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- Author or Editor: J. Benton Storey x
Abstract
Nutrient spray residue can be removed from leaflets of pecan (Carya illinoensis (Wang.) K. Koch for nutrient absorption measurement. The residue can be removed by washing the leaflets in 0.1% Alconox, rinsed in running tap water followed by a 7 liter 1% HCl rinse and three separate 7 liter demineralized distilled water baths. The elimination of some of the solutions resulted in erroneously high results in adsorption of the nutrients. Young leaflets absorbed more zinc than did the old leaflets. Nutrient sprayed pecan leaflets washed in 0.1% Alconox, rinsed in running tap water, 7 liters 1% HCl, and three separate 7 liter demineralized distilled water baths prior to tissue analysis gave more consistent and reliable data than leaflets washed by any other method. This leaf washing procedure does not remove biologically significant amounts of any of the elements analyzed.
In 1990, a randomized design was set up in a 33 year old orchard on Westwood silty clay loam with 4 main treatment factors: 1990 nut size, chiseling, aeration, and cultivar. Location for this experiment was the Adriance Orchard on the Texas A&M Plantation – Brazos River flood plain. Nut quality was determined by the % kernel and # nuts / kg. Yield was measured per tree and calculated for g/cm2 cross-sectional trunk area. The soil bulk density for each treatment was 1.53 g/cm3 and found to be statistically uniform at the start of the experiment. Results after one year showed that aeration increased the nut size and % kernel of `Mahan' but not of `Desirable' and `Stuart'. Chiseling increased the yield of `Stuart' and `Desirable' and nut size of all 3 cultivars but not % kernel. Aeration increased the % kernel from a mean 48.6% to 56.8% and nut size from 129 nuts/kg to 102 nuts/kg of the 1990 small-nut-size trees but did not significantly increase nut quality for the 1990 normal-nut-size trees.
Objectives of this experiment were: 1) to determine what effect a soil spike aerator had on nut quality and yield, and 2) to determine whether soil compaction influenced nut quality and yield.3) to determine whether tree stress influenced nut quality or yield on pecan trees In 1990, a randomized design was set up in a 33 year old orchard on Westwood silty clay loam with 3 main treatment factors: 1990 nut size (measure of tree stress), aeration, and cultivar. Location for this experiment was the Adriance Orchard on the Texas A&M Plantation - Brazos River flood plain. Nut quality was determined by the % kernel and # nuts/kg. Yield was measured in kg per tree. Results after two years showed that aeration increased the nut size of stressed trees in 1991 and non-stressed trees in 1992 Yield was unaffected by aeration in both years but stressed trees produced lower yields in 1992. Aeration increased nut size, but not significantly from 119 nuts/kg to 111 nuts/kg in 1991. There was a significant increase with aeration in 1992 from 121 nuts/kg to 113 nuts/kg. Yield and % kernel were not significantly different for both years with aeration Stress did not increase % kernel in either 1991 or 1992 but nut size was larger on non-stressed trees for both years. Stressed trees produced fewer nuts per tree in 1992.
Abstract
Adjuvants at various concentrations were evaluated for phytotoxicity and capacity to enhance foliar absorption of N and P. Some adjuvants among the following classes were phytotoxic to soybean (Glycine max Merr.) leaves at concentrations of 0.25% and 0.5% active ingredient on a volume or weight/volume basis: sulfonates, alcohols, ethyoxylated hydrocarbons, esters, sulfates, and amines. Many adjuvants in the following classes: alcohols, sulfonates, ethoxylated hydrocarbons, polyethylene glycols, carbohydrates, proteins, and phosphates were not phytotoxic at concentrations as high as 1.0%. Sometimes increasing phytotoxicity occurred at increasing concentrations, but the humectants, such as glycerol and propylene glycol, were not phytotoxic at concentrations of 10.0%. Selected adjuvants were mixed with a foliar fertilizer (12.0N–1.7P–3.3K–0.5S) and evaluated for enhancement of foliar absorption of N and P. The average increases in percentage of N and P for the glycerol, lecithin, and Pluronic L-121 (an ethyoxylated hydrocarbon), and foliar fertilizer combinations, respectively, were 8.9%, 2.2%, and 2.5% for N and 34.2%, 27.6%, and 20.8% for P over the foliar fertilizer control, respectively, for the 3 adjuvants.
Abstract
Tank mixing Uran (0.5% by weight) with ZnSO4 increased leaflet Zn concentration compared to ZnSO4 alone in pecan [Carya illinoensis (Wang) K. Koch]. Zinc nitrate was more efficient than ZnSO4 in increasing leaflet Zn concentration especially if tank mixed with Uran (0.5%). Zn concentration of spray solutions can be reduced by 1/8 to ¼ of the current recommended rate of Zn at 86 g/100 liters of water as ZnSO4. Use of the lowest rate of Zn(NO3)2, 10.8 g/100 liters of water + Uran, increased yield and income over the recommended rate of ZnSO4.
Four cultivars of pecan [Carya illinoinensis (Wangenh.) K. Koch] were selected for the study (`Cheyenne', `Mohawk', `Pawnee', and `Osage'). The influence of total climatic heat units, during nut filling, on nut quality was compared from 14 geographic locations over a 3-year study. Nut quality parameters included nut size by weight, kernel percentage by weight, kernel color by Hunter Color Difference Meter, fatty acid profile by GC, and total oil by NMR. Nuts were harvested at shuck split, dried to 3% moisture, and stored at –20C prior to analysis. Monounsaturated fatty acids (MUFA) and total oil increased, and polyunsaturated fatty acids (PUFA) decreased in `Mohawk' 2 out of 3 years with increased heat units. Fatty acids in `Pawnee' responded the same as in `Mohawk' in 1992, but were variable in 1991. In 1993, `Pawnee' kernel whiteness and total oil decreased with increased heat units. Higher heat units caused the testas of `Cheyenne' to be darker in all 3 years. MUFA of `Cheyenne' increased with increased heat units 1 out of 3 years. The PUFA content of `Cheyenne' decreased with increased heat units in 1993. `Osage' showed a reversal of MUFA and PUFA with increased heat units. High negative correlation between oleic and linoleic acid were obtained for all cultivars.
Stumps remaining after tree removal during orchard thinning will characteristically produce extensive shoot growth in response to the massive root systems that previously supported large trees. A 38-year-old pecan orchard was thinned from 15 × 15 m to 21 × 21 m. Stumps ranging from 45 to 65 cm in diameter were treated in seven replications with 0.19, 0.37, and 0.75 kg KNO3, respectively, per stump in drilled holes. Two controls consisted of stumps with drilled holes and intact stumps with no holes. Eight holes per stump were drilled with a 2.54-cm-diameter power auger to a depth of 15 cm. The number and weight of regrowing sprouts was measured annually. The 0.75 kg KNO3 rate significantly reduced the number and weight of sprouts regrowing the first year. The drilled stumps showed a significant decrease in new sprouts over the undrilled control. The low KNO3 rate stimulated regrowth. The key to regrowth suppression is to use a high rate of KNO3 in sufficient holes to allow penetration. KNO3 stump treatment should be a safe practice because no more than, perhaps, 2.25 kg of KNO3, depending on trunk diameter, will be used per site, which will then provide nutrients to existing trees as it dissipates.
The influence of temperatures during nut filling on nut size, kernel percentage, kernel color, percent oil, and fatty acid composition were evaluated over 3 years in `Cheyenne', `Mohawk', and `Pawnee' pecans [Carya illinoenensis (Wangenh.) C. Koch]. Nuts were harvested at shuck split at 14 sites located in Texas, Oklahoma, Kansas, Nebraska, Arizona, and California and Coahuila, Mexico. Weather data for 12 weeks before shuck split at each site were used to determine degree days by the formula: degree days = summation n(m–t) where n = number of days, m = (max + min temperature) ÷2, and t = 10°C. The degree days ranged from 996 to 1675. The oleic: linoleic ratios in all three cultivars were positively correlated with degree days in 2 of 3 years. `Mohawk' nut size was positively correlated with degree days all 3 years and `Cheyenne' and `Pawnee' were larger 2 of 3 years in the warmer climates. `Pawnee' kernel percentage and oil content was higher in the warmer climates. Warmer developmental temperatures had no influence on `Cheyenne' kernel color. `Mohawk' kernels were not affected 2 of 3 years, but `Pawnee' developed darker colors 2 of 3 years.
The Packhard treatment included Packhard® Caenise at 3 qt/A rate applied at four equally spaced intervals beginning on 1 May 1996 and continuing until harvest on 29 July 1996. After harvest, treated and nontreated peaches were stored at 1°C, 95% RH. For up to 42 days, after which they were allowed to ripen for 6 days at 18°C. Fruit from 5-day storage intervals and 2-day ripening intervals were then evaluated for firmness, color, brown rot lesions, soluble solids, titratable acidity, starch, pectin, total Ca, and fruit epidermis thickness. Packhard protected the fruit in cold storage for 42 days from brown rot compared to the controls, which began to breakdown in 26 days. The ripening studies have given mixed results suggesting that there is no difference in the degree of brown rot contamination between Packhard-treated fruit and control fruit after removal from storage. Fruit firmness was increased by Packhard in the majority of the storage periods. Sucrose content seemed to have been reduced in the Packhard-treated fruit compared to the controls, possibly due to increased respiration. The Packhard-treated fruit retained more moisture than the control fruit,, which indicates that Ca2+ from Packhard may have increased the integrity of the plasma membranes of treated fruit. In general, the Packhard-treated fruit held up much better in cold storage than the control fruit but was not different in brown rot infection during ripening. Packhard increased fruit firmness and allowed the fruit to retain more moisture than the control fruit. Sucrose content decreased in Packhard-treated fruit compared to the controls.
Abstract
Ethephon was trunk injected into the transpiration stream of pecan trees 10 to 21 days before shuck split in an attempt to expedite shuck opening in 1983. Ethephon concentrations were based on the estimated amount of water flowing through the tree per day. At College Station and Hondo, Texas, a 10 ppm injection significantly increased shuck opening. Leaf drop was only 35% at 10 ppm compared to much higher leaf drop in previous research. There was no difference in number of nuts set and the extent of limb dieback between the control trees and those trunk injected with 10 ppm ethephon. At Ft. Stockton and Midkiff, Texas, injections of 10, 20, and 40 ppm increased nut opening and early leaf drop, but reduced fruit set in the following year (1984). There was no limb dieback at these locations. Injections of trees in El Paso failed to cause shuck opening.