irrigation stress (70% ETc) increased the activity of nonenzymatic defense systems of apple trees. Kaolin as a drought stress reducing agent can be recommended in apple orchards of Golab and Shafi-Abadi cultivars as an effective and inexpensive method to improve tolerance to drought stress conditions.

EFFECT OF KAOLIN FOLIAR ON FRUIT SUNBURN, YIELD AND FRUIT QUALITY OF PERSIMMON TREES

A field experiment was conducted during 2016 and 2017 seasons at a private orchard situated in Abu El-Matamir destrict, El-Behaira governorate, Egypt, to study the effect foliar spray 0, 2, 3 and 4% kaolin, twice or three times in June, July and August on vegetative growth, nutritional status, sunburn percentage, yield and fruit quality of Costata persimmon trees. The obtained results showed that, kaolin foliar application at 4% twice or three times (T6 and T7) considered the best treatments for enhance improvement nutritional status trees. Moreover, kaolin foliar applications were effective to control fruit sunburn % as well as reducing severity percentage sunburned fruits as compared to untreated trees. Also, Kaolin foliar application at three times was decreased leaf and fruit surface temperature especially under 3 and 4%. concentrations. In addition, kaolin treatments increased yield and improved fruit quality in terms fruit weight, size, height, and diameter as well as fruit firmness. Kaolin foliar spray was raising fruit values SSC%, and SSC/acid ratio compared to the control, whereas there is no significant variation among kaolin concentrations on this variables. Therefore, it could be recommended that, spraying kaolin at 4% three times in summer months, improving increasing gave the best result for improving trees nutritional status, and also it had a positive effect on preventing fruit sunburn damage and increasment yield and fruit quality Costata persimmon trees.

Foliar Application of Kaolin to Reduce Sunburn in ‘Red Delicious’ Apple

Sunburn may occur in some horticultural crops such as apples, and can cause a lot of damages to fruit of most cultivars, especially red apples, such as Red Delicious cultivar. In the present research, the effect of different treatments of kaolin (0.00, 2.50, 5.00, and 7.50%) was studied on the severity of sunburn on fruit of apple ‘Red Delicious’. Foliar spraying of kaolin was carried out in two times including early-June and early-July. The results of early-June spraying showed that the amount of sunburn on the fruits was affected by the treatments so that there were no significant differences between treatments of 2.50, 5.00, and 7.50% kaolin, but those treatments showed significant differences with the control (0.00). In addition, the results of early-July showed that the amount of sunburn on the fruits was affected by the kaolin treatments so that the highest amount of sunburn was observed in the control fruits and lowest sunburn was in the fruits treated with 7.50% kaolin. The treatments of 5.00 and 7.50% kaolin in both spraying times had the highest effect on reduction of fruit sunburn. It can be concluded the treatment of 7.50% kaolin in early-June and early-July is the best to reduce the sunburn on fruit of apple ‘Red Delicious’.

Effects of deficit irrigation and kaolin application on vegetative growth and fruit traits of two early ripening apple cultivars

BackgroundDrought is one of the main serious problems for agriculture production which its intensity is increasing in many parts of the world, hence, improving water use efficiency is a main goal for sustainable agriculture.ResultsGrowth indices including relative shoot length growth (SL), relative stem diameter increase (SD) and relative trunk cross sectional area growth (TCSA) measured at the start and end of the season decreased by reducing the irrigation level. Chlorophyll index (CI) was decreased at 70% crop evapotranspiration, however water use efficiency (WUE), leaf and fruit total phenolic content (TPC), and fruit anthocyanin content (AC) were among the traits that showed increment by water deficit stress in both cultivars. Shafi-Abadi cultivar showed to be more sensitive to the water stress than ‘Golab’. Kaolin treatment improved SL, SD and CI traits, but this increase was statistically significant only for SD at 5% level. Kaolin had no significant effect on yield and water use efficiency (WUE), however, it had negative effect on yield efficiency (YE). Kaolin treatments also significantly increased fruit and leaf TPC (P < 0.01) but had no effect on leaf and fruit total antioxidant activity (AA), as well as fruit anthocyanin content (AC) and soluble proteins (SP).ConclusionsIrrigation at 85% ETc showed better results than 100% and 70% ETc levels for yield attributes. It seems that the more pronounced effect of kaolin on vegetative traits but not on the fruits, might be attributed to the early ripening and harvest time of the examined cultivars.

Kaolin treatments on Pinot noir grapevines for the control of heat stress damages

The aim of the study was to verify if vineyard kaolin application during the 2017 hot summer could reduce the negative effects of high temperatures and heat stress on canopy physiological processes, yield and fruit quality. The kaolin was applied once at the beginning of August, at 3% concentration, in a Pinot Noir vineyard. The application was performed only to the west side of the rows, where the vines were more subjected to heat stress. The 2017 summer was very hot, with maximum air temperature higher than 35 °C for several consecutive days in June, July and August and with heat waves that reached 42.3 °C in August. The kaolin coating works by significantly reducing leaf temperatures in comparison to untreated vines, with an average of about − 4 °C and up to −6 °C. Moreover, it maintains high the photosynthetic activity preventing irreversible photoinhibition phenomena, whereas untreated vines exhibit a marked physiological damage with chlorotic and necrotic leaves, dehydrated berries and sunburn damages. At harvest, 30-35% of the untreated vines were affected by severe water stress symptoms and produced unmarketable fruits. In comparison to the untreated vines, those sprayed with kaolin showed a higher yield (+27%), higher anthocyanins (+35%) and higher concentration of organic acids (+11%)

Evaluation of kaolin and cinnamon essential oil to manage two pests and a fungal disease of sour cherry at different tree canopy levels

We studied the effects of kaolin particle film applications on major sour cherry (Prunus cerasus L.) pests and fruit quality and evaluated the ability of cinnamon essential oil (Cinnamomum verum J. Presl) to reduce infestations by cherry fruit fly, Rhagoletis cerasi (Linnaeus 1758) (Diptera: Tephritidae), in the field. Efficacy of kaolin particle films (Surround WP, Engelhard Corporation; applied at 4% concentration) was compared at two application frequencies (one and two applications). The essential oil of cinnamon (applied at 0.25% concentration) was sprayed five times on selected trees. As the amount of damage caused by pests may vary between different parts of the canopy, both kaolin and essential oil treatments were evaluated at two canopy levels. We found that the damage of R. cerasi and stone fruit weevil, Anthonomus rectirostris (Linnaeus 1758) (Coleoptera: Curculionidae), on the fruits occurred primarily in the upper third of the canopy, while the incidence of sour cherry anthracnose caused by Colletotrichum acutatum J. H. Simmonds 1968 (Glomerellales: Glomerellaceae) was concentrated to the lower third of the canopy. Two kaolin particle film applications significantly reduced the fruit injury caused by R. cerasi by 62% (Abbott’s efficacy). In contrast, the treatments showed no activity against A. rectirostris and C. acutatum, although infestation by A. rectirostris was numerically lower on the trees treated with kaolin (19–32% efficacy). The kaolin applications did not affect the average fruit weight (g/100 cherries) and soluble solid content (SSC, %). The cinnamon essential oil applications did not control infestations by R. cerasi. Overall, our results suggest that kaolin particle film technology is a promising tool in pest management programs in organic sour cherry production, at least against R. cerasi.

Kaolin particle film alleviates adverse effects of light and heat stresses and improves nut and kernel quality in Persian walnut

Abstract Spraying with kaolin is becoming a feasible and cheap treatment to alleviate the destructive effects of light and heat stresses. Here, the effects of spraying with kaolin were investigated on leaf temperature, photosynthesis and gas exchange rate, sunburn and quality of nut and kernel, potassium (K) and sodium (Na) concentrations and proline content of the walnut. Three spraying levels of kaolin (0%, 3% and 6%) were used in 5 replicates during two consecutive years. Results indicate that the kaolin spray increases leaf area and chlorophyll content (up to 14.71% and 11.99%, respectively) comparing to the control. The severity of leaf, husk, and kernel sunburn of kaolin treated trees was reduced up to 50% comparing to the control plants. Considering physiological parameters kaolin treatment reduced leaf temperature (4.4 °C and 5.6 °C, respectively in kaolin 3% and 6% compared to the control), but increased photosynthesis rate (Amax), gas exchange (gs), internal CO2 partial pressure (Ci) and the water use efficiency (up to 29.85%, 30%, 10.97% and 19.88%, respectively) comparing to the control. Kaolin application also improved nut and kernel weight, kernel percentage and kernel oil content (up to 8.2%, 16.1%, 7.7% and 11.29%, respectively) comparing to the control. Kaolin treatments increased potassium level and K:Na ratio, but decreased Na and proline content, both in leaf and kernel, in comparison with the control. However, there was no significant difference between the results of applying kaolin at concentrations of 3% and 6% in almost all of the measured characteristics, but improved results were obtained with higher levels of kaolin, except for nuts and kernel quantities. Considering global warming, using kaolin application can be recommended as a suitable and cheap method for the acclimation of walnut to high temperatures and solar radiation.

Effects of irrigation regime and application of kaolin on canopy temperatures of sweet pepper and tomato

Abstract The effect of different irrigation regimes and the application of kaolin on the canopy temperatures of sweet pepper (Capsicum annuum L.) and tomato (Lycopersicon esculentum Mill.), determined by a nondestructive imaging method, is discussed in the paper. The research was conducted in an open field on carbonate chernozem soil at Stara Pazova (40 km north of Belgrade, Serbia), over a period of three years (2011, 2012 and 2013). The setup was a two-factorial, completely random block system, with three replications. The first factor was the irrigation regime and the second the application of kaolin. The experimental pepper plants were subjected to thre different irrigation regimes: a) full irrigation (F), covering 100% of ETc (cultivar’s evapotranspiration rate); b) deficit irrigation at 80% of ETc (R1); and deficit irrigation at 70% of ETc (R2). Two different irrigation regimes were monitored in the case of tomato: full irrigation (F), covering 100% of ETc, and b) deficit irrigation at 50% of ETc (D). The kaolin treatments of both crops were: a) control without kaolin (C) and 5% kaolin suspension (K). The results of this research indicated that the irrigation regime had a very significant effect on the temperature of pepper and tomato; the higher the level of irrigation, the lower the temperature. The dual-effect of kaolin impacted the heat balance of the plants.

Harmonious interaction of kaolin and two insect predator species in plant protection

ABSTRACTLacewings and lady beetles represent two important groups of natural enemies for pest control. Kaolin is used in various crop ecosystems to reduce abiotic plant stressors and pest colonization. Compatible methods aimed at reducing abiotic and biotic plant stressors are desired in crop management systems. Therefore, this work evaluated the development and survival of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) and Eriopis connexa (Germar) (Coleoptera: Coccinellidae) larvae of different ages treated with kaolin at three different concentrations (ca. 60, 80, and 100 g/L) and prey consumption when treated with kaolin at a field rate of 60 g/L. The prey used were the whitefly Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) and the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae). Survival rates and development durations for E. connexa larvae topically treated with kaolin at different ages were similar to those for untreated larvae. However, larvae of C. externa reduced survival and delayed development when treated with kaolin concentrations greater than the recommended field rate. Otherwise, kaolin treatments did not affect prey consumption by larvae and adults of both predator species.

EFFECT OF KAOLIN APPLICATIONS ON FRUIT SUNBURN, YIELD AND FRUIT QUALITY OF BALADY MANDARIN (Citrus reticulata, Blanco)

Sunburn is a major problem caused by high temperature and direct solar radiation, which leads to significant economic losses in Balady mandarin yield. So, a field experiment was conducted during 2014 and 2015 seasons at a private orchard situated in Motobus, Kafr El-Sheikh governorate, Egypt, to study the effect of foliar spray of 0, 2, 3 and 4% kaolin, twice or three times at May, June and July on sunburn percentage and fruit quality of Balady mandarin trees. The obtained results showed that, kaolin foliar applications were effective to control fruit sunburn as well as reducing severity percentage of sunburned fruits as compared to untreated trees. Moreover, Kaolin foliar application at three times was decreased leaf and fruit surface temperature especially at the concentrations of 3 and 4%. In addition, kaolin treatments increased yield and improved fruit quality in terms of fruit size, diameter, weight, peel thickness and vitamin C. Kaolin foliar spray was raising fruit values of SSC%, acidity and SSC/acid ratio compared to control trees, whereas there is no significant variation among kaolin concentrations on this variables. Therefore, it could be recommended that, spraying kaolin at 3 or 4% three times in summer months, because it had a positive effect on preventing fruit sunburn damage and improvement yield and fruit quality of Balady mandarin trees.

The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna.

Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised 22% in the feeding suspension, both MP types decreased food intake by 30%, while kaolin had no effect. Moreover, SMPs were found to homoaggregate in a concentration-dependent manner, which resulted in a 77% decrease of the ingested SMPs compared to PMPs. To better understand MP-processing in the gut, gut passage time (GPT) and evacuation rate of MPs were also assayed. SMPs and PMPs differed in their effects on daphnids; moreover, the particle effects were dependent on the MP: algae ratio in the suspension. When the MP contribution to the particle abundance in the medium changed from 1 to 4%, GPT for daphnids exposed to SMPs increased 2-fold. Our results suggest that MPs and, in particular, SMPs, have a greater capacity to negatively affect feeding in D. magna compared to naturally occurring mineral particles of similar size. Moreover, grazer responses observed in experiments with PMPs cannot be extrapolated to the field where SMPs dominate, because of the greater effects caused by the latter.

Effect of irrigation regime and application of kaolin on yield, quality and water use efficiency of tomato

Modern agriculture is faced with two tasks: (1) to produce enough food for a growing global population, and (2) to ensure satisfactory crop quality while using water resources efficiently. A study of the effect of kaolin on the yield, quality and water use efficiency of tomato (Lycopersicon esculentum Mill.), grown under different irrigation regimes, is reported in the paper. The research was conducted in an open field with carbonate chernozem soil, at Stara Pazova (40km north of Belgrade, Serbia). It lasted for three years (2011, 2012, and 2013). The experimental setup was a two-factorial, completely random block system, with three replications. The first factor was the irrigation regime and the second the application of kaolin. Two irrigation treatments were studied: (a) full irrigation (F), covering 100% of ETc (crop evapotranspiration), and (b) deficit irrigation (D) at 50% of ETc. The kaolin treatments were: (a) control treatment, without kaolin (C) and treatment with a 5% suspension of kaolin (K).On average, the highest fresh tomato fruit yields were achieved under full irrigation, with kaolin (FK) (21.0kgm−2). The FK treatment also resulted in the greatest dry weight of the fruits (1.1kgm−2). The average fruit weight was rather uniform and ranged from 71.7g with DC to 75.4g with DK. The average sugar and lycopene content was quite uniform over the study period, while the irrigation regime had a significant effect on the average organic acid content and total antioxidant activity. Deficit irrigation treatments resulted in a higher organic acid content and higher total antioxidant activity than full irrigation. The application of kaolin had a greater effect of the water use efficiency of tomato than the irrigation treatment.

Effect of irrigation regime and application of kaolin on yield, quality and water use efficiency of sweet pepper

The present paper reports research that focused on the effect of kaolin on the yield, quality and water use efficiency of the sweet pepper Capsicum annuum L., grown under different irrigation regimes. The research was conducted in an open field with carbonate chernozem soil, at Stara Pazova (40km north of Belgrade, Serbia). It lasted for three years (2011, 2012, and 2013). Three irrigation regimes and two kaolin treatments were compared. The irrigation regimes were: (i) full irrigation (F) ensuring 100% of crop evapotranspiration (ETc), (ii) deficit irrigation at 80% ETc (R1), and (iii) deficit irrigation at 70% ETc (R2). The kaolin treatments were: (i) control without kaolin (C) and (ii) treatment with kaolin application (K). The setup was a two-factorial, completely random block system, with three replications. The first factor was the irrigation regime and the second kaolin application.On average, the highest fresh sweet pepper yields were achieved under full irrigation (10kgm−2). Also, FC and FK treatments resulted in the highest first-class, second-class and first+second class yields. On average, the lowest percentage of sunburn was noted in the case of the FK treatment (10%), and the highest with the R2C treatment (about 27%). The sugar content of the pepper was quite consistent, while the organic acid content varied from 15.0mLg−1 with R1C to 18.7mLg−1 with FK. The application of kaolin and the irrigation regime did not have a statistically significant effect on the antioxidant activity of the pepper and ranged from 5538.4 to 6447.4μmol TUg−1. The highest yield water use efficiency (yWUE) of first-class and first+second class yields was recorded with the FC, FK and R1C treatments. Throughout the study period, yWUE levels of the second-class yields, and of the total yield, were rather uniform, regardless of the type of treatment.

Kaolin and potassium soap with thyme essential oil to control Monosteira unicostata and other phytophagous arthropods of almond trees in organic orchards

Monosteira unicostata (Mulsant & Rey) (Hemiptera: Tingidae) is an important pest of almond trees in the Mediterranean region requiring alternative control methods for organic farming. Kaolin and potassium salts of fatty acids combined with thyme essential oil (PSTEO) have shown high efficacy for the control of this insect in laboratory assays. Field studies were conducted during two consecutive years to test the feasibility of these products applied at the maximum field recommended concentrations to control this pest and other arthropods that damage al- mond trees. In 2009, two kaolin applications reduced the abundance of M. unicostata approximately by half, whereas in 2010, identical applications reduced the abun- dance by a third. This produced a damage reduction of 26 and 11 %, respectively. Concerning PSTEO, a 40 % re- duction in M. unicostata abundance was obtained in 2009, producing a 14 % damage reduction, whereas no sig- nificant effect was observed in 2010. The effect of the treatments on M. unicostata was only observed at the lower part of the trees. Other phytophagous arthropods of almond trees, such as Cicadellidae, Aphididae, Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae) and Phyllonorycter co- rylifoliella Hubner (Lepidoptera: Gracillariidae), were also negatively affected by kaolin treatments, but PSTEO had no effect on herbivorous arthropods other than M. uni- costata. Kaolin could be useful to control M. unicostata in the field, but repeated applications might be required to achieve good tree coverage and pest control. PSTEO ap- pears more limited in its efficacy.

Shade coffee in Hawai‘i – Exploring some aspects of quality, growth, yield, and nutrition

In a harsh (Kunia) and an ideal (Kona) growing region of Hawai‘i, sun grown Coffea arabica L. was compared to coffee shaded with varying degrees of black and aluminized shade cloth, macadamia trees, and a novel, spray-on shade composed mostly of kaolin. Shading did not appreciably affect organoleptic quality. Shading resulted in statistically different yields in the macadamia (16% of sun) and kaolin (199% of sun) treatments in the second year compared to full sun treatments in their respective locations, although a negative, linear trend was observed with increased shading. The lack of significant differences in yields between the shade cloth and sun treatments was likely a result of large yield variation among replicates. Bean sizes differed little between shade treatments and the percentage of defects and broken beans were generally not significantly different among the treatments in Kunia. Kona bean sizes and characteristics were not different. Shading reduced surface leaf temperatures and increased specific leaf area but generally did not affect lateral nodal growth. Leaf nutrient concentration differed between treatments.