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  • Author or Editor: Dennis Clason x
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Six varieties of Cupsicum annuum, L were selected for the study (Joe Parker, NuMex Sweet, NuMex R Naky, Tam VeraCruz, Sandia, and Conquistador). All seeds were primed in -.90 MPa NaCl, -1.35 MPa NaCl; -1.24 MPa CaCl2, -1.94 MPa CaCl2, -1.43 MPa K2HPO4, -2.09 MPa K2HPO4, and a nonprimed control at 23C in an incubator for 5 days. Seeds were dried for 2 days at 23C, then planted in soilless media under a 10/14 day/night cycle in incubators at either 23C or 15C. Emergence was counted daily for 21 days. Statistical analysis was performed on the rate of emergence and the maximum number of seeds emerged by day 21. There was a significant variety × treatment × temperature interaction when the rate of emergence was used as the variable. Priming improved the rate of emergence over the control among all varieties, treatments and temperatures, but the effect of seed priming on the maximum emergence varied from one variety to the other. Priming was more effective at 15C. The start of emergence averaged 3.5 days over the control at 23C and 7.3 days over the control at 15C. Seeds emerged an average of 7 days faster at 23C than at 15C. Sandia and Conquistador appear to be sensitive to priming treatments and temperature.

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Experiments were conducted to determine variation of in vitro microsclerotia production, pigmentation, and growth of five Pyrenochaeta terrestris (Hans.) Gorenz, Walker, and Larson isolates from Texas and New Mexico. Isolates of P. terrestris, the causal agent of pink root rot, were placed on agar with lo-mm-long sections of sterile onion (Allium cepa L.) roots. Microsclerotia were present after 20 days at 20, 25, 27, or 32C, with the number of microsclerotia dependent on the isolate. Microsclerotia were absent at 35C. One isolate produced few microsclerotia at all temperatures. Optimum temperatures for growth on potato dextrose agar for the isolates tested were 25 and 27C. Pigment production in roots on agar varied depending on isolate and temperature. Three isolates produced high levels of pigment in onion roots at 15, 20, 25, and 27C. A New Mexico isolate produced significantly less visible pigment than the other New Mexico and Texas isolates. One isolate produced very little pigment at all temperatures tested. Constant fluorescent light stimulated pycnidia production in one isolate and reduced microsclerotia production in all other isolates. Isolates varied significantly in microsclerotia production and pigment synthesis.

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