An Unmanned Aerial Vehicle Based Artificial Pollination in a Frost-affected Walnut (Juglans regia L.) Orchard
Year 2023,
Volume: 29 Issue: 3, 765 - 776, 25.09.2023
Dilan Ahı Koşar
,
Eküle Sönmez
,
Adem Argaç
,
Umran Ertürk
Abstract
The winter and spring frosts are an important problem in some walnut cultivation areas. The frost damage of catkins and female flowers results in low fruit set and yield. The temperature dropped -17.2 °C in January 2021 in the Yenişehir, Bursa, an important walnut production area in North-Western Turkey. The present study was carried out to determine the natural frost damage on catkins of some walnut cultivars and the effectiveness of an unmanned aerial vehicle (UAV) pollination, which has been developed and used in artificial pollination studies recently, on fruit set and fruit characteristics. In the experiment, two pollen concentrations (T1: 5% pollen two times; T2: 5% pollen in the first, 20% pollen in the second time) and the open pollination (control) were tested. Observations showed that frost damage on catkins varied from 57.31% (Ronde de Montignac) to 99.33% (Franquette). The initial fruit set was significantly higher in the T1 (87.74%) followed by T2 (83.89%). The final fruit set in T2 (75.16%) was higher than the T1 (74.11%), but the difference was insignificant. The box and whisker plot shows that UAV pollination treatments (T1, T2) increased the fruit set, but it was not uniform on the tree compared to open pollination. The highest nut weight, thickness, and length were obtained from control, followed by T1. The results showed that the fruit set was higher in pollination with UAV, and using less pollen (T1) was sufficient. The research results provide support for UAV treatment on supplementary pollination for walnut.
References
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- Aleta N, Vilanova A, Tomas E & Guardia M (2014). Frost resistance in seven commercial walnut cultivars. Acta Horticulturae 1050: 389-393.
- Al-Wusaibai N A, Ben Abdallah A, Al-Husainai M S, Al-Salman H & Elballaj M A (2012). Comparative study between mechanical and manual pollination in two premier Saudi Arabian date palm cultivars. Indian Journal of Science and Technology 5(4): 2487–2490
- Aslamarz A A, Vahdati K, Rahemi M, Hassani D & Leslie C (2010). Supercooling and cold-hardiness of acclimated and deacclimated buds and stems of Persian walnut cultivars and selections. HortScience 45(11): 1662-1667
- Awad M A (2010). Pollination of date palm (Phoenix dactylifera L.) cv. Khenazy by pollen grain-water suspension spray. Journal of Food Agriculture and Environment 88(3): 313-317
- Ayfer M (1967). Antepfıstığında Megasporognesis, Megagametogenesis, Embriyogenesis ve Bunlarla Meyve Dökümleri Arasındaki Münasebetler. Tarım Bakanlığı Teknik Kitap, İstanbul
- Barnett J, Seabright M, Williams H, Nejati M, Scarfe A, Bell J & Duke M (2017). Robotic Pollination - Targeting kiwifruit flowers for commercial application. In: International Tri-Conference for Precision Agriculture, 16-18 October, Hamilton, New Zealand
- Charrier G, Poirier M, Bonhomme M, Lacointe A & Améglio T (2013). Frost hardiness in walnut trees (Juglans regia L.): How to link physiology and modelling?. Tree Physiology 00: 1–13
- El-Mardi M O, Al Said F A J, Sakit C B, Al Kharusi L M, Al Rahbi I N & Al Mahrazi K (2007). Effect of pollination method, fertilizer and mulch treatments on the physical and chemical characteristics of date palm (Phoenix dactylifera) fruit. I: Physical characteristics. Acta Horticulturae 736: 317-328
- Gandev S (2013). Winter hardiness of reproductive organs of the walnut cultivars Izvor 10, Lara and Fernor at extreme low temperatures in South Bulgaria. Bulgarian Journal of Agricultural Science 19: 1068-1071
- Gianni T & Michelotti V (2018). Artificial Pollination in Kiwifruit and Olive Trees. In: Mokwala P W (Eds). Pollination in Plants, London, pp. 59-66.
- Gonzalez R, Lemus G & Reginato G (2018). Pistillate Flower abscission symptoms of Serr walnut (Juglans regia L.). Chilean Journal of Agricultural Research 68: 183-191
- Gün A, Erdogan V, Akçay M E, Fidanci A & Tosun İ (2010). Pistillate Flower Abscission in Turkish Walnut Cultivars and Its Reduction. In: 2nd International Symposium on Sustainable Development (ISSD'10). Proceedings, Science and Technology. Sarajevo, 3: pp. 29-34
- Jameela R V & Alagirisamy M (2021). Effect of Mechanical (Dry and Wet) Pollination of Date Palms on Cultivar Naghal in the Sultanate of Oman. In: 2021 International Conference on Information and Communication Technology Convergence (ICTC), 20-22 October, pp. 967-972
- Kaveckaja A A & Tokar K O (1963). The unfavorable effect of large amount of pollen in the pollination of walnuts. Botanichnyi Zhurnal 48: 580-585
- Kim J, Kim S, Ju C & Son, H (2019). Unmanned Aerial Vehicles in Agriculture: A Review of Perspective of Platform, Control, and Applications. IEEE Access, 7: 105100-1051015
- Kuru C (1995). Artificial pollination of pistachio trees under unsufficient pollination conditions. Acta Horticulturae 419: 121-123
Lan Y, Shengde C & Fritz B K (2017). Current status and future trends of precision agricultural aviation technologies. International Journal of Agricultural and Biological Engineering 10(3): 1-17
- Lapins K (1961). Artifical freezing of 1-year old shoots of apple varieties. Canadian Journal of Plant Science 41: 381-393
Lemus G (2010). PFA Control in 'Serr' in Chilie. Acta Horticulturae 861: 263-266
- Li J, Zhou Z, Lan Y, Hu L, Zang Y, Liu A & Zhang T (2015). Distribution of canopy wind field produced by rotor unmanned aerial vehicle pollination operation. Transactions of the Chinese Society of Agricultural Engineering 31: 77–86
- Li J Y, Lan Y B, Wang J W, Chen S D, Huang C, Liu Q & Liang Q (2017). Distribution law of rice pollen in the wind field of small UAV. International Journal of Agricultural and Biological Engineering 10(4): 32–40
- Liu A, Zhang H, Liao C, Zhang Q, Xiao C, He J, Zhang J, He Y, Li J & Luo X (2017). Effects of supplementary pollination by single-rotor agricultural unmanned aerial vehicle in hybrid rice seed production. Agricultural Science and Technology 18: 543–547
- Liu Y, Dang P, Liu L & He C (2019). Cold acclimation by the CBF–COR pathway in a changing climate: Lessons from Arabidopsis thaliana. Plant Cell Reports 38(5): 511-519
- Luedeling E, Girvetz E H, Semenov M A & Brown P H (2011). Climate change affects winter chill for temperate fruit and nut trees. PLoS ONE 6: e20155
- Malone S R & Ashworth E N (1991). Freezing Stress Response in Woody Tissues Observed Using Low-Temperature Scanning Electron Microscopy and Freeze Substitution Techniques. Plant Physiology 95(3): 871-81.
- Matt Koball W M (2019). “Dropcopter” [Internet]. Retrieved in February,10, 2022 from: https://www.dropcopter.com/
- Mazinani M, Dehghani M, Zarafshan P, Etezadi H, Vahdati K & Chegini G (2021). Design and Manufacture of an Aerial Pollinator Robot for Walnut Trees. In: Proceedings of the 9th RSI International Conference on Robotics and Mechatronics (ICRoM), 17-19 Novermber, Tehran, Iran, pp. 445-450
- McGranahan G H, Voyatzis D G, Catlin P B & Polito V S (1994). High pollen loads can cause pistillate flower abscission in walnut. Journal of the American Society for Horticultural Science 119(3): 505-509
- Meng X, He Y & Han J (2019). Survey on Aerial Manipulator: System, Modeling, and Control. Robotica 38(7): 1288-1317
- Mert C (2009). Temperature responses of pollen germination in Walnut (Juglans regia L.). Journal of Biological and Environmental Science 3(8): 37-43
- Mostan A (2012). Mechanization in Date Palm Pollination. In: Manickavasagan A, Mohamed Essa M, Sukumar E (Eds.), An overwiev of date palm production, New York, pp. 129-39
- Pagter M & Williams M (2011). Frost dehardening and rehardening of hydrangea macrophylla stems and buds. HortScience 46 1121-1126
- Poirier M, Bodet C, Ploquin S, Saint-Joanis B, Lacointe A & Ameglio T (2005). Walnut Cultivar Performance of Cold Resistance in South Central France. Acta Horticulturae 705: 281-285
- Poirier M, Lacointe A & Améglio T (2010). A semi-physiological model of cold hardening and dehardening in walnut stem. Tree Physiology 30: 1555–1569
- Polito V, Coates B, Grant J, Hasey J, Micke W, Olson B & Pinney K (1996). Pollen, Pistillate flower abortion/ abscission. Walnut research reports 77-87
- Polito V S, Pinney K, Weinbaum S, Aradhya M K, Dangl J, Yanknin Y & Grant J A (2005). Walnut Pollination Dynamics: Pollen Flow in Walnut Orchards. Acta Hort. 705: 465-472
- Por A & Por J (1990). The effect of the excess pollen on the fruit set of walnuts in Balatonboglar. Acta Horticulturae 284: 253-256
- Razeto B, Reginato G & Larraín A (2005). Hand and Machine Pollination of Kiwifruit. International Journal of Fruit Science 5: 37-44
Robichaud R L (2007). Pollen Gene Dispersal in Black Walnut across a Heterogeneous Landscape in Central Indiana [dissertation]. PhD Thesis, Purdue University, Indiana
- Rochette P, Angers D A, Bélanger G, Chantigny M H, Prévost D & Lévesque G (2004). Emissions of N2O from alfalfa and soybean crops in Eastern Canada. Soil Science Society of America Journal 68: 493-506
- Shepherd T G (2016). Effects of a warming Arctic Science 353(6303): 989-990
- Soliman S S, Alebidi A I, Al-Saif A M, Al-Obeed R S, Al-Bahelly A N (2017). Impact of pollination by pollen-grain-water suspension spray on yield and fruit quality of segae date palm cultivar (Phoenix dactylifera l.). Pakistan Journal of Botany 49(1): 119-123
- Şen S M (1986). Ceviz Yetiştiriciliği. Eser Matbaası, Samsun
- Şen S M (2011). Ceviz yetiştiriciliği ve besin değeri.. ÜÇM Yayıncılık, Ankara
- Takeda F, Arora R, Wisniewski M E Davis G A & Warmund M R (1993). Assessment of freeze injury in 'Boskoop Giant' black currant buds. HortScience 28: 652–654
- Tang Y, Hou C J, Luo S M, Lin J T, Yang Z & Huang W F (2018). Effects of operation height and tree shape on droplet deposition in citrus trees using an unmanned aerial vehicle. Computers and Electronics in Agriculture 148: 1-7
- UPOV (1994). Walnut (Juglans regia L.) Guidelines for the Conduct of Test for Distinctness, Uniformity and Stability. Int. Union Production New Varietes Plants, Geneva, Switzerland
- Vahdati K, Arab MM, Sarikhani S, Sadat Hosseini M, Leslie C A & Brown P J (2019). Advances in walnut breeding strategies. In: Al-Khayri, J.M., Jain, S.M., Johnson, D.V. (Eds.), Advances in Plant Breeding Strategies: Nut and Beverage Crops. Springer Press
- Wang P, Hu L, Zhou Z, Yang W, Liu A, Luo X, Xue X, He J & Yan Y (2013). Wind field measurement for supplementary pollination in hybrid rice breeding using unmanned gasoline engine single-rotor helicopter. Transactions of the Chinese Society of Agricultural Engineering 29: 54–61
- Wang S, Lei X, Tang Y, Chang Y& Lv X (2020). Pear tree spray pollination technology based on multi-rotor UAV. Jiangsu Agricultural Sciences 48: 210-214
Webster AD, Looney NE. World distribution of sweet and sour cherry production: national statistics. In: Webster, AD, Looney NE (Eds.), Cherries, crop physiology, production and uses, Cambridge, pp. 25–69
- Whiting M (2015). Mechanical pollination for yield security. Retrived in March, 10, 2022 from http://jenny.tfrec.wsu.edu/wtfrc/PDFfinalReports/2016FinalReports/WhitingPollinationFinal.pdf
- Williams H, Nejati M, Hussein S, Penball N, Lim J Y, Jones M H, Ahn H S, Bradley S, Schaare P, Martinsen P, Alomar M, Patel P, Seabright M, Duke M, Scarfe A & MacDonald B (2019). Autonomous pollination of individual kiwifruit flowers: Toward a robotic kiwifruit pollinator. Journal of Field Roboics 37(2): 246-262
- Zhang P, Deng L, Lyu Q, He S, Yi S, Liu Y, Yu Y & Pan H (2016). Effects of citrus tree-shape and spraying height of small unmanned aerial vehicle on droplet distribution. International Journal of Agricultural and Biological Engineering 9(4): 45-52
- Zhang S, Cai C, Li J, Sun T, Liu X, Tian Y & Xue X (2021). The Airflow Field Characteristics of the Unmanned Agricultural Aerial System on Oilseed Rape (Brassica napus) Canopy for Supplementary Pollination. Agronomy 11(10): 1-13
Year 2023,
Volume: 29 Issue: 3, 765 - 776, 25.09.2023
Dilan Ahı Koşar
,
Eküle Sönmez
,
Adem Argaç
,
Umran Ertürk
References
- Akhavan F, Kamgar S, Nematollahi M A, Golneshan A A, Nassiri S M & Khaneghah A M (2021). Design, development, and performance evaluation of a ducted fan date palm (Phoenix dactylifera L.) pollinator. Scientia Horticulturae 277: 1-6
- Aleta N, Vilanova A, Tomas E & Guardia M (2014). Frost resistance in seven commercial walnut cultivars. Acta Horticulturae 1050: 389-393.
- Al-Wusaibai N A, Ben Abdallah A, Al-Husainai M S, Al-Salman H & Elballaj M A (2012). Comparative study between mechanical and manual pollination in two premier Saudi Arabian date palm cultivars. Indian Journal of Science and Technology 5(4): 2487–2490
- Aslamarz A A, Vahdati K, Rahemi M, Hassani D & Leslie C (2010). Supercooling and cold-hardiness of acclimated and deacclimated buds and stems of Persian walnut cultivars and selections. HortScience 45(11): 1662-1667
- Awad M A (2010). Pollination of date palm (Phoenix dactylifera L.) cv. Khenazy by pollen grain-water suspension spray. Journal of Food Agriculture and Environment 88(3): 313-317
- Ayfer M (1967). Antepfıstığında Megasporognesis, Megagametogenesis, Embriyogenesis ve Bunlarla Meyve Dökümleri Arasındaki Münasebetler. Tarım Bakanlığı Teknik Kitap, İstanbul
- Barnett J, Seabright M, Williams H, Nejati M, Scarfe A, Bell J & Duke M (2017). Robotic Pollination - Targeting kiwifruit flowers for commercial application. In: International Tri-Conference for Precision Agriculture, 16-18 October, Hamilton, New Zealand
- Charrier G, Poirier M, Bonhomme M, Lacointe A & Améglio T (2013). Frost hardiness in walnut trees (Juglans regia L.): How to link physiology and modelling?. Tree Physiology 00: 1–13
- El-Mardi M O, Al Said F A J, Sakit C B, Al Kharusi L M, Al Rahbi I N & Al Mahrazi K (2007). Effect of pollination method, fertilizer and mulch treatments on the physical and chemical characteristics of date palm (Phoenix dactylifera) fruit. I: Physical characteristics. Acta Horticulturae 736: 317-328
- Gandev S (2013). Winter hardiness of reproductive organs of the walnut cultivars Izvor 10, Lara and Fernor at extreme low temperatures in South Bulgaria. Bulgarian Journal of Agricultural Science 19: 1068-1071
- Gianni T & Michelotti V (2018). Artificial Pollination in Kiwifruit and Olive Trees. In: Mokwala P W (Eds). Pollination in Plants, London, pp. 59-66.
- Gonzalez R, Lemus G & Reginato G (2018). Pistillate Flower abscission symptoms of Serr walnut (Juglans regia L.). Chilean Journal of Agricultural Research 68: 183-191
- Gün A, Erdogan V, Akçay M E, Fidanci A & Tosun İ (2010). Pistillate Flower Abscission in Turkish Walnut Cultivars and Its Reduction. In: 2nd International Symposium on Sustainable Development (ISSD'10). Proceedings, Science and Technology. Sarajevo, 3: pp. 29-34
- Jameela R V & Alagirisamy M (2021). Effect of Mechanical (Dry and Wet) Pollination of Date Palms on Cultivar Naghal in the Sultanate of Oman. In: 2021 International Conference on Information and Communication Technology Convergence (ICTC), 20-22 October, pp. 967-972
- Kaveckaja A A & Tokar K O (1963). The unfavorable effect of large amount of pollen in the pollination of walnuts. Botanichnyi Zhurnal 48: 580-585
- Kim J, Kim S, Ju C & Son, H (2019). Unmanned Aerial Vehicles in Agriculture: A Review of Perspective of Platform, Control, and Applications. IEEE Access, 7: 105100-1051015
- Kuru C (1995). Artificial pollination of pistachio trees under unsufficient pollination conditions. Acta Horticulturae 419: 121-123
Lan Y, Shengde C & Fritz B K (2017). Current status and future trends of precision agricultural aviation technologies. International Journal of Agricultural and Biological Engineering 10(3): 1-17
- Lapins K (1961). Artifical freezing of 1-year old shoots of apple varieties. Canadian Journal of Plant Science 41: 381-393
Lemus G (2010). PFA Control in 'Serr' in Chilie. Acta Horticulturae 861: 263-266
- Li J, Zhou Z, Lan Y, Hu L, Zang Y, Liu A & Zhang T (2015). Distribution of canopy wind field produced by rotor unmanned aerial vehicle pollination operation. Transactions of the Chinese Society of Agricultural Engineering 31: 77–86
- Li J Y, Lan Y B, Wang J W, Chen S D, Huang C, Liu Q & Liang Q (2017). Distribution law of rice pollen in the wind field of small UAV. International Journal of Agricultural and Biological Engineering 10(4): 32–40
- Liu A, Zhang H, Liao C, Zhang Q, Xiao C, He J, Zhang J, He Y, Li J & Luo X (2017). Effects of supplementary pollination by single-rotor agricultural unmanned aerial vehicle in hybrid rice seed production. Agricultural Science and Technology 18: 543–547
- Liu Y, Dang P, Liu L & He C (2019). Cold acclimation by the CBF–COR pathway in a changing climate: Lessons from Arabidopsis thaliana. Plant Cell Reports 38(5): 511-519
- Luedeling E, Girvetz E H, Semenov M A & Brown P H (2011). Climate change affects winter chill for temperate fruit and nut trees. PLoS ONE 6: e20155
- Malone S R & Ashworth E N (1991). Freezing Stress Response in Woody Tissues Observed Using Low-Temperature Scanning Electron Microscopy and Freeze Substitution Techniques. Plant Physiology 95(3): 871-81.
- Matt Koball W M (2019). “Dropcopter” [Internet]. Retrieved in February,10, 2022 from: https://www.dropcopter.com/
- Mazinani M, Dehghani M, Zarafshan P, Etezadi H, Vahdati K & Chegini G (2021). Design and Manufacture of an Aerial Pollinator Robot for Walnut Trees. In: Proceedings of the 9th RSI International Conference on Robotics and Mechatronics (ICRoM), 17-19 Novermber, Tehran, Iran, pp. 445-450
- McGranahan G H, Voyatzis D G, Catlin P B & Polito V S (1994). High pollen loads can cause pistillate flower abscission in walnut. Journal of the American Society for Horticultural Science 119(3): 505-509
- Meng X, He Y & Han J (2019). Survey on Aerial Manipulator: System, Modeling, and Control. Robotica 38(7): 1288-1317
- Mert C (2009). Temperature responses of pollen germination in Walnut (Juglans regia L.). Journal of Biological and Environmental Science 3(8): 37-43
- Mostan A (2012). Mechanization in Date Palm Pollination. In: Manickavasagan A, Mohamed Essa M, Sukumar E (Eds.), An overwiev of date palm production, New York, pp. 129-39
- Pagter M & Williams M (2011). Frost dehardening and rehardening of hydrangea macrophylla stems and buds. HortScience 46 1121-1126
- Poirier M, Bodet C, Ploquin S, Saint-Joanis B, Lacointe A & Ameglio T (2005). Walnut Cultivar Performance of Cold Resistance in South Central France. Acta Horticulturae 705: 281-285
- Poirier M, Lacointe A & Améglio T (2010). A semi-physiological model of cold hardening and dehardening in walnut stem. Tree Physiology 30: 1555–1569
- Polito V, Coates B, Grant J, Hasey J, Micke W, Olson B & Pinney K (1996). Pollen, Pistillate flower abortion/ abscission. Walnut research reports 77-87
- Polito V S, Pinney K, Weinbaum S, Aradhya M K, Dangl J, Yanknin Y & Grant J A (2005). Walnut Pollination Dynamics: Pollen Flow in Walnut Orchards. Acta Hort. 705: 465-472
- Por A & Por J (1990). The effect of the excess pollen on the fruit set of walnuts in Balatonboglar. Acta Horticulturae 284: 253-256
- Razeto B, Reginato G & Larraín A (2005). Hand and Machine Pollination of Kiwifruit. International Journal of Fruit Science 5: 37-44
Robichaud R L (2007). Pollen Gene Dispersal in Black Walnut across a Heterogeneous Landscape in Central Indiana [dissertation]. PhD Thesis, Purdue University, Indiana
- Rochette P, Angers D A, Bélanger G, Chantigny M H, Prévost D & Lévesque G (2004). Emissions of N2O from alfalfa and soybean crops in Eastern Canada. Soil Science Society of America Journal 68: 493-506
- Shepherd T G (2016). Effects of a warming Arctic Science 353(6303): 989-990
- Soliman S S, Alebidi A I, Al-Saif A M, Al-Obeed R S, Al-Bahelly A N (2017). Impact of pollination by pollen-grain-water suspension spray on yield and fruit quality of segae date palm cultivar (Phoenix dactylifera l.). Pakistan Journal of Botany 49(1): 119-123
- Şen S M (1986). Ceviz Yetiştiriciliği. Eser Matbaası, Samsun
- Şen S M (2011). Ceviz yetiştiriciliği ve besin değeri.. ÜÇM Yayıncılık, Ankara
- Takeda F, Arora R, Wisniewski M E Davis G A & Warmund M R (1993). Assessment of freeze injury in 'Boskoop Giant' black currant buds. HortScience 28: 652–654
- Tang Y, Hou C J, Luo S M, Lin J T, Yang Z & Huang W F (2018). Effects of operation height and tree shape on droplet deposition in citrus trees using an unmanned aerial vehicle. Computers and Electronics in Agriculture 148: 1-7
- UPOV (1994). Walnut (Juglans regia L.) Guidelines for the Conduct of Test for Distinctness, Uniformity and Stability. Int. Union Production New Varietes Plants, Geneva, Switzerland
- Vahdati K, Arab MM, Sarikhani S, Sadat Hosseini M, Leslie C A & Brown P J (2019). Advances in walnut breeding strategies. In: Al-Khayri, J.M., Jain, S.M., Johnson, D.V. (Eds.), Advances in Plant Breeding Strategies: Nut and Beverage Crops. Springer Press
- Wang P, Hu L, Zhou Z, Yang W, Liu A, Luo X, Xue X, He J & Yan Y (2013). Wind field measurement for supplementary pollination in hybrid rice breeding using unmanned gasoline engine single-rotor helicopter. Transactions of the Chinese Society of Agricultural Engineering 29: 54–61
- Wang S, Lei X, Tang Y, Chang Y& Lv X (2020). Pear tree spray pollination technology based on multi-rotor UAV. Jiangsu Agricultural Sciences 48: 210-214
Webster AD, Looney NE. World distribution of sweet and sour cherry production: national statistics. In: Webster, AD, Looney NE (Eds.), Cherries, crop physiology, production and uses, Cambridge, pp. 25–69
- Whiting M (2015). Mechanical pollination for yield security. Retrived in March, 10, 2022 from http://jenny.tfrec.wsu.edu/wtfrc/PDFfinalReports/2016FinalReports/WhitingPollinationFinal.pdf
- Williams H, Nejati M, Hussein S, Penball N, Lim J Y, Jones M H, Ahn H S, Bradley S, Schaare P, Martinsen P, Alomar M, Patel P, Seabright M, Duke M, Scarfe A & MacDonald B (2019). Autonomous pollination of individual kiwifruit flowers: Toward a robotic kiwifruit pollinator. Journal of Field Roboics 37(2): 246-262
- Zhang P, Deng L, Lyu Q, He S, Yi S, Liu Y, Yu Y & Pan H (2016). Effects of citrus tree-shape and spraying height of small unmanned aerial vehicle on droplet distribution. International Journal of Agricultural and Biological Engineering 9(4): 45-52
- Zhang S, Cai C, Li J, Sun T, Liu X, Tian Y & Xue X (2021). The Airflow Field Characteristics of the Unmanned Agricultural Aerial System on Oilseed Rape (Brassica napus) Canopy for Supplementary Pollination. Agronomy 11(10): 1-13