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.
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.
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.
Preharvest germination (viviparity) can be a problem with nuts of pecan [Carya illinoinensis (Wangenh.) K. Koch]. Two southern-adapted cultivars (`Cherokee' and `Wichita') and one northern-adapted cultivar (`Johnson') were paternal parents in controlled crosses with the maternal parent `Wichita'. `Wichita' × `Johnson' seed took much longer to germinate than seed from either the `Wichita' × `Cherokee' cross or the `Wichita' self, therefore indicating that pollen source may influence germination characteristics.
Three-dimensional leaf and fruit distribution was studied in a 26-year-old `Success' pecan tree [Carya illinoinensis (Wangenh.) K. Koch]. The tree was typical of the trees in this orchard and typical of thousands of hectares of mature pecan trees growing in a crowded condition. There are fewer leaves and fruit in the lower and central canopy than in the rest of the tree. To obtain an adequate sample, measurements should be taken from branches arising at a height ≥4.75 m and from 1.9 m from the center of the tree trunk to the edge of the canopy around the trees. Fruit could be sampled from branches arising at ≥3.76 m from the ground and from 3.37 m from the center of the tree trunk to the edge of the canopy around the tree.
Fall soil treatments of ZnEDTA and ZnSO4 at three increasing rates (32.2, 64.4 and 128.8 g. Zn/tree) and 1, 2 and 3 spring foliar sprays of NZN (0.35 g. Zn/tree/application) were tested to correct Zn deficiency in three year old `Earligrande' peach trees. All Zn carriers increased the Zn leaf content. Peach trees treated with three applications of NZN were equal to the medium or high rates of soil applied ZnEDTA or ZnSO4 respectively, in appearance, chlorophyll content and foliar Zn content. Three applications of NZN at 0.35 g. of Zn/tree (473 ml/378 gal H2O) gave excellent tree response and was cost effective.
`Cheyenne', `Mohawk', `Pawnee', and `Osage' grown in different locations in the United States were analyzed for fatty acid composition. The effect of heat units accumulated 12 weeks prior to shuck split were studied. Growing area affected the fatty acid profile for all cultivars. `Cheyenne' and `Mohawk' showed a positive correlation between heat units and oleic/linoleic acid ratios (r = 0.905 and r = 0.720 respectively), a positive correlation between heat units and oleic acid content (r = 0.863 and r = 0.773 respectively), and a negative correlation between heat units and linoleic acid content (r = -0.871 and r = -0.792 respectively). However, no correlation was obtained between heat units and the fatty acid profiles for `Osage' and `Pawnee'.
Evidence of professional competence is needed for those whose activities affect the well-being of the general public. Graduates of BS and MS programs in horticulture are not distinguishable from self styled individuals who assume the title of “Horticulturist” without earning it. Certification of horticultural graduates is the first step in gaining a recognition for the Horticultural Profession. ASHS has established a Certified Professional Horticultural Sub-Board of the American Registry of Certified Professionals in Agronomy, Crops and Soils (ARCPACS). Professional core requirements include courses horticultural crop management, pest management, soil science, plant physiology, botany, chemistry, and genetics. Supporting core courses include math, communication skills, and horticultural specialization courses. Applications from individual horticultural graduates will soon be accepted. Details of the curriculum, continuing education, ethics, and other eligibility requirements will be detailed.
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.