[PDF] Floret Fertility And Seed Yield In Selected Perennial Ryegrass Cultivars As Affected By Time And Rate Of Nitrogen N Application eBook

Author : Ali Salih Gangi
Publisher :
Page : 118 pages
File Size : 34,10 MB
Release : 1984
Category : Grasses
ISBN :

GET BOOK

To increase efficiency of seed production, it is important to understand the effects of nitrogen (N) fertilizer rate and time of application. In particular, the effects on floret fertility should be examined since only a small proportion of florets actually produce harvestable seed. For these reasons, experiments were conducted in the field in 1981 and 1982 to study the effect of rate and time of nitrogen application at different growth stages on potential and actual seed yield and floret fertility. Specific effects of nitrogen on rate of floret filling in the top, intermediate and the bottom locations of the spike were observed. Two cultivars of perennial ryegrass were used in this study: Linn, an early maturing forage cultivar and Pennfine, which is a later maturing turf-type cultivar. Different nitrogen rates were applied at the vegetative phase, during spikelet initiation phase and at both stages. Nitrogen application increased the seed yield potential by increasing the number of fertile tillers per unit area and/or number of florets per spikelet. Nitrogen rate and time of application had no effect on floret fertility. Floret fertility percentage in all treatments were initially about 61%, but by final harvest had decreased to 20-32%. This reduction was likely due to loss of light seed during har vesting and cleaning. There was a slightly lower floret fer tility in the top compared with the intermediate and bottom location of the spike, but this was not affected by nitrogen rate or timing. Linn cultivar showed a higher rate of floret filling than the Pennfine; however, nitrogen rate and time of application showed no effect on rate of floret filling. Seed yield was affected by nitrogen application only in 1981, due to lodging, excessive vegetative tillering, and yield com ponent compensation. Results in this study do not support the hypothesis that management practices should be aimed at increasing head size rather than head numbers.

Author : William Clyde Young
Publisher :
Page : 244 pages
File Size : 35,58 MB
Release : 1987
Category : Lolium perenne
ISBN :

GET BOOK

Seed yield in perennial ryegrass is the product of yield components that develop during the life of the plant. Crop yield potential is defined by the number of fertile tillers, spikelets per spike, and florets per spikelet. It has been shown that perennial ryegrass realizes only a small percentage of the potential as harvested seed, and is an inherently poor seed producer as cultivars have been selected primarily for vegetative production or desirable turf characteristics. The Willamette Valley of Oregon produces nearly all of the perennial ryegrass seed grown in the United States. Environmental conditions during plant growth control potential yield development and the efficiency with which it is used. To increase the efficiency of seed production, it is important to understand the effects specialized cultural management techniques have in this producing region. In these studies on perennial ryegrass, the effects of varying the amount and time of spring applied nitrogen (N), and the effects of the plant growth retardant paclobutrazol were investigated under field conditions using the cultivar Pennfine. In addition, the influence of high levels of early spring N, combined with growth retardant use was investigated. Increased tiller densities, the result of higher N level, can result in a greater seed yield potential. However, as tiller densities become greater, the components of seed yield on individual tillers become smaller. In addition, earlier and more severe lodging result in greater tiller mortality and harvest dry weight losses. Split spring applications totaling 120 to 150 kg N ha−1 appeared to provide a better balance between compensating yield components, while maintaining an economic seed yield. Spring application of paclobutrazol delayed the onset and severity of lodging, resulting in an increased number of fertile tillers in the stand, and a greater number of potential seed sites per unit area. Earlier dates of application had a greater effect in reducing lodging in 1983, but no difference was observed between two spring growth stages in 1984. Reduced lodging appears to enhance seed set, resulting in a greater number of seeds recovered at harvest and a higher floret site utilization (FSU). Harvest index was also increased with paclobutrazol. Application of paclobutrazol significantly increased seed yield, a result of improved seed recovery due to more seeds per spike. However, the increased yield potential resulting from higher N rate was not recovered by application of paclobutrazol where severe lodging conditions occurred prior to the completion of seed filling. Under more normal environmental conditions, 120 kg N ha−1, followed with a growth retardant application, had a significantly greater seed yield than the other treatments.

Author :
Publisher :
Page : 4 pages
File Size : 39,54 MB
Release : 2001
Category :
ISBN :

GET BOOK

This report describes & presents results of a study to determine effects on seed yields of nitrogen fertilizer applied on three cultivars of Westerwolds ryegrass (Lolium multiflorum) over a three year period. Field experiments were conducted on Prince Edward Island 1998-2000 with fertilizer applied at three different rates, either all at seeding or 60% at seeding & 40% at tillering stage. The experimental design was a randomized block with four replications. Results are presented regarding seed yield, plant characteristics, and ryegrass composition.

Author :
Publisher :
Page : 814 pages
File Size : 22,68 MB
Release : 1989
Category : Agriculture
ISBN :

GET BOOK

Includes abstracts of the annual meetings of the American Society of Agronomy; Soil Science Society of America; Crop Science Society of America ( - of its Agronomic Education Division).

Author : Matthew William Mulanax
Publisher :
Page : 118 pages
File Size : 16,29 MB
Release : 1971
Category : Grasses
ISBN :

GET BOOK

The effect of clipping and supplemental nitrogen application on seed production of Linn perennial ryegrass and Merion Kentucky bluegrass was studied. Clipping and nitrogen treatments did not significantly affect the seed yield of Linn perennial ryegrass during the 1967 growing season. The seed yield of Merion Kentucky bluegrass was significantly increased by a combined winter-spring clipping regime when compared with the unclipped control. Application of 136 pounds of nitrogen in two equal spring applications significantly reduced the seed yield of Merion Kentucky bluegrass. Spring clipping tended to reduce the number of fertile tillers per unit area for both species. Supplemental nitrogen generally increased the number of fertile tillers per unit area for Linn perennial ryegrass. Application of 30 pounds of additional nitrogen delayed the period of head emergence for Linn perennial ryegrass. The time of pollen shed of Merion Kentucky bluegrass was delayed by all clipping regimes.

Author : Barbara J. Hinds-Cook
Publisher :
Page : 84 pages
File Size : 41,96 MB
Release : 2017
Category : Lolium perenne
ISBN :

GET BOOK

Perennial ryegrass (Lolium perenne L.) is a widely grown cool season, bunch type, short lived perennial grass that is native to Europe, Asia, and North Africa, but has been adapted globally. Perennial ryegrass is quick to establish, has a long growing season, and produces high seed yield and forage or turf quality (high density, fine leaves, and dark green color). Mesotrione is a selective 4-hydroxyphyenyl pyruvate dioxygenase (HPPD) inhibiting herbicide used for weed control in perennial ryegrass seed production and turfgrass in the USA. HPPD inhibiting herbicides cause a reduction in carotenoids which protect chlorophyll from high energy light. The photodegradation of chlorophyll results in a bleaching of leaf tissue in susceptible plants. In seed production, mesotrione, commercialized in the USA as Callisto®, is applied postemergence in the spring to fall planted perennial ryegrass seed crops. Mesotrione for use in turfgrass, commercialized in the USA as Tenacity®, is applied pre or postemergence. The effects of a postemergence application of mesotrione on chlorophyll concentration, dry biomass, plant height, and seed yield and germination compared to an application of another HPPD inhibitor, pyrasulfotole-bromoxynil, on perennial ryegrass cultivars were evaluated. There were differences in perennial ryegrass cultivar response to a postemergence application of both HPPD inhibitors in chlorophyll concentration and to a postemergence application of pyrasulfotole-bromoxynil in dry biomass. No reduction in plant height was caused by the HPPD inhibitors. Seed yield of the perennial ryegrass cultivars was not negatively impacted by a postemergence application of mesotrione. However, only twelve perennial ryegrass cultivars were evaluated in this study; therefore, caution may be warranted when using mesotrione with other perennial ryegrass cultivars. The effects of mesotrione applied postemergence on perennial ryegrass cultivars at three different temperatures, 5, 25, and 35°C, on chlorophyll concentration, leaf color, and total chlorophyll were investigated. At each temperature, there was a response within some cultivars. The cultivar ‘Derby Xtreme’ exhibited the most sensitivity to mesotrione at 5°C and ‘SR 4660ST’ was the most sensitive at 35C. The cultivar ‘PR 8821’ was the most sensitive overall at all evaluation timings and temperatures. The cultivar exhibiting the most tolerance to mesotrione was ‘Esquire’. Assessing perennial ryegrass cultivar response to mesotrione at one temperature versus another temperature resulted in ‘Allstar 3’ exhibiting less sensitivity at 35 than at 5 or 25°C. The majority of cultivars exhibited more sensitivity at 25 than at either 5 or 35°C. Turfgrass managers should use caution when applying mesotrione postemergence to some perennial ryegrass cultivars if temporary bleaching of the turf is undesirable.