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  • Author or Editor: P. C. Andersen x
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Leaf physiology and plant growth of Rhododendron × `Pink Ruffles' were compared under conditions of 100% sun and under polyethylene shadecloth with specifications of 69%, 47%, and 29% light transmittance. Net CO2 assimilation (A) and stomatal conductance to water vapor (gs) were often reduced for plants in the 100% sun regime, although few differences existed among the 69%, 47%, and 29% sun treatments. Stomatal conductance was very sensitive to leaf to air vapor pressure deficits (VPD), as evidenced by an 85% increase in gs with a decrease in VPD from 3.2 to 2.2 kPa. Light response curves established for plants after 54 days of exposure to 100% and 29% sun were similar, although A was consistently higher at all levels of photosynthetic photon flux for plants in the 29% sun regime. Maximum A was ≈5 and 6 μmol·m-2·s-1 for 100% and 29% sun-grown plants, respectively; light saturation occurred at ≈ 800 μmol·m-2·s-1 Midday relative leaf water content and leaf water potential were not affected by sun regime. The plant growth index decreased with increasing light level. Leaf, stem, and root dry weights; total leaf number and dry weight; total and individual leaf area; dry weight per leaf; and leaf chlorophyll concentration were reduced in 100% sun, yet few differences existed among the 69%, 47%, and 29% sun treatments. Shoot: root ratio and specific leaf weight were proportional to light level. Plants grown in the 100% sun regime were chlorotic and dwarfed, and plants in 29% sun were not sufficiently compact. One year after transplanting to the field under 100% sun, plants of all treatments were chlorotic and failed to grow.

Free access

Abstract

‘Sungem’ nectarine [Prunus persica (L.) Batsch] (Fig. 1) was released to provide an early ripening nectarine for commercial markets. All nectarines released by the Univ. of Florida begin with the prefix “Sun”. ‘Sun-gem’ is expected to be successful for homeowners, consumer harvest, local markets, and commercial growers with large acreage.

Open Access

Abstract

Nine pesticides (chlorothalonil, captan, benomyl, permethrin, methomyl, parathion, carbaryl, dicofol, and S) were sprayed on peach (Prunus persica L. Batsch ‘June Gold’) to determine pesticide-induced effects on leaf conductance (gl), transpiration (E), and net CO2 assimilation rate (A). Parathion was the only material to reduce A when applied <3 times. Net CO2 assimilation rate declined by 10% to 25% for parathion-, methomyl-, chlorothalonil-, benomyl-, and captan-treated trees after 3 applications; however, gl was reduced only for the parathion and chlorothalonil treatments. The pesticide-sensitivity of peach A appears to be much less than pecan and somewhat similar to apple. Chemical names used: 2,4,5,6-tetrachloro-l,3-benzenedi-carbonitrile (chlorothalonil); 3a,4,7,7a-tetrahydro-2-[(trichloromethyl)thiol]-lH-isoin-dole-l,3(2H)-dione (captan); methyl[l-](butylamino)carbonyl]-lH-benzimidazol-2-yl]carbamate (benomyl); (3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate (permethrin); methyl N-[[(methylam-ino)carbonyl]oxy]ethanimidothioate(methomyl); 0,0-diethyl 0-p-nitrophenylphospho-rothioate (parathion); 1-naphthalenyl methylcarbamate (carbaryl); and 4,4′-dichloro-α-trichloro-methylbenzhydrol (dicofol).

Open Access

Abstract

The development of a high yielding, pink root-resistant [Pyrenochaeta terrestris (Hansen) Gorenz, Walker, and Larson], mild, sweet, shortday onion (Allium cepa L.) with improved shipping quality was the objective for the onion breeding program in the Texas Agricultural Experiment Station. ‘Texas Grano 1015Y’ (TG1015Y) is a very mild and sweet cultivar with those quality characteristics.

Open Access

Abstract

The development of a high yielding, pink root resistant, medium length storage shortday onion (Allium cepa L.) with improved shipping quality and maturing slightly later than ‘Texas Early Grano 502’ (TEG502) was the objective in the development of this cultivar. ‘Texas Grano 1025Y’ (TG1025Y) extends the South Texas onion season by 7 to 10 days beyond the ‘TEG502’ maturity season.

Open Access

Abstract

The development of a late maturing, high yielding, pink root resistant shortday onion (Allium cepa L.) with improved shipping quality was the objective for introduction of this cultivar.

Open Access

Abstract

The development of a late maturing, high yielding, disease resistant shortday onion (Allium cepa L.) with improved shipping quality and medium length storage characteristics was the objective leading to selection and increase of this cultivar.

Open Access