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Open access

Gilbert Miller

Delineating the depth and extent of the industrial hemp (Cannabis sativa L.) root zone assists with proper irrigation management and minimizes nutrient leaching. The objective of this 3-year field study was to measure root distribution and root length density of industrial hemp cultivars produced for cannabinoids grown under polyethylene mulch with drip irrigation. Root length density (RLD) was measured from 75-cm-deep soil cores obtained during vegetative growth, at early bloom, and at flower harvest. Cores were taken in-row and 15 cm to the side of each plant. In addition to root cores, the trench profile method was used during 2020 to observe in situ gross root architecture of a direct-seeded cannabinoid cultivar. RLD was significantly greater in the 0- to 30-cm soil depth and dropped dramatically below 30 cm; RLD was not significantly affected by cultivar. These findings suggest that the effective root zone depth for industrial hemp cultivars produced for cannabinoids is 0 to 30 cm and that the cultivars tested in this study do not differ in root system size or location.

Open access

Mohammed A. S. Alyafei, Abdullah Al Dakheel, Mohamed Almoosa, and Zienab F. R. Ahmed

Traditional pollination of date palms is a time-consuming and labor-intensive process. Hence, the objectives of this study were 1) to develop a rapid, efficient, and low-cost pollination method that results in an acceptable level of fruit set (FS) with smaller amount of pollen grains, and labor costs using a platform-mounted robotic (drone) supplemented with water-suspended pollen grains, and 2) to investigate the effect of this method on date palm FS percentage, pollination efficiency (PE), fruit retention, total yield, and fruit quality. Date palm cultivars Barhi, Lulu, and Khesab were pollinated using traditional hand pollination (HP), spray pollination (HS), and drone pollination (DS) with water-suspended pollen grains (3 g/L). The results revealed that DS had a significantly lower FS percentage than the HP and HS methods in the Lulu and Khesab cultivars, but the difference was not statistically significant in Barhi cultivar. Fruit PE was unaffected by any of the pollination methods in Barhi and Lulu cultivars, but in the Khesab cultivar, DS pollination had lower PE (0.81) than HS (0.94) and HP (0.99) methods. DS had significantly lower levels of fruit retention and bunch weight than other methods. DS significantly improved fruit physical quality at harvest in all cultivars compared with HP and HS methods. Nevertheless, fruit color, firmness, total soluble solids (TSS) %, acidity, pH, and vitamin C level were unaffected by any of the pollination methods. Although the DS method produced lower FS percentage and bunch weight, the obtained FS percentages were within the commercially acceptable range for all cultivars. To the best of our knowledge, this is the first field study to indicate the possibility of pollinating date palm using drones with water-suspended pollen grain. To validate the commercial application, more research is needed to justify the optimum time and duration of application, which may vary according to cultivar and region.

Open access

Gursewak Singh, William Patrick Wechter, Bhupinder Singh Farmaha, and Matthew Cutulle

Anaerobic soil disinfestation (ASD) is a preplant pest management technique that involves amending the soil with a labile carbon source, irrigating the soil to stimulate decomposition, and then covering the soil with polyethylene film (polyfilm) to limit gas exchange. During the ASD process, soil microorganisms shift from aerobic to anaerobic metabolism and release phytotoxic byproducts such as organic acids and gases. Although it has been shown that these phytotoxic by-products have a negative impact on weed survival, questions remain about whether commercial-level weed control can be achieved using ASD alone or in combination with other chemicals. Greenhouse and field studies were conducted to evaluate ASD with mustard (Brassica sp.) meal, molasses, and herbicide applications for yellow nutsedge (Cyperus esculentus) control in tomato (Solanum lycopersicum). The treatments in these studies included factorial of two carbon sources [mustard meal + molasses (MMM) or no carbon amendment], three herbicide treatments [halosulfuron applied preemergence (PRE), halosulfuron applied postemergence (POST), and no herbicide] and two polyfilm treatments (polyfilm cover or polyfilm uncover). In field trials two polyfilm cover treatments were punctured and nonpunctured. Soil treatments included molasses at 14,000 L·ha−1 and mustard meal at 2100 kg·ha−1. Halosulfuron was applied at a rate of 1 oz/acre for PRE or POST applications. Greater anaerobic conditions were achieved in polyfilm cover treatments amended with MMM. In greenhouse and field trials, the most effective treatments for reducing yellow nutsedge populations were ASD with MMM or combined with halosulfuron application (PRE- or POST-ASD), which delivered significantly higher weed control than all other treatments tested or controls. In field trials, ASD with MMM caused plant growth stunting 14 d after transplantation (DAT); however, plants recovered, and stunting or injury was often not observed at 42 DAT. These studies demonstrated that ASD using MMM can be an effective strategy for reducing yellow nutsedge populations; however, the more research is needed to ensure crop safety while using ASD technology.

Open access

Michael J. Bradshaw, Luis Quijada, Patrick C. Tobin, Uwe Braun, Cindy Newlander, Tom Potterfield, Élan R. Alford, Carlos Contreras, Allen Coombes, Swarnalatha Moparthi, Erin Buchholz, Daniel Murphy, Wade Enos, Amy Fields-Taylor, Anna Bower, and Donald H. Pfister

Botanical gardens have extensive spatial databases of their plant specimens; however, the fungi occurring in them are generally unstudied. Botanical gardens, with their great plant diversity, undoubtedly harbor a wide range of symbiotic fungi, including those that are plant-pathogenic. One such group of fungi is powdery mildews (Erysiphaceae). The powdery mildews are among the most prevalent and economically important plant pathogens in the world, with an estimated 906 species in 19 genera. They are known to infect more than 10,000 species of flowering plants and although some species occur across a range of hosts, many are associated with specific plants. Powdery mildews have undergone a long and dynamic coevolution with their host plants, resulting in co-speciation. Botanical gardens provide a living laboratory in which to study these fungi, leading to a wealth of undiscovered fungal diversity. Furthermore, monitoring pathogens in botanical gardens has led to important ecological findings related to the plant sciences and plant protection. Between 2018 and 2022, a collaborative citizen science project was established with 10 botanical gardens in the United States and Mexico. A total of more than 300 powdery mildew specimens were collected on 220 different host taxa. We sequenced the entire internal transcribed spacer (ITS) and large subunit (LSU) rDNA loci and phylogenetically and morphologically analyzed these collections revealing 130 species, of which 31 are likely unknown to science. This research highlights the importance of botanical gardens as a reservoir of fungal diversity. Future research will further elucidate the coevolutionary relationship between powdery mildews and their hosts and extend the current study to evaluate other plant pathogens and fungi in botanical gardens.

Open access

Juan Zhou, Xuetao Ma, Yaxin Zhao, Sijie Wang, Chen Lian, Jingran Lian, and Yan Ao

Open access

Qian-nan Diao, Yan-yan Cao, Hong Wang, Yong-ping Zhang, and Hai-bin Shen

The objective of the present study was to consider the regulatory role of exogenous nitric oxide (NO) supplementation in response to chilling stress impose alterations on different physiological parameters in melon seedlings. Melon seedlings were treated with sodium nitroprusside (SNP, an NO donor), hemoglobin (a NO scavenger), NG-nitro-L-arginine methyl ester (an NO synthase inhibitor), and tungstate (a nitrite reductase inhibitor) under chilling stress conditions. The results showed that exogenous SNP improves the growth of melon seedlings under chilling stress conditions and ameliorates the harmful effects of chilling stress by increasing the levels of chlorophyll and soluble solutes, elevating the activity of sucrose phosphate synthase by enhancing the expression level of CmSPS. Moreover, exogenous NO significantly enhances the expression of genes and activities of antioxidant enzymes under chilling stress, resulting in lower reactive oxygen species accumulation. However, the protective effects of SNP are reversed by both NO scavenging and inhibition. Collectively, our results reveal that NO has the ability to ameliorate the harmful effects of chilling stress on melon seedlings by regulating carbohydrate metabolism and the antioxidant defense system.

Open access

Jing-Jing Zou, Gaoling Wu, and Zhenqi Wang

Open access

Erik Feibert, Clint Shock, Stuart Reitz, Alicia Rivera, and Kyle Wieland

Each year ≈24,000 acres of onions (Allium cepa) are produced in the Treasure Valley of eastern Oregon and southwestern Idaho, which accounts for 20% of U.S. dry-bulb onion acreage. Onions in this region are long-day onions and are irrigated by either furrow irrigation or drip irrigation, with drip irrigation having become the predominant system in the past 10 years. Onion production in the Treasure Valley faces many biotic pressures and changing market conditions that renders cultivar development and testing of critical importance to the onion industry. Direct-seeded yellow, white, and red onion cultivars have been evaluated yearly at the Malheur Experiment Station, Oregon State University, in Ontario, OR, USA, since 1975. From 2010 to 2020, 10 onion seed companies participated in the trials. There were 21 to 32 yellow cultivars, two to 10 red cultivars, and one to seven white cultivars entered in the trial each year. Only five cultivars were entered all 11 years. Total yields for the yellow cultivars ranged from an average of 680 cwt/acre in 2010 to 1277 cwt/acre in 2018, and averaged 961 cwt/acre over the 11 years. Yield of yellow bulbs larger than 4 inches (colossal and super colossal) ranged from 13% in 2010 to 61% in 2018, and averaged 34% over the 11 years. Single centered yellow bulbs ranged from 46% in 2013 to 70% in 2014. Total yields for the red cultivars averaged 520 cwt/acre and total yield of white cultivars averaged 988 cwt/acre over the 11 years. Over the 11 years, single-centered bulbs of red cultivars averaged 65% and single-centered bulbs of white cultivars averaged 45%. Some newer cultivars show improvements in single centeredness, resistance to Iris yellow spot virus, and yield of larger bulbs over cultivar Vaquero, which was released in 1993, indicating the success of breeding efforts. Yields of five yellow cultivars that were in the trials every year since 2010, increased over time. This increase can be partly attributed to improvements in cultural practices over the years: adoption of drip irrigation, more intensive nutrient management, refined onion thrips (Thrips tabaci) control, and higher plant population.

Open access

Erin L. Treiber, Laise S. Moreira, and Matthew D. Clark

The University of Minnesota Grape Breeding Program has developed cold-hardy wine grape cultivars that have facilitated the establishment of an economically important grape industry for the Midwest region. In recent years, the program has renewed efforts to breed cold-hardy table grapes. Table grapes might require postharvest storage if they are to be transported or stored for any period of time. Rachis dehydration, berry splitting, and decay can affect the postharvest quality of table grapes. In this study, we evaluated these postharvest traits in six released cultivars and nine advanced selections in the breeding program. For two growing seasons, we used industry standard packaging to assess postharvest traits (rachis dehydration, berry splitting, decay, and overall acceptability) at 2, 4, and 6 weeks of cold storage at 2.2 °C. The growing season had a significant effect on postharvest traits; therefore, the two were examined separately. There were significant differences in postharvest storage times for all traits, except berry splitting in 2020. Mean rachis dehydration reached unacceptable values (>3) after 4 weeks of postharvest storage in 2019 and after 6 weeks in 2020. All other trait means remained acceptable for many cultivars even after 6 weeks of postharvest storage. Advanced selections performed at and above the level of released cultivars, suggesting that selections will perform well in cold-hardy regions. The data collected regarding fruit quality and postharvest storage for two seasons will help to inform and improve breeding of cold-hardy grape cultivars.

Open access

Marcellus Washington, Mark Farnham, David Couillard, H. Tyler Campbell, Brian K. Ward, and Matthew Cutulle

Increased broccoli production in the eastern United States necessitates the exploration of novel concepts to improve weed management in this region. Currently, there are minimal selective postemergent herbicide options available for broccoli growers in the southeastern United States. Research was conducted to determine if bentazon, an effective nutsedge herbicide, could be used safely for broccoli when tank-mixed with chelated iron in both greenhouse and field settings. Initial greenhouse screens in Charleston, SC, demonstrated that when 224 g⋅ha−1 active ingredient of chelated iron was tank-mixed with bentazon, a reduction in injury occurred in most of the cultivars that were evaluated. However, based on injury ratings, yield parameters, and broccoli quality observed in the field, it appears that the applications of chelated iron yielded no positive effects. Furthermore, for some of the broccoli cultivars it appeared to exacerbate bentazon injury in the field.