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J. A. Flore and Edgardo Disegna

Terbacil an inhibitor of photosynthesis was applied to 10-year-old `Redchief' apple trees in the field carrying a heavy or light fruit crop, or to trees in pots. This simulated the effect of photosynthetic inhibition (PN-I) by either biotic or abiotic stress. Current as well as the next season's crop and physiology were determined. The magnitude and duration of photosynthetic inhibition was dose-dependent. A concentration of 63 mg·liter–1 was applied at 15-day intervals from bloom through harvest. Photosynthesis was in inhibited by 50% to 80% within 24 h of application, but recovered to control levels 10 to 14 days later. Terbacil at 15 and 30 DAFB induced fruit abscission, but not at later dates. The earlier the application the greater the effect on current seasons yield and fruit size. There was also a significant interaction with crop load. There were no significant effects on fruit soluble solids, fruit firmness, fruit density, or fruit color at harvest. Terbacil did not affect cold acclimation, deep winter hardiness, or deacclimation. Pn inhibition at 30, 60, 80, and 100 DAFB reduced return bloom.

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Jim Syvertsen and Yoseph Levy

Multiple stresses almost always have synergistic effects on plants. In citrus, there are direct and indirect interactions between salinity and other physical abiotic stresses like poor soil drainage, drought, irradiance, leaf temperature, and atmospheric evaporative demand. In addition, salinity interacts with biotic pests and diseases including root rot (Phytophthora spp.), nematodes, and mycorrhizae. Improving tree water relations through optimum irrigation/drainage management, maintaining nutrient balances, and decreasing evaporative demand can alleviate salt injury and decrease toxic ion accumulation. Irrigation with high salinity water not only can have direct effects on root pathogens, but salinity can also predispose citrus rootstocks to attack by root rot and nematodes. Rootstocks known to be tolerant to root rot and nematode pests can become more susceptible when irrigated with high salinity water. In addition, nematodes and mycorrhizae can affect the salt tolerance of citrus roots and may increase chloride (Cl-) uptake. Not all effects of salinity are negative, however, as moderate salinity stress can reduce physiological activity and growth, allowing citrus seedlings to survive cold stress, and can even enhance flowering after the salinity stress is relieved.

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Kenneth R. Summy and Christopher R. Little

Remote sensing has been used for the last several decades to detect both abiotic and biotic stressors affecting agricultural crops. Studies have traditionally focused on aerial image acquisition using color infrared (CIR) photography of plant

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Yu Liu, Miao He, Fengli Dong, Yingjie Cai, Wenjie Gao, Yunwei Zhou, He Huang and Silan Dai

-associated NAC transcription factor ( SlNAC35 ) from tomato plays a positive role in biotic and abiotic stresses Physiol. Plant. 158 45 64 Wang, J.Y. Wang, J.P. Yuan, H. 2013 A Populus euphratica NAC protein regulating Na + /K + homeostasis improves salt

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Jonathan P. Lynch

or biotic stress. For example, delayed phenology (i.e., delayed flowering or maturity) may enhance plant growth under phosphorus stress by increasing time available for soil exploration, soil exploitation, and phosphorus use in the plant ( Lynch and

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Xiaojuan Zong, Jiawei Wang, Li Xu, Hairong Wei, Xin Chen, Dongzi Zhu, Yue Tan and Qingzhong Liu

crucial roles in regulating many biological processes in plants, such as growth, development, and responses to biotic and abiotic stresses ( Ligterink, 2000 ; Ligterink and Hirt, 2001 ; MAPK Group, 2002 ; Mizoguchi et al., 2000 ; Nakagami et al., 2005

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Jiao Chen, De-bao Yuan, Chao-zheng Wang, Yi-xing Li, Fen-fang Li, Ke-qian Hong and Wang-jin Lu

family. A number of zinc finger proteins have been found to be involved in abiotic and biotic stress responses ( Cui et al., 2002 ; Huang et al., 2005 ; Kim et al., 2001 ; Mukhopadhyay et al., 2004 ; Sakamoto et al., 2004 ). One interesting zinc

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Holly A. Little, Rebecca Grumet and James F. Hancock

and biotic stresses ( Abeles et al., 1992 ). Thus, altering ethylene signaling for a characteristic such as increased flower longevity may, in turn, result in secondary changes in abiotic stress responses or disease resistance. We discuss approaches

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Cristhian Camilo Chávez-Arias, Sandra Gómez-Caro and Hermann Restrepo-Díaz

addition, MDA and proline production have been used as biochemical markers to characterize plant responses to abiotic and biotic stresses ( Dar et al., 2016 ; Irulappan and Senthil-Kumar, 2018 ). Chlorophyll fluorescence parameters also are affected by

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Zhigang Ouyang, Huihui Duan, Lanfang Mi, Wei Hu, Jianmei Chen, Xingtao Li and Balian Zhong

reported to play roles in multiple aspects of plant life, such as developmental progress, and responses to abiotic and biotic stress. However, direct evidence is limited. Wang et al. (2017a) reported that overexpressing MhYTP1 or MhYTP2 in Malus