Search Results
Abstract
A questionnaire on genetics and breeding of horticultural crops, in conjunction with our responsibilities to the National Plant Genetics Resources Board (an advisory board to the Secretary of Agriculture under authority of Secretary’s Memorandum 1875 Revised dated 23 Feb. 1978), was sent to appropriate department chairmen or program leaders in Land Grant Universities, 1890 institutions, and the USD A Agricultural Research Service (ARS). The purpose of the questionnaire was to survey past, present, and anticipated programs on breeding and genetics of horticultural crops and to solicit views on national needs for germplasm of horticultural crops. Responses on the status of programs were received from all 98 questionnaires, and 74 respondents made comments on national needs.
Purpletop [Tridens flavus (L.) Hitchc.] and big bluestem (Andropogon gerardii Vitman) are incorporated into native grass seed mixes for use in ecological restoration. Alleviation of low seed vigor and poor stand establishment would benefit the restoration process by increasing the animal habitat in restored zones. This study determined the effectiveness of prechilling with distilled water (dH2O) versus potassium nitrate (KNO3), sodium hypochlorite (NaOCl) treatments, and short-term storage conditions on seed germination, seedling growth, and stand establishment of purpletop and big bluestem. Prechilling of ‘Niagara, NY Ecotype’ big bluestem for 7 days at 5 °C in dH2O increased final germination percentage (FGP) and germination rate provided caryopses were not dried before sowing. Optimal FGP, germination rate, and germination synchrony were obtained for ‘VA Ecotype’ purpletop after prechilling for 14 days at 5 °C in dH2O without subsequent caryopsis drying or at 0.2% KNO3 with or without subsequent caryopsis drying. Prechilling increased germination synchrony for purpletop but not for big bluestem. NaOCl treatments did not enhance germination or seedling vigor of purpletop or big bluestem. Using nonstored, prechilled caryopses resulted in greater root lengths than stored caryopses or nontreated controls, although optimal purpletop growth required that they be sowed moist, whereas optimal big bluestem growth required that they be dried-back before sowing. In greenhouse experiments, higher seeding rates were correlated with increased number of seedlings for nontreated or prechilled big bluestem and for prechilled purpletop, but not for nontreated purpletop, which had poor stand establishment at all seeding rates. The results indicate that prechilling of caryopses before incorporation into a warm-season grass seed mix increased seedling establishment of purpletop but not big bluestem.
Turfgrass management best management practices (BMPs) encompass a wide variety of activities, including fertilization, irrigation, mowing, pest control, and soil management. Little attention is given to determining just how effective information regarding BMPs is being assimilated and used by professional turfgrass managers. The objectives of this study were to assess the current perception and implementation of selected turfgrass BMPs and to determine whether or not those perceptions and implementations differed 1) between turfgrass advisors and managers and 2) between general and sports turfgrass managers. Professionals from the turfgrass industry, with an average of 13 years of experience and largely comprised of decision-makers (88%), were surveyed at the University of California, Riverside, Turfgrass Research Conference and Field Day in Fall 1998 and 1999. Turfgrass managers, especially sports turfgrass managers, were found to be the most committed to implementing the BMPs in the survey. Overall, survey respondents considered BMPs to be important and not highly difficult to implement. Limitations to the adoption of BMPs were a lack of financial backing, employee education, and necessary time—all of which could be remedied with a sufficient commitment of resources by the turfgrass industry.
Abstract
Fruit on shoots trained to grow above the main foliar canopy (exposed) of 6-year-old ‘pergola’-trained kiwifruit vines were significantly larger than fruit on shoots trained to grow below the canopy (shaded). Fruit size increased with seed number in both fruit groups, but fruit from exposed shoots were consistently larger than shade-grown fruit with the same seed count. Shade-grown shoots had smaller basal diameters and less dry matter than exposed shoots. Winter mortality among buds on formerly shaded and exposed shoots was 34% and 5%, respectively. Formerly shaded shoots had fewer mixed buds with less flowers per inflorescence than exposed shoots the following spring.
Abstract
Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.
Abstract
Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.
Abstract
‘Jersey Centennial’ asparagus (Asparagus officinalis L.), tested under the designation Rutgers-Michigan Hybrid 202, is a new cultivar that is more vigorous, rust resistant, and productive than the ‘Mary Washington’ strain when grown on the fusarium-infested soils of New Jersey. It was also the most productive asparagus cultivar in a Michigan yield trial on noninfested soil.
Bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt-Davy] greens across the southern United States are normally overseeded in the fall to provide a uniform green playing surface and tolerance to wear during winter bermudagrass dormancy. The spring transition from overseed grass back to bermudagrass is a major problem associated with overseeding because there can be a decline in putting green quality and playability. There have been recommendations, but relatively few published reports, on the effect of treatments associated with seedbed preparation and overseeding on bermudagrass spring transition. The objective of this 2-year study was to determine if spring transition of an overseeded `Tifgreen' bermudagrass green was influenced by fall-applied scalping level, chemical, and seed rate treatments. Treatment factors and levels were designed to reflect the range of practices used by golf course superintendents in the region at the time of the study. The green was located in the Palm Springs, Calif. area, which has relatively mild winters and a low desert, southern Calif. climate. The first year of the study was from September 1996 to July 1997 and the second year was from September1997 to July 1998. Scalping level treatments included a moderate and severe verticut and scalp; chemical treatments included a check, trinexapac-ethyl at two rates, and diquat; and seed rate treatments included a high and low rate of a mixture of `Seville' perennial ryegrass (Lolium perenne L.) and `Sabre' rough bluegrass (Poa trivialis L.). The plot was maintained under golf course conditions and a traffic simulator was used to simulate golfer traffic. Visual ratings of percent green bermudagrass coverage were taken every 3 weeks from 20 Feb. 1997 to 29 July 1997 and from 11 Nov. 1997 to 22 July 1998. Visual turfgrass quality ratings were taken during the second year of the study. Results showed that spring transition was not influenced by fall-applied treatments during both years. Also, visual turfgrass quality was not influenced during the second year. Chemical names used [4(cyclopropyl-_hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl); 9,10-dihydro-8a-, 10a-diazoniaphenanthrene (diquat).
Summer decline of annual bluegrass (Poa annua L.) putting greens is a major concern of golf course superintendents. Low soil water infiltration rates and high concentrations of salts in the root zone are contributing factors. This study was conducted to determine the effects of summer cultivation treatments on field infiltration rates of water, soil salinity, oxygen diffusion rates (ODR), bulk density, total and air-filled porosity, and root weight density. This research was conducted during two summer seasons (1996 and 1997) on a practice putting green located at Industry Hills Golf Courses, City of Industry, Calif. The green was constructed to U.S. Golf Association (USGA) specifications in 1978. Cultivation treatments consisted of: 1-3) water injection cultivation (WIC) applied with a Toro HydroJect every 21 d (raised position), and every 14 or 21 d (lowered position); 4) solid tine cultivation (STC) applied every 14 d; and 5) no cultivation (check). Results showed WIC and STC significantly increased field infiltration rates of water and lowered overall soil electrical conductivity of the extract (ECe) at depths of 2.5 to 7.5 cm and 7.5 to 15.0 cm in the root zone. The effects of WIC, raised position, did not differ significantly from those of STC, but infiltration rates of water were greater on all rating dates. Cultivation treatments had no significant effects on overall soil ODR, bulk density, and porosity or on overall root weight density.
Bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt-Davy] greens across the southern United States are normally overseeded in the fall to provide a uniform green playing surface and tolerance to wear during winter bermudagrass dormancy. The spring transition from overseed grass back to bermudagrass is a major problem associated with overseeding because there can be a decline in putting green quality and playability. There have been recommendations, but relatively few published reports, on the effect of treatments associated with seedbed preparation and overseeding on bermudagrass spring transition. The objective of this 2-year study was to determine if spring transition of an overseeded `Tifgreen' bermudagrass green was influenced by fall-applied scalping level, chemical, and seed rate treatments. Treatment factors and levels were designed to reflect the range of practices used by golf course superintendents in the region at the time of the study. The green was located in the Palm Springs, Calif., area, which has relatively mild winters and a low desert, southern California climate. The first year of the study was from Sept. 1996 to July 1997 and the second year was from Sept. 1997 to July 1998. Scalping level treatments included a moderate and severe verticut and scalp; chemical treatments included a check, trinexapac-ethyl at two rates, and diquat; and seed rate treatments included a high and low rate of a mixture of `Seville' perennial ryegrass (Lolium perenne L.) and `Sabre' rough bluegrass (Poa trivialis L.). The plot was maintained under golf course conditions and a traffic simulator was used to simulate golfer traffic. Visual ratings of percent green bermudagrass coverage were taken every 3 weeks from 20 Feb. 1997 to 29 July 1997 and from 11 Nov. 1997 to 22 July 1998. Visual turfgrass quality ratings were taken during the second year of the study. Results showed that spring transition was not influenced by fall-applied treatments during both years. Also, visual turfgrass quality was not influenced during the second year. Chemical names used: [4(cyclopropyl-αhydroxy-methylene) -3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl); 9,10-dihydro-8a-, 10a-diazoniaphenanthrene (diquat).