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Yang Gao and Deying Li

Foliar application of fertilizers on turfgrass via overhead fertigation or spray can improve nutrient absorption efficiency and uniformity. Foliar fertilizers can also be combined with other chemical applications to save labor and energy. However, foliar application of nitrogen may result in root growth reduction. The objective of this study was to evaluate if a liquid organic amendment can be tank-mixed with liquid fertilizer to improve creeping bentgrass (Agrostis stolonifera) performance. This greenhouse study was conducted on ‘Penncross’ creeping bentgrass grown in sand or 90 sand:10 peat (v/v) root zones. Three fertilizer packages (4N–0P–0.8K, 29N–0.9P–2.5K, and 20N–8.8P–16.6K) with or without the organic amendment, a liquid suspension derived from naturally mined humic materials, were tested in the study. Tank-mixing organic amendment resulted in better or same turfgrass visual quality and lower clipping yield compared with foliar fertilization alone. Tank-mixing organic amendment in liquid fertilizers resulted in an average increase of root/shoot biomass ratio from 0.62 to 0.65 grown in the sand-based root zones. The effect of organic amendment was shown in all liquid fertilizers tested except 20N–8.8P–16.6K. The results showed tank-mixing organic amendment with the right liquid fertilizer can reduce mowing frequency without reducing the turf quality. Field work is needed to test if the increased root/shoot biomass ratio by tank-mixing organic amendment with liquid fertilizer can contribute to drought tolerance in creeping bentgrass maintained at fairway height in sand-based root zones.

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Longyi Yuan, Yang Gao and Deying Li

Petroleum-based spills on turfgrass often occur during lawn care maintenance. Damage caused by diesel and hydraulic fluid is particularly difficult to correct. The objective of this study was to compare the effectiveness of combining mulching with remediation for reseeding spilled areas in lawns. Diesel and hydraulic fluid were applied to plots at a rate of 15 L·m−2. Immediately after the spill treatments, two liquid humic amendments and an activated flowable charcoal were applied at a volume rate of 8 L·m−2, respectively, with tap water/dishwashing detergent used as a control. Nitrate nitrogen was added to each remediation treatment to facilitate remediation. The spilled areas were reseeded with perennial ryegrass (Lolium perenne) and then mulched with biochar, peat pellets, and paper pellets, respectively. At 6 weeks after seeding, humic amendment 1 and activated charcoal showed better turf quality than humic amendment 2. Peat pellet mulching presented better turf quality than other mulching methods. Reseeding perennial ryegrass and mulching with peat pellets after remediation with either humic amendment 1 or activated charcoal resulted in acceptable turf quality 6 weeks after diesel and hydraulic fluid spills. Therefore, this reestablishment method is recommended as a practical way to deal with diesel or hydraulic fluid spills in cool-season turfgrasses.

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Chao Gao, Rui Yang and Deyi Yuan

Camellia oleifera is an important woody edible oil plant in southern China. In this study, the developmental differences in ovules at different positions in the ovary of C. oleifera were observed. The developmental type and characteristics of aborted ovules, ratios of normal and aborted ovules, and their developmental differences after flowering were examined. Ovules near the stylar end and in the middle exhibit normal development and are able to form embryo sacs; lower ovules near the pedicel end are usually aborted. The proportion of abortion of four examined cultivars ranges from 10.2% to 33.3%. Aborted ovules can be divided into four categories: 1) nascent egg apparatus lacking distinguishable cells; 2) completely absent egg apparatus structure consisting of flocculent tissue; 3) lack of tissue, comprising only integument cells; and 4) the inner integument not constituting a micropyle channel, with incomplete egg apparatus development and generating abnormal ovules. At 120 days after pollination (DAP), significant distinguishable size differences were found between fertile and aborted ovules; aborted ovules ceased growth at 180 DAP. On fruit maturation, aborted seeds were still attached to the placenta.

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Zhengke Zhang, Zhaoyin Gao, Min Li, Meijiao Hu, Hui Gao, Dongping Yang and Bo Yang

‘Tainong 1’ mango fruit were treated with hot water for 10 minutes at 55 °C and then stored at 5 °C for 3 weeks. After removal from low-temperature storage, the effects of hot water treatment (HWT) on chilling injury (CI), ripening and cell wall metabolism during storage (20 °C, 5 days) were investigated. HWT reduced the CI development of the fruit as manifested by firmer texture, external browning, and fungal lesions. A more rapid ripening process, as indicated by changes in firmness, respiration rate, and ethylene production, occurred in heated fruit after exposure to low temperature as compared with non-heated fruit. At the same time, the cell wall components in heated fruit contained more water-soluble pectin and less 1,2-cyclohexylenedinitrilotetraactic acid (CDTA)-soluble pectin than those in non-heated fruit. HWT also maintained higher polygalacturonase [enzyme classification (EC) 3.2.1.15] and β-galactosidase (EC 3.2.1.23) activities as well as lower pectin methylesterase (EC 3.1.1.11) activity. In general, the changes of ripening and cell wall metabolism parameters in the heated fruit after low-temperature storage exhibited a comparable pattern to that of non-cold-stored fruit.

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Zhao Xiang, Zhu Huisen, Gao Yang and Li Deying

Tall fescue [Schedonorus arundinaceus (Schreb) Dumort] has potential in cool arid regions, where it is often subject to salinity stress. The objective of this 2-year field study was to investigate the effect of nitrogen sources on tall fescue turf quality under salinity stress in the northern Great Plains of North America. ‘Wolfpack’, ‘Wolfpack II’, ‘Tar Heel’, ‘Tar Heel II’, ‘Jaguar 3’, ‘Jaguar 4G’, and ‘Arid 3’ were treated with NaCl and CaCl2 in equal amounts. Six N sources were used for fertilization: nitrate-N, urea-N, ammonium-N, urea-N/ammonium-N/nitrate-N, urea-N with urase and nitrification inhibitor, and organic N. Salt treatment reduced turf quality of all cultivars. Turf quality was affected differently by N source. Regardless of salt treatments, urea stabilized with a urease inhibitor and a nitrification inhibitor consistently had the best turf quality. Equal amounts of nitrate, ammonium, and urea-N yielded the lowest turf quality. However, there was no interaction between N source and salt treatment. These results were also supported by green density (GD), dark-green color index (DGCI), shoot chlorophyll (Chl) content, and leaf relative water content (RWC). Tall fescue cultivars responded to salinity treatment differently, with ‘Wolfpack II’ being the cultivar ranked consistently at the top and maintained above the acceptable level of visual quality.

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Longyi Yuan, Deying Li, Yang Gao and Wenjing Xiao

Deicing salts often are applied to sidewalks and roadways to enhance pedestrian and driving safety during freezing weather. For example, in eastern North Dakota, average annual snow days and amount are 29 days and 40 inches, respectively. This study was conducted in Fargo, ND, to investigate the population dynamics of turfgrass mixtures composed of kentucky bluegrass [KB (Poa pratensis)], creeping red fescue [RF (Festuca rubra)], and alkaligrass [ALK (Puccinellia sp.)] with the goal of optimizing turf quality by selecting seed ratios containing these species in home lawn mixtures and subject to frequent applications of deicing salts. A total of 21 mixtures were generated based on simplex-lattice design with KB, ALK, and RF contributing to 0%, 20%, 40%, 60%, 80%, and 100% of their respective full-seeding rate of 150, 150, and 300 lb/acre, respectively, after pure live seed (PLS) adjustment. The mixtures were tested at annual deicing salt rates of 0, 160, 320 lb/acre, which represent typical application. The results showed that the botanical component of the stands of grasses shifted over a 2-year period for all salt levels. Despite the good salinity tolerance of ALK reported elsewhere, it did not contribute to the improvement of turf quality in mixtures receiving deicing salts at 320 lb/acre per year. Therefore, ALK is not recommended for lawn, but mixing KB and RF in 48% and 52% of their respective full-seeding rates was recommended for areas adjacent to deicing salt applications.

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Hua Gao, Zheng-yang Zhao, Lei-cun Wang, Zhen-zhong Liu and Ya-zhou Yang

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Yuee Tian, Zhiping Che, Di Sun, Yuanyuan Yang, Xiaomin Lin, Shengming Liu, Xiaoyu Liu and Jie Gao

Tree peonies are valuable ornamental plants and are widely cultivated in China and many other countries. Gray mold caused by Botrytis cinerea is an increasingly severe disease in Luoyang of China and seriously affects the ornamental value of tree peonies both in the open air and in greenhouses. However, the resistance of different tree peony cultivars to B. cinerea remains unknown. In this study, 15 tree peony cultivars belonging to three different flowering times were evaluated for resistance to B. cinerea by detached leaf assay measure. Results showed that the resistance of early-flowering peonies was stronger than that of later flowering peonies. Moreover, the correlation between flowering time and resistance of tree peonies was extremely significant (P < 0.01). The information obtained in this study can provide theoretical basis both for further exploring the resistance genes of tree peony to B. cinerea and for the prevention and controlling of the gray mold.

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Yi Kai, Yang Bin, Zhang Min, Gao Ainong, Zhang Jinger, Liu Zhi, Sha Shoufeng and Xie Chongxin

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Chao Gao, Deyi Yuan, Ya Yang, Bifang Wang, Dongming Liu and Feng Zou

Camellia oleifera is an important plant species that produces edible oils. Understanding the double fertilization of this plant is critical for studies concerning crossbreeding, self-incompatibility, and the biological mechanisms underlying hybridization. We aimed to characterize pollen tube growth and double fertilization in C. oleifera. The female and male parent cultivars (Huashuo and Xianglin XLC15, respectively) were used for artificial pollination. Growth of the pollen tube in the style, ovary, and ovule from pollination to fertilization and the cytological characteristics of female and male gamete fusion during double fertilization were observed using fluorescence and scanning electron microscopy (SEM). Numerous pollen grains germinated 2 to 4 hours after pollination. The pollen tubes entered the interspaces between the papillar cells, grew along the stylar canal, and aggregated at the one-third site of the style. They grew in the gradually narrowing stylar canal, entering the locule. The tubes turned 90° and entered the embryo sac through the micropyle; subsequently, they entered a degenerated synergid, where the spermatids were released. One sperm nucleus fused with the polar nucleus, forming the primary endosperm nucleus, whereas the other sperm fused with the egg, forming the zygote. The polar nucleus was fertilized earlier than the egg. Double fertilization of C. oleifera is characterized as pre-mitotic gametogony. The current results lay a theoretical foundation for studies concerning the crossbreeding and embryology of C. oleifera and provide fundamental data concerning the reproductive biology of the genus Camellia.