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Exposure of young pepper plants to chilling temperatures delays the development of terminal flower buds to flowering during post-stress growth. Degree of adverse influence depends on chilling intensity, exposure duration and varietal sensitivity. `Ma Belle' pepper plants were grown in a greenhouse (GH) during winter months on the St. Paul campus, No supplemental lighting was provided. When plants were at the 2- to 3-leaf stage, they were foliar sprayed with mefluidide (Technical grade) at 0, 5, 10 and 15 ppm. One day after treatment, some plants were transferred from GH to a cold room (3° ∼4°C day/night) with 12-h photoperiod. Treatad plants remaining in the GH served as the control. Plants were chilled for 1, 2, 4 and 6 days and then brought back to the GH for post-stress growth and development observation. Treated and untreated plants grown in the GH showed no difference in days to flowering, and reached 50% flowering at about 62 days after treatment. When untreated plants were chilled for 1,2,4 and 6 days, they showed a delay of 8, 18, 30 and 34 days, respectively, to flowering, If not killed, as compared to the control The long delay to flowering was due to the injury of the terminal flower buds. After 4 and 6 days of chilling, most terminal flower buds were killed. However, when plants were treated with mefluidide and subsequently chilled days to flowering were significantly shortened. A difference of 10-12 days was observed between chilled untreated plants and chilled treated plants. Concentrations of 5 to 15 ppm were equally effective in protection against chilling.
Exposure of young pepper plants to chilling temperatures delays the development of terminal flower buds to flowering during post-stress growth. Degree of adverse influence depends on chilling intensity, exposure duration and varietal sensitivity. `Ma Belle' pepper plants were grown in a greenhouse (GH) during winter months on the St. Paul campus, No supplemental lighting was provided. When plants were at the 2- to 3-leaf stage, they were foliar sprayed with mefluidide (Technical grade) at 0, 5, 10 and 15 ppm. One day after treatment, some plants were transferred from GH to a cold room (3° ∼4°C day/night) with 12-h photoperiod. Treatad plants remaining in the GH served as the control. Plants were chilled for 1, 2, 4 and 6 days and then brought back to the GH for post-stress growth and development observation. Treated and untreated plants grown in the GH showed no difference in days to flowering, and reached 50% flowering at about 62 days after treatment. When untreated plants were chilled for 1,2,4 and 6 days, they showed a delay of 8, 18, 30 and 34 days, respectively, to flowering, If not killed, as compared to the control The long delay to flowering was due to the injury of the terminal flower buds. After 4 and 6 days of chilling, most terminal flower buds were killed. However, when plants were treated with mefluidide and subsequently chilled days to flowering were significantly shortened. A difference of 10-12 days was observed between chilled untreated plants and chilled treated plants. Concentrations of 5 to 15 ppm were equally effective in protection against chilling.
Insect resistance in vegetable crops carries a new urgency as insecticide availability and usage become more restricted. The European corn borer (ECB) long has been the most costly sweet corn pest in the northern states, with corn earworm (CEW) and southwestern stalk borer most serious farther south. Resistance to ECB and CEW, as developed by classical methods, will be discussed. Newer methods (such as RFLPs) should speed transfer of this resistance to commercial stocks, and also facilitate transfer of resistance from other species. Gene modification and endophyte exploitation are longer-term possibilities. Resistance must be free from association with undesirable traits, such as long silk channel length (r = 0.3 to 0.4), unless consumer and processor specifications change.
184 random F2 plants from a high temperature (HT) sensitive X HT tolerant snap bean cross were advanced to the F5 by single seed descent. At anthesis and after HT pre-treatment, all plants in each generation were evaluated in the laboratory for leaf ethylene evolution (EE), % viable pollen (VP), and leaf cell membrane thermostability (CMT). Population means among generations differed significantly for VP and CMT in a paired t-test, while EE means in the F3, F4, and F5 were similar. Correlations among traits were very low (≤.25) with a consistent negative correlation between VP and the others (high VP is a positive trait while low EE and CMT are considered positive). VP and total pollen were highly correlated (r≤.81). To determine if the 3 traits might predict HT tolerance in the field, F5-derived F6 lines were grown at Becker, MN (control), and Isabella, PR (HT environment). Yield component data were collected at both locations. Tolerance may be computed as % yield of the lines in the HT vs. the control environment for any or all of the yield components. Regression analysis showed a very low r2 (≤.16) when EE, VT, and CMT were used to predict tolerance as estimated by pod production. However, as expected, the F5 best predicted F6 performance. Further results from Minnesota field and greenhouse and from Puerto Rico field data will be discussed.
European corn borer, Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. The isolation and identification of allelochemicals that detrimentally affect O. nubilalismay improve breeder selection for host plant resistance, thus reducing the need for insecticide application. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. Ground lyophilized tissue from field-grown plants was added to a nutritionally complete larval diet before infestation with O. nubilalis neonates. Larval weights on a 10-day basis and time to pupation were recorded to estimate larval development. Tissue and genotype main effects affected (P ≤ 0.05) 10-day larval weight and time to pupation. Silk tissue (P ≤ 0.05) reduced 10-day larval weight and increased the time to pupation compared with kernel tissue and the cellulose control, which did not differ. Silk tissue reduced larval weight by 65% and increased time to pupation by 4.0 days compared with the cellulose control. Genotypes variously affected (P ≤ 0.05) larval growth and development, reducing 10-day larval weight up to 51% and increasing the time to pupation up to 4.2 days when comparing the best genotype for each developmental stage with the cellulose control. Silk tissue of some genotypes may contain allelochemicals that decrease the rate of larval growth and development. The status of allelochemical detection in silk tissue will be discussed.
A group of 53 institutions of higher education in the United States and Canada offering degrees in horticulture, or closely related plant science degrees, was surveyed to determine various characteristics associated with the degree programs offered, demographics of students and faculty, and selected procedures and practices associated with administration of these graduate programs. Total response rate was 94%, yielding 85% usable completed surveys. Very few programs (0-3 per degree type) were offered via distance education and on average only 4.1% to 4.5% of resident instruction program students participated in distance education courses. Domestic students averaged 64% to 75% of enrollment. Students were 69% to 73% white. Asian students were the predominant minority group at 12% to 16% of enrollment, followed by African Americans (3% to 8%) and Hispanics (1% to 4%). Most institutions provided out-of-state tuition waivers (75%), and often in-state-tuition waivers (61%), to those students on assistantships or fellowships. Typical commitments to students were 3 years for a PhD and 2 years for a master's degree program. Research assistantships were the dominant form of assistance at all institutions (38% to 53% of students), while teaching assistantships contributed significant secondary funding (7% to 13%). With the exception of mean maximum fellowships, mean maximum assistantships ($11,499-$13,999) at non-1862 Morrill Act universities (NMAU) averaged near the mean minimums ($13,042-$14,566) for the corresponding assistantship types at 1862 Morrill Act universities (MAU). Requirements for teaching experience ranged from 41% of PhD programs to 18% of non-thesis master's degree programs. Typical departments contained 29 faculty members, of which 44% were full professors, 27% associate professors, 19% assistant professors, 6% junior or senior lecturers, and 3% were in other classifications. Traditional 12-month appointments (65.9% of faculty) were predominant at MAU. With the exception of junior lecturer positions, mean salaries at MAU averaged $9125, $6869, $8325, and $28,505 more for professor, associate professor, assistant professor, and senior lecturer, respectively, than at NMAU. This study provides useful information for departments undergoing external review or revision of graduate programs.
A computerized information delivery system (AgTiIPS) was developed to deliver lawn, garden, and horticultural information to the public. AgTiIPS was based on voice-mail technology, which allows the public to access about 100 messages through a tone-producing telephone. AgTiIPS has been functioning in a Wyoming community of 47,000 since July 1990, and has delivered more than 700 messages in 1.5 years. Economic analyses for setting up voice-mail systems were conducted and the role of voice-mail in delivering lawn, garden, and horticultural information was discussed.
Yield in common bean, Phaseolus vulgaris L., can be significantly reduced by high temperature (I-IT) during bloom. Ethylene production from plant tissue increases as a consequence of various stresses, including heat stress. The inheritance of leaf ethylene evolution rate (EER) of HT-stressed (35/30C day/night) progenies from crosses among bean genotypes previously categorized as HT sensitive or tolerant, based on cell electrolyte leakage, was investigated. Evidence from generation means analysis of Fl, F2, and backcross progenies shows EER to be genetically controlled, with additive, dominance, and epistatic effects indicated for low EER. The range (0.62 to 2.52 μg-1·hr-1) of EER from field-grown lines and cultivars suggests the existence of considerable genetic variability. EER was associated (r = –0.70) with heat tolerance, as estimated by cell electrolyte; leakage.
A comprehensive survey of American and Canadian universities that offer masters, doctoral, or both degrees in horticulture resulted in responses from 27 academic units. Units were surveyed regarding types of degrees offered, admissions policies, demographic characteristics of students, financial assistance provided to students, faculty ranks and salaries, and metrics by which the programs were evaluated by university administration. About 80% of the programs resided in 1862 Morrill Act land-grant institutions (LG) with the remainder housed in other non-land-grant institutions (NLG). Thirty-eight percent of reporting LG programs existed as stand-alone horticulture departments, whereas horticulture programs were combined with other disciplines in the remainder. Admissions criteria were most consistent among LG programs. Participation in distance education programs was low, but growing. Financial support of graduate students was more common in LG programs. Most schools offered some sort of tuition reduction to those students on assistantships/fellowships and offered health insurance options. Payment of fees was rare and the level of stipends provided varied substantially among programs. International student enrollment was greatest at LG programs and had remained steady in recent years. Gender equity was present among graduate students, with nearly equal male and female enrollment. Most graduate students at both LG (63.6%) and NLG (75.0%) programs were non-Hispanic White; although overall minority enrollment had increased but was still not similar in distribution to that of the general U.S. population. Professors (46.7%) and Associate Professors (28.3%) dominated the faculty ranks while Assistant Professors (19.3%) and lecturers/instructors (5.7%) constituted a much smaller portion of the faculty. Faculty salaries varied tremendously among institutions, especially for senior faculty. Female and ethnic minorities were underrepresented in faculty ranks compared with the general U.S. population. Aside from total graduate program enrollment, the relative importance of various evaluation metrics for programs was highly variable among institutions. Data discussed herein should be useful to universities with horticulture graduate programs for peer institution comparisons during program assessments, accreditation reviews, or for strategic planning purposes.