Influence of time and level of urea application on seed production of Paspalum plicatulum at Mt. Cotton, south-eastern Queensland

1973 ◽  
Vol 13 (62) ◽  
pp. 275 ◽  
Author(s):  
PA Chadhokar ◽  
LR Humphreys
Keyword(s):  
Podzolic Soil ◽  
Nitrogen Concentration ◽  
Seed Viability ◽  
Moisture Stress ◽  
Early Summer ◽  
Nitrogen Supply ◽  
Floral Initiation ◽  
Plant Nitrogen ◽  
Cotton South ◽  
Tiller Density

Five levels of urea were applied as single or split dressings in early summer, at floral initiation (about Febraury 14), or at inflorescence exsertion to Paspalum plicatulum cv. Rodds Bay grown in rows on a red-yellow podzolic soil. All components of seed yield-tiller density, tiller fertility, raceme number and seed number, and seed size-were influenced by external nitrogen supply. The effects of adequate nitrogen supply during one development phase usually persisted subsequently when differences in plant nitrogen concentration had disappeared. Nitrogen applications during the vegetative and floral initiation stages were most influential. The efficiency of response varied from 5.6 kg additional crude seed produced per kg N at the 50 kg N ha-1 level to 1.2 at the 400 kg N ha -1 level. High levels of urea (200 or 400 kg N ha-1) induced lodging and poor recovery of seed at harvest during a wet year, accentuated moisture stress during a dry year, but improved seed viability.

Seed production in Brachiaria decumbens and Paspalum plicatulum as influenced by system of residue disposal

1987 ◽  
Vol 38 (5) ◽  
pp. 869
Author(s):  
WW Stnr ◽  
LR Humphreys
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Nitrogen Supply ◽  
Floral Initiation ◽  
Spikelet Number ◽  
Brachiaria Decumbens ◽  
Short Day ◽  
Cotton South ◽  
Defoliation Treatment

Long-established swards of Brachiaria decumbens cv. Basilisk and of Paspalum plicatulum cv. Rodds Bay at Mt Cotton, south-east Queensland, were cut, field dried and burnt, or cut and the residues removed in late November or early January. Burning initially reduced tillering, especially when the interval between cutting and burning was 7 days, but this difference disappeared in P. plicatulum when there was a long interval to floral initiation. A juvenility requirement was evident in the short day P. plicatulum swards, where late burning or cutting delayed floral initiation 11 days relative to early defoliation. Strong compensatory and hierarchical effects on the components of seed yield occurred, and seed yield was similar in cut or burnt treatments, except for 23% decrease in late cut P. plicatulum. Late defoliated B. decumbens yielded 31% more seed than early defoliated swards, due mainly to reduced spikelet number per raceme (branch). Burning slightly increased synchrony of inflorescence exsertion in P. plicatulum and reduced crop lodging, although in a subordinate experiment with P. plicatulum lodging was positively related to level of nitrogen supply rather than to defoliation treatment.

Phosphate response of mixed swards, at Mt. Cotton, south-eastern Queensland

1970 ◽  
Vol 10 (45) ◽  
pp. 431 ◽  
Author(s):  
CG Blunt ◽  
LR Humphreys
Keyword(s):  
Podzolic Soil ◽  
Nitrogen Concentration ◽  
Competitive Interactions ◽  
Phosphorus Concentration ◽  
Dihydrogen Phosphate ◽  
Nitrogen Response ◽  
Nitrogen Yield ◽  
South Eastern ◽  
Cotton South ◽  
Phosphate Response

Five levels of calcium dihydrogen phosphate were applied on a red-yellow podzolic soil to plots either unsown or sown to Kazungula setaria together with greenleaf desmodium, lotonis, stylo, or siratro. First season pasture yields varied from 2000 to 7400 lb an acre. Volunteer species and lotononis swards reached maximum yields at lower phosphate levels than the remaining legumes, which continued to respond at 80 lb P an acre. Maximum setaria yield occurred at 40 lb P an acre. Increasing phosphate level reduced nitrogen concentration of non-legumes, increased phosphorus concentration of all species, and substantially increased nitrogen yield of legumes (1.0-1.9 lb nitrogen response per lb P applied). Seasonal yield patterns and competitive interactions are discussed.

Effect of tiller age and time of nitrogen stress on seed production of Paspalum plicatulum

1973 ◽  
Vol 81 (2) ◽  
pp. 219-229 ◽  
Author(s):  
P. A. Chadhokar ◽  
L. R. Humphreys
Keyword(s):  
Ammonium Nitrate ◽  
Seed Size ◽  
Seed Yield ◽  
Growth And Development ◽  
Nitrogen Nutrition ◽  
Development Stage ◽  
Nitrogen Supply ◽  
Nitrogen Stress ◽  
Floral Initiation ◽  
Final Maturation

SummaryPaspalum plicatulum was grown at Brisbane in boxes of sand receiving basal nutrients and frequent irrigation; weekly levels of ammonium nitrate application were varied according to growth and development stage.The rate of tiller appearance increased to a maximum 40–50 days after sowing and almost ceased thereafter. Tiller leaf number, survival, fertility, inflorescence branching, seeds per raceme and seed size were positively related to tiller age. Young tillers were more sensitive to variations in nitrogen supply than old tillers.Adequate nitrogen nutrition during the vegetative phase from sowing to floral initiation (93 days) increased tiller and hence inflorescence density; increased inflorescence branching was compensated by fewer seeds per raceme. Good nitrogen nutrition during the phase from floral initiation to inflorescence exsertion (142 days) increased survival of late-formed tillers and hence inflorescence density; inflorescence branching, seeds per raceme and seed size were also increased. Nitrogen stress during the final maturation phase did not affect seed yield.

Nitrogen Rate and Timing Effects on Collard Yield and Plant Nitrogen Concentration

jpa ◽  
1997 ◽  
Vol 10 (3) ◽  
pp. 438-441
Author(s):  
E. A. Guertal ◽  
E. van Santen
Keyword(s):  
Nitrogen Concentration ◽  
Nitrogen Rate ◽  
Plant Nitrogen ◽  
Timing Effects

Investigation of flowering in Banksia baxteri R. Br. and B. hookeriana Meissner for improving pruning practices

1994 ◽  
Vol 34 (8) ◽  
pp. 1209 ◽  
Author(s):  
LJ Rohl ◽  
AM Fuss ◽  
JA Dhaliwal ◽  
MG Webb ◽  
BB Lamont
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Floral Development ◽  
Early Summer ◽  
Stem Length ◽  
First Year ◽  
Floral Initiation ◽  
Scanning Electron

Floral initiation and development in relation to time of flowering were investigated in Banksia baxteri and B. hookeriana with the aid of scanning electron microscopy. Floral initiation occurred in spring in B. baxteri and in early summer in B. hookeriana. Floral development was rapid in B. baxteri (3 months to reach anthesis in summer). In B. hookeriana, development took 5 months, with anthesis occurring in winter. Most B. hookeriana blooms were produced on 2-year-old shoots, while B. baxteri produced about half of its blooms on 2-year-old shoots and almost as many on 3-year-old shoots. In both species, shoots that flowered within 2 years were longer and thicker in their first year than other shoots. A critical minimum stem length was determined for the first year's growth, to be used as a criterion for determining which shoots to remove during pruning. Details are provided for the timing of pruning to achieve maximum bloom production in B. baxteri and B. hookeriana.

Effects of nitrogen and lime on growth of Leucaena leucocephala cv. Cunningham on a red-yellow podzolic soil in south-eastern Queensland

1986 ◽  
Vol 26 (1) ◽  
pp. 23 ◽  
Author(s):  
S Sivasupiramaniam ◽  
R Akkasaeng ◽  
HM Shelton
Keyword(s):  
Podzolic Soil ◽  
Nitrogen Concentration ◽  
Dry Weight ◽  
Maximum Growth ◽  
Field Application ◽  
South Eastern ◽  
Shoot Dry Weight ◽  
Application Rates ◽  
Lime Application ◽  
Low Nitrogen

Field and glasshouse experiments were conducted on an acidic red-yellow podzolic soil of low nitrogen status from south-eastern Queensland to examine the use of nitrogen and lime in promoting leucaena growth. In the field, application of 25 kg nitrogen ha-l at planting increased shoot dry weight by 77, 88, 52 and 51% at weeks 5, 15, 32 and 52 respectively. Equivalent responses to lime (2.5 t ha-1) were 8, 3 1, 64 and 74% respectively. In the glasshouse, shoot, root and nodule dry weights were increased by nitrogen application rates of 50, 100 and 200 kg ha-1. Number, size and dry weight of nodules were suppressed at the highest rate (400 kg ha-1). Nitrogen concentration in youngest fully expanded leaves was increased to over 5% by nitrogen, and a critical nitrogen content of 4.5% (90% of maximum growth) is suggested. Inexplicably, lime application reduced shoot, root and nodule weights at high nitrogen applications. The apparent partial effectiveness of commercial leucaena Rhizobium and the implications of starter nitrogen and lime for leucaena establishment are discussed.

Tactical versus continuous stocking for persistence of perennial ryegrass (Lolium perenne L.) in pastures grazed by sheep in south-western Victoria

1999 ◽  
Vol 39 (3) ◽  
pp. 265 ◽  
Author(s):  
R. A. Waller ◽  
P. E. Quigley ◽  
G. R. Saul ◽  
G. A. Kearney ◽  
P. W. G. Sale
Keyword(s):  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Seedling Recruitment ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Fold Increase ◽  
Early Summer ◽  
Lolium Perenne L ◽  
Western Victoria ◽  
Tiller Density

The survival of perennial ryegrass (Lolium perenne L.) plants was studied in sheep pastures in south-western Victoria during the dry summer of 1996–97. Recruitment of perennial ryegrass seedlings into the pasture sward was also monitored in the autumn–winter periods in 1997 and 1998. The objective was to investigate whether a tactical stocking strategy, consisting of variable length summer, autumn and winter rotations and continuous stocking in spring, might increase perennial ryegrass tiller survival and seedling recruitment in the autumn, compared with continuous stocking all year. The grazing strategies were compared on 2 contrasting pastures: an upgraded pasture [sown with newer cultivars of perennial ryegrass and subterranean clover (Trifolium subterraneum L.) with 26 kg phosphorus/ha.year as applied fertiliser] and a naturalised perennial ryegrass pasture receiving 6 kg P/ha.year. Paddocks were grazed by Border Leicester × Merino ewes, mated to a terminal sire so as to lamb in September. Perennial ryegrass tiller density was higher on the upgraded pasture with a mean density of 7750 tillers/m2 in early summer which declined to zero live tillers by mid summer. Live tillers began to reappear before the opening rains and then increased after the rain. Mean tiller density in the upgraded pasture declined over the 2 summers, with only 2050 tillers/m2 being present 2 months after the opening rains in 1998. There were no effects (P>0.05) of pasture type or grazing strategy on the number of tagged tillers that survived the summer period. Only 12% of the vegetative tillers, randomly tagged in December 1996, survived to May 1997. More than half of the tillers (56%) that produced a seedhead produced daughter tillers which survived the dry summer–autumn period. A significant (P<0.05) interaction between grazing strategy and pasture type occurred with the number of perennial ryegrass seedlings that had established 4 weeks after the opening rains in 1997. There was a 5–11-fold increase in seedling numbers which regenerated in the tactically stocked, upgraded pasture compared with the other treatments. Seedling recruitment was considerably lower in the autumn of 1998, due presumably to an overall decline in perennial ryegrass density relative to annual grasses in 1997. A second experiment investigated the effect of excluding sheep from grazing at anthesis until seedhead maturation or until the opening rains, together with a mechanical seed dislodgment treatment at seed maturity. All exclusion treatments increased seedling recruitment 4–7-fold, compared with continuous stocking. The results suggest a possible mechanism by which perennial ryegrass density can be increased without expensive reseeding.

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