Hand-harvesting parameters and postharvest marketability attributes of fresh-market blackberries (Rubus L. subgenus Rubus Watson) were characterized to develop a prototype for a soft-robotic gripper for robotic harvesting. A custom-made, force-sensing apparatus attached to the thumb and fingers of a person hand-harvesting blackberries was developed to quantify forces used to harvest and to identify appendages for harvesting. Four cultivars of blackberries grown in Arkansas were harvested at optimal ripeness and stored at 2 °C for 21 days to determine the impact on marketability attributes (leakage, decay, and red drupelet reversion). The forces during harvest imparted by the thumb and middle finger were greatest (0.77 N and 0.37 N, respectively), whereas the index and ring fingers used lower forces (0.16 N and 0.06 N, respectively), primarily to stabilize the blackberry. The forces applied to grab, stabilize, and harvest blackberries caused minimal marketability damage (leakage, <10%; decay, <2%; and red drupelet reversion, <8%) after postharvest storage. This project quantified harvest and postharvest parameters, allowing data-driven design of a three-prong soft-robotic gripper for harvest of fresh-market blackberries.
Andrea Myers, Anthony Gunderman, Renee Threlfall, and Yue Chen
Rebekah C.I. Maynard and John M. Ruter
Salvia is a genetically diverse genus in the Lamiaceae family, with hundreds of species distributed globally. With base chromosome numbers ranging from 6 to 19 and ploidy levels ranging from diploid to octoploid, the genus has been proposed to be subdivided based on molecular data rather than morphology. However, little is known about total DNA content across the genus. The DNA content of 141 Salvia genotypes were analyzed using flow cytometry. Samples of Salvia were stained with propidium iodide and compared with the internal standards Pisum sativum ‘Ctirad’ and Solanum lycopersicum ‘Stupické’ to generate estimations of DNA content. Holoploid 2C genome sizes of the analyzed Salvia ranged from 0.63 pg to 6.12 pg. DNA content showed a wide distribution across chromosome number, ploidy, and clade. The wide distribution of DNA content across the genus further indicates the diversity of Salvia and may be useful for future breeding efforts.
Xiao-ting Li and Jian-ping Bao
In this study, the effects of different Xinjiang pear varieties and ‘Korla Fragrant Pear’ pollination on the stone cells and lignin of fruit were investigated. The contents of stone cells and lignin, and the activities of related enzymes [polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonium lyase (PAL)] were analyzed in fruit from different pollination combinations at different growth and developmental stages. Results showed that the stone cell mass density decreased rapidly at 60 to 90 days and 90 to 120 days after flowering. The stone cell and lignin contents, and activities of the three enzymes (PPO, POD, and PAL) decreased rapidly at 60 days after flowering. The stone cell mass density, stone cell and lignin contents, and enzyme activity of fruit from different pollination combinations varied at different timescales. The pear variety ‘Bayue‘ had the lowest stone cell and lignin contents in mature fruit from different pollination combinations. The stone cell content correlated positively with lignin content, stone cell mass density, and enzyme activity.
Limei Yang, Ye Peng, Feng Yang, Donglin Zhang, and Wangxiang Zhang
China is the distribution center of
Le-Jing Lin, Li Lin, and Zhi-Yong Zhu
Li Xu, Fangyun Cheng, and Yuan Zhong
Paeonia ostii ‘Feng Dan’ is an economically important, multipurpose woody plant in terms of its medical, ornamental, and oil values; however, there is a noticeable contradiction between the increasing demands and the lack of excellent germplasm resources because of traditional breeding and propagation approaches. In vitro embryo culture is an attractive option for this issue. This study presents a protocol for in vitro immature embryo culture in P. ostii ‘Feng Dan’, which involves two steps: 1) immature seeds at 30 days after anthesis (DAA) (cellularization stage of endosperm, proembryo stage) or after being cultured in vitro for cotyledon embryo formation (upward micropyle with placenta was the best inoculation method with the highest ratio of seed with cotyledon embryo of 66.67%); and 2) seedling establishment was realized within 7 months via embryo (at 40 DAA or after) germination, shoot induction, rooting, and acclimatization. The multiplication potential was increased with embryo maturity. This protocol provides an available reference for embryo rescue and propagation of tree peony and will be beneficial to shortening the breeding cycle.
Herbaud P.F. Zohoungbogbo, Enoch G. Achigan-Dako, Judith Honfoga, Shih-Wen Lin, Tsung-Han Lin, Yen-Wei Wang, Yuan-Li Chan, Peter Hanson, and Derek W. Barchenger
Habanero (Capsicum chinense Jacq.) is widely grown and consumed in West and Central African countries, and viral diseases represent an important production challenge. Diagnosis of the viral species affecting habanero productivity in Benin is limited, and understanding this will enable more efficient host resistance breeding. During 2019 and 2020, we characterized the incidence and severity of the viral diseases infecting nine promising habanero breeding lines and one commercial hybrid check under open field conditions in Benin. The horticultural performance, including yield and yield component traits of the entries, was determined during the 2 years of the experiment. A randomized complete block design was used with three replications, each with 24 plants. Data were recorded on days to 50% flowering and 50% fruit maturity, yield and on the yield components of fruit weight (g), fruit length (cm), and fruit width (mm), as well as disease incidence and severity. In total, 35 leaf samples were collected for viral diagnosis among habanero breeding lines. We found that Pepper veinal mottle virus (PVMV; Potyvirus) was the overwhelmingly predominant virus in our trials, with an 80% incidence; however, we found frequent coinfection of PVMV with Cucumber mosaic virus (CMV, Cucumovirus), Polerovirus, and, to a lesser extent, Chili veinal mottle virus (ChiVMV; Potyvirus). The mean disease incidence across all entries was 60%. AVPP1932 and PBC 2010 had the lowest disease incidence (35% and 43%, respectively), whereas AVPP1929 had the highest (86%) disease incidence. The F1 hybrid check Afadja had the overall highest yield, with 30 t⋅ha−1, followed by AVPP1932, with 19 t⋅ha−1, both in 2019. There was a negative correlation between disease incidence and total yield (r = −0.44; P < 0.001), supporting previous studies indicating that viral diseases are major production constraints for habanero in West Africa. This study provides insight regarding the need to improve habanero for resistance to aphid-transmitted viruses and develop integrated pest management strategies to limit losses in Benin.
Kenneth Buck, Margaret Worthington, and Patrick J. Conner
Rooting hardwood cuttings from muscadine (Vitis rotundifolia Michx. syn. Muscadinia rotundifolia) vines has traditionally been considered an exceptionally difficult task. Many previous studies observed almost no root formation, leading to a general consensus that muscadines should either be propagated by softwood cuttings or vegetative layering. However, the University of Arkansas System Division of Agriculture Fruit Breeding Program has been using a hardwood rooting protocol for muscadines with moderate success for the past 10 years. The application of this protocol to meet the modest propagation needs of the breeding program has significantly shortened the time required to advance selections. The goal of this research was to more adequately describe the factors affecting the rooting ability of hardwood muscadine cuttings. This research investigated the effects of cultivar, bottom heat, cold storage, vineyard location, and cutting collection date on the outcome of muscadine hardwood cuttings. The study was conducted during the dormant seasons of 2019–20 and 2020–21, and an overall rooting percentage of 16% was observed. There were multiple higher-order interactions affecting rooting efficacy. Cuttings taken in November generally rooted at higher rates, although interactions with vineyard location and cultivar played a significant role in those results. The Ocilla, GA, location performed exceptionally well in November with rooting percentages greater than 40%. The effects of supplying bottom heat and/or a cold storage treatment on rooting success declined as the dormant season progressed. Other variables such as increased cutting length and diameter were associated with increased rooting success. A second statistical analysis using only data from November showed that when cuttings were not given a cold storage treatment that rooting percentages were greater than 27%. Ultimately, this research shows that institutions with modest muscadine propagation needs can successfully propagate plants from hardwood cuttings.