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• 1. [Article] Effect of sulfur on dinitrogen fixation of alfalfa (Medicago sativa L.)

  Field experiments were established in 1982 and 1983 on a Woodburn silt loam soil (Aquultic Argixeroll) to examine the effect of S fertilizer on dinitrogen fixation and dry matter yield of 10 week-old seedling ...

  Citation × Citation Citation Abstract Copy Title: Effect of sulfur on dinitrogen fixation of alfalfa (Medicago sativa L.) Author: Lopez-Jurado, Gerardo Field experiments were established in 1982 and 1983 on a Woodburn silt loam soil (Aquultic Argixeroll) to examine the effect of S fertilizer on dinitrogen fixation and dry matter yield of 10 week-old seedling alfalfa (Medicago sativa L. cv. 'Apollo'). Six levels of S fertilizer (0 to 67.2 kg S/ha) were applied as powdered gypsum. The experimental design was a split-block with one half of the seeds inoculated with commercial inoculum, and the other half non-inoculated. Inoculation effects were highly significant in both years, indicating that the indigenous population of Rhizobium meliloti at the experimental sites was ineffective in N₂-fixation. Dry matter yields were higher in inoculated than in non-inoculated treatments. Inoculated plants also showed a significantly higher acetylene reduction rate, N concentration, and total tissue N and S. No significant differences in any of these parameters were detected for the different S treatments. Sulfur fertilization increased the S concentration of non-inoculated plants more than inoculated plants, and decreased the N:S ratio in the forage by increasing tissue S content. The highest value of N₂-fixed by the inoculated plants was obtained from the 44.8 kg S/ha treatment. Greenhouse experiments were performed to evaluate the effect of varied nutrient solution concentrations of sulfate on the yield, nodulation, dinitrogen fixation, N and S concentrations, and partitioning of N and S into shoots and roots of six week-old alfalfa seedlings. Four levels of S (0, 1, 2.5, and 25 mg S/L) were applied in a randomized complete block design, with three replications. Seeds were inoculated with commercial inoculum, planted in plastic containers of acid-washed sand, and irrigated with nutrient solution for one minute, at 2 h intervals. The addition of 2.5 mg S/L to the nutrient solution resulted in the highest total dry matter, acetylene reduction rate, total N content, percent S recovery, and percent increase in N due to dinitrogen fixation. N:S ratios were 50% higher in shoots (16:1) than roots (9:1), with S fertilization decreasing the N:S ratios. Data from field and greenhouse experiments support the conclusion that S fertilization will increase seedling alfalfa yield when S levels in the plant are below 2.5 mg S/g (0.25%). In inoculated plants S fertilization increased both total N and S, demonstrating the importance of S in symbiotic N₂-fixation and the quality of forage produced. Title: Effect of sulfur on dinitrogen fixation of alfalfa (Medicago sativa L.) Author: Lopez-Jurado, Gerardo Field experiments were established in 1982 and 1983 on a Woodburn silt loam soil (Aquultic Argixeroll) to examine the effect of S fertilizer on dinitrogen fixation and dry matter yield of 10 week-old seedling alfalfa (Medicago sativa L. cv. 'Apollo'). Six levels of S fertilizer (0 to 67.2 kg S/ha) were applied as powdered gypsum. The experimental design was a split-block with one half of the seeds inoculated with commercial inoculum, and the other half non-inoculated. Inoculation effects were highly significant in both years, indicating that the indigenous population of Rhizobium meliloti at the experimental sites was ineffective in N₂-fixation. Dry matter yields were higher in inoculated than in non-inoculated treatments. Inoculated plants also showed a significantly higher acetylene reduction rate, N concentration, and total tissue N and S. No significant differences in any of these parameters were detected for the different S treatments. Sulfur fertilization increased the S concentration of non-inoculated plants more than inoculated plants, and decreased the N:S ratio in the forage by increasing tissue S content. The highest value of N₂-fixed by the inoculated plants was obtained from the 44.8 kg S/ha treatment. Greenhouse experiments were performed to evaluate the effect of varied nutrient solution concentrations of sulfate on the yield, nodulation, dinitrogen fixation, N and S concentrations, and partitioning of N and S into shoots and roots of six week-old alfalfa seedlings. Four levels of S (0, 1, 2.5, and 25 mg S/L) were applied in a randomized complete block design, with three replications. Seeds were inoculated with commercial inoculum, planted in plastic containers of acid-washed sand, and irrigated with nutrient solution for one minute, at 2 h intervals. The addition of 2.5 mg S/L to the nutrient solution resulted in the highest total dry matter, acetylene reduction rate, total N content, percent S recovery, and percent increase in N due to dinitrogen fixation. N:S ratios were 50% higher in shoots (16:1) than roots (9:1), with S fertilization decreasing the N:S ratios. Data from field and greenhouse experiments support the conclusion that S fertilization will increase seedling alfalfa yield when S levels in the plant are below 2.5 mg S/g (0.25%). In inoculated plants S fertilization increased both total N and S, demonstrating the importance of S in symbiotic N₂-fixation and the quality of forage produced. Close

• 2. [Article] Factors affecting establishment, survival, and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.)

  Field, greenhouse, growth chamber and laboratory experiments evaluated factors affecting establishment, survival and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa ...

  Citation × Citation Citation Abstract Copy Title: Factors affecting establishment, survival, and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.) Author: Cooper, Clee Scott Field, greenhouse, growth chamber and laboratory experiments evaluated factors affecting establishment, survival and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.) Field studies investigated the effects of a barley companion crop, seedling year harvest management and nitrogen and phosphorus fertilization upon stands, survival and subsequent production of legumes. Seedings were made in each of two years. Stands of legumes were not affected by fertilization or harvest management, but decreased with increasing levels of companion crop competition. Death of seedlings occurred early in the establishment period and the degree of loss was similar for both species. Additional losses of plants did not occur during the establishment year. Losses of birdsfoot trefoil plants established with a companion crop occurred during the first winter following seeding. Stand reduction in the seeding year persisted for the duration of the experiment. Companion crops inhibited the growth of surviving seedlings. Growth inhibition was less when barley was clipped periodically than when it was matured to grain. In the absence of a companion crop, growth of seedlings was inhibited more by frequent clipping of thin weed stands than by allowing weeds to mature. Yields of weeds were inversely proportional to density of barley plants. Wild oats was more detrimental to seedling growth and was less readily controlled by clipping than redroot pigweed or pigeon grass. The percentage of solar radiation intercepted by barley varied from 89 in early morning or late evening to 22 at noon. Light intensity was reduced more by barley in early season and less by barley in late season than by wild oats. Yields of mixtures in the year after seeding were reduced as a result of establishment with a companion crop and to a greater degree and for a longer period of time when barley had been allowed to mature. Yield reductions of legumes were compensated for by increased grass yields. Grass grown with birdsfoot trefoil yielded significantly more in early season and significantly less in late season than grass grown with alfalfa. Greenhouse studies evaluated the influenee of soil temperature and phosphorus fertilization upon growth and phosphorus uptake of birdsfoot trefoil and alfalfa. Root growth of both species increased with increasing soil temperatures. Weight of alfalfa roots was twice that of birdsfoot trefoil at all temperatures. Top growth of birdsfoot trefoil increaeed to a greater degree than that of alfalfa with increasing temperature. The greater top growth of birdsfoot trefoil resulted in reduced root-shoot ratios. Birdsfoot trefoil produced less dry matter per cm.² of leaf area than alfalfa. Root growth of both species increased with increasing applications of P fertilizer. Phosphorus appeared to be more important to growth at low than at high temperatures. Phosphorus and nitrogen uptake by both species increased with increasing soil temperature. Growth chamber studies evaluated the influence of low light intensities and seedling age upon growth of seedlings and distribution of accumulated dry matter. Seedlings gained weight at light intensities of 200 to 800 f.c. With decreasing light intensity, stem elongation occurred at the expense of roots. A smaller percentage of accumulated dry matter went into roots of two-week than in older seedlings. Roots of two-week old seedlings of alfalfa lost weight at 200 f.c. Laboratory studies evaluated oxygen uptake of germinating birdsfoot trefoil and alfalfa seeds. Average oxygen uptake by both species on a per unit weight basis was similar. Alfalfa, due to its greater size, had a greater oxygen uptake on a per plant basis than did birdsfoot trefoil. Title: Factors affecting establishment, survival, and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.) Author: Cooper, Clee Scott Field, greenhouse, growth chamber and laboratory experiments evaluated factors affecting establishment, survival and production of birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.) Field studies investigated the effects of a barley companion crop, seedling year harvest management and nitrogen and phosphorus fertilization upon stands, survival and subsequent production of legumes. Seedings were made in each of two years. Stands of legumes were not affected by fertilization or harvest management, but decreased with increasing levels of companion crop competition. Death of seedlings occurred early in the establishment period and the degree of loss was similar for both species. Additional losses of plants did not occur during the establishment year. Losses of birdsfoot trefoil plants established with a companion crop occurred during the first winter following seeding. Stand reduction in the seeding year persisted for the duration of the experiment. Companion crops inhibited the growth of surviving seedlings. Growth inhibition was less when barley was clipped periodically than when it was matured to grain. In the absence of a companion crop, growth of seedlings was inhibited more by frequent clipping of thin weed stands than by allowing weeds to mature. Yields of weeds were inversely proportional to density of barley plants. Wild oats was more detrimental to seedling growth and was less readily controlled by clipping than redroot pigweed or pigeon grass. The percentage of solar radiation intercepted by barley varied from 89 in early morning or late evening to 22 at noon. Light intensity was reduced more by barley in early season and less by barley in late season than by wild oats. Yields of mixtures in the year after seeding were reduced as a result of establishment with a companion crop and to a greater degree and for a longer period of time when barley had been allowed to mature. Yield reductions of legumes were compensated for by increased grass yields. Grass grown with birdsfoot trefoil yielded significantly more in early season and significantly less in late season than grass grown with alfalfa. Greenhouse studies evaluated the influenee of soil temperature and phosphorus fertilization upon growth and phosphorus uptake of birdsfoot trefoil and alfalfa. Root growth of both species increased with increasing soil temperatures. Weight of alfalfa roots was twice that of birdsfoot trefoil at all temperatures. Top growth of birdsfoot trefoil increaeed to a greater degree than that of alfalfa with increasing temperature. The greater top growth of birdsfoot trefoil resulted in reduced root-shoot ratios. Birdsfoot trefoil produced less dry matter per cm.² of leaf area than alfalfa. Root growth of both species increased with increasing applications of P fertilizer. Phosphorus appeared to be more important to growth at low than at high temperatures. Phosphorus and nitrogen uptake by both species increased with increasing soil temperature. Growth chamber studies evaluated the influence of low light intensities and seedling age upon growth of seedlings and distribution of accumulated dry matter. Seedlings gained weight at light intensities of 200 to 800 f.c. With decreasing light intensity, stem elongation occurred at the expense of roots. A smaller percentage of accumulated dry matter went into roots of two-week than in older seedlings. Roots of two-week old seedlings of alfalfa lost weight at 200 f.c. Laboratory studies evaluated oxygen uptake of germinating birdsfoot trefoil and alfalfa seeds. Average oxygen uptake by both species on a per unit weight basis was similar. Alfalfa, due to its greater size, had a greater oxygen uptake on a per plant basis than did birdsfoot trefoil. Close

• 3. [Article] The influence of cutting treatments on yield and quality of two alfalfa (Medicago sativa L.) varieties

  A field experiment was conducted to study the influence of cutting treatments on the yield and quality of non-irrigated alfalfa in western Oregon. Spring clipping treatments included (1) not clipped, (2) ...

  Citation × Citation Citation Abstract Copy Title: The influence of cutting treatments on yield and quality of two alfalfa (Medicago sativa L.) varieties Author: Contreras, David A field experiment was conducted to study the influence of cutting treatments on the yield and quality of non-irrigated alfalfa in western Oregon. Spring clipping treatments included (1) not clipped, (2) clipped when 6 inches high and (3) clipped when 12 inches high. The hay harvest criteria were (1) near full light interception by the vegetative canopy, (2) crown bud stage and (3) one-tenth bloom stage. Combinations of these criteria included first hay harvest based on light interception followed by either of the other criteria at subsequent harvests, and first harvest based on crown bud development in combination with one-tenth bloom criterion for subsequent harvest. Two alfalfa varieties, Vernal and Du Puits, were subjected to each of the 18 treatments (6 x 3 in all combinations). Results of one growing season indicated that the influence of spring clipping was not reflected in yield of dry matter (hay) except at the relatively small third harvest when spring clipping showed a deleterious effect. The yields obtained by the spring clipping were sufficient to offset the reduction at the third hay harvest. It was observed that the total yields for the season did not differ. Cutting at the one-tenth bloom stage showed an advantage in yield but with a greatly reduced crude protein percentage. Cutting on the basis of nearly complete light interception resulted in harvest at an immature stage in early May and at a very mature stage in late season. Highest yields, with leafiness and crude protein suitable for high quality hay, were obtained by cutting at the crown bud stage throughout the season, or by taking the first harvest on the basis of light interception and subsequent harvests on the basis of either crown buds or one-tenth bloom. The varieties produced approximately the same total for the season. Vernal was slightly leafier than Du Puits at the second and third hay harvests. A highly significant negative correlation was found between yield of dry matter and percentage protein and between yield of dry matter and leaf-stem ratio. The correlation between percentage protein and leaf-stem ratio was significant and positive. Title: The influence of cutting treatments on yield and quality of two alfalfa (Medicago sativa L.) varieties Author: Contreras, David A field experiment was conducted to study the influence of cutting treatments on the yield and quality of non-irrigated alfalfa in western Oregon. Spring clipping treatments included (1) not clipped, (2) clipped when 6 inches high and (3) clipped when 12 inches high. The hay harvest criteria were (1) near full light interception by the vegetative canopy, (2) crown bud stage and (3) one-tenth bloom stage. Combinations of these criteria included first hay harvest based on light interception followed by either of the other criteria at subsequent harvests, and first harvest based on crown bud development in combination with one-tenth bloom criterion for subsequent harvest. Two alfalfa varieties, Vernal and Du Puits, were subjected to each of the 18 treatments (6 x 3 in all combinations). Results of one growing season indicated that the influence of spring clipping was not reflected in yield of dry matter (hay) except at the relatively small third harvest when spring clipping showed a deleterious effect. The yields obtained by the spring clipping were sufficient to offset the reduction at the third hay harvest. It was observed that the total yields for the season did not differ. Cutting at the one-tenth bloom stage showed an advantage in yield but with a greatly reduced crude protein percentage. Cutting on the basis of nearly complete light interception resulted in harvest at an immature stage in early May and at a very mature stage in late season. Highest yields, with leafiness and crude protein suitable for high quality hay, were obtained by cutting at the crown bud stage throughout the season, or by taking the first harvest on the basis of light interception and subsequent harvests on the basis of either crown buds or one-tenth bloom. The varieties produced approximately the same total for the season. Vernal was slightly leafier than Du Puits at the second and third hay harvests. A highly significant negative correlation was found between yield of dry matter and percentage protein and between yield of dry matter and leaf-stem ratio. The correlation between percentage protein and leaf-stem ratio was significant and positive. Close

• 4. [Article] The influence of herbicides, phosphorus fertilization, and mechanical and chemical seedbed preparation on the establishment of alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus conrniculatus L.)

  Initial establishment of legume forage crops is of prime importance in determining future forage and seed production. The objective of this study was to determine the influence of herbicides, phosphorus fertilization, and seedbed preparation on the establishment of alfalfa and birdsfoot trefoil. Experiments were designed to study the influence of herbicides applied alone or in combination with phosphorus fertilization on the establishment of alfalfa and birdsfoot trefoil. The phosphorus treatments consisted of different levels of P₂O₅ ...

  Citation × Citation Citation Abstract Copy Title: The influence of herbicides, phosphorus fertilization, and mechanical and chemical seedbed preparation on the establishment of alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus conrniculatus L.) Author: Valdes Lamar, Ramon Initial establishment of legume forage crops is of prime importance in determining future forage and seed production. The objective of this study was to determine the influence of herbicides, phosphorus fertilization, and seedbed preparation on the establishment of alfalfa and birdsfoot trefoil. Experiments were designed to study the influence of herbicides applied alone or in combination with phosphorus fertilization on the establishment of alfalfa and birdsfoot trefoil. The phosphorus treatments consisted of different levels of P₂O₅ (0-50-100 pounds per acre) using two methods of application, broadcast and band. The herbicide treatments included Ethyl N, N-dipropylthiolcarbamate (EPTC) at 3 pounds active ingredient per acre (lb. ai/A) + 4-(2, 4-dichlorophenoxy) butyric acid (2, 4-DB amine) at 1 lb. ai/A; EPTC 3 lb. ai/A + 2-sec-butyl-4, 6-dinitrophenol (DNBP amine) at 2 lb. ai/A; 2, 2-dichloropropionic acid (dalapon) 5 lb. ai/A + 2, 4-DB amine 1 lb. ai/A; and an untreated control. EPTC was applied as a pre-plant incorporated treatment, whereas DNBP, 2, 4-DB, and dalapon were applied when the legumes were in the two to four true leaf stage of growth. Results for both alfalfa and birdsfoot trefoil were similar. Phosphorus applications did not enhance the establishment of the legumes. This may have been due to an adequate phosphorus supply already present in the soil. Phosphorus application without herbicide application resulted in weedy stands in which the legume yield was greatly reduced. The addition of phosphorus to herbicide treatments did not enhance the yield of alfalfa or birdsfoot trefoil any more than did the herbicide treatments alone. The effectiveness of herbicide applications in eliminating weed competition from the legume seedlings varied considerably. The best treatment for the establishment of both alfalfa and birdsfoot trefoil was the combination of EPTC + DNBP amine. This treatment gave good to excellent control of oats (Ayena spp.), ryegrass (Lolium spp.), cornflower (Centaurea cyanus L.), burnet (Sanguisorba spp.), henbit (Lamium amplexicaule L.), and mayweed (Anthemis cotula L.); fair control of wild radish (Raphanus raphanistrum L.), and wild mustard (Brassica kaber (D. C.) Wheeler var. pinnatifida (Stokes) Wheeler); and poor control of vetch (Vicia spp.). EPTC + 2, 4-DB amine was significantly better than dalapon + 2, 4-DB or the untreated control. This combination gave good to excellent control of oats, ryegrass, burnet, henbit, and mayweed, but poor control of wild radish, wild mustard, cornflower, and vetch. The dalapon + 2, 4-DB amine treatment was not significantly different from the check and resulted in poor control of all weed species. Two experiments were designed to compare the effectiveness of chemical seedbed preparation using 1, 1'-dimethyl-4, 4'-dipyridy-lium salt (Paraquat), mechanical seedbed preparation by use of a rotary tiller or a rake, and the chemical treatment of EPTC 3 lb. ai/A + DNBP amine 2 lb. ai/A on the establishment of alfalfa and birdsfoot trefoil. Duplicate experiments were conducted on alfalfa and birdsfoot trefoil. The treatment involving EPTC + DNBP amine was the most effective treatment for the establishment of both alfalfa and birdsfoot trefoil. Paraquat and rototilling or raking were ineffective in controlling weeds. In each case, the high weed population greatly decreased the alfalfa or birdsfoot trefoil yields. The poor results obtained with paraquat were due to poor weed emergence prior to the application of the chemical. Raking gave poor control of germinating weed seeds present in the top inches of the soil. The rotary tilling may have brought dormant weed seeds to the surface where they germinated and emerged after the tillage treatment. Title: The influence of herbicides, phosphorus fertilization, and mechanical and chemical seedbed preparation on the establishment of alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus conrniculatus L.) Author: Valdes Lamar, Ramon Initial establishment of legume forage crops is of prime importance in determining future forage and seed production. The objective of this study was to determine the influence of herbicides, phosphorus fertilization, and seedbed preparation on the establishment of alfalfa and birdsfoot trefoil. Experiments were designed to study the influence of herbicides applied alone or in combination with phosphorus fertilization on the establishment of alfalfa and birdsfoot trefoil. The phosphorus treatments consisted of different levels of P₂O₅ (0-50-100 pounds per acre) using two methods of application, broadcast and band. The herbicide treatments included Ethyl N, N-dipropylthiolcarbamate (EPTC) at 3 pounds active ingredient per acre (lb. ai/A) + 4-(2, 4-dichlorophenoxy) butyric acid (2, 4-DB amine) at 1 lb. ai/A; EPTC 3 lb. ai/A + 2-sec-butyl-4, 6-dinitrophenol (DNBP amine) at 2 lb. ai/A; 2, 2-dichloropropionic acid (dalapon) 5 lb. ai/A + 2, 4-DB amine 1 lb. ai/A; and an untreated control. EPTC was applied as a pre-plant incorporated treatment, whereas DNBP, 2, 4-DB, and dalapon were applied when the legumes were in the two to four true leaf stage of growth. Results for both alfalfa and birdsfoot trefoil were similar. Phosphorus applications did not enhance the establishment of the legumes. This may have been due to an adequate phosphorus supply already present in the soil. Phosphorus application without herbicide application resulted in weedy stands in which the legume yield was greatly reduced. The addition of phosphorus to herbicide treatments did not enhance the yield of alfalfa or birdsfoot trefoil any more than did the herbicide treatments alone. The effectiveness of herbicide applications in eliminating weed competition from the legume seedlings varied considerably. The best treatment for the establishment of both alfalfa and birdsfoot trefoil was the combination of EPTC + DNBP amine. This treatment gave good to excellent control of oats (Ayena spp.), ryegrass (Lolium spp.), cornflower (Centaurea cyanus L.), burnet (Sanguisorba spp.), henbit (Lamium amplexicaule L.), and mayweed (Anthemis cotula L.); fair control of wild radish (Raphanus raphanistrum L.), and wild mustard (Brassica kaber (D. C.) Wheeler var. pinnatifida (Stokes) Wheeler); and poor control of vetch (Vicia spp.). EPTC + 2, 4-DB amine was significantly better than dalapon + 2, 4-DB or the untreated control. This combination gave good to excellent control of oats, ryegrass, burnet, henbit, and mayweed, but poor control of wild radish, wild mustard, cornflower, and vetch. The dalapon + 2, 4-DB amine treatment was not significantly different from the check and resulted in poor control of all weed species. Two experiments were designed to compare the effectiveness of chemical seedbed preparation using 1, 1'-dimethyl-4, 4'-dipyridy-lium salt (Paraquat), mechanical seedbed preparation by use of a rotary tiller or a rake, and the chemical treatment of EPTC 3 lb. ai/A + DNBP amine 2 lb. ai/A on the establishment of alfalfa and birdsfoot trefoil. Duplicate experiments were conducted on alfalfa and birdsfoot trefoil. The treatment involving EPTC + DNBP amine was the most effective treatment for the establishment of both alfalfa and birdsfoot trefoil. Paraquat and rototilling or raking were ineffective in controlling weeds. In each case, the high weed population greatly decreased the alfalfa or birdsfoot trefoil yields. The poor results obtained with paraquat were due to poor weed emergence prior to the application of the chemical. Raking gave poor control of germinating weed seeds present in the top inches of the soil. The rotary tilling may have brought dormant weed seeds to the surface where they germinated and emerged after the tillage treatment. Close

• 5. [Article] Effects of plant regulators on growth development and seed production of alfalfa development

  Experiments were conducted to determine the effects of certain plant regulatory chemicals on seed production of alfalfa (Medicago sativa L.). Two plant regulators, SADH (succinic acid 2,2-dimethylhydrazide) ...

  Citation × Citation Citation Abstract Copy Title: Effects of plant regulators on growth development and seed production of alfalfa development Author: Phillips, John Charles Experiments were conducted to determine the effects of certain plant regulatory chemicals on seed production of alfalfa (Medicago sativa L.). Two plant regulators, SADH (succinic acid 2,2-dimethylhydrazide) and TIBA (2,3,5- triiodobenzoic acid), received particular attention. Replicated field tests of the plant regulators were carried out on the cultivar 'Talent' in southern Oregon and on 'DuPuits' in the Willamette Valley. Other experiments were conducted in the greenhouse, laboratory, and in controlled environment chambers to explore possible modes of action. In 1972 foliar sprays of SADH and an experimental formulation of succinic acid derivatives, TD-6266-R, resulted in seed yields of 'Talent' of approximately 400 kg ha⁻¹ compared to 168 kg ha⁻¹ in untreated plots. These responses were statistically significant, while lesser seed yield increases due to 2,4-DB [4-(2,4-dichlorophenoxY) butyric acid] and chlormequat [(2-chloroethyl)trimethylammonium chloride] were not significant. Similar field testing in 1973 resulted in no seed yield enhancement by any plant regulator. However, precipitation at the experimental site during the 1973 growing season was only 0.4 cm in contrast to the 30-year average of 4.3 cm. A plant regulator-environment interaction is suggested. Yield component analysis showed that the number of seeds per pod was increased significantly by the same treatments which promoted yield. Number of pods per raceme was also a strong determinant of seed yield. The relative importance of one component of yield, the number of seedbearing racemes per unit land area, is yet to be established. After treatment with SADH and TIBA in 1973, fieldgrown 'DuPuits' alfalfa accumulated more total dry matter and up to twice as much dry matter in pods as did untreated plots. Shoots treated with TIBA exhibited a mean net carbon dioxide exchange (NCE) rate of 21 mg CO₂ dm⁻² leaf area hr⁻¹ compared to 16 mg CO2 dm⁻² hr ⁻¹ for SADH-treated and control shoots. However, dry matter accumulation and NCE responses were statistically nonsignificant at the .05 probability level. Specific leaf weight exhibited an increased diurnal maximum when treated with SADH and TIBA, while the diurnal minimum remained equal to that of control plants. The principal effect of TIBA on reproductive development was via its promotion of the growth and raceme initiation of axillary branches. In a dosage response study, 10 ppm TIBA was most effective, resulting in a fourfold increase in total branch length per primary stem and a highly significant increase in total raceme production. The finding that two axillary structures generally arise from an alfalfa leaf axil may be useful in understanding the phenomena of branching and floral initiation in this crop. Alfalfa genotypes differed in their growth response to environmental conditions. It appeared possible that genotypes also differed in response to applied plant regulators. This research has shown that applied plant regulators can promote flowering in alfalfa and has suggested that the carbon budget of alfalfa may also be affected. These changes may or may not be translated into increased seed production. The net effects are a result of plant regulator interaction with environmental conditions and plant genotype. Thus, variability in the response to plant regulators can be expected. Title: Effects of plant regulators on growth development and seed production of alfalfa development Author: Phillips, John Charles Experiments were conducted to determine the effects of certain plant regulatory chemicals on seed production of alfalfa (Medicago sativa L.). Two plant regulators, SADH (succinic acid 2,2-dimethylhydrazide) and TIBA (2,3,5- triiodobenzoic acid), received particular attention. Replicated field tests of the plant regulators were carried out on the cultivar 'Talent' in southern Oregon and on 'DuPuits' in the Willamette Valley. Other experiments were conducted in the greenhouse, laboratory, and in controlled environment chambers to explore possible modes of action. In 1972 foliar sprays of SADH and an experimental formulation of succinic acid derivatives, TD-6266-R, resulted in seed yields of 'Talent' of approximately 400 kg ha⁻¹ compared to 168 kg ha⁻¹ in untreated plots. These responses were statistically significant, while lesser seed yield increases due to 2,4-DB [4-(2,4-dichlorophenoxY) butyric acid] and chlormequat [(2-chloroethyl)trimethylammonium chloride] were not significant. Similar field testing in 1973 resulted in no seed yield enhancement by any plant regulator. However, precipitation at the experimental site during the 1973 growing season was only 0.4 cm in contrast to the 30-year average of 4.3 cm. A plant regulator-environment interaction is suggested. Yield component analysis showed that the number of seeds per pod was increased significantly by the same treatments which promoted yield. Number of pods per raceme was also a strong determinant of seed yield. The relative importance of one component of yield, the number of seedbearing racemes per unit land area, is yet to be established. After treatment with SADH and TIBA in 1973, fieldgrown 'DuPuits' alfalfa accumulated more total dry matter and up to twice as much dry matter in pods as did untreated plots. Shoots treated with TIBA exhibited a mean net carbon dioxide exchange (NCE) rate of 21 mg CO₂ dm⁻² leaf area hr⁻¹ compared to 16 mg CO2 dm⁻² hr ⁻¹ for SADH-treated and control shoots. However, dry matter accumulation and NCE responses were statistically nonsignificant at the .05 probability level. Specific leaf weight exhibited an increased diurnal maximum when treated with SADH and TIBA, while the diurnal minimum remained equal to that of control plants. The principal effect of TIBA on reproductive development was via its promotion of the growth and raceme initiation of axillary branches. In a dosage response study, 10 ppm TIBA was most effective, resulting in a fourfold increase in total branch length per primary stem and a highly significant increase in total raceme production. The finding that two axillary structures generally arise from an alfalfa leaf axil may be useful in understanding the phenomena of branching and floral initiation in this crop. Alfalfa genotypes differed in their growth response to environmental conditions. It appeared possible that genotypes also differed in response to applied plant regulators. This research has shown that applied plant regulators can promote flowering in alfalfa and has suggested that the carbon budget of alfalfa may also be affected. These changes may or may not be translated into increased seed production. The net effects are a result of plant regulator interaction with environmental conditions and plant genotype. Thus, variability in the response to plant regulators can be expected. Close

• 6. [Article] Alfalfa cutting management in the Columbia Basin

  Field studies to determine appropriate cutting management regimes consistent with yield, quality, and persistence of stand were conducted on several alfalfa varieties in the Columbia Basin region of Oregon. Two ...

  Citation × Citation Citation Abstract Copy Title: Alfalfa cutting management in the Columbia Basin Author: Suttner, Donald Lee Field studies to determine appropriate cutting management regimes consistent with yield, quality, and persistence of stand were conducted on several alfalfa varieties in the Columbia Basin region of Oregon. Two groups of treatments, including consecutive cuts at the same stage of maturity and cuts made at varying maturities, were imposed on Anchor, Apex, and Washoe. The first group consisted of tenth bloom with and without fall cutting and full bud all season. The next group contained early or pre-bud followed by tenth bloom, full bud followed by tenth bloom, and tenth bloom followed by full bud. The varieties, N-102, Saranac, and Vernal, were subjected to three and four cuts per season which corresponded to intervals of 44 and 35 days, respectively. Results with Anchor over a two year period indicated consistently high yields of dry matter and protein using a full bud followed by tenth bloom schedule. Full bud all season or early bud followed by tenth bloom offered increased protein concentration at some sacrifice in dry matter yield. Treatments effected only small differences in stand density. The variety Apex underwent rapid stand decline during the course of the studies. When persistence is not an overriding consideration, full bud all season afforded increased protein content without appreciable loss in dry matter yield in comparison with most other treatments. Treatments displayed little differential effect on stand density. Dry matter yield of Washoe was unaffected by treatments imposed. Full bud all season and immature followed by tenth bloom resulted in increased protein concentration. Differential effects evoked by treatments on stand density early in the experiment had essentially dissipated at its conclusion. The varieties, N-102, Saranac, and Vernal, gave increased protein content with more frequent cutting without significant change in dry matter yield. Title: Alfalfa cutting management in the Columbia Basin Author: Suttner, Donald Lee Field studies to determine appropriate cutting management regimes consistent with yield, quality, and persistence of stand were conducted on several alfalfa varieties in the Columbia Basin region of Oregon. Two groups of treatments, including consecutive cuts at the same stage of maturity and cuts made at varying maturities, were imposed on Anchor, Apex, and Washoe. The first group consisted of tenth bloom with and without fall cutting and full bud all season. The next group contained early or pre-bud followed by tenth bloom, full bud followed by tenth bloom, and tenth bloom followed by full bud. The varieties, N-102, Saranac, and Vernal, were subjected to three and four cuts per season which corresponded to intervals of 44 and 35 days, respectively. Results with Anchor over a two year period indicated consistently high yields of dry matter and protein using a full bud followed by tenth bloom schedule. Full bud all season or early bud followed by tenth bloom offered increased protein concentration at some sacrifice in dry matter yield. Treatments effected only small differences in stand density. The variety Apex underwent rapid stand decline during the course of the studies. When persistence is not an overriding consideration, full bud all season afforded increased protein content without appreciable loss in dry matter yield in comparison with most other treatments. Treatments displayed little differential effect on stand density. Dry matter yield of Washoe was unaffected by treatments imposed. Full bud all season and immature followed by tenth bloom resulted in increased protein concentration. Differential effects evoked by treatments on stand density early in the experiment had essentially dissipated at its conclusion. The varieties, N-102, Saranac, and Vernal, gave increased protein content with more frequent cutting without significant change in dry matter yield. Close

• 7. [Article] Selective control of volunteer wheat (Triticum aestivum (L.) em. Thell.) in new seedlings of alfalfa (Medicago sativa L.) with fluazifop-butyl and sethoxydim

  Volunteer winter wheat (Triticum aestivum 'Daws') severely suppressed growth of fall-planted alfalfa (Medicago sativa (L.) 'Vernal') seedlings. Wheat competition began soon after alfalfa emerged and continued until ...

  Citation × Citation Citation Abstract Copy Title: Selective control of volunteer wheat (Triticum aestivum (L.) em. Thell.) in new seedlings of alfalfa (Medicago sativa L.) with fluazifop-butyl and sethoxydim Author: Ott, Pablo Volunteer winter wheat (Triticum aestivum 'Daws') severely suppressed growth of fall-planted alfalfa (Medicago sativa (L.) 'Vernal') seedlings. Wheat competition began soon after alfalfa emerged and continued until the first forage harvest the following May. Alfalfa yield at the first cutting was reduced by 1% for each day volunteer wheat was allowed to grow within the period of 20 to 41 days after planting. When the wheat remained until harvest, alfalfa yield was reduced by 85%. Fluazifop-butyl (+) -butyl 2-[4-[[5-(trifluoromethyl)- 2- pyridinyl] oxy] phenoxy] propanoate and sethoxydim 2- (1- (ethoxyimino)butyl] 5- [2- (ethylthio)propyl] -3-hydroxy- 2-cyclohexen-l-one at rates as high as 3.2 kg/ha (plus phytobland oil at 2.3 L/ha) did not injure the alfalfa or reduce the yield of alfalfa hay when applied at any stage of growth from the unifoliate to the fully developed stages. Control of wheat was better when fluazifop-butyl and sethoxydim were applied in the fall than in the summer. Both herbicides controlled wheat slightly better when applied in the one- to five- tiller stages than at earlier or later stages of growth. In general, fluazifop-butyl was more effective than sethoxydim when applied at any given rate. Under favorable conditions, rates of fluazifop-butyl and sethoxydim as low as 0.12 and 0.18 kg/ha, respectively, killed wheat. Wheat growth was suppressed at even lower rates. However, higher rates (0.2 and 0.4 kg/ha of fluazifop- butyl and sethoxydim, respectively) were required to provide a long term effect under a broad range of conditions. The activity of fluazifop-butyl applied at the twotiller stage of wheat took place mainly through foliar rather than root exposure. Fluazifop-butyl at 0.2 kg/ha killed wheat regardless of the soil moisture content (8% vs 15%). The activity of fluazifop-butyl at 0.12, 0.18, and 0.24 kg/ha on wheat was severely reduced when combined with the dimethylamine salt of 2,4-DB [4- (2,4- dichlorophenoxy) butyric acid] at 1.8 kg/ha, but the antagonism was overcome by increasing the rate of the grass killer to 0.36 kg/ha. Title: Selective control of volunteer wheat (Triticum aestivum (L.) em. Thell.) in new seedlings of alfalfa (Medicago sativa L.) with fluazifop-butyl and sethoxydim Author: Ott, Pablo Volunteer winter wheat (Triticum aestivum 'Daws') severely suppressed growth of fall-planted alfalfa (Medicago sativa (L.) 'Vernal') seedlings. Wheat competition began soon after alfalfa emerged and continued until the first forage harvest the following May. Alfalfa yield at the first cutting was reduced by 1% for each day volunteer wheat was allowed to grow within the period of 20 to 41 days after planting. When the wheat remained until harvest, alfalfa yield was reduced by 85%. Fluazifop-butyl (+) -butyl 2-[4-[[5-(trifluoromethyl)- 2- pyridinyl] oxy] phenoxy] propanoate and sethoxydim 2- (1- (ethoxyimino)butyl] 5- [2- (ethylthio)propyl] -3-hydroxy- 2-cyclohexen-l-one at rates as high as 3.2 kg/ha (plus phytobland oil at 2.3 L/ha) did not injure the alfalfa or reduce the yield of alfalfa hay when applied at any stage of growth from the unifoliate to the fully developed stages. Control of wheat was better when fluazifop-butyl and sethoxydim were applied in the fall than in the summer. Both herbicides controlled wheat slightly better when applied in the one- to five- tiller stages than at earlier or later stages of growth. In general, fluazifop-butyl was more effective than sethoxydim when applied at any given rate. Under favorable conditions, rates of fluazifop-butyl and sethoxydim as low as 0.12 and 0.18 kg/ha, respectively, killed wheat. Wheat growth was suppressed at even lower rates. However, higher rates (0.2 and 0.4 kg/ha of fluazifop- butyl and sethoxydim, respectively) were required to provide a long term effect under a broad range of conditions. The activity of fluazifop-butyl applied at the twotiller stage of wheat took place mainly through foliar rather than root exposure. Fluazifop-butyl at 0.2 kg/ha killed wheat regardless of the soil moisture content (8% vs 15%). The activity of fluazifop-butyl at 0.12, 0.18, and 0.24 kg/ha on wheat was severely reduced when combined with the dimethylamine salt of 2,4-DB [4- (2,4- dichlorophenoxy) butyric acid] at 1.8 kg/ha, but the antagonism was overcome by increasing the rate of the grass killer to 0.36 kg/ha. Close