Biology of Fire Ephemerals of the Sandplains of the Kwongan of South-Western Australia

1985 ◽  
Vol 12 (6) ◽  
pp. 641 ◽  
Author(s):  
JS Pate ◽  
NE Casson ◽  
J Rullo ◽  
J Kuo
Keyword(s):  
Life Cycle ◽  
Reproductive Biology ◽  
Seedling Growth ◽  
Western Australia ◽  
Growth Rates ◽  
Dry Matter ◽  
Dry Weight ◽  
Growing Season ◽  
Adaptive Significance ◽  
Sexually Dimorphic

The growth, longevity, mineral relationships and reproductive biology of 18 species of fire ephemerals were examined in sclerophyllous shrubland, located mainly within the Jurien : Badgingarra region of the Northern Sandplains of the kwongan of SW. Australia. Ten of the species were monocarpic, completing their life cycle within the 6-8 month winter growing season after a summer or autumn fire. The remaining species were polycarpic, commencing reproduction in their second season and surviving and reproducing for a further two to eight seasons (depending on species). Detailed study was made of growth and dry matter allocation in the dioecious, sexually dimorphic, polycarpic species Tersonia brevipes (Gyrostemonaceae). Monocarpic species tended to produce smaller seeds, and exhibited greater seed output per unit biomass and higher harvest indices for dry matter and minerals than polycarpic species. Certain monocarpic species showed great plasticity in final dry weight, e.g. a 2700-fold difference between largest and smallest individuals in a sample of 250 plants of Stipa elegantissima (Poaceae), and a 180-fold range in a similarly sized sample of Macarthuria apetala (Aizoaceae). The fire ephemerals studied generally exhibited faster seedling growth rates, greater concentrations of P and N (but not of Ca, Mg and K) in seedling dry matter, but usually lesser concentrations of P and N (but not of Ca, Mg and K) in seed dry matter than in cohabiting obligate seeder or sprouter species with potential life spans exceeding 15 years. The above-mentioned features of fire ephemerals are suggested to be of special adaptive significance within the context of exploitation of transiently non-limiting habitat resources immediately following fire.

Effects of Temperature and Photoperiod on Texas Panicum (Panicum texanum) and Wild Proso Millet (Panicum miliaceum)

Weed Science ◽  
1986 ◽  
Vol 34 (6) ◽  
pp. 876-882 ◽  
Author(s):  
David T. Patterson ◽  
Ann E. Russell ◽  
David A. Mortensen ◽  
Robert D. Coffin ◽  
Elizabeth P. Flint
Keyword(s):  
United States ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Dry Weight ◽  
Growing Season ◽  
Southern United States ◽  
Panicum Miliaceum ◽  
Proso Millet ◽  
Effects Of Temperature ◽  
Total Dry Weight

Texas panicum (Panicum texanumBuckl. # PANTE) is a native of the Southwest, now increasing as a weed throughout the southern United States, whereas wild proso millet (Panicum miliaceumL. # PANMI) is an introduced weed currently increasing in importance in the northern Midwest. In controlled-environment chambers, both species produced more tillers, greater leaf area, and more total dry weight at 30/24 C day/night (simulated growing season temperature in Georgia) than at 24/18 C (simulated growing season temperature in Minnesota). Texas panicum accumulated more dry matter at 30/24 C than did wild proso millet, while wild proso millet accumulated more dry matter at 24/18 C than did Texas panicum. When the two species were grown together, Texas panicum was the superior competitor at 30/24 C while wild proso millet was superior at 24/18 C. Exposure to short photoperiods at an intermediate temperature of 27/21 C accelerated flowering and limited vegetative growth in both species. In the range of photoperiods (10 to 16 h) examined, wild proso millet always flowered earlier and, consequently, produced less vegetative growth than Texas panicum. Its responses to temperature and photoperiod indicate that wild proso millet probably would be competitively inferior to Texas panicum and other adapted grass weeds in the southern United States.

MORPHOLOGICAL DEVELOPMENT OF TWO ALFALFA CULTIVARS UNDER VARIOUS HARVESTING SCHEDULES

1974 ◽  
Vol 54 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Y. SINGH ◽  
J. E. WINCH
Keyword(s):  
Growth Rates ◽  
Dry Weight ◽  
Growing Season ◽  
Field Conditions ◽  
Morphological Development

Two alfalfa cultivars grown under field conditions were harvested at different stages of maturity during the growing season of 1969. The number of buds and stems that originated from various locations on the plant and the dry weight of the stems were recorded periodically. The pattern of regrowth was the same for both cultivars. During regrowth, following all stages of harvest, many buds that developed early failed to produce mature stems. Uncut alfalfa produced a second crop of regrowth stems from the bases of stems that formed the first growth. After each harvest regrowth stems originated mainly from the stubble of the most recently harvested stems. Yield reductions occurring in successive regrowths of each harvest schedule were due mainly to the production of smaller stems. Increased growth rates following more mature stages of cutting resulted mainly from faster elongation of stems developing from larger buds. The implications of these findings with respect to the breeding of alfalfa are discussed.

High ear number is key to achieving high wheat yields in the high-rainfall zone of south-western Australia

2007 ◽  
Vol 58 (1) ◽  
pp. 21 ◽  
Author(s):  
Heping Zhang ◽  
Neil C. Turner ◽  
Michael L. Poole ◽  
Senthold Asseng
Keyword(s):  
Western Australia ◽  
Spring Wheat ◽  
Harvest Index ◽  
Dry Matter ◽  
Growing Season ◽  
Growth And Yield ◽  
Yield Potential ◽  
Dry Matter Accumulation ◽  
High Rainfall ◽  
Sink Capacity

The growth and yield of spring wheat (Triticum aestivum L.) were examined to determine the actual and potential yields of wheat at a site in the high rainfall zone (HRZ) of south-western Australia. Spring wheat achieved yields of 5.5−5.9 t/ha in 2001 and 2003 when subsurface waterlogging was absent or minimal. These yields were close to the estimated potential, indicating that a high yield potential is achievable. In 2002 when subsurface waterlogging occurred early in the growing season, the yield of spring wheat was 40% lower than the estimated potential. The yield of wheat was significantly correlated with the number of ears per m2 (r2 = 0.81) and dry matter at anthesis (r2 = 0.73). To achieve 5–6 t/ha of yield of wheat in the HRZ, 450–550 ears per m2 and 10–11 t/ha dry matter at anthesis should be targetted. Attaining such a level of dry matter at anthesis did not have a negative effect on dry-matter accumulation during the post-anthesis period. The harvest index (0.36−0.38) of spring wheat was comparable with that in drier parts of south-western Australia, but relatively low given the high rainfall and the long growing season. This relatively low harvest index indicates that the selected cultivar bred for the low- and medium-rainfall zone in this study, when grown in the HRZ, may have genetic limitations in sink capacity arising from the low grain number per ear. We suggest that the yield of wheat in the HRZ may be increased further by increasing the sink capacity by increasing the number of grains per ear.

Responses of intensively grazed dairy pastures to applications of fertiliser nitrogen in south-western Australia

2007 ◽  
Vol 47 (8) ◽  
pp. 927 ◽  
Author(s):  
M. D. A. Bolland ◽  
I. F. Guthridge
Keyword(s):  
Western Australia ◽  
Dry Matter ◽  
Maximum Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Mineral Elements ◽  
Italian Ryegrass ◽  
Total N ◽  
Dry Matter Digestibility

For the first time, we quantified pasture dry matter (DM) responses to applied fertiliser nitrogen (N) for intensively grazed, rain-fed, dairy pastures on sandy soils common in the Mediterranean-type climate of south-western Australia. The pastures are composed of subterranean clover (Trifolium subterraneum L.) and annual and Italian ryegrass (Lolium rigidum Gaud. and L. multiflorum Lam.). Six rates of N, as urea (46% N), were applied to 15 m by 15 m plots four times during 2002 and after each of the first 5–7 grazings in 2003 and 2004, throughout the typical April–October growing season. Total rates of N applied in the first year of the experiments were 0, 60, 120, 160, 200 and 320 kg N/ha, which were adjusted in subsequent years as detailed in the ‘Materials and methods’ section of this paper. The pastures in the experiments were rotationally grazed, by starting grazing when ryegrass plants had 2–3 leaves per tiller. The amount of pasture DM on each plot was measured before and after each grazing and was then used to estimate the amount of pasture DM consumed by the cows at each grazing for different times during the growing season. Linear increases (responses) of pasture DM to applied N occurred throughout the whole growing season when a total of up to 320 kg N/ha was applied in each year. No maximum yield plateaus were defined. Across all three experiments and years, on average in each year, a total of ~5 t/ha consumed DM was produced when no N was applied and ~7.5 t/ha was produced when a total of 200 kg N/ha was applied, giving ~2.5 t/ha increase in DM consumed and an N response efficiency of ~12.5 kg DM N/kg applied. As more fertiliser N was applied, the proportion of ryegrass in the pasture consistently increased, whereas clover content decreased. Concentrations of nitrate-N in the DM consistently increased as more N was applied, whereas concentrations of total N, and, therefore, concentration of crude protein in the DM, either increased or were unaffected by applied N. Application of N had no effect on concentrations of other mineral elements in DM and on dry matter digestibility and metabolisable energy of the DM. The results were generally consistent with findings of previous pasture N studies for perennial and annual temperate and subtropical pastures. We have shown that when pasture use for milk production has been maximised in the region, it is profitable to apply fertiliser N to grow extra DM consumed by dairy cows; conversely, it is a waste of money to apply N to undergrazed pastures to produce more unused DM.

The life history of Branchinecta mackini Dexter (Crustacea: Anostraca) in an argillotrophic lake of Alberta

1977 ◽  
Vol 55 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Graham R. Daborn
Keyword(s):  
Organic Matter ◽  
Life History ◽  
Life Cycle ◽  
Growth Rates ◽  
Dry Weight ◽  
Fairy Shrimp ◽  
Maximum Biomass ◽  
History Of ◽  
Mean Size

The life history of B. mackini was studied in a large argillotrophic lake during 1970–1972. Hatching began immediately after spring thaw and was terminated by rising salinity 10 days to 2 weeks later. Growth rates reached maxima of 1 mm/day at 4 weeks of age and then declined as mean size approached 22–23 mm at 7–8 weeks. Clutch sizes varied as a function of female length. Maximum biomass of 580 mg dry weight/m2 (2700 cal/m2) was reached in late May, of which 3.9% per day was consumed by B. gigas. Source of the energy is presumed to be a bacteria – organic matter complex associated with suspended particles. Life cycle details are compared with other fairy shrimp species and the role of B. mackini in the community is discussed.

scholarly journals Effect of ammonium and nitrate source of nitrogen on productivity of photosynthesis in Scots pine (Pinus silvestris L.) seedlings

2015 ◽  
Vol 42 (4) ◽  
pp. 599-605 ◽  
Author(s):  
A. Łotocki ◽  
W. Żelawski
Keyword(s):  
Gas Exchange ◽  
Scots Pine ◽  
Growth Rates ◽  
Dry Matter ◽  
Nitrogen Nutrition ◽  
Growing Season ◽  
Sand Culture ◽  
Pinus Silvestris ◽  
Water Culture ◽  
Matter Production

Water culture and sand culture seedlings of Scots pine were investigated in respect to their reaction to ammonium or nitrate source of nitrogen nutrition. Photosynthesis, respiration, and dry matter production were studied in three and four months old plants. The results are preliminary but they have indicated that the effect of various form of nitrogen nutrition on gas exchange and growth rates could change during the growing season.

BEEF PRODUCTION ON PASTURE AND LUCERNE

1974 ◽  
pp. 73-79
Author(s):  
B.G. Croy ◽  
W.C. Weeda
Keyword(s):  
Conversion Efficiency ◽  
Growth Rates ◽  
Dry Matter ◽  
Growing Season ◽  
The Other ◽  
Stocking Rate ◽  
Beef Production ◽  
Before And After ◽  
Two Generations ◽  
Successive Generations

In 1971-3 and 1972-4 two successive generations of Friesian male weaners were carried to slaughter on two self-contained farmlets, one all pasture, the other with half its area in pasture and half in lucerne. The pasture farmlet produced slightly less herbage dry matter than the pasture/lucerne farmlet. Average net hot carcass production was 922 and 829 kg/ha/yr respectively. The stocking rate was 4.85 animals/ha with an overlap of two generations from November to February. Herbage yields and animal intakes were estimated by before and after grazing cuts. The lucerne was grazed at a 40-day rotation in its growing season. To obtain high cattle growth rates, much stalk was left ungrazed, being 15 to 20% of the total dry matter standing before grazing above a height of 3 to 4 cm. Overall conversion efficiency of ingested forage was lower on the lucerne/pasture farmlet than on the pasture farmlet and it was also more variable on the former. With the grazing rotation and pressure adopted in this trial, bloat was no serious problem.

Quantifying pasture dry matter responses to applications of potassium fertiliser for an intensively grazed, rain-fed dairy pasture in south-western Australia with or without adequate nitrogen fertiliser

2009 ◽  
Vol 49 (2) ◽  
pp. 121 ◽  
Author(s):  
M. D. A. Bolland ◽  
I. F. Guthridge
Keyword(s):  
Dairy Cows ◽  
Western Australia ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Soil Samples ◽  
Italian Ryegrass ◽  
Soil Test ◽  
Soil Test K

Rain-fed dairy pastures on sandy soils common in the high rainfall (>800 mm annual average) Mediterranean-type climate of south-western Australia comprise the annual species subterranean clover (Trifolium subterraneum L.) and annual and Italian ryegrass (Lolium rigidum Gaud. and L. multiflorum Lam.). In wet years, clover becomes potassium (K) deficient and shows large dry matter (DM) responses to applied fertiliser K due to leaching of K in soil by rainfall. In contrast, ryegrass rarely shows DM responses to applied K. Many dairy pastures in the region are now intensively grazed to maximise pasture use for milk production, and nitrogen (N) fertiliser is applied after each grazing. It is not known if frequent applications of fertiliser N to these pastures changes pasture DM responses to applied K. Therefore, a long-term (2002–07) field experiment was undertaken on an intensively grazed dairy pasture in the region to quantify pasture DM responses to applied fertiliser K with or without applications of adequate fertiliser N (141–200 kg N/ha per year). Soil samples (top 10 cm of soil) were collected from each plot of the experiment each February to measure soil test K by the standard Colwell sodium bicarbonate procedure used for both K and phosphorus soil testing in the region. When no N was applied, pasture comprised ~70% (dry weight basis) clover and 25% ryegrass, compared with ~70% ryegrass and 25% clover when adequate N was applied. Significant linear responses of pasture DM to applied K occurred in 3 of the 6 years of the experiment only when no N was applied and clover dominated the pasture. The largest response varied from ~1.7 to 2.0 t/ha DM consumed by dairy cows at all grazings in each year, giving a K response efficiency of between 8 and 10 kg DM/ha per kg K/ha applied. Significant pasture DM responses to applied N occurred at all grazings in each year, with ~2–3 t/ha extra DM consumed by dairy cows at all grazings in each year being produced when a total of 141–200 kg N/ha was applied per year, giving an N response efficiency of ~7–19 kg DM/ha per kg N/ha applied. Soil test K values were very variable, attributed to varying proportions of soil samples per plot collected between and within cow urine patches, containing much K, arbitrarily deposited on experimental plots during grazing. Soil test K values were not significantly affected by the rates of K applied per year. A re-evaluation of results from the major soil K test study conducted for pastures in the region confirm that ryegrass rarely showed DM responses to applied K, and that for clover, soil K testing poorly predicted the likelihood of K deficiency in the next growing season.

Optimizing growth and development of 2-0 Douglas-fir seedlings by altering light intensity

1983 ◽  
Vol 13 (3) ◽  
pp. 425-428 ◽  
Author(s):  
Allan P. Drew
Keyword(s):  
Light Intensity ◽  
Root Development ◽  
Growth And Development ◽  
Dry Matter ◽  
Dry Weight ◽  
Growing Season ◽  
Douglas Fir ◽  
Total Weight ◽  
Planting Stock

Douglas-fir (Pseudotsitgamenziesii (Mirb.) Franco) seedlings were grown outdoors in pots under 71% of full light the first growing season and full light the second. Another group of seedlings was given full light continuously for 2 years. At the end of the 1st year, seedlings given initial shade had grown larger in total weight (root + shoot) than those grown under full light. With removal of shading, the larger plants with lower shoot/root ratios began to allocate increased dry matter to root development relative to their shoots. By the end of 2 years, shoot/root ratios for the two groups were no different, yet the plants shaded in their 1st year were 69% larger in dry weight. By proper use of shading during development, larger 2-0 planting stock having good root development may be produced. Such stock, grown without the use of costly fertilizer, may be better suited to regeneration of droughty sites in the Northwest than the usual 2-0 planting stock, nursery grown under full light.

The growth and yield of tall and short sorghums in Nigeria

1970 ◽  
Vol 75 (1) ◽  
pp. 109-122 ◽  
Author(s):  
P. R. Goldsworthy
Keyword(s):  
Growth Rates ◽  
Dry Matter ◽  
Inverse Relationship ◽  
Unit Area ◽  
Dry Weight ◽  
Crop Growth ◽  
The Other ◽  
Developmental Changes ◽  
Growth And Yield ◽  
Short Season

SUMMARYA Nigerian, long-season, sorghum produced 15 tons of dry matter/acre in about 155 days, but the grain yield was small (2000 lb/acre or 2242 kg/ha) because only part of the dry matter formed after heading went into the grain. In contrast, an American, short-season hybrid which formed only from one-half to one-third as much dry weight as Farafara, gave over 4000 lb of grain/acre (4484 kg/ha) in 100 days. A Nigerian sorghum of intermediate height and a long-season hybrid, produced by crosses between Nigerian varieties and an American, short-season sorghum, gave larger yields than the tall variety because they formed more heads/unit area and more grains/head.Crop growth rates of the three long-season sorghums sown in June increased to a peak in July, but declined sharply to very small values in September, and then increased again very rapidly at the end of September as heads emerged. The most important factors causing the decline were a decrease in radiation and a loss in dry weight from decay and detachment of dead leaves. An increase in radiation at the end of September and developmental changes associated with head emergence contributed to the increase in growth rates just before heading.A large proportion of the dry weight formed after heading in Farafara accumulated in the stem but a smaller proportion in the other long-season variety and the longseason hybrid. There was an inverse relationship between the increase in stem weight and the yield of grain. For large grain yields, sorghums are needed that will produce heads with sufficient grains to accommodate all the assimilate that the leaves produce at the end of the rains when crop growth rates are increasing.

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