Kiwifruit Orchards Research Articles

Clostridium bifermentans and C. subterminale are associated with kiwifruit vine decline, known as moria, in Italy

AbstractSince 2012, a new pathogenic syndrome has frequently been observed in many areas of kiwifruit cultivation in Italy. The main symptoms include an initial withering of the leaves followed by a total and sudden collapse of plants, mainly occurring during summer. The withered leaves fall and the main and secondary feeder roots appear rotten, sometimes showing a reddish‐brown discoloration. The disease, that affects both the green and yellow‐fleshed cultivars, has been called kiwifruit vine decline and is locally known as moria. The syndrome has been found consistently associated with soil waterlogging, which frequently occurs either after the traditional agronomical practice of irrigating orchards through surface irrigation or after very heavy rainfall. So far, the role played by bacteria in this syndrome has not been investigated. In the present study, Clostridium spp. were isolated from both rotten roots and soils obtained from Italian kiwifruit orchards affected by the syndrome, indicating for the first time that anaerobic bacteria are able to cause damage to woody crops. C. bifermentans and C. subterminale incited symptoms in kiwifruit in both in vivo and in vitro pathogenicity tests. Soil waterlogging seems to potentially favour colonization of kiwifruit roots by anaerobic bacteria, probably because saturation of the soil can facilitate proliferation and persistence of these bacteria during long periods of the vegetative growth of the crop. The occurrence of anaerobic bacteria does not exclude the possibility that other microorganisms can play additional/synergic role(s) in causing the kiwifruit vine decline.

Shifts in microbial communities and networks are correlated with the soil ionome in a kiwifruit orchard under different fertilization regimes

This study investigated the shifts in the community composition and co-occurrence networks of soil microbiota in relation to the soil ionome in a kiwifruit orchard under different fertilization regimes. A 9-year split-plot field experiment (2009–2018) was conducted in Meixian county, Shaanxi province, China. Two main plots were assigned to bio-organic fertilization (0 vs. 8000 kg ha−1 y−1), each containing two subplots assigned to chemical fertilization (0 vs. 300 kg N ha−1 y−1, 225 kg P ha−1 y−1, and 150 kg K ha−1 y−1). High-throughput sequencing and inductively coupled plasma-mass spectrometry were used to analyze soil microbial community composition and ion concentrations, respectively. Results showed that bio-organic fertilization increased soil Ni, Se, total C, total N, and pH levels, whereas soil Mg, Cu, Zn, and Sr concentrations were decreased. Mantel testing indicated that bacterial community composition was influenced more easily by the availability of soil ions (e.g., Zn, Ni, Co, Cu) than fungal community composition. Bio-organic fertilization also increased bacterial α-diversity indices that were strongly correlated with the availability of soil ions (e.g., Fe, Mn, and Ca). Network analysis revealed that bio-organic fertilization generated more links (especially positive links) between microbial taxa in the community. Fewer but highly interconnected modules were found in the network formed under bio-organic fertilization, for which fewer nodes and negative links occurred concurrently. After selecting putative keystone species, the network with bio-organic fertilization was characterized by more generalists than the network without bio-organic fertilization. In contrast to the network without bio-organic fertilization, none of the generalists in the network with bio-organic fertilization were correlated with soil total C and N contents; however, high correlations were found with soil ions (e.g., Fe, Mn, Co, and Al). These results demonstrate that a better-organized and more stable network of soil microbial communities can assemble in a kiwifruit orchard under bio-organic fertilization, as mediated by alterations to the soil ionome. This study highlights that the less-commonly researched soil ions (e.g., Ni, Mo, Se, Sr) may play a crucial role in the response of soil microbial communities to bio-organic fertilization in agricultural ecosystems.

Work distribution of multiple Cartesian robot arms for kiwifruit harvesting

Employing multiple robot arms for kiwifruit harvesting can raise the efficiency since the task completion time is shortened. However, task partitioning and reachability are two major concerns. It is found that the task completion time is minimized if task partitions for robot arms are uniform. However, the partition uniformity is influenced by the fruit indivisibility and fruit cluster growing style. It is also constrained by the fruit distribution across the canopy and the robot arm positions which affect the fruit reachability. This article investigates how to partition the tasks of kiwifruit harvesting so that the harvesting can be completed by multiple robot arms in the minimum time with an assumption that the fruits can be harvested by any robot arm. A parameter termed work distribution is introduced to measure how the task partitioning is different from the optimum. A research platform with two robot arms is implemented to show how to approximate the assumption. Ten field experiments of kiwifruit harvesting had been run by the research platform in two kiwifruit orchards in New Zealand with satisfactory outcomes.

Optimization of working parameters for 3MGY-200 axial air-assisted sprayer in kiwifruit orchards

Axial air-assisted sprayers can distribute pesticides efficiently in kiwifruit orchards. Because of improper parameter settings, most sprayers deliver either too much or too little pesticide. To identify appropriate sprayer parameters for kiwifruit trees, the vertical distribution profiles of the applied liquid spray were examined in this study. The effects of spray fan speed (SFS), spray pressure (SP) and spray distance (SD) on the distributions of the sprayed liquid in the vertical profiles were studied. Combined actions of the above parameters were systematically analysed using the quadratic general rotary design test method. Regression equations for the spray liquid distributions and working factors are presented. Field confirmation experiments were carried out to optimize the parameters. Data analysis showed that the optional sprayer working parameters are those of Group 3, with an SFS equal to 1900 r/min and SP equal to 3.25 MPa. The results of this study provide a reference for future applications of this type of axial air-assisted sprayer in kiwifruit orchards. Keywords: sprayer parameters, quadratic general rotary unitized design, regression equation, optimization, kiwifruit tree DOI: 10.25165/j.ijabe.20201302. Citation: Gu C C, Liu Z J, Pan G T, Pu Y J, Yang F Z. Optimization of working parameters for 3MGY-200 axial air-assisted sprayer in kiwifruit orchards. Int J Agric & Biol Eng, 2020; 13(2): 81–91.

Use of phage ϕ6 to inactivate Pseudomonas syringae pv. actinidiae in kiwifruit plants: in vitro and ex vivo experiments

Over the last years, the global production and trade of kiwifruit has been severely impacted by Pseudomonas syringae pv. actinidiae (Psa), a phytopathogen that causes a disease in kiwifruit plants known as bacterial canker. The available treatments for this disease are still scarce, with the most common involving frequently spraying the orchards with disinfectants, copper-based bactericides and/or antibiotics. Moreover, these treatments should be avoided due to their high toxicity to the environment and promotion of bacterial resistance. Phage therapy may be an alternative approach to inactivate Psa. The present study investigated the potential application of the already commercially available bacteriophage (or phage) ϕ6 to control Psa infections. The inactivation of Psa was assessed in vitro, using liquid culture medium, and ex vivo, using artificially contaminated kiwifruit leaves with two biovar 3 (a highly aggressive pathogen) strains (Psa CRA-FRU 12.54 and Psa CRA-FRU 14.10). In the in vitro experiments, the phage ϕ6 was effective against both strains (maximum reduction of 2.2 and 1.9CFU/mL for Psa CRA-FRU 12.54 and Psa CRA-FRU 14.10, respectively). In the ex vivo tests, the decrease was lower (maximum reduction 1.1 log and 1.8CFU/mL for Psa CRA-FRU 12.54 and Psa CRA-FRU 14.10, respectively). The results of this study suggest that the commercially available phage ϕ6 can be an effective alternative to control Psa infections in kiwifruit orchards.

Kivi Omcalarındaki Gövde Şekli ve Dalların Gövdeye Olan Uzaklığının Meyve Özellikleri Üzerine Etkileri

In this study, different trunk shapes and distance of shoots to trunk in kiwifruit vine on fruit characteristics were determined. The effects of distance of shoots to the trunk on fruit quality parameters of kiwifruit vine have different trunk shape (upright and unshaped) were investigated in two different commercial kiwifruit orchards (well-cared and uncared). Three branches for each kiwifruit vine were selected in terms of distance of branches to trunk (near to trunk: ~20 cm (NT), medium distance to trunk: ~40 cm (MT) and far to trunk: ~60 cm (FT)). It depends on the study years fruit number (10.00-48.80), fruit diameter (5.07-6.12 cm), fruit length (6.41-7.70 cm), fruit weight (91.73-142.06 g), fruit flesh firmness (5.20-7.55 kg), TSS amount in harvest maturity (14.35-16.37%), TSS amount in ripening (6.80-12.00%), TA in harvest maturity (1.24-1.85%) and TA in ripening varied. As a result, trunk shape (upright and unshaped) was found to affect fruit quality parameters in order that upright trunk shape should be formed for fruit quality and convenience in cultural applications.

Design and testing of a heavy-duty platform for autonomous navigation in kiwifruit orchards

Horticultural robots designed for in-field use usually require a means of transportation around orchards or farms. A common approach is to directly integrate a drive system – at the expense of increasing overall complexity. Alternatively, robots can be modularised and attached to general purpose platforms. General purpose platforms reported previously are designed to carry relatively light payloads orientated toward ground based crops. This paper presents a heavy-duty platform, capable of carrying modules of up to 1000 kg, beneath 1.4 m high pergola-style kiwifruit canopies. We discuss the design of the vehicle's software, electrical system, and mechanical structure. Sensors suitable for autonomous navigation are evaluated in-orchard and tested with prototype algorithms. Row following trials show a repeatability of within ± 75 mm using only a multi-layer lidar. With a method of automatically turning between rows, the vehicle traversed over 10 km of orchard rows unassisted.

Land‐use change from cropland to orchard leads to high nitrate accumulation in the soils of a small catchment

AbstractLand‐use change from cereals to fruit orchards usually results in a high nutrient surplus in soil. The excessive accumulation of nitrogen (N) in soil, mainly as nitrate, leached from the root zone may serve as a long‐term source of surface or groundwater pollution. The N balances and nitrate accumulation in the soil profiles of cereal fields and kiwifruit orchards in the Yujiahe catchment, Shaanxi, China, were compared. Excessive N fertilisation resulted in an excessive N surplus (1,133 kg N ha−1 yr−1) in orchards (8‐times higher than that in cereal fields). More than 77.5% of nitrate in the soil profile (0–400 cm) of the orchards was below a soil depth of 100 cm. The average accumulated nitrate within a profile 0–400 cm of orchards was 3,288 kg N ha−1, which was 16‐fold higher than that of cereal fields. The accumulated nitrate in soil profiles on the downslope (5,959 kg N ha−1) was approximately 2 times higher than that of the upslope in the same sloping orchards. The accumulated nitrate in soil profiles at the lowland zone of the catchment was higher than that of the upland zone. Excessive nitrate moves not only vertically downwards to deeper soil depth but also laterally into lower elevations at both field and catchment scales. The total stored nitrate in the upper soil profile of 400 cm in the catchment was 464.8 Mg N, whereas 94.8% (440.8 Mg N) was in orchards. Thus, changing land use from cereal crops to orchards leads to a high nitrate accumulation in the catchment.

Energy optimization and greenhouse gas emissions mitigation for agricultural and horticultural systems in Northern Iran

The objective of this study is to comprehensively optimize energy usage and determine mitigation of greenhouse gas (GHG) emissions in agricultural and horticultural crops of Guilan Province, Iran. For this purpose, required data are collected from eggplant, garlic, tea, hazelnut, kiwifruit and tangerine producers through questionnaires. In this study, GHG emissions are investigated under both On-Farm and Off-Farm sectors. Data envelopment analysis method is employed for the optimization of GHG emissions and energy flow. The highest and lowest energy consumption are related to tea and kiwifruit production, respectively. Results show that kiwifruit and eggplant have the highest scores in technical efficiency whilst tangerine and tea have the highest values in pure technical efficiency. The largest amount of energy is saved in kiwifruit orchards with 8316.29 MJ ha−1. Nitrogen fertilizer and diesel fuel have the topmost energy saving potential in most crops. Kiwifruit orchards have the highest potential for mitigation of GHG gas emissions (520.79 kg CO2 eq. ha−1). Results show that an appropriate usage of nitrogen fertilizer and replacement by organic fertilizer will mitigate GHG emissions as well as energy consumption. It can be concluded that GHG emissions can be mitigated by energy optimization in all the studied crops.

Time course of physiological responses in kiwifruit induced by bicarbonate

KEY MESSAGE: Ionic imbalance is one adaptive strategy of kiwifruit to bicarbonate, as indicated mainly by NH₄⁺ accumulation and increased NH₄⁺/NO₃⁻ in bicarbonate-treated roots as well as decreased NH₄⁺/NO₃⁻ in bicarbonate-treated leaves. Bicarbonate-induced leaf chlorosis is frequently observed in kiwifruit orchards. A time-course experiment was conducted to investigate the effects of bicarbonate stress on the growth, root acidification, and organic acid and nutrient concentrations of kiwifruit plants treated for 7, 14, 21, 28, and 42 days in hydroponics. After 21 days of bicarbonate treatment, the kiwifruit vines exhibited leaf chlorosis, as indicated by decreased SPAD, chlorophyll a and b as well as carotenoid. Moreover, bicarbonate treatment induced NH₄⁺ accumulation and NO₃⁻ reduction in roots from day 21 onward, thereby increasing the ratio of NH₄⁺ to NO₃⁻ in roots, and the opposite was true for leaves that seemed to respond to bicarbonate earlier than roots but in an inconsistent manner. Before leaf chlorosis, bicarbonate imposition induced succinic acid accumulation and K reduction in roots from day 14 onward. However, the K concentration increased in bicarbonate-treated leaves from day 28 onward. Bicarbonate treatment also reduced P in all plant parts and Fe in leaves from day 21 onward, lowered Zn and enhanced Ca and Mg in roots from day 28 onward. In addition, bicarbonate treatment increased citric acid and ferric chelate reductase (FCR) activity in roots at days 7 and 14, but decreased citric acid and H⁺ extrusion at day 28 and decreased FCR activity at day 42, respectively, indicating that root acidification is duration dependent. These results suggest that, except for succinic acid accumulation, ionic imbalance in the whole kiwifruit plants (particularly N form’s shift) might be an alternative strategy to adapt to bicarbonate stress.

<i>Neofabraea actinidiae </i>in New Zealand kiwifruit orchards: current status and knowledge gaps

Neofabraea actinidiae (syn. Cryptosporiopsis actinidiae) is a member of a suite of fungi associated with ‘ripe rots’ of kiwifruit. Although it has been recorded regularly from kiwifruit in New Zealand over the past 30-40 years, initially as ‘Cryptosporiopsis sp.’, there is a general lack of knowledge of this fungus. This paper provides a review of the current records and available literature on the taxonomy and biology of the organism, and assesses the knowledge gaps in the disease cycle and epidemiology of N. actinidiae in kiwifruit orchards. The conidia of the fungus are likely to be water borne, infect fruit during or near to flowering and remain latent until harvest and subsequent ripening. The source of inoculum remains unknown. This review may stimulate new research into this pathogen and give insights into potential control strategies.

Improvements to and large‐scale evaluation of a robotic kiwifruit harvester

AbstractThe growing popularity of kiwifruit orchards in New Zealand is increasing the already high demand for seasonal labourers. A novel robotic kiwifruit harvester has been designed and built to help meet this demand [H. A. Williams et al. Biosystems Eng. 181 (2019), pp. 140–156]. Early evaluations of the platform have shown good results with the system capable of harvesting 51.0% of 1,456 kiwifruit in four bays with an average cycle‐time of 5.5 s/fruit. However, the harvester's high cycle‐time, and high fruit loss rate at 23.4%, prevent it from being commercially viable. This paper presents two new developments for the harvesting system, a new vision system and two new gripper variations designed to overcome the harvester's previous limitations. Furthermore, we have designed and conducted the largest real‐world evaluation of a robotic fruit harvesting system published to date with over 12,000 kiwifruit involved. The results of this trial demonstrated that our kiwifruit harvester is one of the most effective selective fruit harvesters in the world capable of successfully harvesting 86.0% of reachable fruit, and 55.8% of all kiwifruit with a cycle‐time of 2.78 s/fruit.

Study on the epidemic evolution of leaf spot symptoms caused byP. syringaepv.actinidiaeon kiwifruit

The aim of the study was to observe the occurrence and development of the leaf spot symptoms caused by Pseudomonas syringae pv. actinidiae (Psa) on kiwifruit during the growing season in order to determine both the climatic predisposing factors and plant susceptibility. The observation was carried out over the years 2013 and 2014 in naturally infected kiwi fruit orchards. Two kiwi fruit orchards of the ‘Hayward’, and three of the ‘Hayward’, ‘Erika Bo’, ‘Jin Tao’ were observed in 2013 and 2014 respectively. 15-20 shoots of 6 untreated plants were randomly chosen, marked and weekly observed from bud break until leaf fall, scoring the number of new leaves and the number of spots per leaf. In this way it was possible to know the age of the leaf at the onset of the first symptoms and the evolution of the symptoms on the leaves during the season. Weather data were also recorded so as determine the period in which the infection presumably took place. Results showed that, under the climatic conditions of Emilia Romagna, foliar symptoms seem to occur only in springtime and that from the first two weeks of June even newly formed leaves do not show new symptoms of the disease. Finally, the leaves with spots born in spring were randomly collected before their fall and analyzed. From such leaves PSA was always isolated. Therefore, bacterial leaf spots formed in spring remain active until autumn.

Occurrence of the virulent strain of Pseudomonas syringae pv. actinidiae in Japan: a case study of a field in Shizuoka Prefecture

Pseudomonas syringae pv. actinidiae (Psa) has been shown to have heterotypic populations including a pandemic highly virulent strain (Psa3 or Psa-V). Although Psa was first recorded in Japan, the virulent strain Psa3 had not been observed until spring of 2014, when the sudden outbreak of Psa3 took place in Japan. Also in Shizuoka Prefecture, we noticed the incidence of bacterial leaf spots in several kiwifruit orchards in June 2014. Isolation of the causal bacterium and identification through PCR and other techniques confirmed that the pathogen was Psa3. In one representative field, the disease was observed on Actinidia deliciosa 'Hayward'. Similar leaf spots were also observed on A. chinensis cultivars planted in the same field, however, the pathogen was identified as a strain of Pseudomonas syringae causing flower-rot (blossom blight) disease of kiwifruit (Ps-fr). The differences between Psa3, Psa1 and Ps-fr were confirmed. Sometimes, Psa3 and Ps-fr were isolated from a single lesion. The transition of the disease incidence from 2014 to 2015 was described. It was demonstrated that Ps-fr inhibited the growth of Psa3 in vitro.

Measuring the survival of White Peach Scale (Pseudaulacaspis pentagona) on kiwifruit (Actinidia chinensis var. deliciosa ‘Hayward’) in coolstorage in Italy

ABSTRACTThe survival of overwintering adult White Peach Scale (WPS) (Pseudaulacaspis pentagona) on kiwifruit (Actinidia chinensis var. deliciosa ‘Hayward’) in a commercial coolstore in Italy was measured using a biochemical live/dead test. Fruit infested with adult female (overwintering) WPS were collected from two Italian kiwifruit orchards at harvest in October 2016 and stored in a commercial coolstore at 0–1°C. The time required to kill 99% of the WPS on the fruit was 203 days (95% CI 199–208 days). Insect mortality did not rise above background rates until after 80 days in coolstorage. Mature WPS adults on fruit removed from the coolstore after 128 days were able to mature eggs normally, and subsequent crawler settlement was observed after 22 days out of coolstore at 20°C. Italian kiwifruit infested with WPS is imported into New Zealand during January and February each year, after a coolstore duration of 60–130 days. Most of the mature WPS will be alive and viable in terms of egg development and crawler production.

Soil fertility, leaf nutrients and their relationship in kiwifruit orchards of China’s central Shaanxi province

ABSTRACT Understanding soil fertility and leaf nutrients provides the basis for optimizing fertilization for fruit crop production. However, for central Shaanxi province of China, the largest kiwifruit-producing region in the world, limited information is available on soil fertility and leaf nutrients of these orchards. Here, we assessed 17 soil fertility parameters and 12 leaf elements for 116 kiwifruit orchards in central Shaanxi. The investigated region included five locations: Zhouzhi, Mei, Yangling, Wugong and Qishan. The soils in this region had an average pH of 7.54 and exchangeable Ca of 5.68 g/kg, indicating that the soils were calcareous. Over a quarter of the orchards were deficient in soil organic matter. Although over 50% of the soils were excessive in NO3 –-N and over 25% both deficient and excessive in P and K, more than 65.0% of the orchards were deficient in leaf N, P and K, implying the low NPK use efficiency in central Shaanxi. Moreover, Cl and Zn deficiencies as well as Cu and Ca excesses were found in both soil and leaf diagnosis. Analysis of variance showed that, among the study locations, Zhouzhi was characterized by low soil pH, low soil/leaf Ca and high soil/leaf N, whereas Wugong was featured by high soil/leaf Na. Correlation analysis indicated that soil pH positively correlated with soil Ca, and both parameters negatively correlated with soil N, P, Fe, Mn, Cu and Cl (P < 0.01). Additionally, soil N, Ca, Mn and Cl positively correlated with the corresponding leaf elements (P < 0.001). These results could be used to guide the sustainable nutrient management of kiwifruit production in central Shaanxi.

Netted crop covers reduce honeybee foraging activity and colony strength in a mass flowering crop.

The widespread use of protective covers in horticulture represents a novel landscape‐level change, presenting the challenges for crop pollination. Honeybees (Apis mellifera L) are pollinators of many crops, but their behavior can be affected by conditions under covers. To determine how netting crop covers can affect honeybee foraging dynamics, colony health, and pollination services, we assessed the performance of 52 nucleus honeybee colonies in five covered and six uncovered kiwifruit orchards. Colony strength was estimated pre‐ and postintroduction, and the foraging of individual bees (including pollen, nectar, and naïve foragers) was monitored in a subset of the hives fitted with RFID readers. Simultaneously, we evaluated pollination effectiveness by measuring flower visitation rates and the number of seeds produced after single honeybee visits. Honeybee colonies under cover exhibited both an acute loss of foragers and changes in the behavior of successful foragers. Under cover, bees were roughly three times less likely to return after their first trip outside the hive. Consequently, the number of adult bees in hives declined at a faster rate in these orchards, with colonies losing on average 1,057 ± 274 of their bees in under two weeks. Bees that did forage under cover completed fewer trips provisioning their colony, failing to reenter after a few short‐duration trips. These effects are likely to have implications for colony health and productivity. We also found that bee density (bees/thousand flowers) and visitation rates to flowers were lower under cover; however, we did not detect a resultant change in pollination. Our findings highlight the need for environment‐specific management techniques for pollinators. Improving honeybee orientation under covers and increasing our understanding of the effects of covers on bee nutrition and brood rearing should be primary objectives for maintaining colonies and potentially improving pollination in these systems.

Identification of the productivity-limiting nutrients of Xuxiang kiwifruit (Actiniadia chinensis) in China's central Shaanxi province by analyzing soil fertility and leaf elements

A survey was initiated to identify the productivity-limiting nutrients of Xuxiang kiwifruit (Actiniadia chinensis Lindl.) orchards in central Shaanxi province in China during 2016-2017. For this purpose 149 kiwifruit orchards were selected for leaf sampling and 59 of them were randomly selected for soil analysis. These investigated orchards were divided into two subpopulations: high-productivity subpopulation (21 orchards) and low-productivity subpopulation (128 orchards) according to the fruit yield and appearance as well as vine growth performance. The nutrient concentrations in leaves of high-productivity subpopulation were used to compute the norms of the diagnosis and recommendation integrated system (DRIS), and in low-productivity orchards the order of nutrient requirement was found to be Zn&gt;Mn&gt;K&gt;Fe&gt;Cl&gt;P&gt;B&gt;Ca&gt;Mg&gt;Cu&gt;N. Among them, the deficient nutrients were Zn, Mn and K, while the excessive ones were N, Cu and Mg. However, the limiting elements in various locations and orchard ages differed. These results obtained from leaf analysis were further validated by soil fertility evaluation using sufficiency range, 94.9%, 83.1%, 76.3%, 32.2% and 23.7% of the orchards were high in pH, Ca, Mg, nitrate N and Cu respectively. By contrast, approximately 70% of the soils were low in Fe, Mn, Zn and Cl, and over 30% low in K, P and OM. Results obtained could be used for guiding the sustainably-integrated nutrient management for kiwifruit orchards in central Shaanxi and other regions with similar environmental conditions.

Intensive Cultivation of Kiwifruit Alters the Detrital Foodweb and Accelerates Soil C and N Losses.

The detrital food web plays an important role in the functioning of agro-ecosystems due to their positive effect on organic matter transformations and nutrient supply to the growing crops, however, the activities of the organisms involved are strongly influenced by agricultural practices. In NW Spain, commercial Hayward kiwifruit (Actinidia chinensis var. deliciosa) is intensively produced using conventional techniques (CONV), however, more sustainable methods, such as integrated (INT) and organic (ORG), have been increasingly adopted to decrease the negative impacts on the environment. We investigated the effects of these agricultural managements on earthworm abundance and functional diversity as well as microbial biomass and enzyme activity and evaluated the potential implications for nutrient retention and runoff in kiwifruit orchards. Our results showed that the CONV soils significantly contained fewer earthworms (ca. 80% less individuals than the INT and ORG systems), with their communities being mainly dominated by small epigeics, but a higher microbial biomass (0.53 ± 0.06 mg C g-1 dw soil compared to <0.25 mg C g-1 dw soil in INT and ORG), and 20% more activity of the enzymes involved in C (β-glucosidase) and N mineralization (urease). Consequently, more C and N was lost from these soils (on average, >37% more CO2, and five times more DIN) than from the less intensively managed soils. In contrast, the INT and ORG systems sustained a more complex and functionally diverse soil food web that lead to higher soil C and N retention. Therefore, agriculture management (i.e., intensive vs. less intensive) and its effects on the structure of the below-ground communities (i.e., microorganisms plus surface detritivores vs. deep burrowers plus geophagous forms) determine the nutrient sink/source function of these agro-ecosystems. These findings highlight the importance of including the contribution of soil biota to soil processes when optimizing fertilization loads and mitigating environmental impacts of agricultural practices.

Phenotypic and Genetic Characterization of Botrytis cinerea Population from Kiwifruit in Sichuan Province, China.

Botrytis cinerea (anamorph of Botryotinia fuckeliana) causes gray mold on numerous plants, including kiwifruit. The primary aim of this study was to investigate the phenotypic and genetic characteristics of the Botrytis cinerea population from kiwifruit in Sichuan Province, China. In all, 176 isolates were collected from kiwifruit orchards from eight geographic regions in Sichuan. All isolates were identified as B. cinerea sensu stricto based on the combined datasets, including morphological criteria, determination of the Bc-hch allele, and phylogenetic analysis of the genes RPB2, G3PDH, and HSP60. Three colony types (i.e., sclerotial, mycelial, and conidial) were observed on potato dextrose agar after 2 weeks, with sclerotial isolates, the predominant category, accounting for 40.91%. No obvious differences in microscopic characteristics were observed among the three types. Three genotypes of transposable elements were identified in the B. cinerea population: boty, flipper, and transposa types. The most prevalent genotype from different geographic populations of B. cinerea was transposa; in contrast, the flipper genotype accounted for only 3.98% of the total population, whereas the vacuma genotype was absent. According to MAT locus amplification, 87 and 89 isolates are MAT1-1 and MAT1-2 type, respectively, and the two mating types were found to be balanced overall in the population. Forty-eight representative isolates were all able to cause gray mold to some extent, and disease severities were significantly different between the cultivars Hongyang and Hort16A (P < 0.01). Disease severity was significantly greater on young leaves than on mature leaves (P < 0.01). No significant relationship was found between pathogenicity and geographical region, colony type, or transposon distribution. The results obtained in the present study suggest a relatively uniform species diversity of Botrytis but rich phenotypic and genetic differentiation within the B. cinerea population on kiwifruit in China. Utilizing resistant cultivars and rain-shelter cultivation instead of fungicides may be an effective approach to delaying pathogen variability.