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- Author or Editor: C.B. Ely x
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The Department of Plant and Soil Science at Texas Tech University has developed on-line master's of science nonthesis and master's of agriculture nonthesis degree programs in response to the perceived needs of mature place bound students. Initial enrollments have been successful. The development of these types of programs requires time, funding and technically capable personnel. In addition, there are administrative, curricular and personnel issues involved with the implementation of such a project. These issues and the solutions we have employed will be discussed.
The trailing blackberries (Rubus sp. L.), particularly `Marion', are the primary blackberries grown for the processing market and they are largely machine harvested. While `Marion' is well known for its processed fruit quality, particularly flavor, aroma, and perception of low seediness, it has spines (thorns) that can be dislodged when machine harvested and end up in the product. A primary goal of the USDA–ARS blackberry breeding program in Corvallis is the development of cultivars that are comparable to `Marion' in fruit quality but are spineless (thornless). Nine thornless selections were compared with four standard cultivars as individually quick-frozen (IQF) and puree products in a blind evaluation. Each sample was scored panelists from the blackberry industry and research program. IQF samples were scored for appearance, color, seediness, flavor, and overall quality by 21 panelists and purees were scored for color, flavor, aroma, and overall quality by 25 panelists. Both panels used a 9 point hedonic scale (1 = dislike extremely, 5 = neither like nor dislike, 9 = like extremely). With the exception of color, there were significant differences among all genotypes for all traits evaluated in the IQF and pureed products. ORUS 1380-1 was ranked similar to `Marion' and significantly better than `Waldo', in overall quality of the IQF product. In puree form, ORUS 1843-1 and ORUS 1843-3 had the highest ranking in overall quality, but were only both statistically different from ORUS 1489-2. For pureed product flavor, ORUS 1843-1 was the highest rated selection but was not statistically different from `Marion'. While ORUS 1843-1 and ORUS 1843-3 hold great promise, they are from a cross between wild collected Rubus ursinus Cham. & Schlt. and `Waldo' and as a result have some negative characteristics of the native species, particularly small fruit size. The puree quality of NZ 9128R-1, NZ 9351-4 and ORUS 1380-1 was similar to `Marion' and these genotypes offer promise as thornless replacements for `Marion'.
Abstract
Breeding programs depend upon genetic variation. Visual plant markers traditionally have been used in crop improvement. However, molecular markers provide additional selection criteria. Of the molecular markers available, isozymes are preferred by many researchers because they are expressed in young tissue as codominants and are easily extracted and detected. Mature plants may bias estimation of hybrid purity, whereas estimations of hybrid purity can be obtained at an early stage by enzyme analysis (1, 2, 4).
The horticulture faculty at Texas Tech Univ. has developed an introductory horticulture laboratory course offered asynchronously through several media. A print version has been developed as a traditional correspondence course. Students can also choose to access the course over the World Wide Web with laboratory instruction provided from an accompanying CD-ROM. The course is based on an introductory horticulture textbook and is supplemented by additional information. Students conduct the laboratory exercises at a location of their choice and return photographs or video tapes of their results along with a formal lab report. Self-help exercises, worksheets, and proctored exams are submitted by correspondence or electronically via the World Wide Web. The most challenging aspect of this project was the development of laboratory exercises that ensured adequate experiential learning. This was accomplished by using easily accessible materials for laboratories that would allow students to apply the scientific method. A CD-ROM version of the lab includes compressed video segments used to demonstrate laboratory techniques. Details of these laboratory components and samples of student work will be presented.
Abstract
Induced resistance to verticillium wilt occurs in fusarium-resistant tomato cultivars from dip inoculation with mixed cultures of Race 1 of Fusarium oxysporum f. lycopersici (F) and Verticillium albo-atrum (V). This induced resistance decreases as F level in mixed inoculi is reduced. Simultaneous screening for resistance to V and F can be achieved by inoculation with V and reinoculating 48 to 72 hours later with F.
Abstract
Interspecific hybridization is a technique commonly used by plant breeders to transfer genes from one species to another. Interspecific hybrids are usually obtained with greater difficulty than intraspecific hybrids because genetic barriers to hybridization usually increase with an increase in genetic unrelatedness (6, 11, 18, 41). Breeders resort to interspecific hybridization only when the characters are absent or inadequately expressed at the intraspecific level. Stone-fruit breeders have made much use of interspecific hybridization in the improvement of Prunus cultivars and rootstocks (3, 5, 6, 8, 12, 14, 15, 18, 19, 28, 34, 36, 37, 41, 42, 43) particularly in the subgenus Prunophora (plums), because plum species tend to intercross more freely than do members of other subgenera (41, 42). This paper will review the problems that have been encountered in making interspecific Prunus hybrids and the techniques that have been used to overcome them. In addition, techniques are presented that have been employed successfully with other interspecific hybridizations which may have application for Prunus.
Abstract
The net present value (NPV) criterion was selected for comparing the monthly net cash flows over a 3-year period resulting from replacing matted row (MR) with annual hill (AH) strawberry (Fragaria × ananassa) production. In the base analysis, AH culture was found to be a profitable alternative to the MR system. The time pattern of the yield response to AH culture (annual cropping) vs. MR (harvesting limited to years 2 and 3 only) is the major economic advantage of the AH system. Discounting at the end of yearly planning periods instead of on a monthly basis overstated the NPV of the AH system.
A recycling nutriculture system was redesigned to improve growth and flowering of Tagetes erecta L., cv., Inca Yellow in four media; loose rockwool (RW), coal bottom ash (CBA), pinewood peelings (PWP) and CBA:PWP (1:1, v/v). Three nutricycle frequencies of 12, 6 and 4 per 12 hour light period were set with a nutricycle duration of 5 minutes. Volume, height and fresh and dry weights of marigolds in CBA, PWP and CBA: PWP were comparable to that of marigolds in RW. Flower diameters of plants in CBA, PWP and CBA:PWP were increased and days to harvest decreased compared to plants in RW. Plants in CBA: PWP increased in fresh weight compared to CBA or PWP plants. No interaction occurred between media and nutricycle frequency at 12 or 4 cycles per 12 hours; however a malfunctioning timer caused prolonged flooding of plant root zones at the 6 cycle setting. This resulted in decreased plant volume and fresh and dry weights at this frequency. These results show that growth and flowering of marigolds in CBA and PWP comparable with that in RW can be achieved with more than 1 nutricycle frequency.
Nitrogen fertilizer rates and timings were reexamined for potatoes (Solanum tuberosum L.) under sprinkler irrigation with scheduling by soil water potential. Four potato cultivars were grown on a silt loam soil in eastern Oregon in 1992, 1993, and 1994. Potatoes were submitted to six treatments: four N fertilizer rates (0, 135, 200, and 270 kg·ha-1) and two split application treatments (67 kg·ha-1 applied three times, and 40 kg·ha-1 applied five times). The crop was irrigated when the soil water potential at 0.2-m depth reached -60 J·kg-1. No more than the accumulated evapotranspiration was replaced at each irrigation. Over 3 years, the cultivars had similar responses to N rates and N timing. In 1992, following alfalfa, tuber yield was not responsive to N fertilization. In 1993 and 1994, following wheat, tuber yield was maximized by N at 211 and 175 kg·ha-1. Split applications of the N fertilizer did not increase tuber yield in any year. In 1993 and 1994, the highest tuber specific gravity was obtained with no N fertilization. Nitrogen rates above the optimum resulted in darker frying tubers in 1992 and 1993. The N rates maximizing tuber yield in this study were lower than the rates recommended in the university fertilizer guides.
Four potato (Solanum tuberosum L.) varieties were grown under four season-long sprinkler irrigation treatments in three successive years (1992-94) on silt loam soil in eastern Oregon. The check treatment was irrigated when soil water potential (SWP) at the 0.2-m depth reached -60 J·kg-1 and received at most the accumulated evapotranspiration (Etc) to avoid exceeding the water-holding capacity of the top 0.3 m of soil. The three deficit irrigation treatments were irrigated when SWP at the 0.2-m depth reached -80 J·kg-1 and had the following percent of the accumulated Etc applied at each irrigation: 1) 100%, 2) 70%, and 3) 70% during tuber bulking with 50% thereafter. Based on regression of applied water over 3 years, potatoes lost both total and U.S. No. 1 yields when irrigations were reduced. Based on regression on applied water, when irrigation was reduced gross revenues declined more than production costs, resulting in a reduction in profits. Leaching potential, as determined by the SWP treatments, was low for all treatments. The results of the study suggest that deficit irrigation of potatoes in the Treasure Valley of Oregon would not be a viable management tool, because the small financial benefits would not offset the high risks of reduced yields and profits from the reduced water applications.