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  • Author or Editor: Marvin L. Baker x
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Fermentation and other seed pregermination treatments of Mayhaw [Crataegus opaca (1.) Hook and Arn-Series Aestivales] (Vines,; Phipps, 1988) were evaluated as potential requirements to increase germination percentages. Low seed germinability and arratic seedling emergence are major problems in Crataegus breeding. Freshly harvested fermented open-pollinated seed from 5 different Mayhaw selections averaged 93.4% at 8 days fermentation and 92.8% at 4 days fermentation. Frozen fruit stored from these 5 selections and later fermented 12 days showed the following higher percentages of germination: frozen storage for 10 days - 87.2% (<4 days fermentation (df); frozen storage for 20 days - 83.8% (<4 days df; frozen storage for 30 days - 74.4% (<8 df; frozen storage for 40 days - 72.6% (<4 df; frozen storage for 60 days - 70.2% (<4 df and frozen storage for 90 days - 60.8% (< 8 df. Positive responses to short fermentation durations (<8 days) were observed, but longer fermentation durations were deleterious. Embryo dormancy requiring acid treatment or stratification and problems with germination inhibiting substances were minimized by fermenting fresh ripened fruit containing large embryos. The fruits and seed were not allowed to dry and they were either prepared immediately or frozen for later use.

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In North America, cultivation of Mayhaws (Crataegus opaca L.) is rare; most commercial harvest is taken from the wild. Crataegus opaca is distributed in northeast Texas, east Texas and southeast Texas along the flood plains of the Angelina and Neuches rivers and their watersheds. Mayhaws are difficult to define due to unusual factors relating to reproduction, including apomixis, or the development of an embryo from cells other than sex cells. Mayhaws are valued for economic use as food, medicine and ornamentals. Since the hawthorn has shown extremely low toxicity in every animal tested, the discovery of isolated constituents thru research has caused pharmacological interest. A small orchard plot of selections with ripened fruit measuring larger than 2.5 cm up to 3.1 cm with bright red or pink color is being established for selecting possible cultivars for medicinal or food uses.

Five Crataegus opaca selections were collected due to showing spurtype, large fruits and thornlessness. Yearly production of fruit was noted for five years (even after late freezes) while selections grew in Taggert's Flat, Neuches river bottom, Angelina County. Seedlings are being grafted for further evaluations and uses in sustainable agricultural ecosystems.

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Liners of Rosa `MEIrutral' (=Red Sunblaze) were potted in 11.5-cm pots using Fison's Sunshine Mix no. 2 amended with 0%, 10%, 20%, or 30% composted poultry litter (PL) by volume. Plants were grown for 3 weeks before cutting back to 5 cm for final forcing (short-cycle) and were fertilized with 200 mg N/liter from 20N–8.9P–16.6K on a three feed and one leach schedule for the duration of the experiment. By flowering, plants growing in the 30% PL media were dead or stunted. However, there was little difference in total number of flowers, days to flower, and root and shoot dry weight between the other treatments. Media pH rose from 6.6 to 7.4 and EC rose from 0.7 to 6 millimhos with increasing PL content. This result alone could explain the poor growth in the highest PL rate treatment. However, tissue N levels were supraoptimal for the 20% and 30% PL rates, and tissue P levels were excessive for all PL rates. If a high-quality source of composted PL is available, it could be used as a media component for potted rose production at rates <20%, but monitoring of pH and EC and modifying fertilization techniques may be necessary to ensure success.

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Eight individual potatoes, exhibiting a wide range of quality characteristics, were cloned at the Texas A&M Vegetable Improvement Center, College Station, Tex., in order to produce a large number of slips for field trials. Leaf photosynthetic light response for six of these clonal selections was determined during a greenhouse experiment conducted at the Texas A&M Univ. Agricultural Research and Extension Center at Overton, Tex. Photosynthesis data were fit to a rectangular hyperbola in order to estimate light saturated leaf photosynthetic rate (Amax), quantum efficiency (QE), and dark respiration rate (Rd). Significant differences (P ≥ 0.05) were detected in all three of these parameter estimates among the six clonal selections. Parameter estimates ranged from 23.4 to 28.8 μmol (CO2) m-2·s-1, 0.056 to 0.071 mol (CO2)/mol (photons), and –0.9 to –2.0 μmol (CO2) m-2·s-1 for Amax, QE, and Rd, respectively. However, these differences were not clearly related to quality characteristics determined for these clones in field trials.

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