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Pecan nuts from eleven different locations ranging from 1000 heat units at Chetopa, Kansas during the twelve weeks prior to shuck split to 1675 heat units in Zavala County, TX. Monounsaturated and polyunsaturated fatty acids increased and decreased respectively in `Mohawk' in 1991 and 1992 as the temperature increased during the kernel development period Fatty acids in `Pawnee' responded the same as in `Mohawk' in 1992 but were variable in 1991. Limited data showed a reversal of mono and polyunsaturated fatty acids in `Osage' in response to kernel development temperature. Higher temperatures caused the testas of `Cheyenne' to be darker in 1991 and 1992. Total oil content of `Mohawk' increased heat units. However, higher temperatures decreased oil content in `Pawnee'. Clinical evaluation of pecans is needed to confirm Grundy's safflower work.
Abstract
Heading-back of about 50% of the previous season’ shoot growth increased leaflet area, internode length and total N of the leaflets. Heading-back did not affect P, K, Zn content of the leaflets or nut yield and quality. SADH increased Zn content of the leaflets, with no effect on N, P, and K. Internode length was reduced with increases in concn of SADH and leaflet area was not affected. Yield and quality were not affected the year of application, but 4,000 ppm significantly increased the yield the next year, an off-production year.
Abstract
‘Milam’ peach (Prunus persica (L.) Batsch) has been released for public use to provide an alternative cultivar to ‘Loring’ especially in areas where ‘Loring’ is unadapted. Fruit of ‘Milam’ (Fig. 1) mature in about the same season at that of ‘Loring’ but ‘Milam’ is productive over a greater part of Texas than ‘Loring’.
Abstract
Ten day-old seedling pecans (Carya illinoensis (Wang.) K. Koch) grown in square plastic pots, speedling containers and styrene cylinders were treated with 1000 mg/liter 6-benzyIamino-purine (BA) and 5000 mg/liter gibberellic acid (GA3) singly and in combination. GA3 at 5000 mg/liter promoted stem diameter enlargement of seedlings grown in cylinders and pots but had no effect on stems of speedling-grown seedlings. BA and container design had no influence on stem diameter. “Air-pruning” of roots which occurred in speedling-grown seedlings produced a compact, fibrous root system. Stem diameter and height were not significantly reduced by root “air-pruning.” GA3 significantly reduced root dry weight of seedlings grown in cylinders.
The degree of salt resistance of Pistacia spp. grown in the western United States is not adequately known. This study evaluated seedling growth and ion uptake characteristics of two Pistacia spp. and one hybrid in outdoor lysimeters for two seasons. After 12 weeks, seedling stem elongation of P. atlantica Desf., P. terebinthus L. (three selections), and P. integerrima Stewart × atlantica (referred to as Gold II) was reduced by an average of 33% at soil solution salinity of 12.6 dS·m-1 (or 8.0 dS·m-1 in the saturation extract). Gold II was the most vigorous genotype and produced the greatest biomass in control and high-salt solutions. Decreases in root and stem growth (average of all seedlings combined) occurred at soil solution salinity of 13.8 dS·m-1 (or 8.7 dS·m-1 in the saturation extract). Increasing salinity resulted in a higher root to stem ratio, which was most pronounced in P. terebinthus. Comparatively small but significant differences in leaf Na and Cl concentrations between species and selections occurred. All species limited Na transport to leaf tissue up to 125 meq Na/liter in soil solution, storing the greatest amount in roots. Chloride concentrations on a dry-weight basis were substantially higher in leaves than in roots. Increasing salinity did not affect leaf K and Mg concentrations, whereas Ca was significantly reduced. Leaf Na and Cl concentrations of P. atlantica and P. terebinthus had significant correlation with Na and Cl concentrations in soil solutions (r = +0.83 to +0.94).
Excised root tips from 3-year-old pistachio rootstock (Pistacia atlantica Desf., P. terebinthus L., and P. integerrima Stewart × atlantica) were exposed to laboratory saline solutions for 24 hr. Treatments simulated the compositions of soil solutions in a previous 2-year study made in outdoor lysimeters. Leakage of UV-absorbing solutes, an indication of cellular damage, occurred with 175 mM Na/12.5 mM Ca, which was comparable to soil salinity which increased leaf Na concentrations and decreased root growth of these species Up to. five times higher leakage occurred from roots of a P. terebinthus genotype having least Na exclusion potential during the lysimeter study. Use of isotonic levels of CaCl2, mannitol, and simulated Na/Ca solutions resulted in similar damage. However, isotonic Na (-Ca) caused highest leakage overall. Correlation between long-term observations in the lysimeters and leakage occurrence-in the laboratory indicates that solute leakage tests may aid in characterizing responses of Pistacia spp. roots cocks to saline conditions.
Growth and B uptake of five pecan [Carya illinoensis (Wangenh.) C. Koch] seedling cultivars were evaluated in two greenhouse experiments. Seedlings were exposed for 7 to 8 months to various B-containing irrigation solutions. In one study, the growth of `Apache', `Riverside', and `Burkett' seedlings declined significantly with a 5.0-mg B/liter application that provided 12.3 mg B/liter in the soil saturation extract. In the second study, B application of 2.5 mg·1iter-1 (6.4 mg·liter-1 in the saturation extract) reduced growth of `Western' and Wichita' seedlings. Seedling sources differed in susceptibility to B applications. `Apache' and `Wichita' seedlings were the more sensitive cultivars in the experiments. Leaf B concentrations increased linearly with concentrations in the saturation extract (r = 0.96 to 0.99), but did not depend on the cultivar. Boron toxicity (leaf interveinal chlorosis and tip necrosis) occurred within several weeks following B application of 1.25 to 2.5 mg·liter-1 (2.8 to 6.6 mg·liter-1 in the saturation extract, depending on cultivar). Three months later, chlorotic areas became necrotic in leaves containing >900 mg B/kg dry weight. Severe necrosis and some defoliation occurred when B concentrations were increased further. Leaves with no injury contained ≤325 mg B/kg.
Seedlings of three pistachio rootstock (Pistacia atlantica Desf., P. terebinthus L., and P. integerrima Stewart × atlantica) and of the pistachio scion cultivar Kerman (P. vera. L.) were grown in calcareous sandy loam irrigated with B solutions (0 to 15 mg·liter-1) in a greenhouse. After 10.5 months of B treatment, rootstock seedling growth (root + stem weight and leaf dry weight, area, and number per plant) had decreased linearly with B application, which provided up to 48.9 mg B/liter in the soil saturation extract. Growth of P. terebinthus was greater than P. atlantica throughout the concentration range, but species sensitivity to B did not differ. Nine months of B at concentrations up to 10.7 mg·liter-1 in the saturation extract did not alter the growth of P. vera seedlings. Leaf B concentrations of all species increased linearly with saturation extract B concentration after each of two growing periods and were higher in leaves of P. terebinthus than P. atlantica. From 62% to 75% of B was present in leaf tissue of the rootstock seedlings, with lower quantities in roots and stems. Boron toxicity appeared initially as interveinal chlorosis and apical necrosis of 1-month-old, fully expanded leaflets of the rootstock species. By 4 months, symptoms in some treatments advanced to severe necrosis of leaflets. Boron addition increased the concentrations of total leaf sugars (glucose, fructose, and sucrose) and root starch, decreased root glucose concentrations, and had no effect on other root carbohydrates of P. vera seedlings. Leaf carbohydrate supply limitations and altered root carbohydrate status may be consequences of high B in P. vera seedling leaves.
A laboratory procedure was used to evaluate saline tolerance of pistachio rootstock species. Results were compared to those from a 2-year, outdoor lysimeter study to test reliability of the method. Excised root tips from seedlings of Pistacia atlantica Desf., P. terebinthus L. (two selections), and P. integerrima Stewart × atlantica (Pioneer Gold II, or PG II), were exposed to laboratory solutions that simulated soil solution electrical conductivity (EC) and Na: Ca ratios in the lysimeters. Following 24 hours of incubation, the efflux of ultraviolet (UV)-absorbing solutes was measured, providing an indication of cell membrane permeability. Leakage occurred with saline solutions comparable to lysimeter soil water salinity that increased leaf Na concentrations and decreased average root growth (175 mm NaCl with 12.5 mm Ca, or EC of 18.1 dS·m-l). Cell injury increased linearly with salinity (R2 = 0.81) and was highest in root tips of a P. terebinthus selection having least Na exclusion capability in the lysimeters. On average, these excised roots lost 38% more solutes than roots of a stronger Na-excluding genotype. There were no differences in leakage responses of the other species and selections. Leakage intensity was independent of various stress media, including isosmotic CaC12, mannitol, and the simulated Na/Ca mixtures in molar ratios of 10:1 to 20:1. With no Ca, however, damage caused by isosmotic NaCl was 76% to 87% higher, indicating that for these species, the Na: Ca ratio can alter root cell membrane permeability. Correlation between long-term observations in the lysimeters and leakage occurrence in the laboratory indicates that solute leakage tests with roots may aid in characterizing Pistacia spp. rootstocks for saline condition.