Tiller Length Research Articles

CORRELATION AND PATH ANALYSIS IN PEARL MILLET (Pennisetum glaucum)

Genotypic and phenotypic correlations were computed in a collection of twelve diverse male sterile lines, five restorers and the resulting sixty hybrids of pearl millet (Pennisetum glaucum(L.) R. Br.). Grain yield per plant showed high positive and significant correlation with plant height, ear length, ear girth and total number of tillers. The path coefficient analysis indicated the highest positive direct effect on grain yield per plant was exhibited by number of productive tillers followed by car girth. Plant height, car length and 1000 grain weight and positive indirect effects through ear girth and the total number of tillers had indirect effect through the number of productive tillers on grain yield.

Effect of decapitation on absorption, translocation, and phytotoxicity of imazamethabenz in wild oat (Avena fatua L.)

The release of apical dominance by the physical destruction in situ of the apical meristem and associated leaf primordia (decapitation) promoted the growth of tillers in non-herbicide-treated wild oat plants, as indicated by increased tiller lengths and fresh weights. At 96 h after [14C] herbicide treatment following decapitation, the absorption of [14C]imazamethabenz and total translocation of radioactivity were respectively increased by 28% and 49%. By 96 h after [14C]imazamethabenz application, the radioactivity detected in the roots of decapitated plants was 45% higher than that in the roots of nondecapitated plants while the radioactivity in tillers of decapitated plants was 2.6-fold that in tillers of intact plants. Decapitation together with foliar spraying of imazamethabenz at 200 g ha−1 further reduced tiller fresh weight, greatly decreased the total tiller number, and thereafter significantly increased overall phytotoxicity by 32% as measured by total shoot fresh weight. The results of this study support the hypothesis that main shoot apical dominance limits translocation of applied imazamethabenz to lateral shoots, rendering tillers less susceptible to growth inhibition by the herbicide.

Studies on Heading Characteristics of Primary and Secondary Tillers in Rice(Oryza sativa L.). I. Influence of leaf cutting on heading characteristics of primary and secondary tillers.

同じ個体の主稈と分げつおよび分げつ相互間に幼穂発育及び出穂日の差が生ずるメカニズムを明らかにしようと試みた. イネ3品種, 農林1号, 日本晴, 農林8号を供試し, 水田土壌を詰めたa/2000ワグネルポットに直播土耕法によって野外で栽培を行った. 葉齢指数約70- 90の時期に伸長した葉を展開完了時に剪除し, 止葉の葉鞘から穂の先端が5 mm以上抽出したものを出穂と認め, その日付を止葉に記入した. 成熟期に抜き取り, 分げつ節位別に出穂日を記録整理した. 分げつの葉を展開完了時に剪除するとその分げつの出穂が遅れたが, それぞれの止葉葉位はほとんど変わらなかった. 出穂に対する分げつ葉剪除の影響はその分げつに著しく見られ, 葉を剪除しない分げつへの影響は少なかった. 剪葉による分げつの出穂遅延は早生品種で著しかった. 二次分げつと一次分げつの出穂日の関係は一次分げつと主稈の関係に類似しているが, 二次分げつ相互間の出穂日の異なることが分かった. 主稈とその二次分げつの出穂日の差は, 晩生品種より早生品種の方が大きかった. 剪葉処理により一, 二次分げつともに出穂が遅れたが, 二次分げつは一次分げつよりも更に遅れ, この傾向は早生品種で著しかった. また, 二次分げつの場合も剪葉処理の影響は剪葉処理を受けなかった分げつでは少なかった. 二次分げつの止葉葉位は一次分げつより増加する傾向を示したが, 剪葉処理の影響は認められなかった. 葉齢指数90の時期の分げつ別の幼穂長が長いほどそれの出穂日が早く,剪一次, 二次分げつの出穂の早晩は幼穂分化の早晩に基づいたものであると推察された.

Studies on Growth and Development of Tillers in Wheat. IV. Analyses of the morphological features of survived tillers from their shoot heights.

In this study, two experiments were carried out to examine how the tillers survived and adapted morphologically to competition in the wheat (Triticum aestivum L.) plant population. In the first experiment, the heights (highest leaf blade height and stem length) of main stem and tillers were measured from tiller emergence to mid-maturity. It was found that, compared with the heights of main stems, the relative heights of the tillers, especially those which appeared from the leaf axils of higher positions and orders, decreased quickly after elongation of the main stems. In the second experiment, firstly, the heights of smallest tillers (ST) survived in local plant groups (about 30-40 plants), and the local shoot densities surrounding the ST were measured. A positive relationship was found between the local densities of shoots and the heights of ST. Then, analysis of the relationships between the shoot heights and the morphological features showed that, as the shoot heights decreased, the morphological features of shoots changed in the direction favorable to light competition, i.e. the specific leaf area, and the ratios of stem length to stem weight and leaf blade weight (of the uppermost 3 leaves) to stem weight inceased. In ST, these changes were closely related to the stem length differences of the main stems and their ST. These results showed that the tiller's survival was affeted not only by the competition in the plant population but also the morphological changes adapted to the competition.

Rate of removal of grass from mixed pastures by cattle, sheep and goat grazing

A study was undertaken to compare the reduction in th elength of grass tillers in two temperate mixed pastures grazed by cattle, sheep and goats alonein spring. One hundred identified tillers in each of 24 plots (2 reps per pasture type) were measured daily during grazing periods of 3 (GD3) or 6 (GD6) days and disappearance rate of grass was determined. Initial pasture mass was similar for all treatments (mean = 3 500 kg dry matter/ha). Paddock area for CD6 was twice that for CD3 so that the nominal daily DM allowance/kg live weight0.9 was the same for each animal group at the start of the trial. Cattle ate taller than average tillers while sheep and goats ate tillers of a length closer to that of the mean tiller length (P

Effects of Kinetin on the Development of Tillers in Rice Plants.

水稲の分げつの発育に及ぼすサイトカイニンの影響を知るため, 水稲を水耕栽培し, 光強度, 窒素濃度などが異なる条件下でカイネチンを水耕液に加えて根から吸収させ, 植物体の生長, 分げつの出現率, 葉齢, 長さなどに対する影響を観察した. また, 異なる要素根からカイネチンを吸収させた時の影響の差異について観察した. 草丈, 苗齢, 葉長などは光強度, 窒素濃度, 吸収要素根を問わずカイネチンによって抑制され, 根数, 根長も少数の例外を除き抑制された. 分げつに対する影響は光条件によって大きく異なり, 自然光下ではカイネチンが分げつ数の増加を抑制し, 分げつの葉齢や長さに対しても一部の例外を除き抑制の傾向を示したが, 遮光下では分げつ数の増加を促進し, また分げつの葉齢や長さにも顕著な促進を示した. 遮光下で出現率が小さかった第2節, 第3節分げつは, カイネチン処理時既に発育を停止していたとみられるが, このような分げつ芽に対しカイネチンが発育を促進して出現率を高めた. 異なる要素根からカイネチンを吸収させても各節分げつに対する影響にはほとんど差異がなかった.

The morphological responses of some Australian tussock grasses and the importance of tiller number in their resistance to trampling

The relationship between the resistance of plants to trampling and their tiller numbers was investigated in two glasshouse experiments. Five tussocky species, Chloris gayana, Eragrostis tenuifolia, Lolium perenne, Panicum maximum and Sporobolus elongatus, used in the first experiment, were subjected to three levels of simulated trampling. For each species, measurements were taken of above-ground biomass, number of tillers, tiller length, tiller diameter and number of broken tillers. Overall, these measurements, except number of broken tillers, were greatest in the control plants, moderate after light trampling and the lowest after heavy trampling. Biomass was used as a basis of the assessment of plant resistance to trampling. Eragrostis tenuifolia, Lolium perenne and Sporobolus elongatus had much higher resistance to trampling than Chloris gayana and Panicum maximum. In the second experiment, Eragrostis tenuifolia and Lolium perenne plants with up to 14 tillers were subjected to simulated trampling and harvested two days later. For both species the increase in tiller number resulted in a significant increase in biomass per plant. The resistance of plants of both species to trampling increased as the number of tillers increased. However, this increase was not significant until four or five tillers were present.

Economic Injury Level for the Russian Wheat Aphid (Homoptera: Aphididae) on Dryland Winter Wheat

This research was designed to determine the economic injury level for Russian wheat aphid, Diuraphis noxia (Mordvilko), on dryland winter wheat, Triticum Aestivum L. Two sample units were evaluated: whole plants and individual tillers. Russian wheat aphid densities were low in the fall but increased rapidly from late February to May. The percentage of the plants infested or damaged by Russian wheat aphid feeding exceeded 90% by March 1987. The same proportion of infested or damaged tillers was not recorded in 1988until late April. There were ≤ 80% and 60%yield reductions from Russian wheat aphid feeding in 1987 and 1988, respectively. Although 27% of the plants were damaged in the fall, there were too few aphids (≤ 2 aphids per plant, 32 aphid-days, by December) to cause a yield loss. Regression analysis was used to compare several independent variables (aphid densities, aphid-days, percentage infested, percentage damaged, and percentage infested + damaged) with yield, number of seeds per spike, tiller length, number of tillers, and plant dry weight for plant and tiller samples. Yield was the only dependent variable that correlated with the independent variables. The best sampling unit was tillers, based on a high R2, low root mean square error, and ease of sampling. There were 0.46 and 0.48% yield losses for each 1% increase in damaged and infested tillers, respectively.

Morphological Characters in Spaced Plants Associated with Forage Yield under Sward Conditions in Timothy (Phleum pratenseL.)

Abstract The purpose of this investigation was to relate morphological and other characters in spaced plants of timothy to yield capacity under sward conditions. Divergent selections were carried out in spaced plants of four varieties of different origin, two Swedish, one Canadian and one Russian. The characters were: leaf width, leaf length, growth habit, earliness, leaf rigidity, leafiness, plant height, tiller density and frequency of generative tillers as well as height of vegetative tillers in regrowth. The conclusion was that the plant breeder should select for an open tillering ideotype with tall, erect and early plants. The leaves should be long and wide. The regrowth ought to have a high frequency of generative tillers. The effectiveness of selection depends upon the status of the original variety.

Effect of Xanthobacter, isolated and characterized from rice roots, on growth of wetland rice

With an autotrophic, N-free medium, Xanthobacter populations were isolated from the roots of wetland rice grown under field conditions. Xanthobacter populations ranged from 3.2×104 to 5.1×105 colony-forming units (cfu) g-1 of root and averaged 47-fold higher on the root or rhizoplane than in the neighbouring nonrhizosphere. Characterization studies indicated dissimilarities in carbon utilization and motility among the isolated Xanthobacter strains and other recognized Xanthobacter species. Under gnotobiotic conditions, the population of one isolate, Xanthobacter sp. JW-KR1, increased from 105 to 107 cfu plant-1 1 d after inoculation when a rice plant was present, but declined to numbers below the limit of detection (<104 cfu assembly-1) after 3 d in the absence of a plant. Scanning electron microscopy revealed Xanthobacter as pleomorphic forms on the rhizoplane. To assess the effect of Xanthobacter on plant growth, rice plants were grown under greenhouse conditions in plant assemblies containing sand and half-strength Hoagland's nutrient solution with and without nitrogen. Plants were either inoculated with 105 cfu Xanthobacter g-1 of sand or left uninoculated. After 40 d, plants without nitrogen showed no significant differences in top or root dry weight, plant height, root length, or number of tillers or leaves, whether the plants were inoculated or uninoculated. However, when nitrogen was added, inoculated plants had a significantly larger top dry weight (15%) and number of leaves (19%) than uninoculated plants. Under conditions of added and no added nitrogen, acetylene reduction assays showed Xanthobacter sp. JW-KR1 produced <0.1 (below detection limit) and 7 nmol C2H4 plant-1 h-1, respectively. Under the conditions studied, the results suggest that both Xanthobacter and wetland rice derive some benefits from their association.

Genetic Diversity in Tall Fescue Ecotypes from Alabama I. Maturity, Morphological Traits, and Disease Reaction

There is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungus Acremonium coenophialum has resulted in substantial acceptance of new endophyte-free cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. ‘Kentucky 31’ populations from 18 to 38 year-old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within-population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r2= 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r2= 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among ‘Kentucky 31’ tall fescue ecotypes from Alabama.

Effect of d2 dwarfing gene on grain yield and yield components in pearl millet near-isogenic lines

A d2 dwarfing gene in pearl millet [Pennisetum glaucum (L.) R. Br.] is currently being extensively used for the development of hybrid parents. Its effect on grain yield and yield components is poorly understood. Twelve pairs of tall and dwarf near-isogenic lines developed in the diverse genetic background of three composites were evaluated for grain yield and yield components for 2 years at two locations in southern India. The d2 gene or the genes linked to it, on an average, reduced plant height by 42%, grain yield by 14%, and head girth by 8% but increased head length and number of tillers per plant by about 5–6%. Large variations were observed among pairs (genetic background) for the difference between tall and dwarf near-isogenic lines for all of the above yield components resulting in no significant difference in five pairs and 17–35% less yield in dwarfs as compared to their tall counterparts in six pairs. Days to 50% flowering and seed weight were least affected by the d2 gene with the average difference between tall and dwarf groups of near-isogenic lines being of the order of 1–2%. These results indicate that the advantageous effects of d2 dwarfing gene can be effectively exploited by manipulating the genetic background. The difference between the average grain yields of tall and dwarf groups of near-isogenic lines showed considerable variation across environments with the dwarfs yielding as much as tall group in one environment and up to 30% less than the tall group in the other, thus, indicating that the d2 gene effect may be substantially modified by the environments.

A Comparison of Soft Red Winter Wheat F2 Populations, Their F1 Hybrids, and Parents

The cost of F1 hybrid soft red winter wheat (Triticum aestivum L.) seed developed with chemical hybridizing agents is from two to three times that of conventionally bred cultivars. Unlike pureline cultivars, it is not possible to save seed from a hybrid wheat crop to produce an identical crop the next year. Costly F1 hybrid seed has led to speculation about using F2 seed for subsequent crop production. The objective of this research was to evaluate this production alternative by comparing F1 hybrids with their respective F2 populations and parents for a number of agronomic traits. Three families (each consisting of an F1, a derived F2, and the original parents) were grown in four environments in Maryland during 1986 and 1987. Treatments were planted in a randomized complete block design in a split-plot arrangement of treatments with families as whole plots and generations as split plots. A significant 8.3% yield decline was found for the F2 populations compared with the F1 hybrids averaged over the environments and families. However, seven of the 12 family-environment combinations had no significant differences for yield between the F1 and F2 populations. High parent heterosis of 4.5% for yield was observed for the hybrids averaged over all families and environments. Only four of 12 family-environment combinations were found to have significant high-parent heterosis. Although significant differences among family members existed for other agronomic traits studied (i.e., spike emergence date, tiller length and variability, test weight, harvest moisture content, and milling and baking quality), none of these differences was judged undesirable for the production of an F2 population. It is concluded that an F2 population, derived from an F1 hybrid wheat, could be successfully used by a farmer for crop production given current hybrid seed costs and market prices. Success is dependent upon the hybrid from which the F2 population is derived and the environment in which it is grown. Furthermore, the low levels of high-parent heterosis suggested that pureline cultivars probably would provide the most economical results for a farmer at the present time.

Effect of date of sampling and plant density upon size and digestibility of reproductive tillers of Lolium perenne L.

Evaluation of forage germplasm digestibility is an important factor in screening programmes. The major problems involve the relevance of estimations made in spaced plants to plot performance, the effect of maturity, leaf: stem ratio and the choice of plant organ to be analysed. The use of stems of reproductive tiller proved successful in Lolium multiflorum. In the present experiment the effect of dates of sampling (date 1=28/6; date 2=5/7; date 3=12/7/83) and of plant densities (spaced plants and plots) on the digestibility of reproductive tillers of L. perenne cv. Marta 23 days after ear emergence was evaluated. After harvesting, the following characters were recorded on each tiller: tiller length and diameter, and spike and flag leaf length. Leaf blades and sheaths were then removed, the tillers dried and milled individually, and the ‘in vitro’ digestibility assessed. The data were analysed by Analysis of Variance, Principal Components Analysis and Numerical Classification followed by a study of how the variables contributed to the derived group structure. Results: I-Plots: digestibility values were 63.4, 60.3 and 56.6% (P<0.01), respectively, for the sampling dates 1, 2 and 3. The Cramer Value (0.41) shows some correlation between tiller size and digestibility. Tillers from date 3 tend to be smaller than the others but the separation is not very clear. II-Spaced plants: digestibility values were 63.2, 60.0 and 60.8%, respectively, for dates 1, 2 and 3. Analysis of variance showed differences (P<0.01) between dates and also between genotypes. The Cramer Value (0.23) shows less correlation between tiller size and digestibility: however, tillers from dates 1 and 3 are clearly separated on the basis of size. Tillers from date 3 being smaller, date 2 tillers are located in between those from dates 1 and 3. III-Plots and single plants combined: Tillers from plots are larger than tillers from spaced plants in sampling dates 2 and 3. The Cramer Value for digestibility (0.14) is the lowest one. The results indicate differences in size and digestibility of reproductive tillers of L. perenne when contrasting situations are being compared, which suggest influence of environmental conditions upon the characters evaluated in the experiment. The differences are sufficiently high so that the use of this technique, when populations of L. perenne with wide variation in flowering dates are being evaluated, is not recommended.

Appearance and heading of tillers in early wheat cultivars of west Japan.

西日本早生コムギ品種である農林26号, 農林61号, オマセコムギを秋季に播種し, 個々の分げつについてその消長を比較検討した。出現分げつ数における3品種間の差は小さかったが, 出穂分げつ数には明らかな品種間差があり, 農林26号が最も少なく, オマセコムギが最も多かった。この差は, 分げつの出現率の差によるのではなく, 出現した分げつ, とくに第二次分げつの出穂率の差に基づいていた。第二次分げつの出現日と出穂率との間に負の相関関係が認められる時期があり, 出穂率が80%または50%になる第二次分げつの出現日は農林26号と農林61号では早く, これらの品種に比べてオマセコムギでは10日内外遅かった。しかも, これらの時期までに出現した第二次分げつ数は, 農林26号と農林61号では少なく, オマセコムギでは多かったので, その結果, 出穂分げつ数に品種間差が生じた。分げつの有効, 無効が明瞭に現れる時期の前25日間 (3月) における第二次分げつの乾物重増加量と出穂率との関係には品種間差が小さかったが, この期間における第二次分げつの乾物重増加量および稗長増加量には品種間差があり, これらの差が第二次分げつの出穂率における品種間差をもたらしたと考えられる。

Evaluation of Fortress 4G for Rice Water Weevil Control, 1987

Abstract The experiment was conducted at the Texas A&amp;M University Agricultural Research and Extension Center at Beaumont. The design was a randomized complete block with 4 treatments and 4 replications. Each plot was 5 × 20 ft and surrounded by a metal barrier to prevent contamination across treatments. Plots were fertilized 20 Apr with urea at 68 lb nitrogen/acre, broadcast seeded the same day with 'Lemont' rice at 100 lb/acre, treated 14 May with propanil + Basagran at 3 + 0.25 lb (AI)/acre, and treated again with propanil at 4 lb (AI)/acre on 19 May. Plots were flush irrigated on 23 Apr and thereafter until the permanent flood, when the soil began to crack from drying. On 25 May the permanent flood was applied and maintained until maturity. Additional urea was applied at 51 lb nitrogen/acre 1 day before the permanent flood and at panicle initiation to give a seasonal total of 170 lb nitrogen/acre. Insecticides were applied with a hand shaker on 1 Jun, 7 days after the establishment of the permanent flood. From 17 to 22 Jun, 10 soil cores (4 inches diam × 4 inches deep) containing 1 plant/core were removed from each plot. Plants were washed in a 40-mesh screen bucket, and rice water weevil larvae and pupae were recovered and counted. Plants were measured for height, root length, and number of tillers and leaves.

Evaluation of Dimilin-25W for Rice Water Weevil Control, 1987

Abstract The experiment was conducted at the Texas A&amp;M University Agricultural Research and Extension Center at Beaumont. The design was a randomized complete block with 5 treatments and 4 replications. Each plot was 6 × 13 ft and surrounded by a metal barrier to prevent contamination among plots. Plots were fertilized 22 May with urea at 110 lb nitrogen/acre. Rice was broadcast in each plot 22 May at 100 lb seed/acre. The plots were flooded 22 May and drained 24 h later. Propanil was applied at 3.0 lb (AI)/acre on 29 May and 16 Jun. On 19 Jun the permanent flood was established and maintained to maturity. Before the onset of the permanent flood and after the first irrigation on 23 May, additional irrigations were applied when the soil cracked from drying. On 9 Jul at panicle initiation, 60 lb nitrogen/acre in the form of urea was applied. Three and 9 days after the onset of the permanent flood, the Dimilin 25W treatments were applied with an atomizer supplied with COa propellant using a spray volume of 10 gal/acre. Furadan 3G was applied at 0.6 lb (AI)/acre 7 days after the onset of the permanent flood using a hand-held shaker. From 10 Jul to 20 Jul, 10 soil cores (4 inches diam × 4 inches deep) containing 1 plant/core were randomly selected and removed from each plot. Plants were washed in a 40-mesh screen bucket, and rice water weevil larvae and pupae were recovered and counted. Washed plants were measured for height, root length, and number of tillers and leaves. Plots were harvested at maturity on 25 Sep.

Agronomic Performance of Wheat (Triticum aestivum L.) as Influenced by Moisture Stress at Various Growth Stages and Seeding Rate

AbstractA field experiment was conducted at Samaru, Nigeria during the 1981–82 dry season to determine the yield and growth responses of wheat (Triticum aestivum L.) to moisture stress imposed at various growth stages and to seeding rate. It was also to identify wheat growth stages that are most sensitive to soil moisture stress. Treatments tested include three seeding rates, namely, 75, 100 and 150 kg per ha, and seven drought treatments, effected by missing one or two consecutive irrigations at different growth stages.Withholding irrigation at any growth stage prior to anthesis had detrimental effects on most of the growth characters and stress during crown root initiation (CRI) and jointing reduced most of the yield characters. Missing two consecutive irrigations at any given growth stage reduced grain yield more than did missing one irrigation; the greatest reductions in grain yield were 13 and 65% when one irrigation was missed at CRI and two consecutive irrigations were missed at jointing (the most sensitive growth stage) respectively. Moisture stress was also detrimental to number of grains, spike number, spike length, leaf area and number of tillers. A seeding rate of 100 kg per ha produced the best wheat performance in the present study.

The effect of tiller length and age on herbage quality of hybrid Pennisetum canopies.

Whole plants were sampled every 10 or 11 days from field-grown P. americanum X P. purpureum canopies which were cut at intervals of 3 or 6 weeks. Tillers of varying lengths were analysed for in vitro dry matter digestibility (IVDMD). During the growing period, average whole tiller digestibility decreased, as did differences between tillers of different lengths. In 42-day-old herbage, no difference in IVDMD was found between 10 and 70 cm tillers. The decline in digestibility with time was attributed to (1) the appearance of tall tillers and (2) the detrimental effects of low light intensities on tillers growing deep in the canopy. Results suggested that it is doubtful whether tiller length or other morphological or physiological traits can be used to predict herbage digestibility, and that in breeding for better digestibility selection for stem digestibility per se should be more promising than selection for reduced stem growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Renovation of pastures containing paspalum 2. Effects of nitrogen fertiliser on the growth and persistence of overdrilled ryegrass

Abstract The effects of nitrogen fertiliser on the growth and persistence of ryegrass seedlings transplanted into plots with high or low levels of paspalum were investigated in two field experiments over successive years. Ryegrass seedlings were introduced in July of each year, simulating autumn overdrilling, and were permanently identified. Rates of nitrogen varied from 48 to 67 kg/ha and were applied between August and October. Plots were grazed by cows at intervals. Half the plots were covered by wooden cages during each grazing and were defoliated by clipping. These experiments confirmed the high summer losses of introduced ryegrass plants as previously reported. Large growth responses to nitrogen fertiliser (50 – 350% for herbage dry weight, tiller length, tiller number) by the introduced ryegrass were obtained, but these were insufficient to improve survival. The effects of grazing interval, climatic stresses, competitive resident species, cow damage during grazing, and the presence of paspalum were...