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  • Author or Editor: U.L. Yadava x
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Abstract

The reliability, capability to predict survival, and convenience of 5 cold hardiness tests — triphenyl tetrazolium chloride reduction (TTC), electrolytic conductance (EC), ninhydrin-reactive compounds (NRC), trunk cambial browning (TCB), and bacterial canker development (BCD) — were evaluated using previous season's twigs of ‘Redhaven’ peach (Prunus persica (L.) Batsch) during the 1976-77 dormancy season. TTC, NRC, and EC were all significantly correlated with TCB as well as percent tree survival (PTS) in the field, and thus proved to be quantitative, reliable and capable of predicting survival at a later date. No statistical correlation was found between BCD and other hardiness tests.

Open Access

Interactions between irradiance levels (5–40 μmol·m-2·s-1) and iron chelate sources (FeEDTA and FeEDDHA) were observed for Carica papaya shoot tip cultures during both the establishment and proliferation stages of microculture. Reduced levels of irradiance (5 μmol·m-2·s-1) favored shoot tip establishment regardless of the source or level of iron. However, the highest percentage of successful explant establishment (100%), and significantly greater leaf length (1.16 cm; over double the size attained in any other treatment), resulted when a low concentration of FeEDTA alone was used at low irradiance. During the subsequent shoot proliferation stage, however, higher irradiance levels (30 and 40 μmol·m-2·s-1) were required, and FeEDTA failed to support culture growth when used as the sole iron source. The highest multiplication rates (3.6 shoots per explant) and leaf chlorophyll concentrations (0.22 mg/g fresh mass), and significantly improved shoot quality were achieved at 30 μmol·m-2·s-1 irradiance when both iron chelate formulations were combined (each at a 100 μM concentration) in the proliferation medium. Chemical names used: benzylamino purine (BA); ferric disodium ethylenediamine tetraacetate or FeNa2EDTA (FeEDTA); ferric monosodium ethylenediamine di(o-hydroxyphenylacetate), (FeNaEDDHA) or Sequestrene 138Fe (FeEDDHA); indoleacetic acid (IAA); 1-naphthaleneacetic acid (NAA).

Free access

Abstract

Effects of 8 peach seedling rootstocks on tree growth, survival, and fruit yield of ‘Redhaven’ and ‘Loring’ peach scion cultivars were tested in Alabama, Arkansas, Georgia, North Carolina, and South Carolina. Lovell seedling rootstock was a standard for comparison. Six years of data indicated that Siberian C was not an acceptable rootstock because tree survival and fruit yield were low. Halford was equivalent to Lovell for tree growth, fruit yield, and survival. Fruit size was unaffected by rootstock. Nemaguard and 2 North Carolina selections were resistant to root-knot nematodes (Meloidogyne spp.) but they were not resistant to ring nematodes [Criconemella xenoplax (Raski) Luc and Raski]. Soil fumigation improved tree survival in nematode-infested soil.

Open Access