Title:

Nonthermal Grass Seed Cropping Systems

Investigators:

Jeffrey Steiner, USDA-ARS Research Agronomist
Stephen Griffith, USDA-ARS Plant Physiologist
George Mueller-Warrant, USDA-ARS Agronomist
Lloyd F. Elliott, USDA-ARS Research Microbiologist
William Horwath, USDA-ARS Research Microbiologist
Donald Churchill, USDA-ARS Agricultural Engineer
Thomas G. Chastain, Oregon State University
William C. Young, III, Oregon State University
Glenn Fisher, Oregon State University

Objective 1:

Determine the effect of non-thermal grass residue management and legume rotation on pest and weed control, fertilizer use efficiency, and soil quality.

Experiment 1. Determine the effect of alternative cropping systems on perennial grass species seed production. Three perennial grass seed species grown in three divergent western Oregon environments are typically grown in continuous grass production systems are being investigated. The treatments include combinations of cropping sequences (continuous grass versus rotations with clover seed and wheat), establishment methods (conventional versus no-till), nitrogen fertilizer (typical amount, one-half typical, no N control), and grass residue management (maximum versus low). The findings presented here are the fundamental pieces of information needed to develop such alternative production systems and to provide a basis for economic evaluation.

No-till wheat was planted into existing perennial grass seed stands at all three locations. Successful final wheat establishment was achieved at the tall fescue and fine fescue sites. Due to the poorly drained soil conditions at the perennial ryegrass site, wheat yields were highly variable between the replications and not considered to be economically viable. Red clover was planted no-till into the established wheat stands (before the wheat began to elongate) at the tall and fine fescue sites in early spring. Many of the established clover plants survived the summer dry period and have reinitiated growth this past fall, but final stands were not acceptable.

Slugs were found at all three experimental sites and were inactive in the fall of 1994 until significant precipitation increased soil moisture. Late September and October are periods when mating and most egg laying occur. In the late winter and spring, if the soil is moist, slugs become active with periods of warm weather. For the slug bait to be effective, it needs to be applied when the slugs are active and weather and field conditions are such that the bait will not break down. A single application of bait in the fall adequately reduced slug populations so that no crop damage was observed through the mid-winter period. Slug populations began to increase again in late winter and early spring as temperatures increased and eggs hatched. Only one application of bait was required to control the slugs in the winter/spring, but at least two applications were needed in winter/spring 1995. This was probably due to the warm and moist field conditions that occurred in 1995. Slug populations were greater in juvenile tall fescue that was planted after red clover than in mature tall fescue stands. The greatest slug populations were found in plots that were harvested for wheat the previous summer. More observations are needed to determine the effects of crop and rotation sequences on slug populations. The amount of post-harvest straw residue appeared to have no affect on slug counts made in tall fescue, perennial ryegrass, and fine fescue plots of this study.

Experiment 2. Determine contribution of volunteer seedlings to seed yield of planted perennial grass species.

A greenhouse experiment was completed that investigated the potential contribution of first-year volunteer seedlings of perennial ryegrass, tall fescue, and fine fescue to established-crop seed yield. Only perennial ryegrass plants produced reproductive tillers that flowered under any of the conditions of the experiment. Given these results for the cultivars used, tall and fine fescue volunteers could be expected to not produce any seeds during their first year of establishment (established mother plants second-year seed crop). Perennial ryegrass will produce reproductive tillers, regardless of seedling age when entering the vernalization period. However, under light competition effects similar to those found to naturally occur in the field that volunteers would be exposed to, there was a 96% reduction in the number of reproductive tillers per plant produced compared to the no-light-limited treatment. Field studies collaborated the greenhouse findings that tall fescue and fine fescue volunteer seedlings do not produce seeds in second-year crops. Therefore, in two-year short-term rotations, applications of herbicides to control volunteers for the purpose of maintaining crop genetic purity may not be necessary.

Planned Activities for 1996:

The long-term effect of crop rotation sequence will continue to be investigated. Emphasis will be placed on the evaluation of minimum input (best management practices including prescription-based management and minimum disturbance (no-till) practices to change crops in sequence. Predictive models will be developed to determine the probability of crop establishment success based on historic climate records.

Objective 2:

Develop methods to determine germplasm diversity and determine causes of genetic shift.

Experiment 1. Identify genotypes based on traditional and biochemical markers that are associated with specific germplasm pools originating from different natural environments.

Based on a conceptual framework that was developed to systematically describe the range and structure of genetic diversity in germplasm collections, combinations of molecular markers, morphological and other whole-plant descriptors are being used to identify potential sources of unique germplasm. Five distinct pools of genetic variation in the NPGS birdsfoot trefoil germplasm collection have been identified. Novel to these analyses have been the use of geographic information system data bases to describe the origins and ecological features of germplasm collection sites to determine the congruence of genetic pools with specific adaptive features. The structure of the birdsfoot trefoil collection was shown to be related to both collection site geographic origin and ecological features such as winter cold tolerance. Also, this research has shown that genetic variation is conserved from the level of specific gene sequence RFLP polymorphisms to the genomic level as measured by RAPDs. This has led to the formulation of ideas about the structuring of genetic variation in germplasm collections and how variation is related to the natural environments from which collected accessions have been naturally selected. Present birdsfoot trefoil cultivars were shown to have developed from a narrow germplasm base and that diverse genetic pools are presently unused which may be of value. These principles are being applied to other diverse Lotus species collections as well as to collections with limited geographic ranges such as those for Mediterranean Trifolium incarnatum, circum-polar Agrostis capillaris, and native North American Trifoliums.

This research has necessitated the development of new methods for DNA extraction and computer data imaging that exceed previously used techniques. Also, new applications of multivariate and categorical statistical methods have been devised.

Planned Activities for 1996:

The relationship of distinct germplasm pools with plant adaptation and performance needs to be determined. The ease of introgressing traits from exotic germplasm sources into commercially acceptable genetic lines is being investigated by determining the fertility of crosses among distant germplasm pools. Further research is needed to determine whether transgressive segregation occurs in which unique traits such as autogamy and rhizominous roots are expressed by progeny of crosses between diverse germplasm pools that do not express these traits.

Objective 3: Develop maximum biological and genetic potential.

Experiment 2. Whole-leaf chlorophyll fluorescence and glutathione reductase thermal responses and their relationship to glutathione reductase specific gene sequence polymorphism.

Basic investigations are being conducted and will continue to determine the intraspecific variation within broadleaf birdsfoot trefoil and the interspecific variation between tall fescue and the native grass species Beckmannia and Deschampsia for these three physio-biochemical traits that may be related to crop adaptation. The usefulness of chlorophyll fluorescence is being investigated as a whole-plant indicator of germplasm thermal tolerance and adaptation. The thermal response curves of glutathione reductase enzyme extracted from tall fescue, Beckmannia, and Deschampsia were measured from 1 to 40° C. Included was a corn control for comparison to similar work previously published by others. A minimum apparent Km was observed at 1° C so no basis for a thermal kinetic window was found. Differences were found between the relative position and slopes of the thermal response curves of the three species tested. Deschampsia was most unlike tall fescue and Beckmannia. A replacement competition series showed the relative competitiveness of the three species at 5, 10, 20, and 30° C to be tall fescue > Beckmannia > Deschampsia. Using the sum of the differences in the slope changes of the glutathione reductase thermal response curves for each species, the same relative rankings for competition based on the replacement series experiments were found which indicates a linkage between enzyme system kinetic responses and whole-plant interspecific competition.

Planned Activities for 1996:

The usefulness of chlorophyll fluorescence thermal tolerance response and its relationship to enzyme thermal kinetics will be investigated as a measure of germplasm adaptation. Also, progeny from specific crosses between distinct germplasm pools will be studied for the inheritance of thermal tolerance and adaptation. Heavy isotope composition of these genotypes will also be studied using mass spectormetry to determine if the water use efficiency is related to germplasm pool adaptation and the environmental factors associated with germplasm collection sites.

Publications:

Refereed Journals:

J.J. Steiner, J.A. Leffel, G. Gingrich, and S. Aldrich-Markham. 1995. Red clover seed production III. Effect of hay harvest time under varying environments. Crop Sci. 35:1667-1675.

J.J. Steiner, C.J. Poklemba, R.G. Fjellstrom, and L.F. Elliott. 1995. A rapid one-step DNA extraction technique for PCR and RAPD analyses. Nucleic Acids Res. 23:2569-2570.

J.J. Steiner, and S.L. Greene. 1996. Proposed ecological descriptors and their utility for plant germplasm collections. Crop Sci. 36:___. accepted 9-15-95

Abstracts:

R.R. Smith, and J.J. Steiner. 1995. Red clover cultivar variability for root rot resistance under forage and seed production systems. Arn. Soc. Agron. Agron. Abst. p. 140. ASA, CSSA, SSSA, Madison, WI.

C.A. Garcia-Diaz, and J.J. Steiner. 1995. Birdsfoot trefoil seed crop water relations. Am. Soc. Agron. Agron. Abst. p. 139. ASA, CSSA, SSSA, Madison, WI.

J.J. Steiner, G. Garcia de los Santos, R. G. Fjellstrom, and C.J. Poklemba. 1995. Glutathione reductase sequences and birdsfoot trefoil germplasm adaptation. Am. Soc. Agron. Agron. Abst. p. 182. ASA, CSSA, SSSA, Madison, WI.

T.G. Brewer, J.J. Steiner, and S. M. Griffith. 1 995 . Glutathione reductase thermokinetics among native wetland and introduced grasses. Am. Soc. Agron. Agron. Abst. p. 126. ASA, CSSA, SSSA, Madison, WI.

Extension activities:

J.J. Steiner. 1995. Applications of non-thermal cropping systems research. Oregon Seed Growers League, Annual Meeting, Portland, OR, December 5. (invited talk)

J.J. Steiner, S.M. Griffith, G.W. Mueller-Warrant, W.R. Horwath, L.F. Elliott, D.B. Churchill, S.C. Alderman, R.E. Barker, T.G. Chastain, R.P. Dick, and W.C. Young, III. 1995. Nonthermal grass seed production system research status report. p. 5- 8. In W.C. Young III (ed.) Seed Production Research at Oregon State University, USDA-ARS Cooperating. Corvallis, OR. (technical bulletin)

G.C. Fisher, and J.J. Steiner. 1995. Slug observations in different grass seed cropping systems. p. 26-29. In W.C. Young III (ed.) Seed Production Research at Oregon State University, USDA-ARS Cooperating. Corvallis, OR. (technical bulletin)

J.J. Steiner. 1995. White clover cultivar responses to different production practices. p. 58-59. In W.C. Young III (ed.) Seed Production Research at Oregon State University, USDA-ARS Cooperating. Corvallis, OR. (technical bulletin)