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This study was carried out to determine the interaction among NH4 +, NO3 -, and Cl- ion uptake and to find the causes of NH4 + -related toxicity symptoms in plants fed with NH4 + as a sole nitrogen source. Seedling plants established in peat-lite and rockwool media were fed with nutrient solutions containing either NH4 + or NO3 - or both NH4 + plus NO3 - with or without Cl-. Plants grown with NH4 + + Cl- contained the highest levels of Cl-. Plants fed with NO3 - + Cl- also showed high levels of Cl- in the tissue. The growth and tissue Cl- contents of plants fed with NH4 + were not affected by changes in Cl- concentration in the nutrient solution. Plants fed with NH4 + that was ion-balanced by high levels of SO4 2- plus low or no Cl- still developed the NH4 + -related toxicity symptoms. This indicates that NH4 + -related toxicity symptoms occur independently of Cl-. It was also shown that the activity of Cl-, a counterion for NH4 + uptake, was suppressed by NO3 -.
Ageratum and salvia were grown in hydroponic solutions containing either NH4 +, NO3 -, or both NH4 + and NO3 - with or without Cl- to study changes in solution pH and ion uptake rate. pH of both NH4 + and NH4 + + NO3 - solutions was steadily decreased as time passed. A drop in pH front 6.50 to 3.57 within 3 days was recorded with NH4 +. The pH changes were also affected by the presence of Cl-. The NO3 - treatment maintained its initial solution pH over time regardless of the presence of Cl-. pH change by ageratum was greater than that by salvia, especially when plants were in NH4 + + NO3 - solution. N uptake was maximum in NH4 + + NO3 - solution with Cl-. Uptake of NO3 - was suppressed by NH4 +, but NH4 + uptake was not affected by NO3 -. NH4 + and NO3 - counteracted each other in influencing the Cl- uptake. Uptake of other ion was also affected by plant species as well as N source and Cl-. In ageratum transpiration rate was lowered by Cl- in both NH4 + and NO3 - treatments.
Abstract
Shoot tips and stem nodes of Asclepias erosa Torr., cultured on a modified (0.5 × major salts) Murashige and Skoog (MS) medium containing 0.54 µm (0.1 mg/liter) NAA and 44.4 µm (10 mg/liter) BA, produced multiple shoots in 5 weeks. Subcultures of the individual shoots on the same medium produced 5-12 new shoots 4 weeks later. Rooting of the resultant shoots was best accomplished by preculturing them for 48 hr on MS medium containing 246 or 492 µm (50 or 100 mg/liter) IB A prior to subculturing for 4 weeks on MS medium devoid of growth regulators. The rooted cultures were established successfully in soil. Chemical names used. NAA: 1-naphthaleneacetic acid. BA:N-(phenylmethyl)-lH-purin-6-amine. IBA: lH-indole-3-butanoic acid.
Abstract
Apical shoot tips and axillary buds of buffalo gourd (Cucurbita foetidissima HBK.) when cultured on Murashige and Skoog (MS) medium supplemented with 4.4-22.2 μm (1-5 mg/liter) BA and 0-0.54 μM (0-0.1 mg/liter) NAA produced 4-9 multiple shoots within 4 weeks. The individual shoots subcultured on MS medium containing 4.9 μm (1 mg/liter) IBA produced a healthy root system in 4 weeks. Rooted cultures were successfully transferred to soil in a greenhouse. Chemical names used. BA:N-(phenylmethyl)-1H-purin-6-amine. NAA:l-naphthaleneacetic acid. IBA: lH-indole-3-butanoic acid.
Abstract
Double eye (DE) and single eye (SE) nodal semihardwood cuttings of jojoba [Simmondsia chinensis (Link) Schneider] treated with 2000 ppm indolebutyric acid were rooted successfully under intermittent mist in a mixture of 1 perlite : 1 vermiculite. Differences in rooting percentages between 5-node, single node DE, and single node SE cuttings were not significant. The root systems of 5-node cuttings were much larger than those of nodal cuttings, and DE cuttings produced significantly more roots than SE cuttings. Clonal differences for rooting capability were evident among 12 clones tested; percentage of rooting varied from 30 to 97 for DE cuttings and from 43 to 95 for SE cuttings. Significantly more cuttings rooted in the 1 perlite: 1 vermiculite rooting mix than in Oasis Root Cubes.
Abstract
In a survey of 49 cultivars of muskmelon (Cucumis melo L.), 12 had bitter seedlings and 37 were non-bitter. Bitterness was shown to be controlled by a single dominant gene designated Bi/bi in crosses of bitter ‘Honey Dew’ and the non-bitter ‘Wheat City’ and ‘Queen of Colorado’.
Abstract
Spraying with (2-chloroethyl)phosphonic acid (ethephon) to increase femaleness in andromonoecious muskmelon (Cucumis melo L.) increased hybrid seed production under natural field crossing from 12.0% to 27.4% in ‘Wheat City’ and from 4.0% to 51.5% in ‘Queen of Colorado’. A dominant seedling marker (Bi) in ‘Honey Dew’, the pollinator for both crosses, was used to identify hybrid seed.
A non-destructive in vivo spectroscopic method for leaf chlorophyll (Chl) measurement was developed. Spectroscopic analyses of intact leaves of ageratum, petunia and salvia showed strong correlations between leaf light absorption at 723 nm and Chl-a contents. NH4 + increased Chl contents in both ageratum and petunia whereas NO3 - increased Chl contents in salvia. Plants fed with NH4 + + NO3 - also contained higher Chl. Chl-a/-b ratio in salvia was lowered by NO3 -. Ageratum, petunia and salvia grown with either NH4 +, NO3 -, or NH4 + + NO3 - were also examined for their light absorption characteristics. Light absorption at 705 nm by ageratum and petunia leaves was increased by NH4 + treatment. NH4 + is believed to have changed the structure of photosystem I in both ageratum and petunia but not in salvia. This result explain reasons for salvia's sensitivity to NH4 + fed as a sole N source.
Toxicity symptom of micronutrients copper, magnesium and zinc were investigated for geranium, marigold, vinca and zinnia. Plants were grown in peat-lite mix in 11 cm plastic pots and watered with nutrient solutions containing 0.05, 0.5, 1, 5, 10 mM concentrations of Cu2+, Mg2+ and Zn2+. In most species, the concentrations of these micronutrients higher than 5 mM greatly reduced plant growth and induced stem and foliar toxicity symptoms. Toxic levels of Cu2+ and Zn2+ reduced plant and leaf sizes without producing leaf spots in all species tested. Toxicity symptom of Mn2+ were characterized by numerous chlorotic or brown leaf spots. Visual leaf toxicity symptoms of these 3 micronutrients in each species are illustrated.
A non-destructive in vivo spectroscopic method for leaf chlorophyll (Chl) measurement was developed. Spectroscopic analyses of intact leaves of ageratum, petunia and salvia showed strong correlations between leaf light absorption at 723 nm and Chl-a contents. NH4 + increased Chl contents in both ageratum and petunia whereas NO3 - increased Chl contents in salvia. Plants fed with NH4 + + NO3 - also contained higher Chl. Chl-a/-b ratio in salvia was lowered by NO3 -. Ageratum, petunia and salvia grown with either NH4 +, NO3 -, or NH4 + + NO3 - were also examined for their light absorption characteristics. Light absorption at 705 nm by ageratum and petunia leaves was increased by NH4 + treatment. NH4 + is believed to have changed the structure of photosystem I in both ageratum and petunia but not in salvia. This result explain reasons for salvia's sensitivity to NH4 + fed as a sole N source.