Source‐sink limitations for grain weight in wheat and barley under waterlogging conditions during pre‐anthesis

Author(s):  
D. E. Becheran ◽  
D. J. Miralles ◽  
L. G. Abeledo ◽  
S. Alvarez Prado ◽  
R. P. San Celedonio
Keyword(s):  
1994 ◽  
Vol 45 (7) ◽  
pp. 1337 ◽  
Author(s):  
GA Slafer ◽  
R Savin

Postanthesis green area duration (GAD) has been associated frequently with yield. The senescence pattern of green organs is a major component of GAD. It has been proposed that delayed or accelerated senescence is strongly controlled by environmental conditions and the level of source or sink limitation on grain growth. In particular, it has been generally reported that the removal of reproductive structures delays the senescence process. However, results reporting this effect in wheat are not conclusive. A field experiment was conducted at the experimental station of The University of Melbourne comprising a factorial combination of a semidwarf and a standard-height wheat, and two levels of sink strength. At anthesis, 20 main shoots were tagged and detillered. Ten days after anthesis all the spikelets from one side of 10 tagged ears were removed by hand. The experiment was performed under natural, and 3 h-extended photoperiods from seedling emergence to heading. The photoperiod treatments induced differing grain filling environments and differing plant characteristics at onset of grain filling. Green area senescence was similar for both sink size treatments at any combination of cultivar and grain filling condition, indicating that the dynamics of plant senescence was insensitive to a severe reduction in number of grains per spike. Therefore, GAD was not significantly affected by the reduction in sink strength. The number of grains per spike were reduced to ca. 50% due to trimming. Therefore, source-sink ratio was doubled, but no significant changes in individual grain weight were found. There was no relationship between GAD and individual grain weight, confirming that grain growth in field-grown wheat is not limited by the strength of the source. Alternatively, our results confirmed that field-grown wheat is sink-limited during grain filling and that the likely accumulation of soluble carbohydrates in leaves does not affect the onset or rate of senescence.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
E. Ballesteros-Rodríguez ◽  
C. G. Martínez-Rueda ◽  
E. J. Morales-Rosales ◽  
G. Estrada-Campuzano ◽  
G. F. González

The source-sink ratio experimental manipulation has helped to define whether a crop is limited by source or sink or co-limited by both. There is no evidence in triticale of source-sink manipulations effects on yield and yield components. Two experiments were accomplished during 2008 and 2009 growing seasons at the Universidad Autónoma del Estado de México, México, and one in 2010 at the National Institute of Agricultural Technology in Pergamino, Argentina. Two triticale cultivars (line 4 and 7) and one wheat cultivar (Tollocan) were used. Source-sink relations were modified at anthesis by thinning, degraining, shading, and total defoliation procedures. Changes in the source-sink relation affected yields in both species differentially. The changes in yield due to cultivars and treatments were explained mainly by the number of grains rather than by their individual grain weight. The number of grains was affected by all treatments in both species, while the individual grain weight was increased by thinning and degraining mainly in triticale. A greater number of fertile florets in triticale were associated with their higher rate of abortion compared to wheat. These results could help to better understand crop management and genetic improvement.


2010 ◽  
Vol 56 (No. 5) ◽  
pp. 218-227 ◽  
Author(s):  
A. Madani ◽  
A. Shirani-Rad ◽  
A. Pazoki ◽  
G. Nourmohammadi ◽  
R. Zarghami ◽  
...  

The experiments were laid out to understand the mechanisms causing yield limitations imposed by post-anthesis water and nitrogen deficiencies in plants with modified source-sink ratios. Two soil-water regimes were allotted to the main plots. At anthesis, three levels of N were applied: none, 25% and 50% of total the N supply. Spike-halving caused reduction in grain yield at both water regimes and all N supply levels, showing that the reduction in grain number can not be compensated by a higher individual grain weight. Sink reduction by trimming 50% of the spikelets reduced grain number per ear by 38.5% and increased individual grain weight by 12.0%, which shows the plasticity in grain weight and grain set of wheat if sufficient assimilates are available. Additional nitrogen supply at anthesis had no significant effect on the total aboveground biomass, but increased grain yield through more allocation of dry matter to grains. Our findings suggest that for rainfed wheat with optimum N supply and supplemental irrigation, wheat growers should choose cultivars with a high grain number per ear and manage the crop to increase grain number per unit of land (sink capacity).


Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1527
Author(s):  
Carolina Rivera-Amado ◽  
Gemma Molero ◽  
Eliseo Trujillo-Negrellos ◽  
Matthew Reynolds ◽  
John Foulkes

Grain filling may be limited by the joint source and sink capacity in modern wheat cultivars, indicating a need to research the co-limitation of yield by both photosynthesis and the number and potential size of grains. The extent to which the post-anthesis source may be limiting final grain size can be estimated by partial degraining of spikes, while defoliation and shading treatments can be useful to estimate if any excess photosynthetic capacity exists. In the current study, degraining was applied to a set of 26 elite spring wheat cultivars from the International Maize and Wheat Improvement Center (CIMMYT)’s core germplasm (CIMCOG) panel, while lamina defoliation and shading through stem-and-leaf-sheath covering treatments were applied to a subset of the same cultivars. Responses to source treatments in grain weight, pre-anthesis reserve contribution to grain weight, dry-matter translocation efficiency, and flag-leaf and spike photosynthetic rate were measured and compared to an unmanipulated control treatment. Grain weight responses to degraining among cultivars ranged from no response to increases of 28%, suggesting a range of responses from sink limitation, to probable source and sink co-limitation of grain growth. Grain weight’s response to degraining increased linearly with the years of cultivar release from 1966 to 2009, indicating that the current highest yield potential CIMMYT spring wheats have a co-limitation of grain growth by source and sink. This may have been due to an increase in grain sink strength with years of cultivar release with no commensurate increase in post-anthesis source capacity. The relatively low decreases in grain weight with defoliation compared to decreases in light interception by defoliation indicated that sink limitation was still likely predominating in the cultivars with co-limitation. The stem-and-leaf-sheath covering treatment decreased grain weight by nearly 10%, indicating that stem-and-leafsheath photosynthesis plays a key role in grain growth during grain filling. In addition, pre-anthesis reserve contribution to grain weight was increased by ca. 50% in response to lamina defoliation. Our results showed that increasing the post-anthesis source capacity, through increases in stem-and-leaf-sheath photosynthetic rate during grain filling and pre-anthesis reserve contribution to grain weight, is an important objective in enhancing yield potential in wheat through maintaining a source–sink balance.


2006 ◽  
Vol 57 (2) ◽  
pp. 227 ◽  
Author(s):  
Daniel F. Calderini ◽  
M. P. Reynolds ◽  
G. A. Slafer

Source limitation during grain filling is important for both management and breeding strategies of grain crops. There is little information on the sensitivity of grain weight of temperate cereals to variations in source–sink ratios, and no studies are available on the comparative behaviour of temperate cereals growing together in the same experiment. The objective of the current study was to evaluate, under field conditions, the response of grain weight to different source–sink ratios during grain filling in high-yielding cultivars of bread wheat, durum wheat, and triticale at 2 contrasting locations. Two experiments were carried out at C. Obregon and El Batan in Mexico. In each location, 6 genotypes (2 bread wheat, 2 durum wheat, 2 triticale) were evaluated. A week after anthesis, 2 source–sink (control and halved spikes) treatments were imposed. Location and genotype significantly (P < 0.01) affected grain yield and components. Significant grain weight increases (P < 0.05) were found only in 2 cases in El Batan. The highest response of 17% was found in triticale, with less than 10% in most of the other genotypes. The effect of genotype and location is discussed.


2017 ◽  
Vol 9 (12) ◽  
pp. 302 ◽  
Author(s):  
Diogo S. Moura ◽  
Giovani G. Brito ◽  
Ângela D. Campos ◽  
Ítalo L. Moraes ◽  
Fabiane G. S. Porto ◽  
...  

Non-structural carbohydrates (NSC) accumulation and photosynthesis traits were studied in two rice (Oryza sativa L.) genotypes maintained under control (22/30 °C - night/day) and at high night temperatures (HNT) (28/30 °C) conditions from heading to milk stage. Rice cultivars were Nagina22 - N22 and BRS Querência - Quer, which are tolerant and sensitive to high temperatures, respectively. The source-sink flow related attributes were tested to understand the nature of NSC accumulation and translocation. Compared to N22, Quer maintained higher stem starch in glucose on seventh day after heading and at milk stage independently of imposed temperatures. However, the levels of starch in glucose were lower for N22 meanwhile their total sugar concentration (TSC) were higher at control and at HNT at milk stage as compared to Quer. N22 maintained unaltered the spikelet sterility and 1000-grain weight across environments showing a consistent trend with its stem NSC translocation. Both genotypes showed similarity in some gas exchange and chlorophyll fluorescence performance suggesting unaffected photosystem II photochemistry, linear electron flux, and CO2 assimilation. Beyond indicating that source functioning was not the limiting factor for low TSC and starch in glucose levels found in N22 on seventh day after heading stage. Moreover, our data suggest that the higher translocation capacity shown by N22 can be involved in their lower spikelet sterility and 1000-grain weight stability across the environments. These results indicate that selecting genotypes with higher capacity to stem NSC translocation at HNT could lead to more grain yield stability in future climate scenarios.


2016 ◽  
Vol 47 (2) ◽  
Author(s):  
Jaddoa & Kadom

A field trial was conducted at Abu-Ghraib Research Station-Agricultural Research Directorate-Ministry of Agriculture during the growing seasons of 2012-2013 and 2013-2014. The objective was to investigate the effect of source-sink Regulation on grain yield  and its companents of five bread wheat cultivars (Triticum aestivum L.). Randomized complete block design with the arrangement of split-plots with three replicates was used. Bread wheat cultivars (Bohooth-22, IPA 99, Abu-Ghraib-3,Al-Fath and Al-Rasheed) occupied the main plots while treatments of source-sink relationship regulation occupied the sub-plots. They included eight treatments: Con. control (Con.), S1 (removal of lamina of the flag leaf of main stem), S2 (removal of laminas of the leaf  beneath the flag leaf), S3 (removal of both lamina of the leaf  and the leaf under flag leaf), S4 (removal of upper third spikelets),S5 (removal of median third spikelets), S6 (removal of lower third spikelets) and S7 (removal all spikelets from one side of spike) . Characteristics of plant height, flag leaf area, spike length, no of spikelet per spike, spike weight, and grain yield and its components were measured and estimated. Results of the present study indicated the followings:  Cultivar (Bohooth-22) gave the highest 1000 grain weight (35.70 and 35.31 g) the highest grain yield (5.467 and 5.148 t.ha-1) in both seasons, respectively compared with Abu-Ghraib3 and Al-Rasheed cultivars which gave lowest grain yield (4.918,4.364, 4.239 and 4.352 t.ha-1) in both seasons, respectively and then less 1000 grain weight (30.15, 32.66, 32.61 and 32.77 g), in both seasons, respectively. Treatment (Con.) i.e no modification of source-sink relationship gave the highest grain yield (5.93 and 5.66 t.ha-1) in both seasons, respectively. Treatments of regulation source (S1 and S3)gave grain yield (4.909, 4.698, 4.621and 4.356 t.ha-1), respectively while (S5) treatment gave the lowest grain yield (4.203 t.ha-1) in the first season and (4.061 t.ha-1) in the second season. This indicates that sink regulation treatment was the most influencial in reducing grain yield than the source regulation treatment, especially, treatment (S5) in both seasons where the  median third of spikelets had been removed due to the reduction of spike growth rate (3.18 and 2.49 g.day-1) in both seasons compared with the (Con) treatment which gave the highest values of spike growth rate (3.91 and 3.12 g.day-1) in both seasons, respectively which resulted in the reduction of dry matter translocation in the (S5) treatment (1.87 and 1.74 g.day -1) and consequently in the reduction of 1000 grain weight (30.09 and 31.199) compared with (34.99 and 37.12 g) in the (Con.) treatment in both seasons, respectively.


2008 ◽  
Vol 59 (6) ◽  
pp. 510 ◽  
Author(s):  
Valeria S. Passarella ◽  
Roxana Savin ◽  
Gustavo A. Slafer

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.


1997 ◽  
Vol 128 (3) ◽  
pp. 273-281 ◽  
Author(s):  
B. C. KRUK ◽  
D. F. CALDERINI ◽  
G. A. SLAFER

Although it has been generally recognized that the difference in yield potential amongst wheat cultivars released in different eras is related to differences in their reproductive sink strength, there have been few investigations about changes in source–sink ratios as a consequence of wheat breeding. In the present study, two field experiments, in which plots were fertilized and irrigated and lodging and diseases were prevented, were carried out with seven cultivars (including a commercial hybrid) representing different periods of plant breeding in Argentina from 1920 to 1990. The cultivars were defoliated during post-anthesis to analyse the response of grain weight at particular positions within the spike (which have intrinsic differences in potential size).Individual grain weight was virtually unaffected by defoliation in the old cultivars, but modern cultivars exhibited a significant reduction in individual grain weight for several positions within the spike, although this reduction was small (c. 15%) and many grains were unaffected. In addition, no relationship was found between individual grain weight in the controls and its reduction due to defoliation.We concluded that if the source–sink ratio is further reduced, the grain yield of modern wheats will be simultaneously limited by the source and the sink. Future breeding should therefore attempt to improve simultaneously both sink and source strengths.


2014 ◽  
Vol 65 (2) ◽  
pp. 185 ◽  
Author(s):  
Román A. Serrago ◽  
Daniel J. Miralles

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.


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