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  • Author or Editor: Yang Gao x
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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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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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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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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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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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Nutrient deficiency leads to a high fruit abscission rate and low yields of Sapindus mukorossi Gaertn. (Soapberry), which is one of the most widely cultivated biodiesel feedstock forests in China. Exogenous sucrose can provide a solution to nutrient deficiency and fruit abscission leading to low yields; therefore, it was applied to whole trees at two stages, 20 days before blooming (DBB stage) and before fruit abscission [days before fruit abscission (DBFA) stage]. Six sucrose concentrations, 0%, 1%, 1.5%, 3%, 5%, and 7%, were sprayed three times using a completely randomized block design with five replications and six treatments. 13CO2 labeling experiments were performed after the three sprayings. The results indicated that the 3% treatment had the highest yield, reaching 15.9 kg/tree. During the DBB stage, the 3% treatment significantly increased the inflorescence fructose and glucose contents 1- to 1.2-times and resulted in the highest fruit gibberellic acid, leaf indole acetic acid (IAA), fruit IAA, and fruit zeatin contents; however, it decreased the inflorescence abscisic acid (ABA) from 16 μg/g to 4 μg/g. The 1.5% and 3% treatments significantly increased the carbohydrate content and decreased the fruit ABA content to 30% to 50% of the control level during the DBFA stage. High-concentration sugar treatment (>3%) increased the nitrogen, phosphorus, and potassium contents, which decreased the calcium and magnesium contents. The 13C-dispatching ability of the inflorescence was three-times greater than that of leaves under the high-concentration sugar treatment during the DBB stage. Supplying 1.5% sucrose nearly doubled the allocation capacity during the DBFA stage. The source-sink nutrient migration pathway showed that leaf and fruit sugars were directly correlated with phosphorus. Fruit fructose and glucose contents affected the leaf mineral element contents.

Open Access

‘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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This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.

Open Access

Petalized anther abortion is an important characteristic of male sterility in plants. The male sterile plants (HB-21) evincing petalized anther abortion previously discovered in a clone population of the Camellia oleifera cultivar Huashuo by our research group were selected as the experimental material in this study. Using plant microscopy and anatomic methods and given the correspondence between external morphology and internal structure, we studied the anatomic characteristics of petalized anther abortion (with a fertile plant as the control group) in various stages, from flower bud differentiation to anther maturity, in hopes of providing a theoretical basis for research on and applications of male sterile C. oleifera plants, a new method for the selection of male sterile C. oleifera cultivars, and improvements in the yield and quality of C. oleifera. In this study, the development of anthers in C. oleifera was divided into 14 stages. Petalized anther abortion in male sterile plants was mainly initiated in the second stage (the stage of sporogenous cells). Either the petalized upper anther parts did not form pollen sacs, or the entire anthers did not form pollen sacs. The lower parts of some anthers could form deformed pollen sacs and develop, and these anthers could be roughly divided into two types: fully and partially petalized anthers. Abnormal callose and the premature degradation of the tapetum occurred in the pollen sacs formed by partially petalized anthers during the development process, resulting in the absence of inclusions in the pollen grains formed. Small quantities of mature pollen grains withered inward from the germinal furrows, exhibiting obvious abortion characteristics. The relative in vitro germination rate of the pollen produced by the partially petalized anthers of sterile plants was 11.20%, and the relative activity of triphenyltetrazolium chloride was 3.24%, while the fully petalized anthers did not generate pollen grains. Either the petalized anthers in male sterile plants did not produce pollen, or the vitality of the small amounts of pollen produced by sterile plants was very low compared with that of fertile plants. Such male sterile plants could be used to select correct clones and have good prospects for application in production.

Open Access