Orchard Production Research Articles

Comparative Profiling of Wood Canker Pathogens from Spore Traps and Symptomatic Plant Samples Within California Almond and Walnut Orchards.

Fungi causing wood canker diseases are major factors limiting productivity and longevity of almond and walnut orchards. The goal of this study was to compare pathogen profiles from spore traps with those of plant samples collected from symptomatic almond and walnut trees and assess if profiles could be influenced by orchard type and age, rainfall amount and frequency, and/or neighboring trees. Three almond orchards and one walnut orchard with different characteristics were selected for this study. Fungal inoculum was captured weekly from nine trees per orchard using a passive spore-trapping device, during a 30-week period in the rainy season (October to April) and for two consecutive years. Fungal taxa identified from spore traps were compared with a collection of fungal isolates obtained from 61 symptomatic wood samples collected from the orchards. Using a culture-dependent approach coupled with molecular identification, we identified 18 known pathogenic species from 10 fungal genera (Ceratocystis destructans, Collophorina hispanica, Cytospora eucalypti, Diaporthe ampelina, Diaporthe chamaeropis/rhusicola, Diaporthe eres, Diaporthe novem, Diplodia corticola, Diplodia mutila, Diplodia seriata, Dothiorella iberica, Dothiorella sarmentorum, Dothiorella viticola, Eutypa lata, Neofusicoccum mediterraneum, Neofusicoccum parvum, Neoscytalidium dimidiatum, and Pleurostoma richardsiae), plus two unidentified Cytospora and Diaporthe species. However, only four species were identified with both methods (Diplodia mutila, Diplodia seriata, Dothiorella Iberica, and E. lata), albeit not consistently across orchards. Our results demonstrate a clear disparity between the two diagnostic methods and caution against using passive spore traps to predict disease risks. In particular, the spore trap approach failed to capture: insect-vectored pathogens such as Ceratocystis destructans that were often recovered from almond trunk and scaffold; Diaporthe chamaeropis/rhusicola commonly isolated from wood samples likely because Diaporthe species have a spatially restricted dispersal mechanism, as spores are exuded in a cirrus; and pathogenic species with low incidence in wood samples such as P. richardsiae and Collophorina hispanica. We propose that orchard inoculum is composed of both endemic taxa that are characterized by frequent and repeated trapping events from the same trees and isolated from plant samples, as well as immigrant taxa characterized by rare trapping events. We hypothesize that host type, orchard age, precipitation, and alternative hosts at the periphery of orchards are factors that could affect pathogen profile. We discuss the limitations and benefits of our methodology and experimental design to develop guidelines and prediction tools for fungal wood canker diseases in California orchards.

Effects of water allocation process on greenhouse gas emissions in drip-irrigated apple orchards on the Loess Plateau, China

Apple tree (Malus pumila Mill.) is a perennial and deciduous tree with large water demand in the growth period. Drip irrigation, as a mature and high-efficiency water-saving irrigation technology, has been widely used in apples, grapes and other economic crops around the world, achieving huge economic benefits. However, studies addressing the effects of drip irrigation on soil greenhouse gas emissions from apple orchards on the Loess Plateau in China are limited, and little is known about the potential drivers of the global warming potential based on the water allocation processes in apple orchards under drip irrigation technology. Hence, the goal of this study was to evaluate the impact of water allocation processes on soil greenhouse gas emissions and potential drivers of the global warming potential in apple orchards based on different irrigation water treatments under drip irrigation technology for a two-year consecutive field experiment in 2019 and 2020. The results showed that soil water-filled pore space, daily mean soil surface evaporation and plant transpiration were all significantly increased by drip irrigation. The peaks of carbon dioxide and nitrous oxide fluxes showed a lagged effect, with fluxes proportional to irrigation amount (with emissions occurring throughout the growth period) while methane fluxes were consumptive. Overall, using higher drip irrigation water in apple orchards increased the growth-period mean emissions of carbon dioxide and nitrous oxide and decreased the growth-period mean uptake of methane. Therefore, optimization of drip irrigation water is needed in practice to mitigate greenhouse gas emissions from apple orchard production. Furthermore, the global warming potential was directly driven by soil water-filled pore space, soil surface evaporation, plant transpiration and indirectly driven by rainfall and drip irrigation. The different water allocation processes were closely linked and interacted with each other, thereby affecting the global warming potential directly or indirectly.

Causes of citrus decline and its management practices adopted in Myagdi district, Nepal

Citrus decline has been the major constraint faced by citrus growers in Nepal. Survey research was conducted in Beni municipality and Malika rural municipality of Myagdi district to study the cause of citrus decline and their management practices. A total of 94 mandarin growing farmers were selected randomly and interviewed with a semi-structured questionnaire. Analytical tools like logistic regression, multiple linear regression, and t-test were used to derive the inferences needed. The study showed that 72.3% of the mandarin growing farmers had experienced citrus decline problems in their orchards. Disease and pest incidence, climatic extremities, poor fertility status of soil, low-quality planting materials, and poor orchard management were found to be positively influencing citrus decline. Insect infestation was 52 percent more likely to cause citrus decline as compared to insect non-infested conditions. The study revealed that 75.5% of the farmers use farmyard manure (FYM) of more than 30 kg per plant per year, 44.7% of the farmers use chemical fertilizers, 85.1% of the farmers irrigate their orchard, 98.94% of farmers practice weeding, 33% of the farmers practice mulching, 84% of the farmers practice pruning, 50% of the farmers use Bordeaux mixture and 61.7% of the farmers manage insects. Moreover, effective orchard management practices like manuring, irrigation, pruning, Bordeaux application, and insect management were significantly associated with a higher percentage of rejuvenation of declining orchards. The productivity of mandarin orchards, in addition, was significantly enhanced by FYM application, chemical fertilizers, irrigation, weeding, and Bordeaux application. This study elucidated that citrus decline has been the major constraint of mandarin farming, and improved management practices are pivotal for combating the citrus decline.

Influence of socio-economic attributes of farmers on the adoption of orchard management practices of mandarin in Myagdi district, Nepal

Mandarin is one of the major and highly commercialized fruit crops of Nepal. However, its productivity is widely varied throughout the country. The association of socio-economic characteristics of the farmers with the adoption of different orchard management practices and ultimately productivity is less known. Therefore, survey research was conducted in the Myagdi district to study the influence of socio-economic attributes on the adoption of different orchard management practices and their relation to the productivity of mandarin. A total sample size of 94 was selected by simple random sampling technique and interviewed with a pre-tested, semi-structured questionnaire. Data were entered and analyzed using MS Excel, Statistical Package for the Social Sciences (SPSS), and STATA, and the inferences were retrieved using the binary logistic regression model and multiple linear regression model. The study showed that the education level of the farmers has a positive influence on the adoption of mulching (p = 0.04) and pruning (p = 0.07). The secondary income source of the household has a positive impact on the adoption of chemical fertilizers (p = 0.08) and pruning (p = 0.03). Commercial mandarin farming in larger area has a positive influence on the adoption of Bordeaux mixture (p = 0.03) and insect management (p = 0.01). Extension services has great influence on the adoption of chemical fertilizers (p = 0.02), mulching (p = 0.03), Bordeaux mixture (p = 0.00) and insect management (p = 0.1). However, education level (p = 0.05), area under mandarin farm (p = 0.09), and extension services (p = 0.00) discourage the adoption of intercropping in the mandarin orchard. The productivity of mandarin orchards was significantly enhanced by FYM application, chemical fertilizers, irrigation, weeding, and Bordeaux application. This study shows that the farmers with better socio-economic conditions are more likely to adopt improved management practices in mandarin orchard which in turn enhance their productivity.

YOLOF-Snake: An Efficient Segmentation Model for Green Object Fruit.

Accurate detection and segmentation of the object fruit is the key part of orchard production measurement and automated picking. Affected by light, weather, and operating angle, it brings new challenges to the efficient and accurate detection and segmentation of the green object fruit under complex orchard backgrounds. For the green fruit segmentation, an efficient YOLOF-snake segmentation model is proposed. First, the ResNet101 structure is adopted as the backbone network to achieve feature extraction of the green object fruit. Then, the C5 feature maps are expanded with receptive fields and the decoder is used for classification and regression. Besides, the center point in the regression box is employed to get a diamond-shaped structure and fed into an additional Deep-snake network, which is adjusted to the contours of the target fruit to achieve fast and accurate segmentation of green fruit. The experimental results show that YOLOF-snake is sensitive to the green fruit, and the segmentation accuracy and efficiency are significantly improved. The proposed model can effectively extend the application of agricultural equipment and provide theoretical references for other fruits and vegetable segmentation.

Assessing the causes of the low productivity of cider apple orchards in the Spanish region of Gipuzkoa

Assessing the causes of the low productivity of cider apple orchards in the Spanish region of Gipuzkoa

Nutrient partition and nutritional efficiency of mango cv. Palmer as a function of plant age in São Francisco Valley, Brazil

Knowing the accumulation of nutrients in mango plants is essential for calibrating fertilization programs aiming to increase yield in nutritionally unbalanced orchards. The work aimed to evaluate mango nutritional efficiency through nutrient accumulation and partitioning in plants of Palmer cultivar grown in sand soils at São Francisco Valley, Northwest Brazil. Commercial orchards located in Bahia and Pernambuco States, Brazil, under semi-arid climate (BShw; 400-800 mm annual rainfall) had the vegetable biomass and nutrient contents in the mango compartments determined in 1, 2, 4, 7, and 12 years old plants, by evaluating four plants of each age from 20 sample units. The separated samples of the harvested trees originated the compartments roots, stems, thick twigs, thin twigs, leaves and fruits. Nutrient contents and plant dry matter per compartment were determined and plant nutrient accumulation evaluated. Biomass and fruits coefficient of biological utilization were calculated. There was increment in the accumulated content of macronutrients in the mango plants over the years, with superiority for N and K, for which there was a sharp increase as compared to the other macronutrients. Manganese and Fe were the most accumulated micronutrients in the plants over the years. The canopy of the mango Palmer plants is the compartment that accumulates more macro and micronutrients, and the partition within the canopy occurs in the sequence: leaf> thin twig> thick twig. Phosphorus and Mg, and Cu and B are the nutrients more efficient to generate plant biomass and fruit production in the mango Palmer orchards.

Modified ECa – ECe protocols for mapping soil salinity under micro-irrigation

Climate change will increase the frequency and intensity of drought in water-scarce agricultural areas that rely on irrigation. The increased strain on finite water resources for irrigated agriculture will cause a shift from sprinkler and flood irrigation to micro-irrigation. Micro-irrigation results in complex 3-dimensional salinity patterns. Current field-scale apparent soil electrical conductivity (ECa) directed soil sampling protocols and guidelines are inadequate for mapping the complex local-scale 3-dimensional nature of salinity resulting from water applications by micro-irrigation systems (i.e., drip, buried drip, micro sprinklers, bubblers, etc.). A field study was conducted to develop additional ECa-directed soil sampling guidelines to map local- and field-scale variability in salinity under drip-irrigation systems within a commercial nut production orchard (i.e., pistachio orchard) using hard (i.e., salinity or ECe, electrical conductivity of the saturation extract) and soft data (i.e., geospatial ECa measurements), which required an accurate ECa – ECe calibration. The revised ECa-directed soil sampling guidelines for drip irrigation on a mature pistachio orchard indicate that a single soil core should be taken 0.9–1.2 m perpendicular to the drip line within the tree root system, rather than at the drip line, to improve the ECa – ECe calibration. Calibration of ECa to ECe, improved from R2 = 0.25 to R2 = 0.73 for site Flores D01, and from R2 = 0.17 to R2 = 0.72 for site Flores D05. The improved guidelines broaden the scope of application of ECa-directed soil sampling to map field-scale salinity on orchards under drip irrigation. The information presented is of value and benefit to producers, agriculture consultants, irrigation practitioners, cooperative extension specialists, Natural Resources Conservation Service field staff, and soil and water researchers.

Physico-chemical Characteristics and Nutrient Status of Guava (Psidium guajava L.) Orchards in North-Western India

One hundred eight soil samples were collected from 12 guava orchards existing at different locations as well as 108 soil samples from non-orchard soils adjoining in the vicinity of selected orchards spread over five blocks of district Rewari namely Bawal, Rewari, Jatusana, Khol and Nahar. The samples were collected from 3 depths (0-15, 15-30, 30-60 cm) and analyzed for physico-chemical properties and available nutrients viz., nitrogen, phosphorus and potassium. The composite leaf sample of guava plants was also collected from each orchard. Rewari district soils (orchard and non-orchard) were sandy loam to loamy sand in nature. The calcium carbonate content in soils showed an increasing trend with depth and it increased significantly with an increase in sand and pH. Soils were alkaline with low organic carbon and nearly one-third of samples were saline. Available nitrogen was low, available phosphorus was low to medium while available potassium was medium to high in soil samples. Despite the high content of available potassium in soils, the plant leaves were found deficient in potassium. Therefore, the use of balanced fertilizers is required for sustainable and enhanced productivity of the guava orchards.

How Could Precision Irrigation Based on Daily Trunk Growth Improve Super High-Density Olive Orchard Irrigation Efficiency?

Water deficit, especially during summer, is currently one of the most important stress factors that influence olive oil production in olive orchards. A precision irrigation strategy, based on daily trunk growth, was assessed and compared with one continuous deficit, one full irrigation, and two different regulated deficit irrigation strategies. All of them were tested in a super high-density olive orchard located in northeast Spain, in which oil production, main oil production components, applied irrigation water, and water productivity were assessed. For this purpose, the crop was monitored from budding to harvesting, mainly during the summer months in which the Precision strategy only applied water after two days of negative daily trunk growth. Maximum monthly water savings for the Precision strategy reached 91.8%, compared with full irrigation, while major annual mean water savings reached 50% for the continuous deficit strategy and 31.2% for the Precision strategy, which also reduced irrigation events by up to 19.7%, compared with the full irrigation strategy. Oil production and oil production components varied depending on the irrigation strategies providing the Control, one of the regulated deficit irrigations, and Precision higher values than the other strategies; oil yield results differ, nonetheless. The Precision strategy showed an overall better performance. Despite this, it did not achieve the highest water saving, it achieved higher water productivity.

Application of somatic embryogenesis for development of emerald ash borer-resistant white ash and green ash varietals.

Emerald ash borer (Agrilus planipennis; EAB) has devastated populations of ash (Fraxinus spp.) trees in dozens of U.S. states and Canada over the past few decades. The continued survival of scattered ash trees known as “lingering ash” in heavily infested natural stands, however, offers evidence of genetic resistance or tolerance to EAB. These surviving or “lingering” ash individuals may form the basis for reforestation programs in EAB-impacted areas, and clonal mass-propagation of these genotypes can help accelerate these efforts. Between 2013 and 2018, we initiated embryogenic cultures by culturing immature zygotic embryos from open-pollinated (OP) seeds collected from several surviving white ash and green ash trees in Michigan and Pennsylvania. In addition, in 2018, we initiated cultures from crosses made between lingering green ash parents from the USDA Forest Service ash breeding program in Ohio. Somatic embryos were produced by growing cultures in liquid suspension, followed by fractionation and plating on semisolid medium to produce developmentally synchronous populations of somatic embryos. Somatic embryo germination and conversion were enhanced by a combination of pre-germination cold treatment and inclusion of activated charcoal and gibberellic acid in the germination medium. Ash somatic seedlings derived from OP explants grew rapidly following transfer to potting mix and somatic seedlings representing nine ash clones were acclimatized, grown in the greenhouse and planted in a preliminary field test, along with EAB-resistant Manchurian ash (F. mandshurica) and EAB-susceptible control seedlings. Somatic seedlings have now been produced from cultures that originated from seeds derived from the progeny of lingering green ash parents and an ex vitro germination protocol has shown some promise for accelerating early somatic seedling growth. Results of this research could provide the basis for scaled-up production of EAB-resistant ash varieties for seed orchard production for forest restoration and cultivar development for urban tree restoration.

Boron Effects on Fruit Set, Yield, Quality and Paternity of Macadamia

Many tree crops experience sub-optimal yields and low fruit quality due to inadequate pollination, low fruit set, and poor crop nutrition. Boron (B) is a critical crop nutrient for fruit set because B levels affect pollen germination and pollen tube growth. However, the relationship between floral B concentration and fruit set is not well understood. The aim of this study was to determine the effect of B applications on the initial fruit set, yield, quality, and paternity of macadamia (Macadamia integrifolia). Cultivar ‘816’ trees received one of three treatments: (a) 0 g, (b) 15 g, or (c) 30 g B per tree prior to flowering. Boron application increased the B concentration of macadamia flowers. Application of 15 g B increased fruit set at 3 weeks after peak anthesis, but this higher initial fruit set was not translated into higher fruit set at 6 or 10 weeks after peak anthesis or higher yield. Boron application increased B concentrations in kernels but did not affect nut-in-shell (NIS) mass, kernel mass, kernel recovery, kernel oil concentration or incidence of whole kernels. Cultivar ‘816’ was highly outcrossing, with 97–98% cross-paternity among kernels from all treatments. Our results indicate that higher B concentration in macadamia flowers can be associated with an increased initial fruit set. However, high B levels did not affect yield, nut quality, or the proportion of self-pollinated fruit at maturity. The heavy dependence on outcrossing highlights the importance of inter-planting different cultivars and managing bee hives to sustain the productivity of macadamia orchards.

Molecular Dissection Unveiling Dwarfing Effects of Plant Growth Retardants on Pomegranate.

Dwarfed stature is a desired trait for modern orchard production systems. One effective strategy for dwarfing cultivation is exogenously applying plant growth retardants (PGRs) to plants. However, for many economic fruit trees, the current knowledge on the regulatory mechanisms underlying the dwarfing effect of PGRs is limited, which largely restricts the agricultural application of PGRs. In this study, we exogenously applied three kinds of PGRs [paclobutrazol, daminozide (B9), and mannitol] to the seedlings of pomegranate (Punica granatum L.) and performed comparative transcriptome analysis to elucidate the molecular features of PGR-induced dwarfing in pomegranates. Our results showed that all the three PGRs could significantly suppress plant growth of pomegranate. The inhibition of auxin biosynthetic processes, as well as auxin-mediated shoot development, may be considered as the main reason for the dwarfing. Besides that, different PGRs were also found to induce dwarfing via specific mechanisms, for example, cellular response to strigolactone was particularly suppressed by the application of paclobutrazol, while the level of carbohydrate homeostasis and metabolism were downregulated in conditions of either B9 or mannitol treatments. Furthermore, exogenous PGR application was supposed to cause adverse impacts on the normal physiological process of pomegranate seedlings, which may bring extra burden to pomegranate plants. These novel findings unveiled the genetic basis underlying the dwarfing in pomegranates, which provides deeper insights into PGR-mediated dwarfing cultivation of pomegranates.

Development of DRIS based soil fertility and leaf nutrient standards for improving the efficiency of Kinnow mandarin (Citrus reticulata Blanco) in semi-arid region of Rajasthan

The study was carried out during 2015-16 at district Sriganganagar under semi arid region of Rajasthan India with the aim to diagnose the soil fertility indicator by using DRIS norms to improve the kinnow orchards efficiency. A total 105 kinnow mandarin orchards were selected through the preliminary survey, all the selected orchards were divided equally 35 each in low, medium and high efficiency based on the yield. The soil and plant sample were collected from the orchards and subjected to analyze by using standard analysis protocols. Five tier DRIS norms were used for determining the soil properties limiting factor. The high efficient orchards had low pH (8.1) and CaCO3, (23.4 g kg-1) whereas, comparatively more organic carbon (2.7 g kg-1) , phosphorus (38.2 kg ha-1) and potassium (296.2 kg ha-1) than medium and low efficient orchards. The nitrogen, phosphorus and potassium contents were also high in high yield orchards and ultimately responsible for the better quality parameters viz. fruit weight (170.35 g), Juice (49.51 %), total soluble sugar (12.88 %) and low acidity (0.81 %) in high efficient orchards. The five tier DRIS norms suggested that < 8.8 pH, < 89.0 g kg-1 CaCO3, < 2.5 g kg-1 organic carbon and 14.2 kg ha-1 phosphorus were limiting soil fertility indicators in relation to fruit yield less than 14.5 t ha-1 for kinnow mandarin orchards of semi arid region of Rajasthan. It is evident from the DRIS norms in relation to soil properties and plant tissue concentration yield should be considered as low when it is less than 14.5 to 20.2 t ha-1. It is therefore imperative to manage these parameters for the better quality production and sustainability of kinnow orchards

Development of DRIS based soil fertility and leaf nutrient standards for improving the efficiency of Kinnow mandarin (Citrus reticulata Blanco) in semi-arid region of Rajasthan

The study was carried out during 2015-16 at district Sriganganagar under semi arid region of Rajasthan India with the aim to diagnose the soil fertility indicator by using DRIS norms to improve the kinnow orchards efficiency. A total 105 kinnow mandarin orchards were selected through the preliminary survey, all the selected orchards were divided equally 35 each in low, medium and high efficiency based on the yield. The soil and plant sample were collected from the orchards and subjected to analyze by using standard analysis protocols. Five tier DRIS norms were used for determining the soil properties limiting factor. The high efficient orchards had low pH (8.1) and CaCO3, (23.4 g kg-1) whereas, comparatively more organic carbon (2.7 g kg-1) , phosphorus (38.2 kg ha-1) and potassium (296.2 kg ha-1) than medium and low efficient orchards. The nitrogen, phosphorus and potassium contents were also high in high yield orchards and ultimately responsible for the better quality parameters viz. fruit weight (170.35 g), Juice (49.51 %), total soluble sugar (12.88 %) and low acidity (0.81 %) in high efficient orchards. The five tier DRIS norms suggested that < 8.8 pH, < 89.0 g kg-1 CaCO3, < 2.5 g kg-1 organic carbon and 14.2 kg ha-1 phosphorus were limiting soil fertility indicators in relation to fruit yield less than 14.5 t ha-1 for kinnow mandarin orchards of semi arid region of Rajasthan. It is evident from the DRIS norms in relation to soil properties and plant tissue concentration yield should be considered as low when it is less than 14.5 to 20.2 t ha-1. It is therefore imperative to manage these parameters for the better quality production and sustainability of kinnow orchards.

Remote sensing and soil moisture data for water productivity determination

This work was initiated in 2019 within the FAO WEPS project framework (2018–2022), aiming to determine the Water Productivity (WP) of the Tunisian olive orchards combining two scales of measurements for soil moisture determination: one for the global analysis (remote sensing) and the other for the field scale application. The experiment was made in 2019 and 2020 in the Centre of Tunisia (Kairouan city, locality of Elhouereb), which is one of the largest irrigation area of Tunisia. WP was computed regarding the actual crop evapotranspiration (ETa) which was determined following the water balance method as: ETa=R+I–ΔS, where ΔS is the amount of water stored in the soil (0–60 cm) and (R) and (I) are the amounts of the seasonal rainfall and the irrigation volume, respectively. The annual ETa reached 293 mm for the rainfed orchard, 823 mm for the semi-intensive irrigated plantation and 819 mm for the intensive fertigated orchard. The WP defined as being the ratio of Yield (kg olives/tree)/ETa ranged between 0.29 kg/m3 (rainfed) and 0.77 kg/m3 (fertigated) depending on the cultivation system. Soil moisture was found to be correlated to the average backscatter coefficient (r = −0.34 for the rainfed and 0.91 for the irrigated orchards) which was determined from the radar images which were treated by using different applications (SNAP, ODK, QGIS.), This result shows the performance of the remote sensing tools for such application. To conclude: WP is at least two times higher in the irrigated orchards than in the rainfed grove; this indicates a great potential of WP improvement if the horticultural practices are well applied in the orchad (pruning, irrigation); so that, the WP can be used as a decision-making-tool for farmers and makers in the future.

Techniques for Reducing the Abundance of Spring–Summer Flush Shoots in Southern Spanish Orange Orchards

The Mediterranean Basin is the second highest citrus growing region in the world behind China. Citrus trees are known to produce several flush shoots per year, particularly during the spring–summer season. Farmers endeavor to reduce the growth of summer shoots by means of hand pruning, especially those located at the top of the tree, as most of these shoots become vigorous, nutrient consuming, non-productive, and attractive to several pests. Furthermore, hand pruning substantially increases the costs of citrus orchards production. This research was therefore intended to study new different treatments to control spring–summer flush shoots and thus reduce growers’ investments in citrus production. Six different treatments were applied in two experimental and high density orange orchards over two consecutive years: (1) control; (2) topping (mechanical pruning); (3) dichlorprop-p; (4) triclopyr; (5) topping + dichlorprop-p; and (6) topping + triclopyr. The treatment of dichlorprop-p alone reduced the number of summer young shoots in both years. Moreover, these applications did not negatively affect yield or fruit quality. These mechanical methodologies help citrus growers manage the density of flush shoots and reduce hand labor costs in citrus orchards.

Impact of local practices and landscape on the diversity and abundance of pollinators in an insect-dependent crop

Insects are a functionally diverse group, with economically relevant roles on key ecosystem services, such as pollination. The current trend of biodiversity loss and consequent degradation of ecosystem services delivered by insects is leading to additional pressure on modern agriculture, particularly in crops that depend on insects for pollination. Understanding how insect pollinator diversity varies at local and landscape scales is very important to recognize trends in pollinator populations. The present work quantified the effect of in-field management practices and different landscape types on insect pollinator communities in kiwifruit, a pollinator-dependent crop. Twenty-two orchards were selected and characterized for in-field practices, landscape structure, plant-pollinator interactions, and productivity. We observed that orchards with practices that are less harmful to insect pollinators are related to a higher pollinator diversity and higher abundances of certain wild pollinator groups, although this was not related with increased productivity. Additionally, in the studied production region, agricultural dominated landscapes harbor lower pollinator diversity, lower wild pollinators abundance and higher managed honeybee abundance than forest and herbaceous dominated landscapes, but no differences were detected in productivity among landscape types. In turn, abundance of Bombus spp. and the use of pollination support practices were significantly and positively correlated with orchard productivity. Despite the differences in pollinator communities, comparable yields were observed across different landscape types. Additionally, simple changes towards less harmful agricultural practices and the presence of forest and herbaceous habitats can promote wild pollinators and respective pollination services.

Light utilisation, leaf canopy properties and fruiting responses of narrow-row, planar cordon apple orchard planting systems—A study of the productivity of apple

Growth (annual increase in total dry mass) and productivity of agricultural cropping systems depend on the fractional interception of total seasonal light energy. With single-row hedgerow intensive apple orchard systems the reported maximum light utilisation is ∼60% fractional interception. This limitation is determined by row layout and hedgerow tree architecture, constraining apple orchard productivity to maxima of 100–120 t ha−1. We hypothesised that reducing the orchard system between-row spacing to 1.5 m to 2.0 m would increase light interception and productivity, using two-dimensional, narrow planar hedgerow trees to maintain within-canopy irradiance. Trees comprised 10 vertical fruiting stems, equally spaced along 3 m of horizontal cordon (the planar cordon tree), requiring 2222 and 1667 trees per ha. By the seventh year the maximum fractional light interception (LI) was 77% in 1.5 m row plots and 66% in 2.0 m row plots, averaged across four cultivars (‘Gala’, ‘Scifresh’, ‘Scilate’, ‘Fuji’). The LAI-light interception response relationship of 6- and 7-year-old plots indicated a potential maximum light interception above 80% at a LAI of 3.5–5.0. Annual yields increased in proportion to increasing annual maximum fractional light interception from year two onwards and described an exponential response: Yield = 5.085e0.0483LI, (R2 = 0.88). The yield response to maximum fractional light interception exceeded the hypothesised 169 t ha−1 at 90% light interception in spindle systems proposed by Palmer et al. (2002). The yield–light utilisation behaviour of planar cordon systems indicate the productivity potential of apple as a crop has been under-estimated; a theoretical maximum annual yield of market-quality apples at ∼90% light utilisation (≥ 2000 MJ m−2 light energy per season) is estimated to be in a range of 250–315 t ha−1. Productivity amongst cultivars and regions will be influenced by the cultivar genetics for fruit size, relative maturation dates and production microclimates, because these orchard systems will function at the upper limit of light utilisation.

Effective Categorization of Tolerance to Salt Stress through Clustering Prunus Rootstocks According to Their Physiological Performances

The effects of climate change on traditional stone fruit producing areas, together with the generation of new varieties with lower chilling requirements that allow the cultivation of previously unexplored areas, are setting up a challenging scenario for the establishment of productive orchards that must be more efficient in their capacity to adapt to new edaphoclimatic conditions. In this context, the rootstock breeding programs are a key piece in the agronomic strategy to achieve this adaptation through the development of rootstocks compatible with the new varieties and capable of transferring their tolerance to stress. An effective categorization of phenotypes within the germplasm involved in a plant breeding program is of utmost importance. Through the measurement of physiological parameters in both roots and leaves, tolerance to saline stress (120 mM NaCl) was evaluated in seven Prunus rootstocks whose genetic background included representatives of the subgenera Prunus, Cerasus, and Amygdalus. To group the genotypes according to their physiological performance under salt stress, an agglomerative hierarchical clustering was applied. The genotypes were grouped into three clusters containing rootstocks very sensitive (‘Mazzard F12/1’), moderately tolerant (‘Maxma 60’, ‘Cab6P’ and ‘AGAF 0204-09’), and tolerant (‘Mariana 2624’, ‘Garnem’ and ‘Colt’) to salt stress. ‘Mariana 2624’, a plum-based rootstock, was identified as the most tolerant Prunus rootstock. The information reported is valuable both in the productive context, for the selection of the most appropriate rootstocks to establish an orchard, and in the context of plant breeding programs, when choosing parents with outstanding traits to obtain progenies tolerant to salt stress.