Orchard Temperature Research Articles

Effects of geographic origin and temperature on survival, development, and emergence of the managed pollinator Osmia lignaria

IntroductionThe blue orchard bee,Osmia lignaria, is a widespread North American native pollinator that can be employed for commercial fruit and nut crop production. The largest supplies of these bees are collected in the wildlands ssssof Utah and Washington, United States. HowO. lignariafrom different geographic regions respond to current recommended management practices or translocation to novel environments is not fully understood.MethodsUtah- and Washington-originatedO. lignariawere reared in laboratory incubators under two thermal regimens: (1) constant temperatures used to manage bees through immature development, adult winter dormancy, and for spring emergence, and (2) hourly fluctuating temperatures programmed to mimic the natural daily (24 h) thermal cycles of the nearest cherry orchard growing region through their life cycles.ResultsIn comparison to rearing bees at orchard temperatures, we found that rearing bees at a constant temperature increased survival and shortened egg–adult development periods. Washington bees were more adversely affected by the consistent warm rearing temperatures than were Utah bees, possibly due to their adaptations to Washington’s relatively moderate climate. At orchard temperatures, Utah bees suffered high prepupal and pupal mortality, while Washington bees suffered high pupal and adult mortality. These late life stages coincided with the hottest maximum temperatures in their respective thermal regimens. Adult females from both states naturally emerged in synchrony with local bloom time, but their emergence period overall was prolonged compared to bees in the constant thermal regimen that were induced to emerge at orchard bloom times.DiscussionOur data support that bees originating from cool montane habitats of different U.S. states suffer from the warmer climatic conditions at lower altitudes of their respective crop-growing regions. A better understanding of optimal management temperatures forO. lignariafrom different geographic regions and the effect of bee origin and temperature on survival and development timing is needed for best managing these pollinators when they are translocated or when climate change results in increased temperatures during bee development periods.

DEVELOPMENT AND EVALUATION OF UNMANNED GROUND VEHICLE FOR AUTOMATED ENVIRONMENTAL MONITORING OF LOW-HEIGHT TUNNEL FARMS

Agricultural machinery is an essential tool for improving agricultural production per unit area. It helps farmers to grow more crops in less time and with greater efficiency to meet food security for exponentially growing population. Tunnel farming is an agriculture technique in which the crop is grown in a long row, covered with plastic sheets to maintain favorable environment for crop growth while minimizing environmental and biological hazards. Tunnel farms are divided into low height tunnel, high tunnel, and walk-in tunnel. It is important to monitor tunnels for temperature and relative humidity because these two factors promote disease and pest attack. In low height tunnels, it becomes difficult to physically monitor temperature variations, humidity variation and pest or disease attack. Therefore, it is required to develop suitable solution to this problem which can be provided in the form of small, unmanned ground vehicle (UGV) equipped with necessary sensing devices. In this study, a small UGV having camera, temperature and humidity sensors was developed and evaluated at four different sites. These sites included lemon orchard, research farms, main boulevard and field farm. The temperature and humidity reading were recorded at 8:00, 11:00, 14:00 and 16:00 a day on 10, 20, 30, 40, and 50 ft. length from field boundary. In lemon orchard temperature is minimum (240C) and humidity is maximum (69%) at 8:00 AM. In the evening at 2:00 PM temperature was maximum (390C) and humidity was minimum (45%). In research farm temperature was minimum (280C) and humidity was maximum (65%) at 8:00AM. In the evening at 2:00PM temperature was maximum (430C) and humidity was minimum (40%). In Kfueit boulevard temperature was minimum (250C) and humidity was maximum (69%) at 8:00AM. In the evening at 2:00PM temperature was maximum (400C) and humidity was minimum (46%). In Progressive farmer farm temperature was minimum (300C) and humidity was maximum (69%) at 8:00AM. In the evening at 2:00PM temperature was maximum (430C) and humidity was minimum (46%).

Intelligent Spraying Water Based on the Internet of Orchard Things and Fuzzy PID Algorithms

During the fruit ripening period, the orchard temperature difference between day and night has a substantial impact on the fruit quality, and it is not easy to be controlled like that of in greenhouse, this paper designed the smart orchard Internet of Things (IoT), through the fuzzy PID (Proportion-Integration-Differentiation) algorithm to control the water spraying to adjust the temperature difference Δ T between day and night in the orchard, intelligently influenced the orchard energy conversion process, and promoted the fruit sugar accumulation. Experiments show that the maximum Δ T can reach 20°C, the intelligent energy regulation based on the IoT has a good effect, and a scheme to intervene the microclimate in farmland (quite different from the greenhouse environment) is provided.

Differential thermal analysis reveals the sensitivity of sweet cherry flower organs to low temperatures.

The frequency and severity of spring frosts increase during the budburst in many regions of the world as global warming increases. Variability in the freezing resistance of sweet cherry flower organs during the active growing period has been rarely documented, especially in regard to the sepal, pedicel, receptacle, petal, stamen, and pistil organs of flower at the deacclimation stage. The freezing resistance of flower organs of six sweet cherry cultivars was investigated at regular intervals from the first white stage through the full bloom stage using differential thermal analysis (DTA) for 2019-2020. For most of the cultivars, petal and stamen organs of flower exhibited higher freezing resistance than other flower organs. There were significant differences in frost tolerance among cultivars, and 'Van' and 'Wild Genotype' had a lower level of low temperature exotherms or critical temperatures (LT50 values) in both stages, whereas 'Merton Late' was more sensitive to frost than other cultivars. Additionally, an increase in LT50 values in all cultivars was observed with the progression of the budburst. The results in the present study can increase the certainty of decision-making regarding the timing and methods to increase the air temperature in orchards during spring frost events to prevent frost damage. Larger data sets are required to further validate our results, and future efforts should thus be focused on determining the critical temperatures of flower organs using different measurement techniques.

Biocontrol Potential of Neoseiulus californicus (Mesostigmata : Phytoseiidae) Against Oligonychus punicae (Acari: Tetranychidae) in Avocado.

Oligonychus punicae (Hirst) (Trombidiformes: Tetranychidae) is a common pest in Mexican avocado orchards. Neoseiulus californicus (McGregor) (Mesostigmata: Phytoseiidae) is frequently found associated with avocado orchards in Mexico and may be an important aid for controlling O. punicae. Given the lack of information in the scientific literature, this study evaluated the predation and oviposition of N. californicus when fed O. punicae at different developmental stages in a no-choice experiment. We also assessed fluctuations in the population size of O. punicae and N. californicus in commercial avocado orchards; correlations among mite density and air temperature, humidity, and precipitation in commercial avocado orchards; and the correlations between prey and predator populations. The no-choice test revealed that N. californicus adult females fed on O. punicae of all developmental stages, with higher levels of predation being recorded for eggs, followed by larvae. The highest oviposition values of N. californicus females were observed when females were fed O. punicae eggs. In orchards, the populations of both mites increased between February and June. The populations peaked during the warmest months of the year, with O. punicae populations peaking between June and July and N. californicus peaking in August. In addition, the population size of N. californicus was significantly and positively correlated with rainfall, air temperature, and the population densities of O. punicae. Meanwhile, O. punicae population size was positively correlated with air temperature, and the population of its predator N. californicus.

UAV-Based Heating Requirement Determination for Frost Management in Apple Orchard

Frost is a natural disaster that can cause catastrophic damages in agriculture, while traditional temperature monitoring in orchards has disadvantages such as being imprecise and laborious, which can lead to inadequate or wasteful frost protection treatments. In this article, we presented a heating requirement assessment methodology for frost protection in an apple orchard utilizing unmanned aerial vehicle (UAV)-based thermal and RGB cameras. A thermal image stitching algorithm using the BRISK feature was developed for creating georeferenced orchard temperature maps, which attained a sub-centimeter map resolution and a stitching speed of 100 thermal images within 30 s. YOLOv4 classifiers for six apple flower bud growth stages in various network sizes were trained based on 5040 RGB images, and the best model achieved a 71.57% mAP for a test dataset consisted of 360 images. A flower bud mapping algorithm was developed to map classifier detection results into dense growth stage maps utilizing RGB image geoinformation. Heating requirement maps were created using artificial flower bud critical temperatures to simulate orchard heating demands during frost events. The results demonstrated the feasibility of the proposed orchard heating requirement determination methodology, which has the potential to be a critical component of an autonomous, precise frost management system in future studies.

An assessment of the attributes of Staccato sweet cherries at harvest and upon storage in relation to orchard growing factors

This work presents new data on the effects of orchard growing factors on storage quality of Staccato sweet cherries grown in the southern Okanagan region of British Columbia, Canada. Quality attributes, respiration rates, and the mineral contents of Staccato sweet cherries were analyzed. Orchard growing factors such as pruning practices, growing temperature, and relative humidity varied by orchard throughout the region, and consequently, the mineral contents, quality attributes, and respiration rates of the Staccato sweet cherries also varied. Principal components analysis revealed relationships among orchard growing factors, cherry fruit mineral content, and fruit quality data. The content of Ca, Mg, N, P, and K in cherry fruit was correlated with quality attributes such as pitting, pebbling, soluble solids, titratable acidity, dry matter, firmness, and stem pull force. Orchard temperatures and relative humidity also influenced flavour quality attributes and appearance. Orchard management practices resulting in large leaf sizes were generally associated with good flavour quality and appearance. This work provides new data to support improved understanding how cherry quality is affected by orchard growing factors in an integrated analysis.

A Methodological Approach to Determine Flower Bud Vulnerability to Low Temperatures for Deciduous Crops in Early Spring Using Degree Days

A common problem for decision makers in selecting frost control options is uncertainty about the level of injury that can be caused by low temperatures. During the past few years, the concept of lethal temperature (LT) at which 10% of the bud population dies (LT10) has been used as an index for evaluating the vulnerability of flower buds to low temperature conditions. This concept has shown to be a useful tool for frost control decision-making. However, the current methods used to obtain LT values assume no spatial or temporal variability, which results in a high level of uncertainty. The goal of this study was to develop an approach that decreases the uncertainty based on the known effects of temperature on bud vulnerability. A growth chamber experiment was conducted to determine flower bud vulnerability to low temperature as a function of temperature. The results from this study showed that thermal time expressed in degree days could explain changes in floral bud development and vulnerability to frost injury. According to our findings, LT10 is a fully acceptable index for determining flower bud vulnerability to low temperatures in orchard crops. Based on this information, we found that among the five apple and cherry cultivars analyzed, ‘Gala’ is the least vulnerable to low temperature because it starts at the beginning of spring with a high level of hardiness and increases its vulnerability at a low rate. The approach described in this article may enhance decision-making certainty associated with the timing and methods to increase air temperature in orchards during low-temperature events to avoid frost damage.

EFFECT OF SOME CHEMICAL CONSTITUENTS OF CERTAIN CITRUS TREE HOSTS ON THE POPULATION DENSITY OF Aonidiella aurantii (Maskell) AND Chrysomphalus aonidum (L.) AND THEIR POPULATION FLUCTUATIONS

This investigation was carried out to study the effect of some chemical constituents (total phenols, total carbohydrates, total proteins and pH values) of three citrus tree host leaves (sweet orange, navel orange and mandarin) on the population density of Aonidiella aurantii (Maskell)and Chrysomphalus aonidum (L.) in relation with prevailing temperature and relative humidity in different citrus orchards at Minia Alkamh district, Sharkia Governorate, Egypt during two successive years extended from December 2012 to November 2014. The results showed that sweet orange appeared to be the most susceptible citrus tree hosts to infestation by the scale insects followed by navel orange and mandarin at the least. The population density of A. aurantii had three peaks on the three citrus tree hosts in the two years. Also, C. aonidum recorded three peaks on the navel orange in the two years, while on sweet orange indicated four peaks occurred during the first year and three peaks of densities were obtained during the second one. On mandarin trees, three and four peaks were observed in the aforementioned years, respectively. The highest population was exhibited by A.aurantii in the first peak by 636 insects/300 leaves on sweet orange on February in the second year while, it was recorded by C. aonidum in the third peak by 59 insects/300 leaves on October in the same year. There was a positive relationship between both of total carbohydrates and total proteins and the population density of A. aurantii and C. aonidum on sweet orange, navel orange and mandarin, while no relation was found between each of total phenols and pH values and the infestation level by the two scale insects.

Performance of three numerical models to assess winter chill for fruit trees—a case study using cherry as model crop in Germany

The Meckenheim fruit growing region in Western Germany may be affected as a consequence of climate change by lack of chilling, i.e. a cold period in the winter required for tree species to flower in the subsequent spring. As sweet cherry requires high chill, 160 potted trees of three sweet cherry cultivars with threefold different chilling requirements were cultivated in a large experiment over 4 years, either in the orchard or in an unheated greenhouse (simulated climate change). The orchard temperatures in the warmer winter (6.0 °C) exceeded those in the unheated greenhouse (4.7 °C) in the cold winter. Chilling computations for this region showed that cherry trees of low chill cultivar ‘6000CZ’ required 22.3–26.6 chill portions (CP), medium chill cv. ‘Brooks’ about 37.9–54.4 CP and the high chill cv. ‘Schneiders spate Knorpelkirsche’ about 54.4–79.3 CP for a natural flowering. Cherry trees cv. ‘6000CZ’ receiving <300 CH, cv. ‘Brooks’ <500 CH and cv. ‘Schneiders spate Knorpelkirsche’ <700 CH were unable to flower, equivalent of 50 % of the assumed chilling optimum of the respective cultivar. Maximum chill accumulation in this region is currently achieved, so that warmer winters may reduce the available chill. The beginning of leaf drop was identified as a suitable initiation point for computing chill accumulation. Overall, the work has shown that environmental change has an effect on chilling availability in Meckenheim and possibly other fruit growing regions along 50°N. The insights gained ultimately highlight the need for cross-sectoral, adaptive management practices that jointly target a sustainable regional development.

Effect of over tree cooling irrigation on ‘Bosc’ pear orchards microclimate

Irrigation in some countries is a horticultural practice mainly used only to supply water. At the same time the use of microsprinklers have a powerful infl uence on the changes of temperature in orchards. When the air’s temperature is high (about 20 °C or higher) the evaporative cooling irrigation signifi cantly decreases the plants’ surface temperature and air temperature. The cooling effect is stronger when the air is dryer. By using cooling irrigation regularly, canopy temperature can be decreased so that the beginning of blooming can be delayed. Also if the blooming is early and frost probability is high, serious damages can happen in orchards. The benefi cial effect of cooling irrigation is the temperature reduction and frost protection. In March 2010, one month earlier than the expected blooming an irrigation system was established to produce anti-frost treatment and regulate the micro-climate of a Bosc pear orchard which belongs to the University of Debrecen (Hungary). The objective of sprinklers was to cool the air by increasing water evaporation and relative humidity. The position of the micro-sprinklers was planned in three levels (around the tree trunks, a few cm near to the soil surface, in the crown region and above the crown, a half meter higher). The results showed that the water sprayed in the orchard by micro-jets infl uenced decisively the temperature of the plantation. At higher temperatures (around 20 °C), the drop of temperature may attain 5–7 °C. A low relative humidity of the air may increase the relative effect. When water was applied at intervals of 15 minutes for ten times a day from 8 am to 18 pm, the air, fl owers and bud’s surface temperature could be kept low. At certain days when the temperature was higher than 10 °C, irrigation was used at night time in similar 15 minutes intervals, from 18 pm and 6 am. The beginning of bloom could be delayed for more than ten days. The Bosc pear variety blooming dynamics was characterized by a logistic curve in the treated as well as in the control plot. In the treated plot, the curve was steeper than in the control one in spite of the equal temperatures measured in the plots. Under Hungarian climatic conditions, the method was successfully used to delay blooming dates. The main result was the diminution of the frost damage in the spring that assured pears yields.

Apple Fruit Diameter and Length Estimation by Using the Thermal and Sunshine Hours Approach and Its Application to the Digital Orchard Management Information System

In apple cultivation, simulation models may be used to monitor fruit size during the growth and development process to predict production levels and to optimize fruit quality. Here, Fuji apples cultivated in spindle-type systems were used as the model crop. Apple size was measured during the growing period at an interval of about 20 days after full bloom, with three weather stations being used to collect orchard temperature and solar radiation data at different sites. Furthermore, a 2-year dataset (2011 and 2012) of apple fruit size measurements were integrated according to the weather station deployment sites, in addition to the top two most important environment factors, thermal and sunshine hours, into the model. The apple fruit diameter and length were simulated using physiological development time (PDT), an indicator that combines important environment factors, such as temperature and photoperiod, as the driving variable. Compared to the model of calendar-based development time (CDT), an indicator counting the days that elapse after full bloom, we confirmed that the PDT model improved the estimation accuracy to within 0.2 cm for fruit diameter and 0.1 cm for fruit length in independent years using a similar data collection method in 2013. The PDT model was implemented to realize a web-based management information system for a digital orchard, and the digital system had been applied in Shandong Province, China since 2013. This system may be used to compute the dynamic curve of apple fruit size based on data obtained from a nearby weather station. This system may provide an important decision support for farmers using the website and short message service to optimize crop production and, hence, economic benefit.

Orchard Design Influences Fruit Quality, Canopy Temperature, and Yield of Satsuma Mandarin (Citrus unshiu ‘Owari’)

Satsuma growers in Alabama have used various orchard designs to minimize freeze damage. These designs include interplanting between pecan and pine trees, and planting behind windbreaks. Interplanting satsuma trees with pine trees resulted in warmer temperatures within the orchard, while the other orchard designs did not moderate orchard temperature during severe freeze events. Satsuma fruit harvested from plots shaded by pine tree canopies had higher soluble solids content and reduced fruit weight. Dense pine tree canopies can provide an insulating effect that reduces freeze damage and yield losses when severe freezes occur, but heavy shading can result in lower yields when damaging freezes do not occur.

Local adaptation of a Drosophila parasitoid: habitat‐specific differences in thermal reaction norms

Local climate is an important source of selection on thermal reaction norms that has been well investigated in cline studies, where populations sampled along altitudinal or latitudinal gradients are compared. Several biotic factors vary with climate, but are rarely integrated as alternative agents of selection to climatic factors. We tested the hypothesis that habitat may select for thermal reaction norms and magnitude of phenotypic plasticity in a drosophila parasitoid, independently of the climate of origin. We sampled populations of Leptopilina boulardi, a Drosophila parasitoid in two different habitats, orchards and forests. Orchards offer laying opportunities over small distances for parasitoids, with a low variability in the number of hosts per patch, while forests offer more dispersed and more variable patches. The sampling was realized in a temperate and a Mediterranean climate. We measured egg load, volume of eggs, longevity and lipid content for parasitoids reared at two temperatures. Reaction norms were opposite for populations from forests and orchards for investment in reproduction, independently of the climate of origin. The maximal investment of resources in reproduction occurred at the lower temperature in orchards and the higher temperature in forests. Host distribution differences between habitats may explain these opposite reaction norms. We also observed a flatter reaction norm for egg load in forests than in orchards. This relative canalization may have been selected in response to the higher variability in laying opportunities observed in forests. Our results demonstrate the potential role of resource distribution in evolution of thermal plasticity.

Effect of Irrigation and Soil cover on Growth of Lemon (Citrus limon(L.) Burm.) cv. Baramasi

Lemon cultivation is becoming exceedingly popular because of its wider utilization than any other citrus fruit. However, due to feeble cultural and environmental conditions the growers are facing serious setback. Lemons are tremendously sensitive to extreme temperature fluctuations. Orchard temperature and microclimate of the trees play a very crucial role in tree growth and productivity. Therefore, it is advisable to irrigate frequently and lightly throughout the growing season and conserve soil moisture using appropriate soil cover. Keeping in mind all these aspects, the study entitled “Effect of irrigation and soil cover on growth of lemon (Citrus limon (L.) Burm.) cv. Baramasi” was carried out during 2009. The plant material was selected from Punjab Government Progeny Orchard and Nursery, Attari, Amritsar. In the trial, eight year old lemon trees uniform in size and vigour free from attack of diseases and pests were selected on which various irrigation and mulching practices were applied. The experiment was planned in randomized block design having six treatments replicated four times. The treatment viz. irrigation at 20% ASMD combined with black polythene mulch proved to be most effective in improving plant growth.

MICROCLIMATE MODIFICATION IN PEAR PLANTATION BY USING COOLING IRRIGATION

Irrigation in some countries is a horticultural practice mainly used only to supply water. At the same time the use of micro-sprinklers have a powerful influence on the changes of temperature in orchards. When the air temperature is high (~20°C or higher) evaporative cooling from irrigation significantly decreases the plant surface temperature and air temperature. The cooling effect is stronger when the air is dryer. By using cooling irrigation regularly, canopy temperature can be decreased so that the beginning of bloom can be delayed. Also if the bloom is early and frost probability is high, serious damages can happen in orchards. The beneficial effect of cooling irrigation is the temperature reduction and frost protection. In March 2010, one month before expected bloom, an irrigation system was established to produce anti-frost treatment and regulate the micro-climate of a ‘Bosc’ pear orchard which belongs to the University of Debrecen (Hungary). The objective of sprinklers was to cool the air by increasing water evaporation and relative humidity. The position of the micro-sprinklers was planned in three levels (around the tree trunks, a few cm near to the soil surface, in the crown region and above the crown, 0.5 m higher). The results showed that the water sprayed in the orchard by micro-jets influenced the temperature decisively. At higher temperatures (~20°C), temperature reduction may attain 5-7°C. Low relative humidity of the air may increase the relative effect. When water was applied at intervals of 15 min ten times per day from 8:00 to 18:00, the air, flower and bud surface temperatures could be kept low. When the temperature was higher than 10°C, irrigation was used at night in similar 15-min intervals, from 18:00 to 6:00. The beginning of bloom could be delayed for more than ten days. ‘Bosc’ pear blooming dynamics were characterized by a logistic curve in the treated as well as in the control plot. In the treated plot, the curve was steeper than in the control in spite of the equal temperatures measured in the plots. Under Hungarian climatic conditions, the method was successfully used to delay bloom dates. The main result was the diminution of the frost damage in the spring that assured pear yields.

Cooling irrigation as a powerful method for microclimate modification in apple plantation

Irrigation in some countries is a horticultural practice mainly used only to supply water. At the same time the use of microsprinklers have a powerful influence on the changes of temperature in orchards. When the air’s temperature is high (about 20 °C or higher) the evaporative cooling irrigation significantly decreases the plants’ surface temperature and air temperature. The cooling effect is stronger when the air is dryer. By using cooling irrigation regularly, canopy temperature can be decreased so that the beginning of blooming can be delayed. Also if the blooming is early and frost probability is high, serious damages can happen in orchards. The beneficial effect of cooling irrigation is the temperature reduction and frost protection. InMarch 2010, one month earlier than the expected blooming an irrigation system was established to produce anti-frost treatment and regulate the micro-climate of a Gala apple orchard which belongs to the University of Debrecen (Hungary). The objective of sprinklers was to cool the air by increasing water evaporation and relative humidity. The position of the micro-sprinklers was planned in three levels (around the tree trunks, a few cm near to the soil surface, in the crown region and above the crown, a half meter higher). The results showed that the water sprayed in the orchard by micro-jets influenced decisively the temperature of the plantation. At higher temperatures (around 20 °C), the drop of temperature may attain 5–7 °C. A low relative humidity of the air may increase the relative effect. When water was applied at intervals of 15 minutes for ten times a day from 8 am to 18 pm, the air, flowers and bud’s surface temperature could be kept low.At certain days when the temperature was higher than 10 °C, irrigation was used at night time in similar 15 minutes intervals, from 18 pm and 6 am. The beginning of bloom could be delayed for more than ten days. The Gala apple variety blooming dynamics was characterized by a logistic curve in the treated as well as in the control plot. In the treated plot, the curve was steeper than in the control one in spite of the equal temperatures measured in the plots. Under Hungarian climatic conditions, the method was successfully used to delay blooming dates. The main result was the diminution of the frost damage in the spring that assured apple yields.

Discriminating irrigated and rainfed olive orchards with thermal ASTER imagery and DART 3D simulation

This work provides a description of the research conducted to assess methods for the discrimination between irrigated and rainfed open-tree canopies using advanced spaceborne thermal emission and reflection radiometer (ASTER) satellite imagery and discrete anisotropic radiative transfer (DART) radiative transfer 3D simulation model. Summer and winter ASTER images were acquired over a study area in southern Spain during a 6-year period. A total of 1076 olive orchards were monitored in this area, gathering the field location, field area, tree density, and whether the field was drip irrigated or rainfed. Surface temperature images from ASTER were estimated using the temperature and emissivity separation (TES) method. A panchromatic ortho-rectified imagery dataset collected over the entire area at 0.5 m resolution was used to estimate orchard vegetation cover for each field. Results for summer ASTER thermal images showed differences between irrigated and rainfed orchards of up to 2 K for fields with the same percentage cover, decreasing the differences in ASTER winter images. An approach based on a cumulative index using temperature and the normalized difference vegetation index (NDVI) information for the 6-year ASTER time-series was capable of detecting differences between irrigated and rainfed open-canopy orchards, obtaining 80% success on field-to-field assessments. The method considered that irrigated orchards with equal vegetation cover would yield lower temperature and NDVI than rainfed orchards; an overall accuracy of 75% and a kappa ( κ) of 0.34 was obtained with a supervised classification method using visible, near infrared and temperature information for the 6-year ASTER imagery series. These experimental ASTER results were confirmed with DART radiative transfer 3D model used to simulate the influence of vegetation cover, leaf area index (LAI) and background temperature on the irrigated and rainfed orchard temperature at the ASTER pixel size.

The Effects of Reflective Film on Fruit Color, Quality, Canopy Light Distribution, and Profitability of ‘Mondial Gala’ Apples

The effects of covering the orchard floor with Extenday™ or Solarmate™ reflective films on fruit color, fruit quality, canopy light distribution, orchard temperature, and profitability of ‘Mondial Gala’ apples (Malus ×domestica) were evaluated over a 3-year period (2000–02) at Lleida (northeastern Spain). Reflective film was laid down 5 weeks before commercial harvest. Photosynthetically active radiation in the lowest part of the tree (1 m aboveground level) increased by 34% and 56%, for Solarmate™ and Extenday™ films, respectively, compared with the control. Fruit color, measured with a portable tristimulus colorimeter, significantly increased on both sides of the fruit (with lower values of L* and hue) when using the film. A higher proportion of red blush over the fruit surface was observed for the fruit in the film treatments. Based on the fruit size and color required to meet European Union grade standards, the use of Extenday™ or Solarmate™ resulted in an increase of 26% and 17%, respectively, when compared with the control, for the number of fruit picked at first harvest. Season clearly affected fruit color development, whereas harvest date, fruit firmness, fruit size, soluble solid concentration, titratable acidity, and maturity were not consistently affected by the use of reflective film. Despite the advance in fruit color, the starch score did not appear to be affected by the use of film. Based on current fruit prices for the study period, both types of film increased orchard profitability compared with the control, but the long-term benefit of this technique will largely depend on fruit prices.

The Effects of Reflective Film on Fruit Color, Quality, Canopy Light Distribution, and Profitability of ‘Mondial Gala’ Apples

The effects of covering the orchard floor with Extenday™ or Solarmate™ reflective films on fruit color, fruit quality, canopy light distribution, orchard temperature, and profitability of ‘Mondial Gala’ apples (Malus ×domestica) were evaluated over a 3-year period (2000–02) at Lleida (northeastern Spain). Reflective film was laid down 5 weeks before commercial harvest. Photosynthetically active radiation in the lowest part of the tree (1 m aboveground level) increased by 34% and 56%, for Solarmate™ and Extenday™ films, respectively, compared with the control. Fruit color, measured with a portable tristimulus colorimeter, significantly increased on both sides of the fruit (with lower values of L* and hue) when using the film. A higher proportion of red blush over the fruit surface was observed for the fruit in the film treatments. Based on the fruit size and color required to meet European Union grade standards, the use of Extenday™ or Solarmate™ resulted in an increase of 26% and 17%, respectively, when compared with the control, for the number of fruit picked at first harvest. Season clearly affected fruit color development, whereas harvest date, fruit firmness, fruit size, soluble solid concentration, titratable acidity, and maturity were not consistently affected by the use of reflective film. Despite the advance in fruit color, the starch score did not appear to be affected by the use of film. Based on current fruit prices for the study period, both types of film increased orchard profitability compared with the control, but the long-term benefit of this technique will largely depend on fruit prices.