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The legacy effects of rubber defoliation period on the refoliation phenology,leaf disease,and latex yield

Plant Diversity 2023年第1期45卷 98-103页

作者： De-Li Zhai Jian-Chu Xu Center for Mountain Futures Kunming Institute of BotanyKunming 650201YunnanChina Institute of Environment and Ecology School of the Environment and Safety EngineeringJiangsu University301 Xuefu RoadZhenjiang212013Jiangsu ProvinceChina Key Laboratory for Economic Plants and Biotechnology Kunming Institute of BotanyChinese Academy of Sciences132 Lanhei RoadKunming 650201YunnanChina East and Central Asia Regional Office World Agroforestry(ICRAF)Kunming 650201YunnanChina

The leaf phenology of trees has received particular attention for its crucial role in the global water and carbon balances,ecosystem,and species distribution.However,current studies on leaf phenology have mainly focused on temperate trees,while few studies including tropical trees.Little attention has been paid to globally extensive industrial plantations.Rubber plantations are important to both the local and global economies.In this study,we investigated the legacy effects of defoliation phenology on the following year’s leaf flushing,leaf disease,and also latex yield of rubber trees,an economically important tree to local people and the world.Results show that extended duration of defoliation increased the subsequent duration of refoliation and rates of infection by powdery mildew disease,but led to reduced latex yield in March.This legacy effect of rubber defoliation may relate to the carbohydrate reserved in the trees.A longer duration of defoliation would consume more reserved carbohydrates,reducing available reserves for disease defense and latex production.Extended duration of defoliation period was associated with either a lower temperature before the cessation of latex tapping in October-November and/or a higher temperature after the cessation of latex tapping in December-January.Leaf falling signals the end of photosynthetic activities in deciduous trees.Thus,the leaf falling phenology will impact ecological processes involving rubber trees.Our findings indicated that the inclusion of defoliation periods in future rubber trees’ research,will be crucial to furthering our understanding of leaf flushing,powdery mildew disease,and latex yield.

关键词： Carbohydrate defoliation Legacy effect Phenology Rubber trees

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defoliation affects the root competitive balance for N between Poa annua plants grown in a split‐root box

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Grassland Research 2022年第2期1卷 94-102页

作者： Sayuki Mori Louis John Irving School of Life and Environmental Sciences University of TsukubaTsukubaJapan

Background:Plants compete aboveground for light and belowground for patchily distributed nutrients.defoliation causes an immediate loss of leaf area and photosynthetic capacity,leading to reduced root growth,with hypothesised implications for nutrient uptake and nitrogen use efficiency.Methods:In Experiment 1,we grew single plants in split root boxes with N supplied equally or unequally,with half the plants subject to repeated defoliation to quantify the impact of each treatment.In Experiment 2,we grew pairs of Poa annua plants in three‐chamber split root boxes,with N supplied either to the outer chambers(no competition)or to a shared centre chamber(competition),to quantify the influence of defoliation on root competition.Results:In Experiment 1,defoliation caused a significant decrease in root mass but did not affect root distribution between chambers,while differential N supply led to an 11%increase in shoot mass.In Experiment 2,strong root competition was seen in undefoliated plants under competitive conditions.Where one plant was defoliated,the other exhibited increased shoot mass and N content in competitive,but not noncompetitive conditions.Conclusions:Our data suggest that plant belowground competitive success following defoliation may be strongly influenced by the spatial distribution of soil resources.

关键词： competition defoliation differential growth nitrogen nitrogen use efficiency Poa annua root

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Improving remote sensing-based net primary production estimation in the grazed land with defoliation formulation model

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Journal of Mountain Science 2019年第2期16卷 323-336页

作者： YE Hui HUANG Xiao-tao LUO Ge-ping WANG Jun-bang ZHANG Miao WANG Xin-xin State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences China University of Chinese Academy of Sciences Key Laboratory of Restoration Ecology for Cold Regions in Qinghai Northwest Institute of Plateau Biology Chinese Academy of Sciences Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Northwest Land and Resources Research Center Shaanxi Normal University Ministry of Education Key Laboratory of Biodiversity Science and Ecological Engineering Institute of Biodiversity Science Fudan University

Remote sensing(RS) technologies provide robust techniques for quantifying net primary productivity(NPP) which is a key component of ecosystem production management. Applying RS, the confounding effects of carbon consumed by livestock grazing were neglected by previous studies, which created uncertainties and underestimation of NPP for the grazed lands. The grasslands in Xinjiang were selected as a case study to improve the RS based NPP estimation. A defoliation formulation model(DFM) based on RS is developed to evaluate the extent of underestimated NPP between 1982 and 2011. The estimates were then used to examine the spatiotemporal patterns of the calculated NPP. Results show that average annual underestimated NPP was 55.74 gC·m^(-2)yr^(-1) over the time period understudied, accounting for 29.06% of the total NPP for the Xinjiang grasslands. The spatial distribution of underestimated NPP is related to both grazing intensity and time. Data for the Xinjiang grasslands show that the average annual NPP was 179.41 gC·m^(-2)yr^(-1), the annual NPP with an increasing trend was observed at a rate of 1.04 gC·m^(-2)yr^(-1) between 1982 and 2011. The spatial distribution of NPP reveals distinct variations from high to low encompassing the geolocations of the Tianshan Mountains, northern and southern Xinjiang Province and corresponding with mid-mountain meadow, typical grassland, desert grassland, alpine meadow, and saline meadow grassland types. This study contributes to improving RS-based NPP estimations for grazed land and provides a more accurate data to support the scientific management of fragile grassland ecosystems in Xinjiang.

关键词： Remote sensing defoliation formulation model Net primary production Grazed land Spatial-temporal patterns Xinjiang

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Effects of planting patterns on yield, quality, and defoliation in machine-harvested cotton

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Journal of Integrative Agriculture 2019年第9期18卷 2019-2028页

作者： WANG Fang-yong HAN Huan-yong LIN Hai CHEN Bing KONG Xian-hui NING Xin-zhu WANG Xu-wen YU Yu LIU Jing-de Cotton Research Institute Xinjiang Academy of Agricultural and Reclamation Science/Northwest Inland Region Key Laboratory of Cotton Biology and Genetic Breeding Ministry of Agriculture and Rural Affairs

The aim of this study was to elucidate the effects of different machine-harvested cotton-planting patterns on defoliation,yield,and fiber quality in cotton and to provide support for improving the quality of machine-harvested cotton.In the 2015 and 2016 growing seasons,the Xinluzao 45(XLZ45)and Xinluzao 62(XLZ62)cultivars,which are primarily cultivated in northern Xinjiang,were used as study materials.Conventional wide-narrow row(WNR),wide and ultra-narrow row(UNR),wide-row spacing with high density(HWR),and wide-row spacing with low density(LWR)planting patterns were used to assess the effects of planting patterns on defoliation,yield,and fiber quality.Compared with WNR,the seed cotton yields were significantly decreased by 2.06–5.48%for UNR and by 2.50–6.99%for LWR,respectively.The main cause of reduced yield was a reduction in bolls per unit area.The variation in HWR yield was–1.07–1.07%with reduced bolls per unit area and increased boll weight,thus demonstrating stable production.In terms of fiber quality indicators,the planting patterns only showed significant effects on the micronaire value,with wide-row spacing patterns showing an increase in the micronaire values.The defoliation and boll-opening results showed that the number of leaves and dried leaves in HWR was the lowest among the four planting patterns.Prior to the application of defoliating agent and before machine-harvesting,the numbers of leaves per individual plant in HWR were decreased by 14.45 and 25.00%on average,respectively,compared with WNR,while the number of leaves per unit area was decreased by 27.44 and 36.21%on average,respectively.The rates of boll-opening and defoliation in HWR were the highest.Specifically,the boll-opening rate before defoliation and machine-harvesting in HWR was 44.54 and 5.94%higher on average than in WNR,while the defoliation rate prior to machine-harvesting was 3.45%higher on average than in WNR.The numbers of ineffective defoliated leaves and leaf trash in HWR were the lowest,decreased by 33.40 and 32.43%,respec

关键词： machine-harvested cotton planting patterns defoliation yield quality

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Impact of Three Isolates of Cercosporidium personatum (Berk. Et M.A Curt.), a Pathogen of Late Leaf Spot, on defoliation and Yield in Groundnut (Arachis hypogaea L.) under Controlled Conditions

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American Journal of Plant Sciences 2023年第10期14卷 1101-1114页

作者： Bawomon Fidèle Neya Tobdem Gaston Dabire Alassane Ouattara Amado Sawadogo Diariétou Sambakhe Kouka Hamidou Sogoba Tounwendsida Abel Nana Ibié Gilles Thio Frank Essem Kadidia Koita University Center of Gaoua Nazi BONI University Bobo Dioulasso Burkina Faso Life and Earth Sciences Unit Joseph KI-ZERBO University Ouagadougou Burkina Faso Senegalese Institute of Agricultural Research/CERAAS Thiès Senegal Institute for the Environment and Agricultural Research (INERA) Ouagadougou Burkina Faso Akenten Appiah-Menka University of Skills Training and Entrepreneurial Development Mampong Ghana

Late leaf spot caused by Cercosporidium personatum is one of the most widespread groundnut leaf diseases. Along with early leaf spot and rust, it is one of the main fungal diseases hampering groundnut production worldwide. Late leaf spot accounts for significant yield losses throughout the world where groundnuts are grown. This reduction in yield caused by the disease could result in yield losses of between 50% and 70%. In Burkina Faso, the disease is present throughout the country, with incidence varying according to region and season. Could the variability in the incidence of the disease be linked to the nature of the isolates or to the conditions from each agro-ecological zone? In this study, the aim was to assess the capacity of three isolates from three agroclimatic zones of the country to defoliate and reduce groundnut yield. To this end, three isolates of Cercosporidium personatum (Berk. Et M.A Curt.) were collected in these zones and evaluated on three contrasting groundnut varieties. A split-splot design was used for the experiment. Isolates were prepared from samples collected in farmers’ fields. After incubation in the laboratory, leaf spots showing good sporulation were scraped off with a scalpel after immersing the leaves in distilled water. Inoculations were carried out under controlled environment. After inoculation with the isolate, the percentage of defoliation and the reduction in yield of these varieties were then evaluated. Inoculation was carried out from the 30th day after sowing with Cercosporidium personatum spore suspensions at 105 spores/ml. The study showed that the percentage of defoliation (P = 0.0001) and the reduction in yield (P = 0.0001) were significant. The study revealed that, whatever the variety, isolate I3TF from the Upper Basins region in the South Sudanese zone caused the greatest defoliation and the greatest reduction in yield. The variety TS32-1, regardless of the isolate used for the treatment, recorded the best yield. The variety PC79-79, regardless of the i

关键词： Arachis hypogaea Isolate Late Leaf Spot Cercosporidum personatum Yield defoliation

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Attenuation of ethylene signaling increases cotton resistance to a defoliating strain of Verticillium dahliae

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作物学报：英文版 2023年第1期11卷 89-98页

作者： Tianyi Wang Muhammad Shaban Junhui Shi Weiran Wang Shiming Liu Xinhui Nie Yu Yu Jie Kong Steven J.Klosterman Xianlong Zhang Alifu Aierxi Longfu Zhu National Key Laboratory of Crop Genetic Improvement Huazhong Agricultural UniversityWuhan 430070HubeiChina Department of Plant Breeding and Genetics University of Agricu Institute of Economic Crops Xinjiang Academy of Agricultural SciencesKuqa 842000XinjiangChina Key Laboratory of Oasis Eco-agriculture of the Xinjiang Production and Construction Crops College of AgronomyShihezi UniversityShihezi 832000XinjiangChina Xinjiang Academy of Agricultural&Reclamation Sciences Shihezi 832000XinjiangChina United States Department of Agriculture Agricultural Research ServiceSalinasCA 93905USA

The severity of Verticillium wilt on cotton caused by defoliating strains of Verticillium dahliae has gradually increased and threatens production worldwide. Identification of the molecular components of leaf defoliation may increase cotton tolerance to V. dahliae. Ethylene, a major player in plant physiological processes, is often associated with senescence and defoliation of plants. We investigated the cotton–V.dahliae interaction with a focus on the role of ethylene in defoliation and defense against V. dahliae.Cotton plants inoculated with V. dahliae isolate V991, a defoliating strain, accumulated more ethylene and showed increased disease symptoms than those inoculated with a non-defoliating strain. In cotton with a transiently silenced ethylene synthesis gene(GhACOs) and signaling gene(GhEINs) during cotton–V. dahliae interaction, ethylene produced was derived from cotton and more ethylene increased cotton susceptibility and defoliation rate. Overexpression of AtCTR1, a negative regulator in ethylene signaling, in cotton reduced sensitivity to ethylene and increased plant resistance to V. dahliae.Collectively, the results indicated precise regulation of ethylene synthesis or signaling pathways improve cotton resistant to Verticillium wilt.

关键词： Cotton Verticillium dahilae Ethylene defoliation

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Cotton maturity and responses to harvest aids following chemical topping with mepiquat chloride during bloom period

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Journal of Integrative Agriculture 2022年第9期21卷 2577-2587页

作者： QI Hai-kun DU Ming-wei MENG Lu XIE Liu-wei AEgrinya ENEJI XU Dong-yong TIAN Xiao-li LI Zhao-hu Engineering Research Center of Plant Growth Regulator Ministry of Education/College of Agronomy and BiotechnologyChina Agricultural UniversityBeijing 100193P.R.China Department of Soil Science Faculty of AgricultureForestry and Wildlife Resources ManagementUniversity of CalabarCalabar 540271Nigeria Hebei Cottonseed Engineering Technology Research Center Hejian 062450P.R.China

Early maturity, complete defoliation and boll opening are essential for the efficient machine harvesting of cotton. Chemical topping, involving one extra application of mepiquat chloride(MC) in addition to its traditional multipleapplication strategy, may be able to replace manual topping. However, it is not known whether this chemical topping technique will influence maturity or cotton responses to harvest aids. In this 2-yr field study, we determined the effects of the timing of chemical topping using various rates of MC on boll opening percentage(BOP) before application of harvest aids(50% thidiazuron··ethephon suspension concentrate, referred to as TE), and the defoliation percentage(DP) and BOP 14 days after TE application. The results indicated that late chemical topping(near the physiological cutout, when the nodes above white flower is equal to 5.0) significantly decreased BOP before TE by 5.9–11.2% compared with early(at peak bloom) or middle(seven days after peak bloom) treatments in 2019, which was a relatively normal year based on crop condition. Also, a high MC rate(270 g ha) showed a significantly lower(22.0%) BOP before TE than low(90 g ha) or medium(180 g ha) rates. In 2020, which was characterized by stronger vegetative growth in the late season, the late chemical topping reduced the number of leaves before TE application relative to early or middle treatments, but had lower DP(23.2–27.2%) 14 days after TE application. The high MC rate showed a leaf count before TE application that was similar to the low and medium rates, but it showed the most leaves after TE and much lower(15.0–21.7%) DP in 2020. These results suggest that late timing of chemical topping and a high MC rate decreased the sensitivity of leaves to harvest aids. Further analysis indicated that the late chemical topping mainly affected the leaf drop from the mainstem and fruiting branches where the late regrowth occurred, and the high MC rate reduced leaf shedding from these parts and also from the vegetative branches. In conclusion

关键词： cotton mepiquat chloride thidiazuron ethephon defoliation maturity

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defoliation in Flue-cured Tobacco and Its Reasons

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Agricultural Biotechnology 2017年第3期6卷 47-50页

作者： Chungui TANG Fan LI Hongwu YANG Pengfeng CHEN Li LI Jiamei LI Xinjian CHEN Hongxiang GUO Weiqun LIU Changsha Municipal Tobacco Company Hunan Provincial Tobacco Company Liuyang Branch of Changsha Tobacco Company College of Life Science Henan Agricultural University

The flue-cured tobacco G80 is not only one of the characteristic varieties in Changsha, but also indispensable raw materials for the series of Baisha ciga- rette. defoliation during the late stage of growth seriously reduces the yield and quality of tobacco, and limits the popularization and application of G80. In this pa- per, in order to investigate the reasons for the defoliation of G80, the transverse section structure, cellulose content and differential proteins of leaf major veins were analyzed. The results revealed that the autolysis and collapse of parenchyma cells is the main cause of defoliation, and fimgal infection is a factor inducing the au- tolysis of parenchyma cells. Application of bud suppression agent is one of the main ways to prevent fungal infection. The low cellulose content, low synthetic ability of xylan and pectin, the low removal ability of abnormal protein and low immune responsiveness are the inner reason for defoliation of flue-cured tobacco G80.

关键词： Tobacco Characteristic varieties G80 defoliation

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Droplets deposition and harvest-aid efficacy for UAV application in arid cotton areas in Xinjiang,China

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International Journal of Agricultural and Biological Engineering 2022年第5期15卷 9-18页

作者： Guobin Wang Jiahui Wang Pengchao Chen Xiaoqiang Han Shengde Chen Yubin Lan School of Agricultural Engineering and Food Science Shandong University of TechnologyZibo 255049ShandongChina National Center for International Collaboration Research on Precision Agricultural Aviation Pesticides Spraying Technology(NPAAC) Ministry of Science and TechnologyCollege of Electronic EngineeringSouth China Agricultural UniversityGuangzhou 510642China College of Agricultural Shihezi UniversityShihezi 832000XinjiangChina Department of Biological and Agricultural Engineering Texas A&M UniversityCollege StationTX 77845

With the development of Unmanned Aerial Vehicle(UAV)sprayers,the application of low-volume spraying of harvest-aid and other agrochemicals to cotton using UAVs is becoming a new agronomic trend worldwide.The effect of spray volume and canopy density for UAV spraying is significant but was rarely studied.In this study,five representative spray volumes were explored to examine the effect of spray volume on deposition and harvest-aid efficacy for cotton using a UAV sprayer.To explore the effect of canopy density,similar tests were carried out in a field located nearby with a lower leaf area index(LAI).A conventional trailer boom sprayer was selected for comparison.Different spray volumes had a significant effect on defoliation,but had no significant effect on boll opening and fiber quality.A higher defoliation rate was achieved in the lower LAI field.The total rate of defoliation using the UAV was inferior to the boom sprayer in the high LAI field for lower deposition and defoliation rate in the lower canopy.Considering the deposition,defoliation rate,and working efficiency,a spray volume of 15.0 L/hm^(2) with an average droplet size of 150μm is recommended for UAV application.

关键词： UAV droplets deposition spray volume canopy density leaf area index defoliation boll opening rate

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Artificial defoliation to Simulate Losses on Production of Bean (<i>Phaseolus vulgaris</i>L. cv. Goytacazes)

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Agricultural Sciences 2019年第8期10卷 1023-1031页

作者： Omar Schmildt Vinicius de Souza Oliveira Dirceu Pratissoli José Augusto Teixeira do Amaral Marcio Paulo Czepak Adriel Lima Nascimento Edilson Romais Schmildt Postgraduate Program in Tropical Agriculture Federal University of Espírito Santo S&#227 o Mateus ES Brazil Department of Agronomy Federal University of Espírito Santo Alegre ES Brazil Departament of Agrarian and Biological Sciences Federal University of Espírito Santo S&#227 o Mateus ES Brazil

The reduction of foliar area can cause yield reduction in common bean crops. The objective of this work was to verify which is the effect of different defoliation levels realized in several development stages of common bean (Phaseolus vulgaris L. cv. Goytacazes) over yield, weight of 100 seeds and number of pods per plant. The experimental design was randomized blocks, in a split-plot arrangement with five replications. The plot corresponded to the five defoliation epochs (first trifoliate leaf, flowering, pods formation, pods filling, and dry pods). In each plot, the split plot was represented by the four defoliation levels (0%, 33%, 67% and 100%). It was observed a decrease of yield for all levels defoliation considering all development stages, except for dried pods. The highest decrease was detected for flowering and pods formation. Through the regression analysis got a greater reduction in yield with 100% defoliation made at 42 days after emergence. The evaluation parameter that showed better relation with yield was a number of pods per plant.

关键词： Common Bean defoliation Grain Productivity Mass of Seeds Pods

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