scholarly journals Variation of grain nitrogen content in relation with grain yield in old and modern Spanish wheats grown under a wide range of agronomic conditions in a Mediterranean region

2009 ◽  
Vol 147 (6) ◽  
pp. 657-667 ◽  
Author(s):  
M. M. ACRECHE ◽  
G. A. SLAFER
Keyword(s):  
Nitrogen Content ◽  
Field Experiments ◽  
Dilution Effect ◽  
Grain Filling ◽  
Nitrogen Accumulation ◽  
Grain Number ◽  
Wide Range ◽  
Manipulative Experiments ◽  
Grain Nitrogen ◽  
Source Sink

SUMMARYWheat yield and grain nitrogen concentration (GNC; mg N/g grain) are frequently negatively correlated. In most growing conditions, this is mainly due to a feedback process between GNC and the number of grains/m2. In Mediterranean conditions, breeders may have produced cultivars with conservative grain set. The present study aimed at clarifying the main physiological determinants of grain nitrogen accumulation (GNA) in Mediterranean wheat and to analyse how breeding has affected them. Five field experiments were carried out in north-eastern Spain in the 2005/06 and 2006/07 growing seasons with three cultivars released at different times and an advanced line. Depending on the experiment, source-sink ratios during grain filling were altered by reducing grain number/m2 either through pre-anthesis shading (unshaded control or 0·75 shading only between jointing and anthesis) or by directly trimming the spikes after anthesis and before the onset of the effective grain filling period (un-trimmed control or spikes halved 7–10 days after anthesis). Grain nitrogen content (GN content; mg N/grain) decreased with the year of release of the genotypes. As the number of grains/m2 was also increased by breeding there was a clear dilution effect on the amount of nitrogen allocated to each grain. However, the increase in GN content in old genotypes did not compensate for the loss in grain nitrogen yield (GNY) due to the lower number of grains/m2. GN content of all genotypes increased (increases ranged from 0·13 to 0·40 mg N/grain, depending on experiment and genotype) in response to the post-anthesis spike trimming or pre-anthesis shading. The degree of source-limitation for GNA increased with the year of release of the genotypes (and thus with increases in grain number/m2) from 0·22 (mean of the four manipulative experiments) in the oldest cultivar to 0·51 (mean of the four manipulative experiments) in the most modern line. It was found that final GN content depended strongly on the source-sink ratio established at anthesis between the number of grains set and the amount of nitrogen absorbed at this stage. Thus, Mediterranean wheat breeding that improved yield through increases in grain number/m2 reduced the GN content by diluting a rather limited source of nitrogen into more grains. This dilution effect produced by breeding was further confirmed by the reversal effect produced by grain number/m2 reductions due to either pre-anthesis shading or post-anthesis spike trimming.

scholarly journals Evidence for improved pollen viability as the mechanism for film antitranspirant mitigation of drought damage to wheat yield

2016 ◽  
Vol 67 (2) ◽  
pp. 137 ◽  
Author(s):  
Minuka M. Weerasinghe ◽  
Peter S. Kettlewell ◽  
Ivan G. Grove ◽  
Martin C. Hare
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Pollen Viability ◽  
Wheat Yield ◽  
Spray Application ◽  
Grain Number ◽  
Climatic Zones ◽  
Boot Stage ◽  
Wide Range ◽  
Drought Damage

Application of film antitranspirant to wheat during late stem extension reduces drought damage to yield, but the mechanism is unknown. Field experiments under rain shelters were conducted over 3 years to test the hypothesis that film antitranspirant applied before meiosis alleviates drought-induced losses of pollen viability, grain number and yield. The film antitranspirant di-1-p-menthene was applied at third-node stage, and meiosis occurred at the early boot stage, with a range of 11–16 days after spray application in different years. Irrigated, unsprayed plots were included under the rain-shelters, and pollen viability, measured in 2 years in these plots, averaged 95.3%. Drought reduced pollen viability to 80.1% in unirrigated, unsprayed plots, but only to 88.6% in unirrigated plots treated with film antitranspirant. Grain number and yield of irrigated plots, measured in all years, were 16 529 m–2 and 9.55 t ha–1, respectively, on average. These were reduced by drought to 11 410 m–2 and 6.31 t ha–1 in unirrigated, unsprayed plots, but only to 12 878 m–2 and 6.97 t ha–1 in unirrigated plots treated with film antitranspirant. Thus compared with unirrigated, unsprayed plots, antitranspirant gave a grain yield benefit of 0.66 t ha–1. Further work is needed to validate the pollen viability mechanism in different climatic zones and with a wide range of cultivars.

Heat stress effects on source–sink relationships and metabolome dynamics in wheat

2019 ◽  
Vol 71 (2) ◽  
pp. 543-554 ◽  
Author(s):  
Mostafa Abdelrahman ◽  
David J Burritt ◽  
Aarti Gupta ◽  
Hisashi Tsujimoto ◽  
Lam-Son Phan Tran
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Negative Impact ◽  
Grain Filling ◽  
Wheat Breeding ◽  
Wheat Genotypes ◽  
Stress Effects ◽  
Wide Range ◽  
High Yields ◽  
Source Sink

Abstract Crops such as wheat (Triticum spp.) are predicted to face more frequent exposures to heat stress as a result of climate change. Increasing the yield and sustainability of yield under such stressful conditions has long been a major target of wheat breeding, and this goal is becoming increasingly urgent as the global population increases. Exposure of wheat plants in their reproductive or grain-filling stage to high temperature affects the duration and rate of grain filling, and hence has a negative impact on wheat productivity. Therefore, understanding the plasticity of the response to heat stress that exists between wheat genotypes, especially in source–sink relationships at the reproductive and grain-filling stages, is critical for the selection of germplasm that can maintain high yields under heat stress. A broad understanding of metabolic dynamics and the relationships between metabolism and heat tolerance is required in order to achieve this goal. Here, we review the current literature concerning the effects of heat stress on sink–source relationships in a wide range of wheat genotypes, and highlight the current metabolomic approaches that are used to investigate high temperature responses in wheat.

scholarly journals Trehalose 6-phosphate signalling and impact on crop yield

2020 ◽  
Vol 48 (5) ◽  
pp. 2127-2137
Author(s):  
Matthew J. Paul ◽  
Amy Watson ◽  
Cara A. Griffiths
Keyword(s):  
Resource Allocation ◽  
Grain Yield ◽  
Green Revolution ◽  
Regulatory System ◽  
Grain Filling ◽  
Stem Height ◽  
Grain Number ◽  
Plant Resource ◽  
Whole Plant ◽  
Source Sink

The domestication and breeding of crops has been a major achievement for mankind enabling the development of stable societies and civilisation. Crops have become more productive per unit area of cultivated land over the course of domestication supporting a current global population of 7.8 billion. Food security crops such as wheat and maize have seen large changes compared with early progenitors. Amongst processes that have been altered in these crops, is the allocation of carbon resources to support larger grain yield (grain number and size). In wheat, reduction in stem height has enabled diversion of resources from stems to ears. This has freed up carbon to support greater grain yield. Green revolution genes responsible for reductions in stem height are known, but a unifying mechanism for the active regulation of carbon resource allocation towards and within sinks has however been lacking. The trehalose 6-phosphate (T6P) signalling system has emerged as a mechanism of resource allocation and has been implicated in several crop traits including assimilate partitioning and improvement of yield in different environments. Understanding the mode of action of T6P through the SnRK1 protein kinase regulatory system is providing a basis for a unifying mechanism controlling whole-plant resource allocation and source-sink interactions in crops. Latest results show it is likely that the T6P/SnRK1 pathway can be harnessed for further improvements such as grain number and grain filling traits and abiotic stress resilience through targeted gene editing, breeding and chemical approaches.

Rate and duration of grain filling and grain nitrogen accumulation of wheat cultivars grown in different environments

1999 ◽  
Vol 50 (6) ◽  
pp. 1007 ◽  
Author(s):  
J. F. Panozzo ◽  
H. A. Eagles
Keyword(s):  
Soil Moisture ◽  
Maximum Rate ◽  
Nitrogen Concentration ◽  
Grain Filling ◽  
Accurate Method ◽  
Triticum Aestivum L ◽  
Logistic Function ◽  
Nitrogen Accumulation ◽  
Grain Nitrogen ◽  
Rate Of Accumulation

In Australia, the period during grain filling for wheat (Triticum aestivum L.) is often associated with increasing ambient temperatures and diminishing soil moisture conditions. This can affect grain size and grain protein concentration. In this study, grain filling and nitrogen accumulation were investigated by sampling every 7 days during grain filling for 4 cultivars: Rosella, Hartog, Halberd, and Eradu. The plants were grown in trials with and without irrigation in 1991 and 1992, which were seasons with divergent temperatures and rainfall during this period. A4-term logistic function, using both days after anthesis (DAA) and growing degree days (GDD), was fitted to data to estimate maximum rate and duration of grain filling. The logistic model proved to be, in most cases, an accurate method to determine the rate and duration of grain filling and nitrogen accumulation. Probably because of differences in availability of soil moisture, the use of GDD did not improve on the estimates obtained from using DAAas the independent variable. In 1991, a relatively dry year, non-irrigated plants showed signs of wilting. In that year, grain nitrogen contents on a per grain basis were similar in both the irrigated and non-irrigated (dryland) environments, but grain weights were much higher from the irrigated environment. The maximum rate and duration of grain filling were lower in the dryland environment. In contrast, whereas the duration of nitrogen accumulation was similarly shorter in the dryland environment, the maximum rate of accumulation was substantially higher. In 1992, a cooler and wetter year, differences between irrigated and non-irrigated environments were smaller, but the trends for rate and duration were similar. We concluded that, under stress conditions, higher rates of accumulation of grain nitrogen and lower rates of accumulation of carbohydrate, rather than differences in duration of accumulation, were primarily responsible for increased grain nitrogen concentrations. In general, cultivars used in this study were ranked similarly for rate and duration of grain filling across environments, with the exception of Hartog, which had a significantly lower maximum rate in the dryland treatment in 1991. This suggests that Hartog may be more sensitive to drier conditions than the other cultivars. In almost all environments, Eradu had a higher maximum rate of accumulation of grain nitrogen than other cultivars; however, the duration was reduced, so that in the mature grain, grain nitrogen concentration was not significantly different.

Cultivar effects on relationship between grain number and photothermal quotient or spike dry weight in wheat

2011 ◽  
Vol 150 (4) ◽  
pp. 442-459 ◽  
Author(s):  
L. LÁZARO ◽  
P. E. ABBATE
Keyword(s):  
Solar Radiation ◽  
Field Experiments ◽  
Dry Weight ◽  
Grain Filling ◽  
Wheat Cultivars ◽  
Grain Number ◽  
Incident Solar Radiation ◽  
Fertility Index ◽  
Sowing Dates ◽  
Intercepted Solar Radiation

SUMMARYIn wheat, the photothermal quotient (Q, the ratio between mean incident solar radiation and mean temperature is greater than 4·5°C in the 30 days preceding anthesis), is a good estimator of grain number/m2 (GN) and of yield. Previous investigations have not analysed in depth whether the responses of GN to Q differ between wheat cultivars, or what is the cause of the eventual variation. In the present work, the results of field experiments carried out between 1994 and 2001 in various locations were used to test the following hypotheses: (i) the responses of GN to Q differ between wheat cultivars; (ii) these differences are caused by differences in the spike fertility index (GN/g spike dry weight/m2 at the beginning of grain filling (SDW)). The responses of GN to Q were compared for five wheat cultivars (four bread wheats and one durum wheat) and it was found that with Q values above 0·3 MJ/m2/d°C, all responses of GN to Q were linear, positive and parallel. A method was then proposed to obtain cultivar-specific GN from a common relationship between GN and Q. This method would facilitate GN estimation in crops with changes in sowing dates, sites or years, starting from data of potential GN and yield that is relatively easy to obtain. Differences among cultivars in response to Q were due to differences in GN response at SDW. Similar SDW values produced different GN, depending on the spike fertility index of each cultivar. The cultivars did not differ in their responses of SDW to Q. The association between spike fertility index and SDW was strongly negative in bread wheat. At lower levels of Q or SDW, the spike fertility index increased in all cultivars, at least when changes in SDW or Q were caused mainly by intercepted solar radiation, but the present results demonstrate that differences between cultivars also exist in this relationship.

Are temperature effects on weight and quality of barley grains modified by resource availability?

2008 ◽  
Vol 59 (6) ◽  
pp. 510 ◽  
Author(s):  
Valeria S. Passarella ◽  
Roxana Savin ◽  
Gustavo A. Slafer
Keyword(s):  
Heat Stress ◽  
Resource Availability ◽  
Grain Filling ◽  
Grain Weight ◽  
Malting Quality ◽  
Malt Extract ◽  
Nitrogen Fertilisation ◽  
Wide Range ◽  
Barley Grains ◽  
Source Sink

Under field conditions the occurrence of brief periods of moderately high (30–32°C) and very high temperatures (>35°C) is quite common during grain filling in small-grain cereals. These events occur under a wide range of different management and environmental conditions, such as different nitrogen supplies and source–sink ratios after flowering. The objective of the present work was to study whether the effect of a brief heat stress is modified by resource availability for the growing grains. We subjected spikes of barley 10 days after flowering to a heat treatment in factorial combination with different nitrogen availabilities and source–sink ratios during post-flowering to determine effects on grain weight and major malting quality attributes. Grain weight and screening percentage (proportion of grains <2.5 mm) were reduced by the mild heat stress. However, the magnitude of the effect was dependent on the nitrogen fertilisation and the source–sink treatments in which the heat stress was imposed. Grain protein and β-glucan percentages were increased by both nitrogen fertilisation and heat stress. Again, the magnitude of the increase was dependent upon the availability of resources. There was a trend to reduce malt extract in all treatments with respect to the control, but the reduction was only statistically significant with heat stress.

scholarly journals Dry Matter and Nitrogen Accumulation During Vegetative and Grain Filling of Lentil (Lens culinaris Medic.) as Affected by Nitrogen Rates

2011 ◽  
Vol 39 (2) ◽  
pp. 196 ◽  
Author(s):  
Nurdilek GULMEZOGLU ◽  
Nihal KAYAN
Keyword(s):  
Dry Matter ◽  
Field Experiments ◽  
Block Design ◽  
Growth Yield ◽  
Biomass Accumulation ◽  
Dry Weight ◽  
Grain Filling ◽  
Nitrogen Accumulation ◽  
N Accumulation ◽  
N Rates

This research aimed to determine the effect of different levels of nitrogen (N) on the growth, yield and the N accumulation of lentil plants grown under rain-fed conditions. The two-year field experiments with lentil were arranged in a randomised complete block design. Nitrogen was applied at four rates (0, 20, 40 and 60 kg ha-1) and all of the plots received half of the N rates before sowing in October and the remaining N rate in spring. The plants were harvested in the following stages: the first multifoliate leaf unfolding at the fifth node (V5) full seed or seed on nodes 10-13 that fill pod cavities (R6) and maturity (R8). The dry weight and N concentration of the shoot (leaf+stem), pod wall, and seed were then measured. It has been found that N application significantly affected the lentil characteristics. The maximum biomass accumulation and N accumulation were obtained at R6, and the N fertiliser had a positive effect on the seed weight and N accumulation. It can be suggest that 20 kg N ha-1 will increase the per-plant dry matter and N accumulation of the seeds under rain-fed conditions.

Source limitations due to leaf rust (caused by Puccinia triticina) during grain filling in wheat

2014 ◽  
Vol 65 (2) ◽  
pp. 185 ◽  
Author(s):  
Román A. Serrago ◽  
Daniel J. Miralles
Keyword(s):  
Water Content ◽  
Leaf Rust ◽  
Puccinia Triticina ◽  
Grain Filling ◽  
Grain Weight ◽  
Grain Number ◽  
Foliar Diseases ◽  
Growing Seasons ◽  
Source Sink ◽  
Source Limitation

Late foliar diseases (especially leaf rust) reduce assimilate supply during post-anthesis, determining fewer assimilates per grain and thereby inducing grain weight reductions. Although the assimilate reduction hypothesis is the most accepted to explain decreases in grain weight due to late foliar diseases, it has not been clearly established whether those reductions could be completely ascribed to source limitations or whether diminished grain weight could be the consequence of reductions in grain weight potential. The objective of this work was to determine whether grain weight reductions due to leaf rust during grain filling could be associated with source–sink limitations. Two experiments (during 2007 and 2008 growing seasons) including healthy and diseased wheat crops were conducted under field conditions. Source–sink manipulation treatments and grain water content measurements were made to test the source- and sink- limitation hypotheses due to the appearance of late foliar diseases during grain filling. Leaf rust was induced to appear exclusively during grain filling, and in both years, it reduced grain yield and grain weight in both experiments. However, except for distal grains, there were no significant differences between healthy and diseased plots in maximum grain water content, indicating that late foliar diseases did not affect the potential size of the grains. The reserves stored in stems were remobilised to the growing grains in both healthy and diseased crops. However, the reserves remaining at physiological maturity were significantly reduced in diseased crops. Reduction in grain number by trimming the spikes increased the grain weight in diseased but not in healthy crops. Grain weight of trimmed spikes in diseased crops reached similar values to those of healthy crops. These results support the hypothesis that foliar diseases could cause source limitation for grain filling beyond differences in grain weight potential when the crops are severely affected by late foliar diseases such as leaf rust.

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.

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