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- Author or Editor: J.W. Daniel x
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The gas exchange of tomato (Lycopersicon esculentum Mill cv. Spring Giant VF) plants exposed to an ethephon root drench of 5 μl·liter-1 or 50 μl·liter-1 was examined for 9 days. Photosynthesis showed a biphasic response to ethephon, wherein elevations of 13.2% and 16.7% were observed over control plants for two of the measurement days for the 50 and 5 μl ethephon/liter concentrations, respectively. Stomatal conductance showed a large increase at 50 μl ethephon/liter on day 2, while 5 μl·liter -1 did not show this difference. A biphasic response of photosynthesis may explain some of the intraspecific variation found in the literature describing ethylene-induced gas-exchange alterations.
Commercial sweetpotato fields are established with asexually derived propagules as either cut or pulled plants. Micropropagation and somatic embryogenesis were/are being investigated to improve seed production. Micropropagation of sweetpotato is utilized in California as part of its seed production program. Several studies have been conducted or are ongoing in North Carolina to evaluate the utility of micropropagation as part of its certification program. In 1992, yield was increased in `Beauregard' with micropropagated plants compared with plants that were derived from the North Carolina Certified Seed Program. However, there were no yield increases in four years of comparisons when `Jewel' and `White Delight' were micropropagated. A trend towards early bulking has consistently been observed in micropropagated `Jewel', `White Delight' and Beauregard. Early plant growth and yields of plants (`White Star') obtained from somatic embryos, micropropagation or vine cuttings were compared. Plants derived from somatic embryos grew slower and yielded less root weight than cut plants; however, more storage roots were obtained from plants obtained from somatic embryos indicating high yield potential if root bulking is achieved.
Abstract
‘Carolina Nugget’ (Fig. 1) is a moist sweet potato developed at N.C. State Univ. in 1954. In 1957 and 1958, it was tested throughout North Carolina in regional tests as the experimental clone NC 172. Although it never has been released officially as a cultivar, it has been grown for commercial use in several southern states under many different names (e.g., Red Nugget, Carolina Nugget, Golden Nugget). The formal release and naming of this sweet potato cultivar should alleviate the confusion that has occurred when growers market or buy plant material.
Abstract
‘Cortland’/Mailing (M) 7 apple trees (Malus domestica Bork.) which were treated at planting time with commercial root promoters, containing either naphthaleneacetamide (NAAm) + naphthaleneacetic acid (NAA), indolebutyric acid (IBA) + fertilizer, or the ectomycorrhizal fungus Pisolithus tinctorius, increased terminal growth. P. tinctorius was superior to either rooting compound for increasing total growth, and only P. tinctorius increased root weight. Colonization of the root system by P. tinctorius was not observed, although the roots of P. tinctorius-treated trees appeared to have more endomycorrhizae. The growth increase was not due to increased nutrient uptake.
Abstract
2-Chloro-9-hydroxyfluorene-9-carboxylic acid (chlorflurenol) 3 at 50 or 100 ppm increased fruit production of a gynoecious cucumber (Cucumis sativus L. cv. MSU 713-5) under field conditions of both normal and reduced pollination. A monoecious cultivar, ‘Wisconsin SMR 18’, treated with (2-chloroethyl) phosphonic acid (ethephon) and then chlorflurenol produced over twice as many fruit as the control when pollen was plentiful, and more than 4 ⨯ as many when pollen supply was limited. Ethephon sprays alone increased pistillate flower formation on the monoecious cultivar but did not increase fruit set. Chlorflurenol treatments increased the proportion of fruit in the smaller, more valuable size grades and appear advantageous for mechanically harvested pickling cucumbers.
Nitrogen at rates of 112 or 224 kg·ha-1 was applied to nonirrigated and drip irrigated mature pecan trees for 9 years. Some irrigated trees received 224 kg·ha-1 N either all broadcast or ½ through the drip irrigation. Other drip irrigated trees received only 112 kg·ha-1 all through the drip irrigation system. Fertigation was in 4 equal monthly doses beginning April 1. Irrigation increased yield for 2 years for Schley and 3 years for Stuart. Nut size was increased by irrigation in 6 years for Schley and 8 years for Stuart. Applying ½ N through the irrigation system caused no detrimental effect on yield or nut quality. The lower rate of N all applied through the drip irrigation system gave yield and nut quality as good as the higher rate either all broadcast or ½ broadcast and ½ fertigated.
Restrictions on pumping water from underground aquifers are limiting vegetable production in Southwest Texas. To determine yield, quality, and water use efficiency (WUE) of muskmelon (Cucumis melo L. group Cantalupensis, `Caravelle'), six irrigation systems with varying input levels and their interactions with stand establishment (containerized transplants vs. direct seeding) were examined. Irrigation systems were: 1) pre-irrigated followed by dryland conditions; 2) furrow/no mulch; 3) furrow/mulch (40-μm-thick black polyethylene); 4) surface drip (0 cm depth)/mulch; 5) subsurface drip (10-cm depth)/mulch; and 6) subsurface drip (30-cm depth)/mulch. Field experiments were conducted on a silty clay loam soil during four seasons (1995-98). In 1995, marketable fruit yields were greater for subsurface drip systems at 30-cm depth than for furrow systems, with or without plastic mulch. Transplants grown with surface drip irrigation produced 75% greater yield in the 9-count fruit class size during early harvest than did those grown with subsurface drip (10- or 30-cm depth), but total yield was unaffected by drip tape depth placement. In 1996, the driest season of these studies, direct-seeded plants had higher total yields than did transplants; yield was greatest for direct-seeded plants on subsurface drip placed at 10- or 30-cm soil depth, and for transplants on subsurface drip at 10-cm depth. Soluble solids content was minimally affected by irrigation method, but was higher in fruit from transplants than in those from direct-seeded plants in 3 years. Across all seasons, the average water applied for drip systems was 53% lower than that for conventional furrow systems, and WUE was 2.3-fold as great.
Annual bluegrass (Poa annua L.) control with postemergence herbicides in cool-season turfgrass is often inconsistent. Amicarbazone and mesotrione have complementary modes of action but have not been evaluated in tank-mixtures for control of mature annual bluegrass in cool-season turfgrass. Field experiments were conducted during 2018 in New Jersey, and in Indiana, Iowa, and New Jersey during 2019 to evaluate springtime applications of amicarbazone and mesotrione for POST annual bluegrass control in cool-season turfgrass. On separate tall fescue (Festuca arundinacea Schreb.) and kentucky bluegrass (Poa pratensis L.) sites in 2018, three sequential applications of amicarbazone (53 g⋅ha−1) + mesotrione at 110 to 175 g⋅ha−1 provided >70% annual bluegrass control, whereas three sequential applications of amicarbazone alone at 53 and 70 as well as two sequential applications at 110 g⋅ha−1 provided <15% control at 14 weeks after initial treatment (WAIT). In 2019, results in New Jersey were similar to 2018 where amicarbazone alone provided less control than mesotrione + amicarbazone tank-mixtures. In Indiana, where the annual bluegrass infestation was severe and most mature, tank-mixtures were more effective than amicarbazone alone at 6 WAIT, but at 12 WAIT all treatments provided poor control. In Iowa, where the annual bluegrass infestation was <1 year old, all treatments provided similar control throughout the experiment and by >80% at the conclusion of the experiment. This research demonstrates that sequential applications of mesotrione + amicarbazone can provide more annual bluegrass control than either herbicide alone, but efficacy is inconsistent across locations, possibly due to annual bluegrass maturity and infestation severity.