Selenium (Se) fertilizer has a good effect on many field crops, but there are few reports on the application of Se fertilizer on citrus. We investigated the effects of 0 mg/L (CK, water treatment), 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L sodium selenite aqueous solutions on the growth, nutrition, and fruit quality of 15-year-old citrus unshiu (Citrus reticulata Blanco cv. Succosa). The results showed that a low concentration of Se fertilizer promoted the growth and development of the citrus plan, and a high concentration of Se fertilizer was found to slightly inhibit the growth and development of the plant. Among the different treatment groups, 150 mg/L selenium fertilizer showed have the best effect on these evaluated parameters. The results thus suggest that 150 mg/L of Se fertilizer promotes the formation of chlorophyll in the leaves of the test plant and increases the longitudinal and transverse diameter of the fruits and weight of single fruit, significantly enhancing the activity of antioxidant enzymes in the leaves, promoting the absorption of nutrients in the leaves, increasing the contents of total sugar and vitamin, and decreasing the acidity in the fruits and the pericarp thickness. It also promoted the accumulation of the total selenium content in the leaves and fruits and consequently improved the quality of the fruits. These results showed that appropriate concentration of Se treatment can improve the activity of antioxidant enzymes to enhance plant stress resistance, regulate the content of sugar and acid in fruits, and improve the quality of fruits.
Mingxia Wen, Peng Wang, Weiqin Gao, Shaohui Wu, and Bei Huang
Karen K. Schneck, Cheryl R. Boyer, and Chad T. Miller
Dahlia (Dahlia ×hybrida) is an important floriculture crop that has gained popularity in recent years. Greenhouse growers have recently reported a phenomenon known as “dahlia decline,” that can affect potted dahlias in greenhouse production. The crop exhibits graying foliage, root decline, and plant death, and the phenomenon has reportedly caused partial or total crop loss and has no known initiating factor. We hypothesized that plant exposure to supraoptimal root-zone temperatures (RZTs) during production may decrease dahlia root quality, especially above 40 °C and could initiate dahlia decline. Because there is a lack of understanding on how supraoptimal RZT may impact dahlia growth and development, experiments were conducted to evaluate the effects of supraoptimal RZTs on seven dahlia cultivars in Spring 2019 and 2020. Dahlias were grown for 4 to 5 weeks in the greenhouse and then root zones were exposed to ≈22 (control), 35, 40, 45, or 50 °C using a water bath. Root quality was rated before treatment and rated weekly after the hot water bath treatment, along with vegetative growth parameters for 4 weeks. In both years, significant decline in root ratings were observed. ‘XXL Veracruz’ and ‘XXL Sunset’ average root ratings decreased after a 45 and 50 °C treatments in year 2 and both cultivars demonstrated increased root rating averages by 3 weeks after treatment. Cultivars exhibited a significant increase in root rating in the final observations when compared with root ratings taken 1 week posttreatment even if the initial decline after treatment was not significant. Overall plant height was significantly impacted, resulting in shorter heights in both years for all cultivars as treatment temperatures increased to 50 °C in comparison with the control and 35 °C, and a few cultivars exhibited significantly shorter height at 40 and 45 °C. Ultimately, our research did not show typical plant responses that were consistent with reported dahlia decline, but we were better able to characterize dahlia response to supraoptimal RZT.
Lisa Wasko DeVetter, Suzette Galinato, Troy Kortus, and Jonathan Maberry
Floricane red raspberry (Rubus idaeus) produces biennial canes that are traditionally managed by annual selective removal of previously fruited floricanes and training of primocanes that will bear fruit in the next growing season. This process of pruning and training is labor intensive and costly, and growers would benefit from more economical methods of pruning and training. This 6-year project evaluated the economic viability of alternate-year (AY) production in a commercial floricane red raspberry field in northwest Washington and compared it to traditional, every-year (EY) production to assess whether the former could save costs. Despite savings from reduced chemicals, fertilizers, labor, general farm supplies, and other variable costs, the overall benefits of AY production were not enough to offset losses in revenue resulting from reduced yields under the conditions of this experiment in northwest Washington.
Yang Hu, Chao Gao, Quanen Deng, Jie Qiu, Hongli Wei, Lu Yang, Jiajun Xie, and Desheng Liao
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.
Yasmina Chourak, El Hassan Belarbi, Evelynn Y. Martínez-Rivera, Tatiana Pagan Loeiro da Cunha-Chiamolera, Ana Araceli Peña-Fernández, José Luis Guil-Guerrero, and Miguel Urrestarazu
Saffron is one of the most appreciated, traditional, and expensive spices in the world. The objective of our study was to evaluate the effect of cooling the nutrient solution on the production, and organoleptic and commercial qualities of saffron grown in soilless culture. The nutrient solution was cooled to 4 to 5 °C whereas the control treatment was the fertigation supplied at ambient temperature. Corms were placed in a controlled cultivation chamber. The number of flowers per corms, and the weight and length of stigmas were measured. The amounts of safranal, crocin, and picrocrocin were analyzed spectrophotometrically according to the International Organization for Standardization [ISO/TS 3632-2 (2011) Normative]. Our results show that cooling of the nutritive solution increased flower production, the commercial phytochemical content, and organoleptic properties.
Alexandra Boini, Enrico Muzzi, Aude Tixier, Maciej Zwieniecki, Luigi Manfrini, and Luca Corelli Grappadelli
Photoselective nets were used to examine apple shoot physiology during dormancy and budbreak. Two trials were conducted: one in the field and one in controlled conditions. In the first, three colored nets (red, blue, and white, shading 20%) covered sections of single trees, leaving an empty portion as control, from December to April. The white net increased canopy air temperature compared with the blue one. Differences were found in carbohydrate seasonal patterns; however, it appeared that soil temperature had higher impacts on sugar movement in the trees. No differences were found in bud phenology. In the second trial, cuttings were placed in boxes constructed with the same-colored nets and monitored from the end of February to April. Results showed differences in phenology and carbohydrate translocation. The white box hastened bloom and its cuttings had higher amounts of carbohydrates at the end of the trial. On the contrary, the blue box delayed bloom while resources were still being consumed and its cuttings had the lowest amounts of reserves at the end of the trial. These results add new insights on apple physiology under different light spectra and commercial applications should not be excluded for improving crop management.
David R. Bryla, Carolyn F. Scagel, Scott B. Lukas, and Dan M. Sullivan
Excess salinity is becoming a prevalent problem for production of highbush blueberry (Vaccinium L. section Cyanococcus Gray), but information on how and when it affects the plants is needed. Two experiments, including one on the northern highbush (Vaccinium corymbosum L.) cultivar, Bluecrop, and another on the southern highbush (V. corymbosum interspecific hybrid) cultivar, Springhigh, were conducted to investigate their response to salinity and assess whether any suppression in growth was ion specific or due primarily to osmotic stress. In both cases, the plants were grown in soilless media (calcined clay) and fertigated using a complete nutrient solution containing four levels of salinity [none (control), low (0.7–1.3 mmol·d−1), medium (1.4–3.4 mmol·d−1), and high (2.8–6.7 mmol·d−1)] from either NaCl or CaCl2. Drainage was minimized in each treatment except for periodic determination of electrical conductivity (EC) using the pour-through method, which, depending on the experiment, reached levels as high as 3.2 to 6.3 dS·m−1 with NaCl and 7.8 to 9.5 dS·m−1 with CaCl2. Total dry weight of the plants was negatively correlated to EC and, depending on source and duration of the salinity treatment, decreased linearly at a rate of 1.6 to 7.4 g·dS−1·m−1 in ‘Bluecrop’ and 0.4 to 12.5 g·dS−1·m−1 in ‘Springhigh’. Reductions in total dry weight were initially similar between the two salinity sources; however, by the end of the study, which occurred at 125 days in ‘Bluecrop’ and at 111 days in ‘Springhigh’, dry weight declined more so with NaCl than with CaCl2 in each part of the plant, including in the leaves, stems, and roots. The percentage of root length colonized by mycorrhizal fungi also declined with increasing levels of salinity in Bluecrop and was lower in both cultivars when the plants were treated with NaCl than with CaCl2. However, leaf damage, which included tip burn and marginal necrosis, was greater with CaCl2 than with NaCl. In general, CaCl2 had no effect on uptake or concentration of Na in the plant tissues, whereas NaCl reduced Ca uptake in both cultivars and reduced the concentration of Ca in the leaves and stems of Bluecrop and in each part of the plant in Springhigh. Salinity from NaCl also resulted in higher concentrations of Cl and lower concentrations of K in the plant tissues than CaCl2 in both cultivars. The concentration of other nutrients in the plants, including N, P, Mg, S, B, Cu, Fe, Mn, and Zn, was also affected by salinity, but in most cases, the response was similar between the two salts. These results point to ion-specific effects of different salts on the plants and indicate that source is an important consideration when managing salinity in highbush blueberry.
Ved Parkash, Sukhbir Singh, Manpreet Singh, Sanjit K. Deb, Glen L. Ritchie, and Russell W. Wallace
Water scarcity is increasing in the world, which is limiting crop production, especially in water-limited areas such as Southern High Plains of the United States. There is a need to adopt the irrigation management practices that can help to conserve water and sustain crop production in such water-limited areas. A 2-year field study was conducted during the summers of 2019 and 2020 to evaluate the effect of deficit irrigation levels and cultivars on root distribution pattern, soil water depletion, and water use efficiency (WUE) of cucumber (Cucumis sativus). The experiment was conducted in a split-plot design with four irrigation levels [100%, 80%, 60%, and 40% crop evapotranspiration (ETc)] as main plot factor and two cultivars (Poinsett 76 and Marketmore 76) as subplot factor with three replications. Results showed that root length density (RLD) was unaffected by the irrigation levels in 2019. In 2020, the RLD was comparable between 100% and 80% ETc, and it was significantly higher in 100% ETc than both 60% Eand 40% ETc. Root surface area density (RSAD) was not significantly different between 100% and 80% ETc, and it was significantly lower in both 60% and 40% ETc than 100% ETc in both years. Soil water depletion was the highest in 40% ETc followed by 60% and 80% ETc, and it was least in 100% ETc in both years. Evapotranspiration (ET) was the highest in 100% ETc followed by 80%, 60%, and 40% ETc. The WUE was not statistically different among the irrigation treatments. However, numerically, WUE was observed in the following order: 80% ETc > 100% ETc > 60% ETc > 40% ETc. The RLD, RSAD, soil water depletion, and ET were not significantly different between ‘Poinsett 76’ and ‘Marketmore 76’. However, fruit yield was significantly higher in ‘Poinsett 76’ than ‘Marketmore 76’, which resulted in higher WUE in Poinsett 76. It can be concluded that 80% ETc and Poinsett 76 cultivar can be adopted for higher crop water productivity and successful cucumber production in SHP.
Ying Fang, Ting Lei, Yanmei Wu, and Xuehua Jin
The calla lily (Zantedeschia hybrida) is a valued ornamental plant due to its unique shape and color variations. To determine the mechanisms responsible for color development in the calla lily spathe, we conducted a comparative transcriptomic analysis of the spathes of the black [Black Girl (B)], pink [Romantic (P)], and white [Ventura (W)] cultivars. The gene expression patterns in six spathe colors, including the preceding three colors as well as the amaranth [Promise (N)], red [Figo (F)], and yellow [Sun Club (Y)] cultivars were analyzed by real-time quantitative polymerase chain reaction (PCR). Transcriptomic analysis identified 25,165 differentially expressed genes. The transcription abundance and expression level of genes annotated as anthocyanidin reductase (ANR1, ANR2), basic-helix-loop-helix (bHLH1), and glutathione S-transferases (GST1) were significantly upregulated in B, and the expression of anthocyanidin synthase (ANS) was highest in B except for N. However, chalcone isomerase (CHI2) and dihydroflavonol 4-reductase (DFR1, DFR2) were expressed at significantly lower levels in P, W, and Y. Correlation analysis revealed that bHLH1 might act as a positive regulator of ANS expression, promoting anthocyanin synthesis. Moreover, GST1-encoded proteins may be related to the accumulation and transport of both anthocyanin and procyanidin in the calla lily spathe. It is speculated that the formation of the black spathe is related to the accumulation of anthocyanins and procyanidins. However, the low expression of CHI2, DFR1, and DFR2 may result in the inhibition of anthocyanin synthesis, which may lead to lightening of the spathe color. This preliminary study revealed the mechanism responsible for calla lily spathe color, identifying the key genes involved, thus providing effective gene resources and a theoretical basis for flower color molecular breeding.
Bruce L. Dunn, Stephen Stanphill, and Carla Goad
This study aimed to identify the best method to improve poor branching of poinsettia ‘Orange Spice’. Treatments included pinched and unpinched alone and in combination with four different rates (3.9, 7.8, 11.7, and 23.4 mL⋅L−1) of Atrimmec. Pinching reduced plant height, as did unpinched + 11.7 mL⋅L−1 and unpinched + 11.7 mL⋅L−1 Atrimmec. Neither pinching nor Atrimmec had any effect on plant width, stem caliper, or shoot dry weight. Atrimmec did not increase the number of laterals in combination for pinched or unpinched treatments, but unpinched plants generally produced more laterals. Unpinched with any rate of Atrimmec resulted in tertiary shoots, which improved the visual appearance and quality.