Effect of paclobutrazol on water stress-induced ethylene biosynthesis and polyamine accumulation in apple seedling leaves

Ethylene biosynthesis and polyamine content were determined in [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol] (paclobutrazol) pre-treated and non-treated water-stressed apple seedling leaves. Paclobutrazol reduced water loss, and decreased endogenous putrescine spermidine content. Gibberellic acid (GA) counteracted the inhibitory effect of paclobutrazol on polyamine content. Paclobutrazol also prevented accumulation of water stress-induced 1-aminocyclopropane-1-carboxylic acid (ACC), 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), ethylene production and polyamines in apple leaves. α-Difluoromethylarginine (DFMA), but not α-difluoromethylornithine (DFMO), inhibited the rise of putrescine and spermidine in stressed leaves. S-Adenosylmethionine (SAM) was maintained at a steady state level even when ethylene and the polyamines were actively synthesized in stressed apple seedling leaves. The conversion of ACC to ethylene did not appear to be affected by paclobutrazol treatment.     

Effect of paclobutrazol on membrane lipids in apple seedlings

The effect of paclobutrazol [( 2RS, 3RS )-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2, 4-triazol-1-yl) pentan-3-ol] on the fatty acid composition of polar lipids and on the sterol content in apple ( Malus domestica Borkh. cv. York Imperial) seedlings was determined. Polar lipids isolated from leaves, stems and roots included mono- and digalactosyldiglycerides and the phospholipids phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The predominant fatty acids in membrane polar lipids were palmitic (C16:0), linolnic (C18:2) and linolenic (C18:3). The predominant sterol, both free and esterified, was β-sitosterol. There were no significant alterations in the fatty-acid composition of glyco- and phospholipids from paclobutrazol-treated apple seedlings. In contrast, a significant decrease in the content of β-sitosterol and campesterol occurred in treated tissues. The decline in sterol content continued with increasing duration of paclobutrazol treatment, and was most pronounced in the root tissue.     

Effect of paclobutrazol on water stress-induced abscisic Acid in apple seedling leaves

Abscisic acid (ABA) was quantitated by enzyme-linked immunosorbent assay (ELISA) in water-stressed leaves from control apple seedlings, and also from apple seedlings treated for 28 days with paclobutrazol ([2RS, 3RS]-1-[4-chlorophenyl]-4,4-dimethyl-2-[1,2,4-triazol-1-yl] pentan-3-ol). The ELISA quantitative estimates were also validated by gas chromatography-electron capture detector and lettuce seed germination inhibition bioassay. Paclobutrazol treatment reduced endogenous ABA levels by about one-third, and prevented the marked accumulation of water-stress-induced ABA that occurred in untreated seedlings. The presence of ABA in the apple leaf extracts was confirmed by gas chromatography-mass spectrometry.     

Effect of paclobutrazol on cell wall polysaccharide composition of the apple tree

The effect of paclobutrazol, a gibberellin biosynthesis inhibitor, on cell wall carbohydrate composition of apple shoots was determined. Inhibition of apple shoot extension corresponded to a change in wall composition. Paclobutrazol did not inhibit shoot growth during the first year (1983) after the treatment. There was also no significant difference in cell wall carbohydrate composition between control and paclobutrazol treated shoots. In the second year (1984), however, paclobutrazol altered the composition of cell wall polysaccharides and inhibited shoot extension. Paclobutrazol treatment increased rhamnose, arabinose and galacturonic acid but decreased cellulose. The ratio of xylem to phloem was also reduced by paclobutrazol treatment.     

Translocation of paclobutrazol, a gibberellin biosynthesis inhibitor, in apple seedlings

The [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1- yl)-pentan-3-ol] (paclobutrazol, PP333) measured in apple seedlings (`York Imperial' Malus domestica Borkh) was confirmed by gas chromatography-mass spectrometry. Data showed that paclobutrazol was taken up through roots and transported primarily in the xylem through the stems and accumulated in leaves. No detectable basipetal movement of paclobutrazol in apple seedlings was found.     

Effect of amino acids on rooting of apple dwarf rootstocksin vitro

The effect of twelve amino acids and lactalbumin hydrolysate in concentration of 200 mg 1^?1 on rooting of the dwarf apple rootstocks P 2 and P 60 was testedin vitro. Arginine, omithine, glutamic acid and glycine enhanced root number of the P 60 rootstock; proline and lactalbumin hydrolysate were neutral; and asparagine, tyrosine, methionine, cysteine and glutamine lowered the root number. Tyrosine, methionine, cysteine and glutamine reduced almost completely rooting of P 60. In the recalcitrant P 2 rootstock aspartic acid, glutamic acid and omithine significantly enhanced the number of roots and rooted shoots, arginine and tryptophan increased the root number only slightly, asparagine was neutral, and proline reduced the root number.     

开垦对绿洲农田碳氮累积及其与作物产量关系的影响

以新疆策勒绿洲近百年来不同开垦年限农田为研究对象,采用空间序列换算时间序列的方法,研究绿洲农田开垦过程中土壤有机碳和全氮密度、碳氮比(C/N)及速效氮含量的垂直变化特征,并探讨了农田土壤碳氮变化与作物产量的关系。结果表明:荒漠土壤开垦后,显著增加了表层土壤(0-20 cm)有机碳和全氮密度,随开垦年限延长对深层土壤(40-200 cm)有机碳密度也有一定的影响,如在开垦30 a左右时下降了36.4%,但在100 a左右时则增加了52.0%。耕层土壤C/N随开垦年限延长而明显增加,深层土壤除100 a农田外其它均有不同程度下降;不同土层C/N与速效氮含量呈负相关关系,仅在开垦初期(0-10 a)达到显著水平。不同年限农田的玉米产量存在显著差异,且和有机碳及全氮密度(0-200 cm)均呈显著正相关;棉花除100和10 a农田产量差异较小外,在其它农田间均达显著水平,但和有机碳及全氮密度无明显相关性。由此可见,在现有投入条件下,提高土壤碳氮累积量对增加玉米产量仍有十分重要作用,但对棉花产量的影响不明显。     

Uptake and translocation of paclobutrazol by shoots of M.26 apple rootstock

When ¹⁴C-paclobutrazol, a gibberellin synthesis inhibitor, was applied to different parts of actively-growing M.26 apple rootstock shoots it was translocated acropetally when applied to the young stem and, to a lesser extent, from the youngest unrolled leaf. Paclobutrazol was not translocated out of leaf laminae, shoot tips or from one-year-old wood but translocation occurred out of a treated petiole into the attached leaf. No basipetal translocation was detected. This translocation pattern suggested movement through the xylem.Localised application of paclobutrazol caused a reduction in shoot extension and leaf production when the young stem or shoot tip were treated; the effect decreased as older parts of the stem were treated. Treatment of laminae or petioles had only a slight effect on shoot extension and treatment of one-year-old wood was ineffective. Combined treatment of the shoot tip plus young stem was similar in effect to treatment of the complete shoot.It is suggested that paclobutrazol exerts its effects on shoot growth by inhibiting gibberellin biosynthesis in the shoot tip and the expanding leaves.The findings contribute to an understanding of the requirements for efficient orchard application of foliar sprays of paclobutrazol.     

Growth retarding effects of paclobutrazol and RSW 0411 on Granny Smith and Fuji apple trees

The growth retardants paclobutrazol (β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol) and RSW 0411 (β-(cyclohexyl methylene)-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol) were tested on two-year-old trees of Granny Smith and Fuji apple. RSW 0411 at 100 mg/L did not cause any growth reduction in Granny Smith, while 500 and 1000 mg/L significantly reduced growth below that of the control between 27 and 40 days after application. Paclobutrazol at 100 mg/L had significantly reduced shoot growth between 27 and 55 days after application, and 1000 mg/L reduced shoot growth between 27 and 82 days after application. By 100 days after application, there were no longer differences between treatments. Shoot growth on Fuji trees was reduced below that of the control as follows: between 14 and 27 days following a single application of 500 mg/L RSW 0411; between 27 and 55 days following two applications; between 14 and 72 days following three applications; and between 14 and 82 days following four applications. Treatments were applied 14 days apart. Paclobutrazol was a more active growth retardant than RSW 0411 at the same rate, and the growth-retarding effects of RSW 0411 were short-lived.     

Effect of bicarbonate on root growth and accumulation of organic acids in Zn-inefficient and Zn-efficient rice cultivars (Oryza sativa L.)

Bicarbonate has been regarded as a major factor for inducing Zn deficiency in lowland rice, but the mechanisms responsible for this effect are not yet fully understood. The objective of the present study was to test whether early effects of bicarbonate (HCO₃ ⁻)are inhibition of root growth due to the accumulation of organic acids induced by HCO₃ ⁻. Solution culture experiments were conducted using two rice cultivars differing in susceptibility to Zn deficiency, and four bicarbonate concentrations (0, 5, 10, 20 mM). Bicarbonate (5–20 mM) strongly inhibited root growth of the Zn-inefficient cultivar within 4 days of treatments. In contrast, root growth of the Zn-efficient cultivar was slightly stimulated with bicarbonate at 5–10 mM and not affected at 20 mM. The inhibitory effect of bicarbonate on root growth in the Zn-inefficient cultivar was mainly that of impairment of new root initiation rather than suppression of elongation of individual roots. Bicarbonate (5–20 mM) increased the concentrations of malate, succinate and citrate in the roots of both cultivars, but to a greater extent for the Zn-inefficient than for the Zn-efficient cultivars. The results suggest that the impairment of root growth was likely to be the initial action of bicarbonate in inducing Zn deficiency in lowland rice, and the inhibitory effect of bicarbonate on root growth of the Zn-inefficient cultivar might result from high accumulation and an insufficient compartmentation of organic acids in the root cells.     

Responses in organic matter accumulation and processing to an experimental wood addition in three headwater streams

1. Additions of large wood are being used to restore streams that have been subjected to channelization, wood removal or riparian timber harvest. This added wood potentially increases channel stability, habitat complexity and organic matter retention and improves habitat and productivity of higher trophic levels. However, few stream restorations monitor restoration effectiveness after project completion. 2. We added 25 aspen logs (each 2.5 m length × 0.5 m diameter) to 100‐m reaches of each of three forested headwater streams in the Upper Peninsula of Michigan, U.S.A. These wood‐poor streams drain forests that were completely harvested of timber over a century ago and have been selectively logged for the past 50–60 years. An upstream unmanipulateds 100‐m reach in each stream served as the control. 3. We evaluated responses in organic matter processing by measuring red maple leaf decomposition 1 year before and 2 years after wood addition. We also quantified coarse organic matter standing stocks in the main channel and in debris accumulations associated with large wood. In response to wood addition, we predicted both organic matter standing stocks and leaf decomposition rates would increase, thereby enhancing resource availability to higher trophic levels. 4. Leaf decomposition rates did not change following wood addition. Temporal variation in rates among streams was mostly explained by differences in degree days, water velocity, scour/burial and water column inorganic nitrogen concentrations, but not large wood. Variation within streams across years was explained by differences in degree days, water velocity and shredder biomass. 5. Contrary to our prediction, organic matter standing stocks did not increase significantly at the reach scale. However, the experimentally added wood retained c. 4% of total annual coarse benthic organic matter (CBOM) in the first year and an additional c. 15% in the second year, suggesting accumulation over time in the manipulated reaches. The CBOM held by the new logs may be more biologically available because it is less susceptible to burial and transport than material in the streambed. 6. Some shredding macroinvertebrates responded to changes caused by the wood additions. In particular, the common caddisfly shredder, Lepidostoma sp., increased in abundance in leaf bags following wood addition, whereas the biomass of the winter stoneflies, Capniidae, declined in the first year. 7. Considerable funds are spent to restore in‐stream habitat, but few restorations are monitored, particularly over long periods (>5 years). Our results show that longer‐term monitoring is needed to determine the efficacy of these restorations on ecosystem function; organic matter decomposition in our low‐gradient streams did not respond to a substantial increase in large wood after 2 years.     

Effect of plant oils and organic acids on rumen fermentation in vitro

We determined the effect of plant oils (rapeseed, sunflower, linseed) and organic acids (aspartic and malic) on the fermentation of diet consisting of hay, barley and sugar beet molasses. Rumen fluid was collected from two sheep (Slovak Merino) fed with the same diet twice daily. Mixed rumen microorganisms were incubated in fermentation fluid, which contained rumen fluid and Mc Dougall's buffer. All supplemented diets significantly increased pH, molar proportion of propionate, and numerically decreased methane production. Lactate production was also decreased significantly (except with malate). Incorporation of plant oils into aspartate- and malate-treated incubations negated the decrease of butyrate, lactate and the increase of pH and ammonia with malate treatment, as well asin vitro dry matter digestibility and pH with aspartate treatment. The effect of combined additives on methane production and molar proportion of propionate was lower compared with additives supplemented separately. Combination of additives had no additive effect on rumen fermentation. All additives decreased total protozoan counts in rumen fluid.     

Influence of an inhibitor of gibberellin biosynthesis, paclobutrazol, on apple seed gibberellin content

Tissue-culture-propagated own-rooted cv. Spartan apple trees (Malus domestica Borkh.) planted in 1979 were treated in 1983 and 1985 via a soil-line trunk drench with the plant growth retardant paclobutrazol [(2RS, 3RS)-1-(4-chlorophenyl)-4.4-dimethyl-2-(1,2, 4-triazol-1-yl) pentan-3-ol]. Seeds of immature fruits from untreated and treated trees were sampled in 1989 ca 75 days after full bloom. After seeds were freeze-dried, gibberellins (GAs) were extracted, purified and fractionated via C₁₈ reversed-phase high-performance liquid chromatography (HPLC). Gibberellins A₁, A₃, A₄, A₇, A₈, A₉, A₁₅, A₁₇, A₁₉, A₂₀, A₂₄, A₃₄, A₃₅, A₄₄, A₅₁, A₅₃, A₅₄, A₆₁, A₆₂, A₆₃ and A₆₈ were identified by using C₁₈ HPLC, gas chromatography-selected ion monitoring and Kovats retention indices. Eight of the GAs identified were also quantified by using deuterated internal standards. The paclobutrazol applications caused a 55% reduction of vegetative shoot elongation in 1989, but both treated and untreated trees had developed a biennial bearing pattern by that time (heavy bloom or “on year’in 1989). Levels of early 13-hydroxylation pathway GAs, viz. GA₅₃, GA₁₉, GA₂₀, GA₁ and also GA₃, were not altered by treatment. However, GA₄, GA₇ and GA₉ were increased 13.4, 6.5 and 3.8 times, respectively, in seeds of fruit from treated compared to untreated trees.     

Effect of paclobutrazol on abscisic acid levels in wheat seedlings

Contradictory results have been reported for the effects of triazoles on abscisic acid (ABA) levels in plants. Paclobutrazol reduced the height, fresh weight, and ABA levels of wheat seedlings. The magnitude of the inhibitory effect of paclobutrazol on ABA levels was dependent on the length of time after application. ABA levels in plants as determined by gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) were reduced by 50–60% 2 days after soil application. A further 15% reduction occurred by the seventh day after treatment. ABA level analyses began at the time of treatment with 4-day-old seedlings and continued until 21 days after treatment when only a 20% reduction was detected. These determinations using GC-SIM-MS should increase the understanding of triazole effects on ABA levels.     

Fatty acids,resin acids and phenols in Pinus muricata

Acetone-soluble extractives of “blue” and “green” strain Pinus muricata D. Don were found to consist of free and “combined” fatty acids, resin acids, and phenols. The composition of the extractives from the two strains was similar though “green” strain P. muricata contained more Δ^8(9),15 isopimaric acid than “blue” strain. This difference may be used to identify these muricata strains if the age of the wood precludes a monoterpene examination.     

Effect of paclobutrazol on abscisic acid levels in wheat seedlings

Contradictory results have been reported for the effects of triazoles on abscisic acid (ABA) levels in plants. Paclobutrazol reduced the height, fresh weight, and ABA levels of wheat seedlings. The magnitude of the inhibitory effect of paclobutrazol on ABA levels was dependent on the length of time after application. ABA levels in plants as determined by gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) were reduced by 50–60% 2 days after soil application. A further 15% reduction occurred by the seventh day after treatment. ABA level analyses began at the time of treatment with 4-day-old seedlings and continued until 21 days after treatment when only a 20% reduction was detected. These determinations using GC-SIM-MS should increase the understanding of triazole effects on ABA levels.