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Marti J.,University of Lleida | Slafer G.A.,University of Lleida | Slafer G.A.,Catalonian Institution for Research and Advanced Studies
Field Crops Research | Year: 2014

It is frequently assumed that durum wheat is more tolerant to stress than bread wheat. Unfortunately few research papers compare the performance of both species side-by-side under a wide range of environments in field conditions. We aimed to compare durum and bread wheat performance in a field study under contrasting treatments of water and nitrogen during three experimental seasons. In addition we compiled a comprehensive database with data from field experiments in which both species were grown in the same field conditions. A cross-over interaction of yield from bread vs. durum wheat was found, but oppositely to the hypothesis, bread outyielded durum wheat in the low-yielding conditions while durum wheat tended to have higher potential yield. We then divided the database in decades in which the cultivars were released and found that in the 1960s bread wheat outyielded durum wheat in almost any comparison whilst in the 2000s durum wheat outyielded bread wheat in most comparisons. Grain weight was constitutively higher in durum than in bread wheat, likely associated with a lower fruiting efficiency in the former; but in both types of wheat grain number per m2 was the component responsible for yield sensitivity to environmental changes. Differences in yield were also related to differences in water and nitrogen use efficiencies: under low-yielding conditions bread wheat was consistently more efficient than durum wheat and under high-yielding conditions durum wheat was more efficient. © 2013 Elsevier B.V. Source


Ferrante A.,University of Lleida | Savin R.,University of Lleida | Slafer G.A.,University of Lleida | Slafer G.A.,Catalonian Institution for Research and Advanced Studies
Field Crops Research | Year: 2015

Future increases in grain number may be achieved through improving fruiting efficiency (FE; grains set per unit spike dry weight at anthesis). In recent experiments it was found a negative relationship between the average weight of the grains and FE. The objective of this paper was to determine whether this negative relationship was constitutive (i.e. the increased FE caused all grains to be smaller) or resulted from the increased proportion of grains of smaller potential size. Four experiments, involving 8 different environmental conditions, were carried out during two consecutive growing seasons (2008-2009 and 2009-2010) in which two durum wheat cultivars contrasting in FE and average grain weight were compared. In these conditions we determined FE and carried out a comprehensive study analysing in detail the weights of each individual grain along each of the spikelets. Averaging all experimental conditions, there was a negative relationship between average grain weight (GW) and fruiting efficiency (FE). Donduro with low FE produced in average heavier grains than Vitron. However, when considering individual grains there were, in general, no differences in GW. Therefore, the negative relationship between average grain weight and FE would not be constitutive, and would mostly represent the increase in the proportion of distal grains within the spikelets or of grains from apical spikelets as a consequence of an increased FE, reducing the average size of the grain but mostly unaffecting the size of particular grains. This provides further and stronger support to the idea of using FE as a criterion to further raise yield potential in wheat breeding programmes. © 2015 Published by Elsevier B.V. Source


Ferrante A.,University of Lleida | Savin R.,University of Lleida | Slafer G.A.,University of Lleida | Slafer G.A.,Catalonian Institution for Research and Advanced Studies
Journal of Experimental Botany | Year: 2013

Survival of floret primordia initiated seems critical for the determination of grain number and yield in wheat, and understanding what determines floret mortality would help in the development of more robust physiological models of yield determination. The growth of the juvenile spikes has been frequently considered the determinant of grain number, implying that floret development would depend on resource availability and that the onset of floret death would be related to spike growth. However, this model has been recently challenged from a study concluding that floret death started when the most advanced floret primordia reached a particular developmental stage. As the few previous studies on this relationship involved photoperiod treatments which affect both floret development and the onset of spike growth, conclusions cannot be considered mechanistic. This comprehensive study analysed in detail floret development in wheat as affected by resource availability (mainly soil nitrogen levels) and found that the onset of floret death may occur when development of the most advanced florets ranged from stages 5 to 9 and that the average and standard deviation of floret developmental stage coinciding with the onset of floret death was not related to the level of availability of resources. These results provide further support to the model relating the onset of floret death with the initiation of active growth of the juvenile spike in which florets are developing. © The Author(2) [2013]. Source


Ferrante A.,University of Lleida | Savin R.,University of Lleida | Slafer G.A.,University of Lleida | Slafer G.A.,Catalonian Institution for Research and Advanced Studies
Journal of Experimental Botany | Year: 2010

In Mediterranean durum wheat production, nitrogen (N) fertilization may be important to stabilize and increase yields. Wheat yield responses to N fertilization are usually related to grains per m2, which in turn is the consequence of processes related to floret development (floret initiation followed by floret death/survival) during stem elongation. The literature is rather scarce in terms of the relevance of floret developmental dynamics, determining the final number of grains in general terms and in particular regarding responsiveness to N. The aim of this study was to determine whether durum wheat responses to N under different water regimes are related to the dynamics of development of floret primordia to produce fertile florets. During the 2006-2007 and 2007-2008 growing seasons, experiments with a factorial combination of two N levels (0 and 100 or 250kg N ha-1) and two levels of water availability (rainfed and irrigated) were carried out (although the water regime was only effective in the second season). The response of yield was largely a consequence of that in grain number per spike. Floret initiation was similar for both N levels in each experiment and water regime, for which the survival of a higher proportion of initiated florets was critical in the response of the crop. The diminished rate of floret abortion during the late part of stem elongation in response to N was associated with a slightly accelerated rate of floret development which allowed a higher proportion of the primordia initiated to reach the stage of fertile floret by flowering. © 2010 The Author. Source


Cossani C.M.,University of Lleida | Slafer G.A.,University of Lleida | Slafer G.A.,Catalonian Institution for Research and Advanced Studies | Savin R.,University of Lleida
Field Crops Research | Year: 2011

Under Mediterranean environments, farmers usually prefer to sow barley rather than wheat as it is generally believed that barley yields more under stressful conditions. As terminal stresses such as high temperature and water are common constraints in Mediterranean regions, higher grain weight stability may confer a clear advantage in order to maintain higher yields. The objective of the present study was to compare the stability in terms of grain weight and its components for barley, bread wheat, and durum wheat, exploring a wide range of nitrogen and water availabilities in experiments conducted in a Mediterranean region. Grain weight ranged from 23.8 to 47.7mg grain -1, being higher for durum wheat than barley and bread wheat. Durum wheat presented higher variability both in maximum grain filling rate and duration of grain filling period than bread wheat or barley. The three species responded similarly in terms of grain nitrogen content to changes in the environmental conditions explored. It is concluded that in terms of grain weight barley is as stable as bread wheat. However, durum wheat presented a lower stability than barley and bread wheat. © 2011 Elsevier B.V. Source

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