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Articles 1 - 30 of 12195
Full-Text Articles in Physical Sciences and Mathematics
Effect Of Crop Age On Seed Yield Of Arachis Pintoi At Two Sites In Costa Rica, Pedro J. Argel, Alfredo Valerio
Effect Of Crop Age On Seed Yield Of Arachis Pintoi At Two Sites In Costa Rica, Pedro J. Argel, Alfredo Valerio
IGC Proceedings (1993-2023)
Arachis pintoi is a forage legume well adapted to the humid tropics of Costa Rica. Seed production studies were carried out at two contrasting localities within the country, Gulipiles (very humid tropics) and San Isidro (seasonal evergreen tropical forest). The accessions CIAT 18748, 18744 and 17434 cv. Amarillo of A. pinloi were vegetatively planted at both sites. Seed yields were measured at 8, 12, 16 and 20 months post- planting inGulipiles, and at·8, 16 and 20 months in San Isidro. Mean seed yields among accessions were similar in San Isidro but significantly different in Gulipiles; however, the contrary occurred in …
Efficient Nitrogen Fertilization In Grass Seed Crops With Regard To Soil Mineral Nitrogen Content And Analyzing Grass Tillers In Spring, W Schoberlein, H J. Wahl
Efficient Nitrogen Fertilization In Grass Seed Crops With Regard To Soil Mineral Nitrogen Content And Analyzing Grass Tillers In Spring, W Schoberlein, H J. Wahl
IGC Proceedings (1993-2023)
When applying the Nmln method in grass seed crops analogously lo that in cereal crops we proceed from the experience that for a mean level of mineralisation, the sum total of soil-borne Nm1n available to plants at the beginning of the growth period and Nd Input in the form of fertiliser will provide sufficient N to the crop. The total quantity of mineral soil-borne N and fertiliser N is considered as the nominal value. The required N input can be derived from the difference between nominal value and mineral soil-borne N (Nd = nominal value• Nrnin>· For Dactylis glomerata …
Effects Of Aneuploidy On Seed Production In Autopolyploid Forage Crops, A Elgersma
Effects Of Aneuploidy On Seed Production In Autopolyploid Forage Crops, A Elgersma
IGC Proceedings (1993-2023)
Between the selection of a population and its commercial use, several generations of multiplication are necessary. The essential feature in variety maintenance is that no genetic changes occur during multiplication. In seed-propagated species, however, during each multiplication cycle natural selection takes place at ihe gamete, zygote, seed and plant level. In induced autopolyploids high frequencies of aneuploids can occur. Aneuploidy not only affects the seed yield level, but also the selection processes that occur during multiplication. It may cause genetic shift and affect variety stability. Species differ in their tolerance to aneuploids. It is not possible to eliminate aneuploidy by …
Effects Of Ratooning And Protection From Diseases And Birds On Seed Production In Guinea Grass, Okoro Oji, F N. Madubuike, F.O C. Ezedinma
Effects Of Ratooning And Protection From Diseases And Birds On Seed Production In Guinea Grass, Okoro Oji, F N. Madubuike, F.O C. Ezedinma
IGC Proceedings (1993-2023)
Effects of ratooning and protection from diseases and birds on seed production in guinea grass (Pannicum maximum L.) were assessed in a study from October 1986 to April 1987. Treatments included ratooning and mancozeb application with or without protection from birds (netting). Highest yield occurred with combined netting and mancozeb application. Mancozeb sp,aying without netting gave lower seed yield than netting without fungicide spraying. Seed yield, which generally decreased with ratooning, was lowest among unnetted and unsprayed crops. Prom anthesis to seed maturation lasted, on average, 9 days, and seeds borne on the upper part of the panicle matured …
Potential For Improved Honey Bee Pollination Efficiency From Easy-To-Trip Lucerne, L R. Teuber, E E. Knapp
Potential For Improved Honey Bee Pollination Efficiency From Easy-To-Trip Lucerne, L R. Teuber, E E. Knapp
IGC Proceedings (1993-2023)
The principal pollinator of lucerne (Medicago sativa L.) in California, USA is the honey bee (Apis mellifera L.). However, honey bees are notoriously inefficient pollinators of lucerne because they learn to avoid tripping the floret. Easy-to-trip lucerne florets could reduce this problem. These studies were designed to determine the inheritance of ease of tripping and assess the effect of ease of tripping on the rate of outcrossing. Both additive and digenic variance for ease of tripping were significant, resulting in a heritability of 34.0:1:16.2%. Ease of tripping had no influence on outcrossing rate, which was estimated to average …
Effect Of Final Cutting For Fodder On Seed Yield And Seed Quality In Berseem, S L. Saini, R K. Chowdhury
Effect Of Final Cutting For Fodder On Seed Yield And Seed Quality In Berseem, S L. Saini, R K. Chowdhury
IGC Proceedings (1993-2023)
The study was conducted to determine the appropriate time of final culling (closing) for fodder to optimise the seed yield and seed quality in berseem (Trifolium alexandrinum L.). Based on 2 years' experimentation, the maximum seed yield was obtained when the final cut for fodder was taken in mid•March and the crop was then closed for seed. Seed yield was reduced drastically when the final cut was delayed to late March•April. The seed quality parameters of standard germination, seed weight and vigour index were also reduced when the final cut for fodder was delayed to late March•early April. Based …
Effect Of Post-Harvest Management Practices On Seed Yields On Fine-Leaf Fescue, Gale A. Gingrich, William C. Young Iii, Thomas B. Silberstein
Effect Of Post-Harvest Management Practices On Seed Yields On Fine-Leaf Fescue, Gale A. Gingrich, William C. Young Iii, Thomas B. Silberstein
IGC Proceedings (1993-2023)
Public opposition and legislative actions have restricted the practice of open-field burning of grass seed fields in Western Oregon's Willamette Valley. Finding economically acceptable alternatives to straw residue removal has become a priority for valley grass seed growers. Trials using 4 residue management practices were established on 2 commercial fine fescue (Festuca rubra) seed fields. Seed yields varied significantly between residue management practices. Seed yields from thermal-treated plots were equal or significantly greater than yields from the non-thermal treatments. Fertile tiller number was also greater with thermal treatments. Most fine fescue fields produce 4-6 seed crops before replanting, …
Floret Site Utilization Of White Clover, A H. Marshall, D H. Hides
Floret Site Utilization Of White Clover, A H. Marshall, D H. Hides
IGC Proceedings (1993-2023)
Plants of white clover (Trifolium repensL.) cv. Olwen were grown in an open glasshouse at 20°C and ovule growth and development measured. Differences in the rate of growth of ovules within ovaries were observed as early as 2 days after pollination. Ovules reached a maximum size after 8 days, with the smallest only half the size of the largest. After 8 days the smallest ovules became flaccid and shrivelled. Ovule position within the ovary had no effect on the frequency of seed set. Inflorescence position and floret position on the inflorescence had a significant effect on the number …
Influence Of Harvest Date On The Yield And Quality Of Seed Of Phalaris, K Reddy, W R. Scott, R J. Lucas
Influence Of Harvest Date On The Yield And Quality Of Seed Of Phalaris, K Reddy, W R. Scott, R J. Lucas
IGC Proceedings (1993-2023)
Grasslands Maru phalaris (Phalaris aquatica L,) was harvested every third day commencing 12 days after mid-anthesis (DAA) to define the optimum time of harvest for seed yield and quality. Harvesting earlier than 21-24 DAA reduced 1000-seed weight and viability. Delaying harvest until 24 days reduced seed yield due to shattering but had no detrimental effect on seed weight and viability. Heavy seed losses occurred 24 DAA when seed moisture fell below 40%. The results of this experiment suggest that Maru phalaris should be harvested 21-24 DAA when the seed moisture is in the range of 40-42% to reduce the …
Annual Bluegrass And Rat's Tail Fescue Control In Perennial Ryegrass, M E. Mellbye, William C. Young Iii, George W. Mueller-Warrant
Annual Bluegrass And Rat's Tail Fescue Control In Perennial Ryegrass, M E. Mellbye, William C. Young Iii, George W. Mueller-Warrant
IGC Proceedings (1993-2023)
Annual bh1egrass (Poa annua L.) and rat's-tail fescue (Vulpia myruros (L.) C.C. Omel.) are common weed contaminants in seed from perennial ryegrass fields Lolium perenne L. grown in Oregon. A trial was conducted to evaluate post-harvest residue removal methods and herbicides to reduce the level of these impurities. The best weed control was obtained from herbicides following crew-cut management, a comparatively thorough non-thermal nppronch to residue removal. Control was good with sequential herbicide treatments, especially when an effective pre-emergence herbicide such as pendimethalin was used, although no treatment completely eliminated annual bluegrass and rat's-tail fescue from threshed seed samples …
Flowering And Seed Production Of Centrosema Spp. In Relation To Day Length And Temperature, R.J M. Gonzalez, R J. Clements, L R. Humphreys
Flowering And Seed Production Of Centrosema Spp. In Relation To Day Length And Temperature, R.J M. Gonzalez, R J. Clements, L R. Humphreys
IGC Proceedings (1993-2023)
The effcc1s of variation in daylength and temperature on the flowering processes leading to seed production were studied in genotypes of 5 Centrosema spp. Short days (11 h) enhanced flowering in accessions of C. virginatum from low latitude but flowering of lines from high latitude was more prolific in 16-h days. A quantitative long-short day response was evident in 2 intermediate latitude accessions. The critical photoperiod for flowering·varied: C. virginianum cross 31 flowered in 13.5 h or less, C. pubescens, C. pascuorum and C. macrocarpum in 12 h or less, and C. schiediam Oowcred only in a 10.5 …
Herbicide Treatments For Non-Thermal Grass-Seed Production, George W. Mueller-Warrant, William C. Young Iii
Herbicide Treatments For Non-Thermal Grass-Seed Production, George W. Mueller-Warrant, William C. Young Iii
IGC Proceedings (1993-2023)
Legislation phasing down open-field burning in the Willamette Valley of Oregon is forcing grass seed growers to alter crop production piactices. Adoption of new mechanical means for straw removal has increased reliance on herbicides. Volunteer seedling control and crop tolerance for 15 herbicide treatment sequences were evaluated in established tall fcscue (Festuca arundinacea) and perennial ryegrass (Lolimn perenne) stands during 2 growing seasons using 5 methods of residue removal. Pre-emergence pendimethalin was extremely safe yet fairly effective on volunteer seedlings in both crops. For perennial ryegrass subsequently treated with post-emergence herbicides, pre-emergence metolachlor was slightly more …
A Development Scale For Perennial Ryegrass, Miriam L. Martin, Roger J. Field
A Development Scale For Perennial Ryegrass, Miriam L. Martin, Roger J. Field
IGC Proceedings (1993-2023)
Vernalised plants of perennial ryeg ra ss (Lolium prenne L. cv. Orasslonds Nui) were grown under controlled conditions and apical development followed by regular excision of apices, which were examined by light and scanning electron microscopy. A 12-point scale describing apical development from the vegetative stage to ear emergence has been produced that is presented in 2 forms: a developmental sequence describing organogenesis events at specific stages, and a commentary on easily recognised features of each stage. The developmental scale provides a detailed analysis that is of value as a botanical description and as a practical aid to those involved …
Seed Yield Potential Of White Clover: Characteristics, Components And Compromise, P.T P. Clifford, I J. Baird
Seed Yield Potential Of White Clover: Characteristics, Components And Compromise, P.T P. Clifford, I J. Baird
IGC Proceedings (1993-2023)
Nd relationship between leaf size and any of the measured variables was found for 63 agronomically superior white clover (Trifolium repens L.) plants of relatively diverse morphological and physiological characteristics, Predominantly crown-flowering plants gave more than double the seed yield of stolon-lip 'flowerers. High seed yields were also associated with delays in peak flowering, harvest date and increased harvest dry matter. Similar associations were evident for inflorescence density. Increased dry matter accumulation was associated with increases in both floret numbers and seeds/ inflorescence.
Studies In Germination And Thousand-Seed Weight In Chicory Cv. Grasslands Puna, W J. Archie, J S. Rowarth, B R. Guy
Studies In Germination And Thousand-Seed Weight In Chicory Cv. Grasslands Puna, W J. Archie, J S. Rowarth, B R. Guy
IGC Proceedings (1993-2023)
A strong, positive correlation was found between 1000-seed weight (TSW) and germination in chicory (Cichorium intybus L.) cv. Grasslands Puna. Low TSW tended to be associated with empty or immature seed; empty seed was associated with exclusion of bees. No significant differences in seed characteristics were found between seeds harvested from different positions (top, middle or bottom third) on the plant. Optimum harvest lime was 4 weeks after peak flowering.
Seed Production Of Plantain (Plantago Lanceolata L.), J S. Rowarth, M P. Rolston, W J. Archie
Seed Production Of Plantain (Plantago Lanceolata L.), J S. Rowarth, M P. Rolston, W J. Archie
IGC Proceedings (1993-2023)
Seed development studies showed that seed maturity in plantain (Plantago lanceolata L,) occurred 6 weeks after anthesis; maximum seed yields were obtained 8 weeks after anthesis. This is consistent with the fact that seed heads take approximately 17 days to complete flowering. Fertiliser nitrogen increased plantain seed yield. Time of closing, timing of nitrogen application and different stand densities did not significantly affect seed yield, probably because plantain can adapt to and compensate for the treatments imposed.
Reproductive Initiation, Closing Dates, Nitrogen Requirements And Harvesting Of Smooth Brome Cv. Grasslands Tiki, J S. Rowarth, W J. Archie
Reproductive Initiation, Closing Dates, Nitrogen Requirements And Harvesting Of Smooth Brome Cv. Grasslands Tiki, J S. Rowarth, W J. Archie
IGC Proceedings (1993-2023)
Reproductive initiation, closing dates, nitrogen requirements and optimum harvest time were investigated for seed production of Grasslands Tiki smooth brome (Bromus inermis Leyss.) in the South Island of New Zealand. Reproductive initiation began in late June, spikelet initiation in mid-September and ear-emergence in midOctober. Seed yield was not affected detrimentally by mowing to 5 cm in mid-September but decreased 24% by mowing in mid-October. Seed yield tended to increase with increasing amounts of N. However, although the highest seed yields were achieved with 50 kg/ha of N in autumn plus I 00 or 150 kg/ha in spring, they did not …
Evaluation Of Non-Thermal Residue-Removal Equipment Used By Willamette Valley Seed Growers As A Substitute For Open-Field Burning, William C. Young Iii, David O. Chilcote, Thomas B. Silberstein
Evaluation Of Non-Thermal Residue-Removal Equipment Used By Willamette Valley Seed Growers As A Substitute For Open-Field Burning, William C. Young Iii, David O. Chilcote, Thomas B. Silberstein
IGC Proceedings (1993-2023)
Recent legislation reducing open-field burning in Oregon has caused many grass seed producers to experiment with non-thermal residue management alternatives. On-farm test sites were selected to evaluate 4 post-harvest residue removal treatments common at 7 locations. Seed yield did not differ significantly when residue management treatments were applied to new stands of perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) after harvest of the first seed crop. Control of weeds and volunteer crop seedlings was poorest where increased amounts of crop residue remained on the soil surface.
Sowing Rate And Row Spacing In Pure Stand Establishment Of Smooth Meadowgrass For Seed Production, Trygve S. Aamlid
Sowing Rate And Row Spacing In Pure Stand Establishment Of Smooth Meadowgrass For Seed Production, Trygve S. Aamlid
IGC Proceedings (1993-2023)
Seed production of smooth meadow grass (Poa pratensis L.) cv. Lavang was compared at 3 sowing rates (2.5, 5.0 and l0.0 kg/ha) and at 2 row spacings (16.5 and :n cm), the wider used in conjunction with carbon banding. Results varied between fields according to temperature after planting and the weed content of the soil, but, on average, 5.0 kg/ha proved to be the optimal sowing rate. 33 cm row spacing and carbon banding caused a higher proportion of tillers to develop panicles and gave a higher seed yield with a better weed control in the first and third …
Role Of Galega Seed In Forage Production, H Raig
Role Of Galega Seed In Forage Production, H Raig
IGC Proceedings (1993-2023)
The effects of different soil types and seeding rates and row spacing on the yield of galega (Galega orientalis) have been determined in long-term trials. Over 10 years al the Estonian Research Institute of Agriculture, IO00-seed weight was 6.7-8.4 g. Ten-yenr average seed yield (kg/hn) was 241, 305 nnd 424 on soils of pH 5.6, 6.0 and 6,3, respectively. Seed yields of galega were about 6 times those of alfalfa in the soil at pH 6.3. Seeding rate and now spacing hnd little effect on seed yields. In south Sakhalin, galega was winter-hardy at - 47°C and survived drought …
Effect Of Paclobutrazol On Seed Yield In The Subtropical Grass Digitaria Eriantha, L Ramirez, J B. Hacker
Effect Of Paclobutrazol On Seed Yield In The Subtropical Grass Digitaria Eriantha, L Ramirez, J B. Hacker
IGC Proceedings (1993-2023)
Lodging of Digitaria erlantha can reduce seed yield of well-fertilised seed crops. This experiment was designed to assess the effect of the growth retardant paclobutrazol on seed production and its components in a spring crop of D. erialllha cv. Premier. Paclobutrazol decreased lodging, reduced tiller height and weight and tended to increase seed set, seed weight and seeds per panicle. However, it also tended to reduce panicle density. Treatment with 0.75 kg ai/ha applied at initial panicle emergence was optimal, increasing pure seed yield from 305 to 462 kg/ha. Paclobutrazol has potential for increasing seed yield in D. erantlta through …
Seed Shattering In Tall Fescue, Mario Falcinelli
Seed Shattering In Tall Fescue, Mario Falcinelli
IGC Proceedings (1993-2023)
Seed shattering in many commercial grass seed crops is a serious problem which makes seed harvesting difficult and which is often a major cause of high losses in seed yield. 2880 plants of tall fescue (Festuca arundinacea) belonging to 48 natural populations collected at sites scattered from northern (46° 10'N) to southern (39°05'N) Italy and 60 plants of the cultivar Fawn were grown in Perugia (Italy) as spaced plants. Al peak anthcsis, 5 panicles from each plant were randomly chosen and 40 days later they were evaluated for seed retention capability. Ten plants, belonging to 9 different populations, …
Achieving Potential Herbage Seed Yields In Species Of Temperate Regions, Franco Lorenzetti
Achieving Potential Herbage Seed Yields In Species Of Temperate Regions, Franco Lorenzetti
IGC Proceedings (1993-2023)
The potential seed yield (PSY) of a crop is represented by the total number of ovules present at anthesis in a unit area and is very high for nil forage species. However, seed yield or the agricultural realised seed potential (ARSP) is very low especially if compared with major grain crops (e.g., 15% vs 40% of PSY, respectively). The need for obtaining primarily high yield of high quality forage indicates that seed yield should be increased by improving the efficiency of the reproductive system rather than increasing its size. Seed setting and development and seed shattering are the characters to …
Stand Age And Closing Date Effects On Seed Yield Of Caucasian And Zigzag Clover Cultivars, G T. Daly, Jiwan Gurung, R J. Lucas
Stand Age And Closing Date Effects On Seed Yield Of Caucasian And Zigzag Clover Cultivars, G T. Daly, Jiwan Gurung, R J. Lucas
IGC Proceedings (1993-2023)
Seed yields of Caucasian clover (Trifolium ambigum} and zigzag clover (T. medium) were obtained over 3 seasons. The effects of 6 closing times in the final year were also measured. Caucasian clover cv. Alpine flowered earlier than cv. Monaro and the zigzag clover lines were last to flower. Seed yield of Monaro Caucasian clover in the second and third seasons averaged 400 kg/ha while cv. Alpine produced a maximum of 355 kg seed/ha. Pests and poor pollination were the major limitations lo high yields of zigzag clover seed. Kentucky zigzag clover produced 300 kg seed/ha when seed …
Breeding Hexaploid Pennisetums For Improved Seed Production, D A. Diz, S C. Schank
Breeding Hexaploid Pennisetums For Improved Seed Production, D A. Diz, S C. Schank
IGC Proceedings (1993-2023)
Interspecific hybrids between pearl millet (Pennisetum glacum) and elephantgrnss (P. purpureum) have many desirable characteristics, but they are sterile and do not have the ability to reproduce subsequent generations from seed. To overcome this barrier, we have obtained fertile hexaploids and have begun a breeding and selection programme among hexaploid progeny which produce seed. Seven hexaploid genotypes were selected and characterised as to panicle, seed and seedling traits. Weight of 100 seeds ranged from 0.152 to 0.247 g for the different genotypes. The number of seed harvested varied from 190 to over 700 per panicle. Germination of …
Herbage Seed Production In Norway, Ragnar Hillestad
Herbage Seed Production In Norway, Ragnar Hillestad
IGC Proceedings (1993-2023)
Seed of all important species of perennial grasses and clover for northern areas can be produced in Norway, with good quality, at about 60°N. Norway has built up its own plant breeding with seed production and is self-supporting in seed of the most important species for use in agriculture. The seed yield per area unit of grass species decreases from south lo north, but there are differences among cullivars depending on where the breeding work has been carried out. The short growing·season makes it difficult for some species to establish a good stand so the plants can flower and give …
Effect Of Propiconazole And Tebuconazole On Seed Production Of Tall Fescue, M D. Hare
Effect Of Propiconazole And Tebuconazole On Seed Production Of Tall Fescue, M D. Hare
IGC Proceedings (1993-2023)
When stem rust (Puccinia graminis Persoon) invaded a tall fescue (Festuca arrundinacea Schreb.) stand a fungicide, propiconazole, applied at 250 g ai/ha, increased seed yields by more than l000 kg/ha compared with untreated plots. Propiconazole applied at ear emergence increased seed yields more than when applied at anthesis or at both times. Propiconazole significantly (P<0.05) increased seeds/spikelet and reduced leaf senescence during seed development and at harvest compared with untreated plots. Stem rust (Puccitiia graminis Persoon) severely infected the control plots but not the plots treated with propiconazole at ear emergence. In a second trial, when only a minor trace of stem rust was observed, propiconazole and tebuconazole did not affect seed yields of tall fescue.
Effect Of Time And Rate Of Application Of The Growth Regulators Paclobutrazol And Flurprimidol On Seed Yield In Tall Fescue, M D. Hare
IGC Proceedings (1993-2023)
Paclobutrazol and flurprimidol were applied to a mature stand of tall fescue (Festuca anmdi11acea Schreb. cv. Grasslands Roa) at l and 2 kg ai/ha at spikelet initiation (SI) and floret initiation (Fl) in 1985. Paclobutrazol at 2 kg ·ai/ha, applied at both SJ and FI, increased P(<0.05) seed yields but the lower paclobutr z I rate and flurprimidol had no significant effect on seed yields.
Effect Of Boron And Nitrogen Application On Seed Production Of Lotus Uliginsus, M D. Hare, R A. Carran
Effect Of Boron And Nitrogen Application On Seed Production Of Lotus Uliginsus, M D. Hare, R A. Carran
IGC Proceedings (1993-2023)
Four rates or boron (B) and 2 rates of nitrogen (N) were applied to a mature stand of lotus 11ligi11os11s Schk. cv. Grasslands Maku before flowering, on 10 November 1988. The 2 rntes of N (40 and 80 kg N/ ha) were either applied once or applied at 5 and 10 kg N/ha respectively, at weekly intervals for 8 weeks. N did not increase seed yields. Weekly applications of N significantly (P<0.05) decreased seed yields by 28%. B at 0.91 kg/ha increased seed yields by 7% but this increase was not significant. While seed yields in some tropical legumes may benefit from N application, Grasslands Maku does not benefit. Rather, seed yields are depressed. The application of B did not significantly change seed yields, but more research on B may be needed in areas where B availability is thought to be low.
Effects Of Defoliation Intensity, Frequency And Time Of Final Defoliation Of Seed Yield Of Barrel Medic, F N. Muyekho, E D. Carter, G K. Mcdonald
Effects Of Defoliation Intensity, Frequency And Time Of Final Defoliation Of Seed Yield Of Barrel Medic, F N. Muyekho, E D. Carter, G K. Mcdonald
IGC Proceedings (1993-2023)
Swards of barrel medic (Medicago truncatula cv. Parnggio), sown at 20 kg/ha (1990), or 20 kg/ha or 200 kg/ha ( 1991 ), were mown to 3 or 6 cm height at intervals up to flowering, or 10 or 20 days after the start of flowering. In 1990, the swards were heavily grazed in July before imposing the defoliation treatments; in 1991 the swards were mown to 3 cm once in July. The responses to defoliation differed between the 2 years, because of the vigour of the sward at the time of imposing the cutting treatments. In 1990 severe defoliation …