Agronomic studies on soybean (Glycine max (L.) Merrill) in the dry season of the tropics. III. Effect of artificial photoperiod extension on phenology, growth and seed yield

1991 ◽  
Vol 42 (7) ◽  
pp. 1109 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Dry Season ◽  
Yield Potential ◽  
Wet Season ◽  
Canopy Development ◽  
North West ◽  
Precocious Flowering ◽  
Natural Photoperiod ◽  
Artificial Photoperiod ◽  
Delayed Flowering

Soybean cultivars developed for the tropical wet season performed poorly when grown in the dry season in north-west Australia. The proposition that breeding for later flowering time might enhance yields was tested by using artificial photoperiod extension (14 h day-1 for 28 days post-emergence) to delay flowering of field plots of agronomically improved genotypes. Canopy development and interception of photosynthetically active radiation (PAR), dry matter (DM) accumulation, seed yield and seed composition were examined, and compared with that from plants grown under natural photoperiods. Photoperiod extension delayed flowering an average 24 days, and maturity by an average 14.5 days, the effect being greater in the earlier-flowering genotypes. Differences among genotypes and photoperiod treatments in above-ground DM at the beginning and end of flowering were almost entirely due to the consequences of differences in phenology for cumulative PAR interception. DM at maturity was a simple linear function of crop duration (r2 = 0.95**), while seed yield exhibited an optimum-type response with DM ( R2 = 0.79**). The net consequence was that photoperiod extension increased DM production by an average 2.23 t ha-1 and seed yield by an average 0.65 t ha-1. The analyses suggested that a crop duration of c. 143-146 days would be needed to maximize seed yield under the agronomic conditions of the study, whereas the longest duration among the agronomically improved genotypes under natural photoperiod conditions was 136 days. It was concluded that breeding to constrain precocious flowering under short day conditions would be a viable strategy to improve the yield potential of soybean in the dry season.

Agronomic studies on soybean (Glycine max (L.) Merrill) in the dry season of the tropics. II. Interaction of sowing date and sowing density

1991 ◽  
Vol 42 (7) ◽  
pp. 1093 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Biomass Production ◽  
Seed Yield ◽  
Management Practices ◽  
Interaction Analysis ◽  
Sowing Date ◽  
Dry Season ◽  
High Yield ◽  
Total Biomass ◽  
Wet Season ◽  
Precocious Flowering

An analysis was undertaken of the development, growth and seed yield of irrigated soybean crops grown during the dry season in the semi-arid tropics of north-western Australia, to establish whether constraints to seed yield induced by precocious flowering could be overcome agronomically by manipulating sowing date and/or sowing density. Three agronomically improved cultivars and a later-flowering landrace cultivar were tested using irrigation, fertility and pest management practices designed to minimize constraints to yield. Maximum seed yields were 3.5-4.0 t ha-1, with large genotype x sowing date x sowing density interaction. Analysis of vegetative growth showed that higher sowing densities stimulated more rapid leaf area development and earlier canopy closure, and enhanced total biomass production. However, very high sowing densities were needed to maximize yields of most genotypes, while lodging precluded high yield being realized from the greater biomass production of high density sowings of the landrace genotype. Delaying sowing from April to June delayed flowering, increased biomass production and marginally enhanced yields, but not sufficiently to offset potential problems caused by maturation into hot dry conditions prior to the wet season. It was concluded that agronomic strategies alone were insufficient to overcome the constraints to yield of present soybean genotypes in the dry season.

Agronomic studies on soybean (Glycine max (L.) Merrill) in the dry seasons of the tropics. I. Limits to yield imposed by phenology

1991 ◽  
Vol 42 (7) ◽  
pp. 1075 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Leaf Area ◽  
Biomass Production ◽  
Seed Yield ◽  
Management Practices ◽  
Dry Season ◽  
Canopy Development ◽  
Precocious Flowering ◽  
The Tropics ◽  
Area Development ◽  
Leaf Area Development

An analysis was undertaken of the development, growth and seed yield of irrigated soybean crops grown during the dry season of the semi-arid tropics in north-western Australia, to establish yield potentials and identify major climatic or physiological constraints. Ten tropically adapted genotypes were grown at three sowing times, using agronomic management practices designed to maximize productivity and minimize constraints due to water supply, fertility, weeds and insects. In addition to phenology, seed yield, dry matter (DM) accumulation, and seed and plant morphological traits, measurements were made at the beginning and end of flowering of DM accumulation, leaf area development and interception of photosynthetically active radiation (PAR). Harvest indices were generally large, but maximum seed yields were only c. 3 t ha-1, apparently because of inadequate biomass production. The analysis of growth and development suggested that DM accumulation during the vegetative phase was limited primarily by cumulative PAR interception by the crop canopy rather than the efficiency of conversion of intercepted PAR. In turn, both cumulative PAR interception, and canopy leaf area development, were constrained by precocious flowering, induced by the comparatively short-day/warm temperature conditions of the dry season. It was concluded that yield improvement strategies for the dry season will need to be based on agronomic and/or breeding strategies to enhance canopy development and improve biomass production.

Effect of hormonal growth promotant implants in weaner and hogget ewes on subsequent growth and reproductive performance

2004 ◽  
Vol 44 (8) ◽  
pp. 755
Author(s):  
G. Bortolussi ◽  
A. R. Bird ◽  
C. L. Playford ◽  
J. Moore
Keyword(s):  
Reproductive Performance ◽  
Average Daily Gain ◽  
Later Life ◽  
Dry Season ◽  
Control Group ◽  
Wet Season ◽  
Negative Effects ◽  
North West ◽  
Daily Gain

Ninety young Merino ewes, depastured on Mitchell (Astrebla spp.) grass pastures in North West Queensland, were used in a hormonal growth promotant implantation study. The ewes were given 1 implant of Compudose, Ralgro, Revalor or Synovex-H, either at lamb marking (mid-dry season) or the start of the following summer wet season, which was ~180 days post-marking. The hormonal growth promotant implanted groups had greater (P<0.05) liveweights than the control group early in the trial (days 22 and 57) and also from the end of the period of activity of the wet season implant (day 277) until the middle of the dry season (day 412). Dry season (at lamb marking) implantation did not improve average daily gain. From the end of the wet season onwards, ewes with a wet season implant were heavier (P<0.05) than those ewes implanted at lamb marking. This liveweight advantage had diminished by the start of the autumn mating. Hormonal growth promotant implantation had a favourable (P<0.05) effect on growth rate, but adversely affected reproduction in the ewes, regardless of time of implantation. Implantation with Compudose or Synovex-H significantly (P<0.001) reduced the demonstration of oestrus, while Revalor or Synovex-H reduced pregnancy rates by up to 100%. Despite Ralgro reducing these variables by up to 25%, its effect was not significant. All ewes that were diagnosed as pregnant at 140 days later produced lambs. It was concluded from this study that hormonal growth promotant implantation at lamb marking provides no later-life advantage, while wet season implantation provides a growth or liveweight advantage to young Merino ewes and this persists for a long period after implantation. Despite the lack of an effect of Ralgro on oestrus and pregnancy results, however, implantation of young breeding ewes of any age should not be carried out, due to the long term and negative effects on reproductive performance. Wet season implantation may be best used for animals intended for slaughter.

Limited impact of irrigation on the phenology of Brachychiton megaphyllus: a deciduous shrub that flowers while leafless during the tropical dry season

2015 ◽  
Vol 31 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Patricia J. Bate ◽  
Donald C. Franklin
Keyword(s):  
Soil Moisture ◽  
Reproductive Activity ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Wet Season ◽  
Canopy Development ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Tap Root ◽  
Leaf Flush

Abstract:A suite of woody plants inhabiting the seasonally dry tropics flower while leafless during the dry season, raising intriguing questions about the role of moisture limitation in shaping their phenology. Brachychiton megaphyllus is one such species, a shrub of open forests and savannas in northern Australia. We documented leaf and reproductive phenology of 14 shrubs, and irrigated a further 15, to determine if soil moisture affected leafiness and reproductive activity. Brachychiton megaphyllus showed first flower buds shortly after the cessation of wet-season rains, and budded and flowered throughout the dry season. In some plants, leaf flush occurred prior to the first rains. Rates of fruit set and maturity were very low. Irrigation did not significantly influence leaf shoot or subsequent canopy development. Contrary to expectation, irrigation decreased the production of buds and flowers though it had no impact on the production of fruit, a response for which we suggest a number of hypotheses. Phenological responses to irrigation may have been limited because B. megaphyllus responds primarily to cues other than soil moisture and is buffered against seasonal drought by a large tap root. This suggests mechanisms by which flowering while leafless may occur in a range of species.

scholarly journals The effect of different pasture management strategies in north-west Queensland on liveweight gain and wool growth rate of several groups of young sheep.

1985 ◽  
Vol 7 (2) ◽  
pp. 75 ◽  
Author(s):  
RGA Stephenson ◽  
DA Pritchard ◽  
PM Pepper ◽  
PT Connelly
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Management Strategies ◽  
Live Weight ◽  
Dry Season ◽  
Wet Season ◽  
Pasture Management ◽  
North West ◽  
Wool Growth ◽  
Significant Difference

The effect of three different pasture management strategies on liveweight gain and wool growth rate of young(weaner) sheep was examined immediately after weaning on Mitchell grass-Flinders grass pastures during the dry season of north-west Queensland. The pasture management strategies were designed to mimic various industry situations, while the performance of four different progeny groups was compared and used to provide an overall assessment of pasture quality. Pasture treatments (experiment 1) consisted of three paddocks, a harvested (c. 8% of pasture harvested and baled) and spelled, a spelled, and a continuously grazed paddock. Spelled paddocks were not grazed during and after the wet season for a period of six months while the continuously grazed paddock was continuously stocked before the experiment. Experiment 2 consisted of spelled and continuously grazed paddocks. Pastures were evaluated by measuring the changes in composition and quality (experiment 1) and the responses in liveweight gain (experiments 1 and 2) and wool growth of the weaners (experiment 1). Marked improvements (c. 100%) in weaner growth rates occurred in the spelled paddocks. Greasy wool production by three groups of ewes in experiment I was about 14% greater in the harvested paddock than in the others. At the start of the trial there were no significant differences in dry matter yield but a significant difference in botanical composition occurred between paddocks. The changes in dry matter that occurred between the beginning and end of grazing were not significantly different between paddocks. Before gazing, forbs made up approximately 16%, 4% and 1% of pastures in harvested, spelled and continuously grazed paddocks respectively. The change in the percentage forbs that occurred between the beginning and end of the grazing period was significantly greater in the harvested paddock than in the other paddocks indicating preferential selection and intake by sheep. The differences in weaner live weight and wool growth between paddocks suggest that paddock management can improve weaner productivity. The study also indicates that paddock management could be successfully used to increase the percentage of forbs and quality of the pasture during the dry season. The superior wool growth of two progeny groups also suggests that improved productivity of breeding flocks in the tropics is possible if superior sheep can be identified. The results highlight the importance of preferential management of pasture for weaners so that productivity advantages can be exploited.

The nitrogen and phosphorus concentrations of some pasture species in the Dichanthium-Eulalia Grasslands of North-West Queensland.

1981 ◽  
Vol 3 (1) ◽  
pp. 67 ◽  
Author(s):  
TJ Hall
Keyword(s):  
Nitrogen Concentration ◽  
Growing Season ◽  
Common Species ◽  
Dry Season ◽  
Phosphorus Concentration ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
North West ◽  
Dry Seasons ◽  
The Mean

The nitrogen and phosphorus concentrations of tops of the most common species at one site on the Dichanthium fecundum. Eulalla fulva grasslands of north-west Queensland were determined. The eight major grasses were sampled between 13 and 16 times over three consecutive dry seasons and three times during the growing season. Selected minor grasses and forbs were sampled on 30 occasions in both seasons over six years. Chrysopogon fallax and Iseilema spp. declined in phosphorus concentration during the dry season while the other major grasses remained constant. The nitrogen concentration of these two grasses and of Astrebla elymoides, A. squarrosa, D. fecundum and Sorghum australiense declined while that of E. fulra and Aristida latifolia was constant during the dry season. Both species of Astrebla had the highest concentrations of the two nutrients. The minor gasses had highest nitrogen and phosphorus concentrations in December at the start of the wet season and rapid declines in both nutrients occurred by March. These species were not intensively sampled during the dry season. The forbs had higher nutriant concentrations than grasses. The mean phosphorus concentration of major grasses in the dry season was highest (0.095%) in 1973 and lowest (0.065%) in 1974 following an abnormally wet summer. There was no difference in mean nitrogen concentration between years. It was 0.61% for the three dry seasons combined. The implications of these data for animal production are discussed.

scholarly journals Assessment of Global Solar Radiation at Selected Points in Nigeria Using Artificial Neural Network Model (ANNM)

2019 ◽  
pp. 376-390 ◽  
Author(s):  
Ibeh Gabriel Friday ◽  
Bernadette Chidomnso Udochukwu ◽  
Tertsea Igbawua ◽  
Tyovenda Alaxander ◽  
Ofoma John Ndubuisi
Keyword(s):  
Transfer Function ◽  
Solar Radiation ◽  
Global Solar Radiation ◽  
Activation Function ◽  
Temporal Variations ◽  
Dry Season ◽  
Coefficient Of Determination ◽  
Wet Season ◽  
North West ◽  
North East

In this study, spatial distribution, temporal variations, annual distribution, estimation and prediction of solar radiation in Nigeria was carried out using ANNs. Levenberg-Marquardt backpropagation algorithms was used for the training of the network using solar radiation data along the years (1979-2014). The data records were divided into three portions (training, testing and validation). The network processed the available data by dividing it into three portions randomly: 70% for the training, 15% for validation and the remaining 15% for testing. Input parameters were chosen as latitude, longitude, day of the year, year while observed solar radiation was chosen as targeted data (from a processed file). The output parameter was the estimated solar radiation. The network designs were tested with root mean square error and then the most successful network (taken to be best network) which is network with less error was used to carry out the study. The hyperbolic tangent sigmoid transfer function was also used between the input and the hidden layers as activation function, while the linear transfer function was used from hidden layers to the output layer as the activation function. The performance of ANNs was validated by; estimating the difference between the annual measured and estimated values were determined using coefficient of determination (R2). Results revealed that the R2 result was 0.82 (82%). The result of spatial variations indicated that both wet and dry seasons have their highest concentration in North-East of Nigeria. It is pertinent to also note that the lowest concentration occurred in North-West during wet season, while the lowest occurred at the South-South and South-West of Nigeria in dry season. In addition, the lowest in dry season is about 25W/m2, while that of wet season is about 15W/m2. The agreement between the temporal and annual variation of observed and estimated solar radiation reveals that the model exhibits good performance in studying solar radiation. The model was further used to predict two years ahead of the years of study.

The effects of seed rate and row spacing on light interception, dry matter accumulation and seed yield, in non-dwarf and dwarf genotypes of autumn-sown determinate white lupins (Lupinus albus) in north-west Europe

2002 ◽  
Vol 138 (1) ◽  
pp. 39-55 ◽  
Author(s):  
I. F. SHIELD ◽  
T. SCOTT ◽  
C. HUYGHE ◽  
M. BRUNEAU ◽  
B. PARISSEAUX ◽  
...  
Keyword(s):  
Seed Yield ◽  
Dry Matter ◽  
Lupinus Albus ◽  
Growing Season ◽  
Yield Potential ◽  
White Lupin ◽  
Row Spacing ◽  
Seed Rate ◽  
North West ◽  
Plant Densities

Two non-dwarf and two dwarf, autumn-sown determinate genotypes of white lupin (Lupinus albus L.) were sown at three sites in north-west Europe in the crop years, 1995–96, 1996–97 and 1997–98. Fully factorial experimental designs were used to analyse all combinations of genotype, seed rate and row spacing. Canopy expansion, expressed as the percentage of Photosynthetically Active Radiation (PAR) intercepted, and above ground dry matter (DM) accumulation were measured at frequent intervals during the main growing season at Rothamsted in the UK and Lusignan in France. The data from Rothamsted were used to derive models for the two processes, which were compared to the data from Lusignan, France.Crops with more than 23 plants/m2, 25 main stem leaves per plant or 1400 leaves/m2 were able to intercept more than 80% of the incident PAR. There were small differences in canopy expansion between genotypes. The non-dwarf genotypes began expansion slightly earlier (100–150 °Cd or thermal time in °Cdays, base temperature = 3 °C) than the dwarf genotypes. Crops sown on rows wider than 40 cm apart or with low plant densities (less than 23 plants/m2) were also slower to expand the canopy and intercept the PAR.The maximum quantity of dry matter accumulated by a genotype in the season (476–1044 g/m2) was related by a conversion efficiency (e) to the cumulative quantity of PAR intercepted. Values of e were generally in the range 0·92–1·65 g DM/MJ PAR during the early part of the growing season, which was comparable with other work on temperate-zone grain legumes. The non-dwarf genotype Ludet achieved an unusually large value of e (3·13 g DM/MJ PAR) and accumulated 1355 g DM/m2 at Lusignan in 1998. Late season drought in 1995–96 at Rothamsted produced some low values of e (0·75 and 0·88 g DM/MJ PAR).The seed yield was not related to the quantity of dry matter accumulated as harvest index varied from 22·3% to 49·7%. Maximum seed yield (4·54 t/ha) was produced from a low plant density (15·9 plants/m2). Mutual shading, caused by any combination of high plant densities, large numbers of leaves per plant or sowing on wide rows (>40 cm; at high plant densities within the rows) appeared to limit seed yield potential.

scholarly journals The effect of irrigation and sowing date on crop yield and yield components of Kabuli chickpea (Cicer arietinum L.) in a cool-temperate subhumid climate

2003 ◽  
Vol 141 (3-4) ◽  
pp. 259-271 ◽  
Author(s):  
M. RAJIN ANWAR ◽  
B. A. McKENZIE ◽  
G. D. HILL
Keyword(s):  
Cicer Arietinum ◽  
Seed Yield ◽  
Growing Season ◽  
Sowing Date ◽  
Yield Potential ◽  
Radiation Absorption ◽  
Growth Stages ◽  
Canopy Development ◽  
Loam Soil ◽  
Intercepted Radiation

The canopy development, radiation absorption and its utilization for biomass production in response to irrigation at different growth stages of three Kabuli chickpea (Cicer arietinum L.) cultivars was studied on a Wakanui silt loam soil in Canterbury, New Zealand (43°38S, 172°30E). The study also aimed at quantifying the yield potential of the crop under varying irrigation regimes and sowing dates. Green area duration (GAD), intercepted radiation (Fi), radiation use efficiency (U) and total intercepted PAR were significantly (P<0·001) increased by irrigation. Total dry matter (TDM) yield was more strongly correlated (R2=0·69–0·83) with GAD than seed yield (R2=0·60–0·69). Accumulation of TDM was highly related to intercepted PAR. Fully irrigated November-sown crops had a final U of 1·46 g DM/MJ PAR. The unirrigated crop had a U of only 0·92 g DM/MJ PAR. The U tended to decrease with delayed sowing.Averaged over the 2 years, irrigation increased seed yield by 74–124% and trends were similar for TDM yield. Seed yield was doubled in November-sown chickpeas (4·6 t/ha) and cv. Sanford produced 14 and 16% more seed than cvs Dwelley and B-90 respectively. Full irrigation from emergence to physiological maturity always gave the highest seed yield (>4·7 t/ha), and there was no indication of a critical period of sensitivity to water stress. Based on results collected in the first growing season a simple model relating seed yield to radiation interception, U and HI was made. Results from the second growing season were then used as a simple verification to test the accuracy of predictions. The results suggest that these varieties have the potential to yield more than 4·5 t/ha of seed in Canterbury.

Adaptation of soybean (Glycine max (L.) Merrill) to the dry season of the tropics. II. Effects of genotype and environment on biomass and seed yield

1991 ◽  
Vol 42 (3) ◽  
pp. 517 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Environmental Effects ◽  
Vegetative Growth ◽  
Dry Season ◽  
Genotypic Differences ◽  
Sowing Dates ◽  
Soybean Genotypes ◽  
Main Basis ◽  
Delayed Flowering ◽  
The Relationship

Eight soybean genotypes were sown at weekly intervals in three tropical dry season environments to examine genotypic and environmental effects on growth and seed yield per plant. In general, dry matter (DM) at maturity increased exponentially with crop duration and so was greater with later maturing genotypes and sowing dates where photothermal conditions slowed development. Across environments, thermal time provided a better description of DM accumulation than did crop duration, indicating direct effects of temperature on growth rates. Among genotypes, the relationship between seed yield and DM production was strongly linear, implying that under the wide spacings of the study, DM production was the main basis of genotypic differences in seed yield. Among environmental means, the relationship was both weaker and curvilinear, suggesting that environmental effects on vegetative growth were not necessarily reflected in seed yield. Further, where photothermal regime delayed flowering and maturity, vegetative growth was often excessive, and harvest index (HI) smaller. HI was also smaller where flowering coincided with cool night temperatures (< c. 14�C) and podset was reduced. Overall, HI was negatively correlated with crop duration. Responses are discussed in terms of the implications for soybean improvement for the tropical dry season.

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