Effects of varying nitrogen supply at different stages of the reproductive phase on spikelet and grain production and on grain nitrogen in wheat

1973 ◽  
Vol 24 (5) ◽  
pp. 647 ◽  
Author(s):  
RHM Langer ◽  
FKY Liew
Keyword(s):  
Leaf Area ◽  
Flag Leaf ◽  
Grain Filling ◽  
Solution Culture ◽  
Nitrogen Supply ◽  
Nitrogen Application ◽  
Stage Number ◽  
Leaf Area Duration ◽  
Three Stages ◽  
Grain Nitrogen

Plants of wheat cv. Arawa confined to the main shoot were grown in solution culture in a glasshouse. Nitrogen supply was either high (150 p.p.111.) or low (15 p.p.m.) at three stages of development: between the double-ridge stage and floret initiation, between then and ear emergence, or after ear emergence, giving eight treatment combinations. Spikelet numbers were increased only by raising nitrogen supply at the doubleridge stage. Number of grains per spikelet also responded to treatment during the same period, but was greatest when high nitrogen was given until ear emergence. This response depended on the position of the spikelet within the ear, and the basal and terminal spikelets contributed least when nitrogen supply was low. Individual grain weight responded less to treatment than grain numbers. Nitrogen application had a large effect on leaf area duration, but the grain/leaf ratio (G) was depressed. Since their appeared to be no nitrogen effects on photosynthesis per unit flag leaf area, it is suggested that grain yield was controlled mainly by the capacity of the ear to accept carbohydrate, depending on the number of sites available for grain filling. Percentage grain nitrogen increased with lateness of nitrogen application. However, raising nitrogen supply before ear emergence and then decreasing it again also affected grain nitrogen in the ear, which suggests redistribution during grain filling

Competition between skeleton weed (Chondrila juncea L) and cereals in relation to nitrogen supply

1958 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
LF Myers ◽  
J Lipsett
Keyword(s):  
Crop Yields ◽  
Nitrogen Supply ◽  
Weed Competition ◽  
Nitrogen Application ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Grain Nitrogen ◽  
Low Nitrogen ◽  
Yield Of Oats ◽  
Plant Growth Regulating Substances

The effect of skeleton weed competition on the yield of wheat and oats was investigated in seasons when rainfall was plentiful. Nitrogen was found to be the major factor limiting crop yields. In soils with comparable nitrogen-supplying powers, skeleton weed density governed the crop's response to applied nitrogen. Competition between skeleton weed and crop was severe at low nitrogen levels, but minor at the high nitrogen levels achieved either by nitrogen application, or when the crop followed a legume-rich pasture. Competition had its effect early in the crop's growth. Temporary removal of competition, by spraying with plant growth regulating substances (JICPA) at different times, was used to determine when competition was critical, and measure its effects. Skeleton weed reduced nitrogen supply early in the crop's growth, and so depressed yield. An application of 1 lb MCPA per acre in the fallow 54 days before sowing, or 10 days after crop emergence, increased the yield of oats from 710 to 1350 lb grain per acre: a response equal to that from 32 lb nitrogen per acre applied at planting in the same experiment. In each case, the response to spraying at the different times was analogous to the effect of a nitrogen application at these times. Early spraying gave responses in yield; later spraying gave responses in grain nitrogen. The results provide a new estimate of the reduction in crop yield due to skeleton weed.

The effect on yield and leaf area of wheat of applying nitrogen as a top-dressing in April or in sprays at ear emergence

1955 ◽  
Vol 46 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Gillian N. Thorne ◽  
D. J. Watson
Keyword(s):  
Winter Wheat ◽  
Nitrogen Content ◽  
Leaf Area ◽  
The Other ◽  
Nitrogen Application ◽  
Area Index ◽  
Rapid Fall ◽  
Shoot Number ◽  
Leaf Area Duration ◽  
Effect On Yield

Nitrogen, at the rate of 0.5 cwt./acre, was applied to winter wheat as an April dressing of nitrochalk, or as eight sprayings of 2% NH4NO3 solution applied either to the soil or to the leaves at about the period of maximum leaf area, before and during ear emergence. All three methods of nitrogen application caused similar increases in yield and nitrogen content of grain. April nitrogen gave a greater yield of straw than the later dressings.Late nitrogen application caused a small increase in leaf area index, first noticeable one week after ear emergence and persisting for another four weeks. L.A.I. of plots that received nitrogen in April was much larger than that of the other plots at the period of maximum leaf area, but by four weeks after ear emergence it was less than that of plots receiving the late nitrogen. Shoot number per metre and leaf area per shoot were increased by early nitrogen, but only the latter was increased by nitrogen applied at ear emergence.Leaf area duration after ear emergence was the same on all nitrogen-treated plots and the yield of grain divided by L.A.D. was nearly constant for all plots.Applying nitrogen late, after an April dressing, did not prevent the rapid fall in L.A.I. from the high value reached at the period of maximum leaf area and caused no greater increase in yield than when applied in the absence of an April top-dressing. A single urea spray applied in early June increased yield to the same extent as the ammonium nitrate sprays.

Inheritance of flag-leaf angle, flag-leaf area and flag-leaf area duration in four wheat crosses

1999 ◽  
Vol 98 (2) ◽  
pp. 310-314 ◽  
Author(s):  
M. R. Simón
Keyword(s):  
Leaf Area ◽  
Flag Leaf ◽  
Leaf Angle ◽  
Leaf Area Duration

An analysis of the factors determining yields in crosses between semi-dwarf and taller wheat varieties

1974 ◽  
Vol 82 (3) ◽  
pp. 483-496 ◽  
Author(s):  
F. G. H. Lupton ◽  
R. H. Oliver ◽  
P. Ruckenbauer
Keyword(s):  
Leaf Area ◽  
Polynomial Regression ◽  
Flag Leaf ◽  
Total Yield ◽  
Dry Weight ◽  
Regression Equations ◽  
Wheat Varieties ◽  
Area Index ◽  
Polynomial Coefficients ◽  
Leaf Area Duration

SUMMARYThe growth and development of two semi-dwarf winter wheat varieties, of two taller varieties, and of random selections from two crosses between semi-dwarf and taller varieties were compared over 2 years. Changes with time of crop dry weight/m2, leaf area index and ear size were expressed as orthogonal polynomial regression coefficients. Significant correlations were obtained between yield, the polynomial coefficients and growth measurements relating to number of tillers and flag leaf area duration, but many of these variables were significantly correlated with each other. Multiple regression equations were therefore calculated expressing yield in terms of the variables. These showed flag leaf area duration and rate of ear growth to be the most important characters determining crop yield. The greatest reduction in total yield variance was obtained by the simultaneous consideration of characters relating to photosynthetic capacity and ear development. The significance of this finding in relation to the relative importance of ‘apos;source’ and ‘sink’ in determining grain yield are discussed.

Growth and N-uptake by wheat as affected by sowing date and nitrogen in irrigated semi-arid conditions

1977 ◽  
Vol 89 (1) ◽  
pp. 35-42 ◽  
Author(s):  
M. A. Khalifa ◽  
M. H. Akasha ◽  
M. B. Said
Keyword(s):  
Leaf Area ◽  
Nitrogen Uptake ◽  
Vegetative Growth ◽  
Sowing Date ◽  
Leaf Expansion ◽  
Nitrogen Application ◽  
Arid Conditions ◽  
Leaf Area Duration ◽  
Semi Arid ◽  
Late Sowing

SummaryField experiments were made under irrigated semi-arid conditions to determine the effects of sowing date and nitrogen application on the growth and yield of wheat and nitrogen-uptake by wheat plants. Early sowing was found to be favourable to high grain production because the post-anthesis period coincided with relatively lower temperatures. Late sowing was unfavourable to grain yields since the period between anthesis and leaf senescence was curtailed by the onset of relatively higher temperature. The benefits from nitrogen were greater with early sowing because of higher nitrogen-uptake during early vegetative growth as a consequence of which, nitrogen was readily available to the plants. This resulted in better leaf expansion, and higher leaf-area indices and leaf-area duration. With late sowing nitrogen-uptake was much lower during early vegetative growth and this resulted in decreased leaf expansion, reduced leaf-area indices and leaf-area duration and therefore diminished response in grain yield to nitrogen application.

The influence of pre- and post-anthesis periods on yields of winter barley varieties in southern Spain

1982 ◽  
Vol 99 (3) ◽  
pp. 521-523 ◽  
Author(s):  
J. M. Ramos ◽  
L. F. Garcia Del Moral ◽  
L. Recalde
Keyword(s):  
Grain Yield ◽  
Leaf Area ◽  
Environmental Conditions ◽  
Grain Filling ◽  
Winter Barley ◽  
Southern Spain ◽  
Yield Variation ◽  
Leaf Area Duration

SUMMARYSix varieties of winter barley were grown during the years 1979, 1980 and 1981 in Granada (southern Spain). Grain yield variation in the 3 years studied was a function of the pre-anthesis period (especially as a determinant of number of ears/m2). In comparison leaf area duration and grain: leaf ratio from anthesis to ripening had far less influence on grain yield variation. Though these findings contrast with the generally accepted view, they can be explained by environmental conditions prevailing in southern Spain during grain filling.

scholarly journals The influence of foliar diseases, and their control by fungicides, on the protein concentration in wheat grain: a review

2002 ◽  
Vol 138 (4) ◽  
pp. 349-366 ◽  
Author(s):  
J. P. R. E. DIMMOCK ◽  
M. J. GOODING
Keyword(s):  
Dry Matter ◽  
Protein Concentration ◽  
Flag Leaf ◽  
Severe Infection ◽  
Cost Effective ◽  
Grain Filling ◽  
Wheat Grain ◽  
Cost Effective Method ◽  
Leaf Area Duration ◽  
Almost All

Experiments investigating effects of foliar disease control on wheat grain protein concentration (GPC) are reviewed. Fungicidal control of rusts (Puccinia spp.) and powdery mildew (Erysiphe graminis) increased or had no significant effect on GPC in almost all cases, whilst control of the Septoria spp. often resulted in reduced GPC, but with exceptions. Reasons for these differences are discussed with reference to host pathogen interactions. Irrespective of infection strategy (biotrophic or necrotrophic), controlling severe infection increased nitrogen yield and the proportion of above-ground crop nitrogen that was partitioned to the grain. Similar effects are recorded for above-ground biomass and dry matter harvest index. The relationships between fungicide effects on green flag leaf area duration (GFLAD) and GPC were examined and shown to be unaffected by mode of action of the fungicide. Interactions between fungicide use and cultivar, nitrogen and growing season are related to the amount and type of pathogen present, and environment. An economic analysis demonstrated that fungicide effects on GPC should not affect the choice of fungicide or application programme, but that applications of foliar urea at the start of grain filling can deliver a cost-effective method of eliminating GPC reductions that may occasionally result from fungicide use.

Source–sink relations and effects of post-anthesis canopy defoliation in wheat at low latitudes

1990 ◽  
Vol 114 (1) ◽  
pp. 93-99 ◽  
Author(s):  
P. K. Aggarwal ◽  
R. A. Fischer ◽  
S. P. Liboon
Keyword(s):  
Grain Yield ◽  
Flag Leaf ◽  
Dry Weight ◽  
Grain Filling ◽  
The Philippines ◽  
New Delhi ◽  
Dry Matter Accumulation ◽  
Area Index ◽  
Grain Nitrogen ◽  
Source Sink

SUMMARYSource–sink balance was studied by imposing different canopy defoliation treatments on wheat crops grown in Los Banos (Philippines) in 1985/86 and 1986/87, Sonora (Mexico) in 1972/73 and 1974/75 and New Delhi (India) in 1987/88. The crops were grown in replicated trials with optimum cultural management. Six defoliation treatments were imposed at anthesis on all shoots in the canopy in an area ranging between 1·65 and 3·0 m2. Defoliation reduced dry weight in proportion to the reduction in percentage light interception. The number of grains per unit land area was reduced slightly, and in most cases not significantly, except when all leaves were removed. Despite reduction of leaf lamina area index to as low as 0·5, the decrease in grain yield was small. In particular, flag leaf removal led to a remarkably small reduction in grain yield. Grain nitrogen content in defoliated crops decreased much less than expected from the amount of N removed by defoliation. The slope of the relation between reduction in grain yield with defoliation and reduction in post-anthesis dry matter accumulation was 0·56, indicating moderate source limitation for grain filling. The crops at the hottest site, in the Philippines, were less limited by source than the other crops. It is suggested that selection for smaller flag leaves may be worthwhile for high-input wheat crops.

Elevated CO2 accelerates flag leaf senescence in wheat due to ear photosynthesis which causes greater ear nitrogen sink capacity and ear carbon sink limitation

2009 ◽  
Vol 36 (4) ◽  
pp. 291 ◽  
Author(s):  
Chunwu Zhu ◽  
Jianguo Zhu ◽  
Qing Zeng ◽  
Gang Liu ◽  
Zubing Xie ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
Leaf Senescence ◽  
Carbon Sink ◽  
Flag Leaf ◽  
Net Photosynthesis ◽  
Grain Filling ◽  
Flag Leaves ◽  
Sink Capacity ◽  
Sink Limitation ◽  
Grain Nitrogen

It was anticipated that wheat net photosynthesis would rise under elevated CO2, and that this would alter the progress of senescence due to the unbalance of carbohydrates and nitrogen. Our study showed that ear carbon sink was limited, and sugar was accumulated, hexokinase activities and levels of phosphorylated sugar were increased within the flag leaves, grain nitrogen sink capacity was enhanced, and flag leaf senescence was accelerated under elevated CO2. However, if the ear of the main stem was covered, these responses to elevated CO2 were absent, and the senescence of flag leaf was not accelerated by elevated CO2. Thus, it appeared that elevated CO2 accelerated the rate of flag leaf senescence, depending on ear photosynthesis. The ears have far higher enhancement of net photosynthesis than flag leaves, and the role of the flag leaf relative to the ear was declined in supplying C assimilation to grain under elevated CO2. This indicates that as CO2 rises, the grain sink needs the N more than C assimilate from flag leaf, so the declining rates of N% and soluble proteins concentration were markedly accelerated under elevated CO2 conditions. This suggests that, the large increase in ear net photosynthesis accelerated grain filling, accelerated remobilising N within flag leaf as the result of the greater grain nitrogen sink capacity. In addition, as the result of grain carbon sink limitation, it limited the export of flag leaf sucrose and enhanced sugar cycling, which was the signal to accelerate leaf senescence. Hence, elevated CO2 subsequently accelerates senescence of flag leaf.

Yield components and nitrogen partitioning of maize in response to nitrogen before and after anthesis

1987 ◽  
Vol 38 (6) ◽  
pp. 1001 ◽  
Author(s):  
CJ Pearson ◽  
BC Jacobs
Keyword(s):  
Dry Weight ◽  
Grain Filling ◽  
Nitrogen Supply ◽  
Nitrogen Partitioning ◽  
Grain Number ◽  
Plant Parts ◽  
Before And After ◽  
Grain Nitrogen ◽  
Effect On Yield ◽  
Nitrogen Treatments

Zea mays hybrid XL66 was grown with irrigation in sand in the field and subjected to different rates of nitrogen supply from floral initiation to anthesis and again from anthesis to maturity. Nitrogen supply during spikelet differentiation affected grain number markedly. Nitrogen supply during grain filling had a small but significant effect on the rate of grain filling and an effect on the rate of nitrogen entry to the grain, causing a 1.3-fold change in percentage grain nitrogen. Increasing the nitrogen supply produced larger plants, but the distribution of nitrogen and dry weight among plant parts were similar and the harvest indices for dry weight (0.46) and nitrogen (0.66) were the same over all nitrogen treatments. We found no evidence that shoot size per se controlled grain number or rate of grain growth; rather, fertilizer management during spikelet differentiation had most effect on yield of XL66.

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