Orville C. Baldos, Aleta Corpuz, and Lindsey Watanabe
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.
Phil Sheridan, Winnie W. Ho, Yann Rodenas, and Donald G. Ruch
Anthocyanin pigmentation is a significant horticultural feature in plants and can be a crucial mediator of plant–insect interactions. In carnivorous plants, the modified leaves that capture prey can be visually striking and are traditionally considered prey attractants. Nevertheless, the question of whether bold color and venation patterns function as lures for insect prey remains ambiguous, and appears to vary across taxa. Furthermore, vegetative pigments can have alternate functions as protectants against thermal and oxidative damage. Our dual-year study compares the wild-type pitcher phenotype with a true-breeding anthocyanin-free mutant of the white-topped pitcher plant (Sarracenia leucophylla Raf.). We bred full-sibling crosses of S. leucophylla carrying either the wild-type anthocyanin gene or the anthocyanin-free variant. In both experimental years, growth points were established in outdoor plots and pitchers were allowed to capture prey before harvest at the end of each growing season. Dry weight of prey biomass was measured from pitchers of both pigment morphs, along with nectary counts, pitcher size, and internal temperature. The presence of anthocyanins in trapping leaves did not affect the biomass of insects captured. Nor did wild-type or anthocyanin-free pitcher morphs differ in size, temperature, or nectary counts. Instead, pitcher height, and, nominally, mouth diameter were better predictors of prey biomass. Despite striking visual differences in pitcher color, wild-type and anthocyanin-free plants did not catch significantly different quantities of prey. Our study provides empirical data that anthocyanin pigmentation in S. leucophylla does not affect the capture of prey biomass, and supports a growing body of literature showing that pigmentation traits serve in multiple contexts.
Bishnu P. Khanal, Indu Acharya, and Moritz Knoche
Recent evidence suggests xylem functionality may decline in developing European plums. Loss of xylem function may have negative consequences for fruit quality. The aim of this study was to establish and localize the loss of xylem functionality, both spatially and temporally using detached fruit. Fruit were detached from the tree under water and fed through a capillary mounted on the cut end of the pedicel. The rate of water movement through the capillary was recorded. Fruit were held above dry silica gel [≈0% relative humidity (RH)] or above water (≈100% RH) to maximize or minimize transpiration, respectively. Water inflow rate depended on developmental stage. It increased from stage I to a maximum at early stage III and then decreased until maturity. Feeding acid fuchsin to developing fruit revealed a progressive decline in dye distribution. The decline progressed basipetally, from the stylar end toward the stem end. At the mature stage III, only the pedicel/fruit junction was stained. The same pattern was observed in four further plum cultivars at the mature stage III. The inflow into early stage III fruit decreased as the RH increased. In contrast, the inflow was less dependent of RH at the mature stage III. Abrading the fruit skin cuticle had no effect on water inflow during early and mature stage III but did markedly increase fruit transpiration rate. Decreasing the osmotic potential (more concentrated) of the feeding solution decreased the water inflow. Our results indicate a progressive loss of xylem functionality in European plum. Transpiration and osmotic pull are the main drivers of this xylem inflow.
Giverson Mupambi, Nadia A. Valverdi, Hector Camargo-Alvarez, Michelle Reid, Lee Kalcsits, Tory Schmidt, Felipe Castillo, and Jonathan Toye
In semiarid apple (Malus domestica) growing regions, high temperatures and excessive solar radiation can increase the risk of sunburn development. Protective netting is increasingly used as a cultural practice under these conditions to mitigate fruit sunburn losses. However, fruit skin color development can be negatively affected under protective nets due to the reduction in light availability. Reflective groundcovers have been previously reported to increase fruit color development, particularly in the inner parts of the tree canopy. Here, we compared two types of reflective groundcover: a woven polyethylene fabric and a film material with a grassed control without reflective material under a protective netting installation that reduced photosynthetically active radiation (PAR) by 17%. The experiment was conducted in a semiarid climate on a 5-year-old ‘Cameron Select Honeycrisp’ apple orchard near Quincy, WA. Light penetration into the canopy was measured with a PAR sensor. At harvest, fruit quality, yield, and size were assessed. The use of reflective groundcover between the rows significantly increased reflected PAR into the lower canopy. Moreover, reflective groundcovers significantly increased the amount of fruit with greater than 25% skin red color compared with the control. Reflective groundcover did not affect fruit weight, yield, and fruit number. The use of reflective groundcover under protective netting can increase light penetration into the canopy, thereby improving fruit skin red coloration in apple.
Wei Wu, Shijia Wen, Tangkai Feng, Guoke Chen, and Bo Yang
Loropetalum chinense, one of three species in its genus in China, is distributed primarily in Hunan and Jiangxi Provinces. By establishing a Loropetalum gene bank and reviewing research on its varieties, genetic traits, and genetic diversity, we hope to promote the full yet sustainable use of this valuable, regionally varied natural resource. Our results will help promote the development of a broader resource economy.
Alfredo Reyes-Tena, Gerardo Rodríguez-Alvarado, José de Jesús Luna-Ruíz, Viridiana Arreola-Romero, Kirsten Lizeth Arriaga-Solorio, Nuria Gómez-Dorantes, and Sylvia P. Fernández-Pavía
Phytophthora capsici is the most important limiting factor in the production of chile pepper in Mexico. This pathogen presents virulence phenotypes capable of infecting diverse cultivars of this crop. The search and development of resistance in chile pepper is an excellent alternative for the management of P. capsici. The objective of this work was to evaluate the response of four pasilla pepper cultivars to infection with five virulence phenotypes of P. capsici. Pasilla pepper landraces PAS-1, PAS-2, PAS-3, and PAS-4 were inoculated with P. capsici isolates MX-1, MX-2, MX-7, MX-8, and MX-10. Two experiments were conducted under greenhouse conditions from April through June 2017 and April through June 2018. ‘California Wonder’ was included as a susceptible control, and uninoculated plants were included as a negative control. In each experiment, groups of six 56-day-old plants from each pepper cultivar were inoculated with each virulence phenotype. Disease severity was evaluated 20 days after inoculation using an individual plant severity scale. All pepper cultivars were classified as resistant = R, moderately resistant (MR), tolerant (T), moderately tolerant (MT), or susceptible (S), according to the frequency of resistant plants (severity 0–1). ‘California Wonder’ and ‘PAS-4’ were susceptible to all five virulence phenotypes. The rest had different responses to the virulence phenotypes, but ‘PAS-2’ and ‘PAS-3’ were susceptible to only one of the five virulence phenotypes. Pasilla peppers with low severity exhibited a slow rate of infection, which is a mechanism we have called “slow wilting.” The pasilla pepper cultivars PAS-1, PAS-2, and PAS-3 could be used in plant breeding programs as sources of genetic tolerance and moderate resistance against P. capsici.
Aime Sommerfeld, Amy McFarland, Tina M. Waliczek, and Jayne Zajicek
Visual-motor integration is influential in childhood development. Historical anecdotal evidence supports gardening as aiding in children’s development of fine and gross motor skills. The main objective of this study was to examine the effect of a school gardening program on children’s development of visual-motor integration. Preschool children ages 2 to 6 years old enrolled in private tuition-based schools were included in the sample. For 6 months, control group students studied using a traditional school curriculum whereas treatment group students participated in gardening as part of their lessons. The Beery-Buktenica visual-motor integration short-form instrument was used to quantitatively measure students’ levels of visual-motor integration. No significant differences were found in overall comparisons between the treatment and control group students. However, in demographic comparisons, significance was found; standardized scores for males in the treatment group improved whereas scores for males in the control group decreased. Results indicated that male preschoolers may respond especially well to gardening programs in the classroom in developing visual-motor integration.
Robert Conway Hochmuth, Marina Burani-Arouca, and Charles Edward Barrett
Carrot (Daucus carota) production has increased in North Florida and South Georgia since 2015. Deep sandy soils, moderate winter climate, availability of irrigation water, and proximity to eastern markets are favorable for carrot production in the region. Nitrogen (N) is required for successful carrot production, and the current recommended N application rate in Florida is 196 kg·ha−1. The objective of this study was to verify the recommended N rate for the sandy soils of North Florida using current industry standard cultivars and practices. Carrot cultivars for the whole carrot fresh market, Choctaw and Maverick, and cultivars for the cut-and-peel market, Triton and Uppercut 25, were direct seeded on 102-cm-wide pressed bed tops on 29 Oct. 2016 and 2 Nov. 2017 in Live Oak, FL. Eight N application rates (56, 112, 168, 224, 280, 336, 392, and 448 kg·ha−1) were tested, and all N applications were placed on the bed top. N rates were split and timed to increase N use efficiency. Regression analyses were used to determine the optimal N rate for carrots in North Florida. A quadratic plateau regression for both seasons combined indicated 206 kg·ha−1 N was the optimal rate for carrots, with marketable yield of 71.3 Mg·ha−1, regardless of cultivar. All four cultivars attained acceptable yield including Uppercut 25, which exhibited significant foliage damage following freezing temperatures. This study resulted in updated information on best management practices for carrot production in Florida, especially nutrient stewardship.
This supplement contains the Abstracts of Presentations from American Society of Horticultural Science 2021 Annual Conference