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- Author or Editor: Frank B. Matta x
Foliar sprays of dikegulac-sodium (sodium salt of 2,3:4,6-bis-0-(1-methylethylidene)-alpha-L-xylo-2-hexulofuranosonic acid) at 722 and 2888 ppm and hand-pinching significantly increased branching of chili pepper cultivars ‘Sandia’, ‘NM 6’, and ‘Espanola 1’ (Capsicum annuum L.). Both dikegulac-sodium concentrations were equally effective in increasing branching. Hand-pinching and dikegulac-sodium at 722 ppm did not influence plant height. Dikegulac-sodium at 2888 ppm significantly reduced plant height. Hand-pinching and dikegulac-sodium at 722 ppm delayed first harvest by 9 days. Dikegulac-sodium at 2888 ppm delayed first harvest by 34 days. Dikegulac-sodium at 5053 ppm resulted in death of treated plants. All concentrations of dikegulac-sodium decreased yield.
Our objectives were to 1) Determine acclimation and deacclimation patterns of buds and stems of four pecan cultivars in Mississippi and 2) to determine the relationship between cold hardiness, based on DTA, and tissue injury, based or viability tests. Stem critical temperatures for September showed that `Hughes' was slower in acclimating than `Jackson'. Maximum hardiness for all cultivars occurred in January, except for `Desirable', which reached maximum hardiness in December but started deacclimating in January. Deacclimation for the remaining cultivars started in February. Bud critical temperatures for September and October also show that `Hughes' was slower in acclimating compared to the remaining cultivars. Maximum bud hardiness for `Desirable' occurred in December, with the remaining cultivars reaching maximum hardiness in January. Bud deacclimation for all cultivars occurred in March. The LD50 for the tetrazolium and electrolyte leakage tests occurred at about –32 and –30C, respectively. In buds, LT50 for the tetrazolium test was –18C. The LT50 electrolyte leakage and browning test was –20C.
Defoliating chemicals (ammonium thiosulfate, ethrel, and thidiazuron) were evaluated on 8-month-old `Canadice' and `Concord' grapes. The effectiveness of chemical defoliators was determined 20 days after application. Vines were pruned after defoliation and dormancy breaking chemicals (thiourea, cyanamide, and gibberellic acid (GA3) were applied 4 days later. All treatments were applied as sprays. All chemicals were effective in defoliating the vines of both cultivars. Generally, the higher concentrations (ammonium thiosulfate, ethrel, and thidiazuron at 15.15, 3.0, and 0.35 g·liter–1, respectively) were more effective. All chemicals reduced days to maximum budbreak of both cultivars. The higher concentrations (thiourea, cyanamide, and GA3 at 30.3, 15.15, and 0.75 g·liter–1, respectively) resulted in greater reductions in days to maximum budbreak. `Concord' was later in reaching maximum budbreak. Total percent budbreak of both cultivars was increased by all chemicals at the higher concentrations. Cyanamide resulted in greater total percent budbreak in both cultivars.
Stem critical temperatures for September showed that `Hughes' was later in acclimating than `Jackson'. Maximum hardiness for all cultivars occurred in January and deacclimation in February. Bud critical temperatures for September and October also showed that `Hughes' acclimated later than the other cultivars. Maximum hardiness for buds occurred in January and deacclimation in March. In December, the LT50 for the tetrazolium test, the electrolyte leakage test, and the tissue browning test were –18, –20, and –20C, respectively, as shown by differential thermal analysis of `Desirable'.
Maturity indices such as fruit size, firmness, fresh fruit weight, soluble solids content, titratable acidity, and juice pH of `Earligold'/EMLA 7, `Jonagold'/EMLA 111, `Improved Golden'/EMLA 7, `Improved Golden'/EMLA 111, `Scarlet Gala'/EMLA 7, `Jonafree'/Mark, `Macspur'/M 7A, `Royal Gala'/MM 111, and `Williams Pride'/M 7A were monitored. Based on maturity indices analysis, the optimal harvest time for each scion rootstock combination was determined. `Scarlet Gala'/EMLA 7, `Williams Pride'/M 7A, and `Earligold'/EMLA 7 were early cultivars, while `Jonagold'/ /EMLA 111, `Improved Golden'/EMLA 7, `Improved Golden'/EMLA 111, and `Macspur'/M 7A were late cultivars. After harvest, all cultivars were stored for 3 months under controlled conditions. Changes in fruit appearance, flavor, sweetness, tartness, and firmness were recorded. Fruit size, firmness, fresh fruit weight, soluble solids content, and juice pH were influenced by the cultivar/rootstock combination. Results of the sensory evaluation indicated that medium and late cultivars were preferred by panelists compared to the early harvested cultivars. `Improved Golden'/EMLA 7, `Royal Gala'/MM 111, and `Jonagold'/EMLA 111 combinations maintained quality during storage, compared with the remaining cultivars/rootstock combinations, and had a longer storage life.
A study of spur-type apple scion cultivars on semi-dwarf and dwarf apple rootstocks was conducted to evaluate and identify suitable scion/stock combination for Mississippi. Fruit weight varied among scion/stock combinations. `Royal Gala' on MM111 and MM106 and `Ultra Gold' on MM106 yielded the heaviest fruit. `Jon-A-Red' on Mark produced the lightest fruit. Fruit length diameter ratio (L/D) was the highest for `Blushing Golden' on M7A and MM111, and `Ultra Gold' on MM111. The L/D ratio of `Royal Gala' was not affected by rootstock. Scion cultivars on M7A and M26 tended to have more red fruit than on the remaining rootstocks. `Ultra Gold' on M26 and `Braeburn' on Mark and MM111 had the firmest fruit. Overall, trees on M7A and Mark rootstock tended to produce firm fruit. Juice pH was significantly affected by scion-stock combination. In general, `Royal Gala', regardless of rootstock, had the highest juice pH, whereas `Ultra Mac' and `Jon-A-Red' produced the lowest pH. `Blushing Golden' on MM111 and `Royal Gala' on M26 had the highest soluble solids concentration (SSC). Soluble solids concentration of scion cultivars on MM106 did not differ.
This study was established to determine the influence of scion/stock combination on leaf area, yield efficiency, and fruit quality attributes in effort to identify the most suitable scion/stock combination for Mississippi. Twenty-nine scion/stock combinations were grown at the Pontotoc Ridge-Flatwoods Research and Extension Center, North Mississippi. The treatments were arranged in a completely randomized design (CRD) with six single tree replications. `Jon-A-Red' on Mark produced the smallest leaf area, while the largest leaf area was produced by the combination of `Royal Gala' on MM106 and `Blushing Golden' on M7A. Scion/stock combinations significantly affected yield efficiency, fruit yellow pigment dvelopment, firmness and fruit mineral composition. Scion cultivars on Mark resulted in the highest yield efficiency, except `Empire'. `Ultra Gold' and `Braeburn' on Mark and `Blushing Golden' on MM111 led to yellow pigmentation in the highest category. Meanwhile, `Braeburn' on Mark was among the scion/stock combinations that produced the firmest fruit. And fruit from trees on Mark consistently had high calcium (Ca) levels. After 7 years, `Royal Gala' on Mark produced the highest yield efficiency. `Braeburn' on Mark resulted in both the firmest fruit and the highest fruit Ca concentration.
Growth regulators ABA and paclobutrazol were used at different concentrations to induce hardiness in blueberry flower buds and floral parts. Critical freezing temperatures and the effectiveness of the treatments were determined by differential thermal analysis (DTA), electrolyte leakage, visual browning, and tetrazolium staining. Treatment effects of growth regulators were nonsignificant on whole flower buds, but treatments induced hardiness in floral parts on the second flush of flowers at stage six produced in April. Induction of cold hardiness by ABA and paclobutrazol was concentration dependent. The higher the concentration, the greater the response. Viability test results on each floral part showed a close relationship with the critical freezing temperatures recorded by DTA. Control treatments showed that floral parts at stage six developed in April were more prone to freezing injury compared to floral parts at stage six developed in early March.
The influence of chemical thinners Accel and ethephon on three apple cultivars Royal Gala, Blushing Gold, and Ultra Gold was investigated. Two experiments were conducted in 1995 and 1996 to determine the effect of Accel at 0, 25, 50, and 75 ppm and ethephon at 0, 100, 200, and 300 ppm on fruit juice SSC, fruit juice sucrose, fruit juice glucose, fruit juice fructose, and fruit set. Accel and ethephon reduced fruit set of `Royal Gala', `Ultra Gold', and `Blushing Golden'. In 1995, chemical fruit thinners Accel and ethephon increased SSC of `Royal Gala' and `Ultra Gold' and did not affect SSC of `Blushing Golden'. In 1996, Accel and ethephon did not effect the SSC of `Royal Gala' and `Blushing Golden'. However, Accel increased SSC of `Ultra Gold'. Accel and ethephon increased sucrose concentration of `Royal Gala', `Ultra Gold', and `Blushing Golden'. Accel increased fruit juice glucose concentration of `Royal Gala', `Ultra Gold', and `Blushing Golden'. Ethephon did not effect fruit juice glucose concentration of `Royal Gala', `Ultra Gold', and `Blushing Golden'. Accel did not effect fruit juice fructose concentration of `Royal Gala'. However, Accel increased fructose levels of `Ultra Gold' and `Blushing Golden' in 1995. Accel did not effect fruit juice fructose concentration of `Blushing Golden' in 1996. Ethephon did not effect fruit juice fructose concentration of `Royal Gala'. Ethephon increased fruit juice fructose concentration of `Ultra Gold'. Ethephon did not effect fruit juice fructose concentration of `Blushing Golden'.
The performance of spur-type apple cultivars was evaluated on MM.111, MM.106, M.7A, M.26, and Mark rootstocks. Shoot growth, leaf area, and total nonstructural carbohydrate (TNC) were affected by scion cultivar and rootstock. Empire on Mark stock had less shoot growth. Ultra Mac on M.7A produced smaller leaf area. `Braeburn' on Mark stock exhibited higher TNC content. Scion cultivar and stock influenced fruit weight and yield, L: D ratio, SSC, pH, and the content of N, P, K in leaves and fruit. `Braeburn' on M.7A, M.26, and MM.111 produced greater yield per tree. L: D ratio was higher in `Ultra Gold' on MM.106. `Ultra Gold' and `Jon-A-Red' had higher SSC on Mark. `Empire' and `Ultra Gold' on M.7A resulted in higher juice pH. `Empire' on MM.106 produced heavier fruit and higher N content in leaves and fruit. `Ultra Mac' on M.7A showed higher P and K content in the fruit.