Publications (8) View all
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Article: Breeding Effects on Grain Filling, Biomass Partitioning, and Remobilization in Mediterranean Durum Wheat
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ABSTRACT: Th is work assesses the changes resulting from durum wheat (Triticum turgidum L. var. durum) breeding in Italy and Spain during the 20th century on grain fi lling, biomass production, and allocation at anthesis, and the remobilization of preanthesis photosynthates to the grain of main stems. Field experiments, involving 12 Italian and 12 Spanish cultivars released at different periods, were conducted at two Spanish sites during three growing seasons. Breeding activities did not modify final grain weight (WG), the maximum rate of grain fi lling (R), nor grain fi lling duration (D) of central grains of main spikes. Genetic variability existed for WG and R within countries and periods. Cycle length (expressed as days from sowing to anthesis [DSA]) was reduced by 2 and 8 d in Italian and Spanish cultivars, respectively. Crop dry weight (CDW) decreased by 21% (0.51% yr–1) and green area index (GAI) by 28% (–0.33% yr–1) in Spanish cultivars. Green area index at anthesis did not differ between old and modern Italian cultivars, while CDW decreased by 9%. Leaf area index (LAI) remained unchanged in cultivars from both countries, while the spike:stem ratio increased by 8 and 10% in Italian and Spanish cultivars, respectively. Changes over time in DSA were positively associated with changes in CDW and GAI. Dry matter translocation (DMT) effi ciency switched from 9% in old cultivars to 20% in modern ones. Th e contribution of preanthesis assimilates to grain yield (CPA) increased to values of 31 and 27% in Italian and Spanish modern cultivars, respectively. Opportunities for further increases in genetic yield potential in Mediterranean-type environments are discussed.Agronomy journal 01/2008; 100:361-370. · 1.79 Impact Factor -
Article: Grain filling and dry matter translocation responses to source-sink modifications in a historical series of durum wheat
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ABSTRACT: To understand yield limitations imposed by the source–sink relationship and the effects that breeding had on it, the source–sink ratio was modifi ed on 24 durum wheat cultivars released in different periods. Field experiments were conducted during 3 yr, with treatments consisting of removing the fl ag-leaf blade, degraining half of the spike, and intact checks. Grains from near-basal spikelets tended to be the most sensitive to source–sink modifications. Degraining increased grain weight up to 15% in modern cultivars, which were more source limited and more responsive to source–sink modifications than the old ones. Our results suggest a source–sink colimitation for grain fi lling in Mediterranean environments. Translocation of preanthesis assimilates was responsible for 25, 27, and 33% of grain weight in old, intermediate, and modern cultivars, respectively. Defoliation did not alter dry matter translocation (DMT) from the main stem, as the reduction in translocation of leaf blades was compensated with translocation increases from the chaff. Sink demand determined DMT that was mostly regulated by the stem. Our results indicate that future yield improvements may be achieved by strengthening the source capacity.Crop Science 01/2008; 48:1523-1531. · 1.64 Impact Factor -
Article: Usefulness of remote sensing for the assessment of growth traits in individual cereal plants grown in the field
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ABSTRACT: Biomass determination usually involves destructive and tedious measurements. This study was conducted to evaluate the usefulness of the Normalized Difference Vegetation Index (NDVI) and the Simple Ratio (SR), calculated from the spectra of individual plants, for the assessment of leaf area per plant (LAP), green area per plant (GAP) and plant dry weight (W) at different growth stages. Two varieties of four cereal species (barley, bread wheat, durum wheat and triticale) were sown in a field experiment at a density of 25 plants m22. The spectra were captured on three plants per plot on eight occasions from the beginning of jointing to heading using a narrow-bandwidth visible-near-infrared portable field spectroradiometer adapted for measurements at plant level. Strong associations were found between NDVI and SR and growth traits, both indices being better estimators of GAP andWthan of LAP. Exponential models fitted to NDVI data were more useful for a wide number of situations than the linear models fitted to SR data. However, SR was able to discriminate between genotypes within a species. The accuracy of the reflectance measurements was comparable to that obtained by destructive measurements of growth traits, in which differences between varieties of over 24% were needed to be statistically significant. However, differences in SR of only 18% were statistically significant (P,0.05). The reliability of the spectral reflectance measurements and the nondestructive nature convert this methodology into a promising tool for the assessment of growth traits in spaced individual plants.International Journal of Remote Sensing 01/2007; 28:2497-2512. · 1.12 Impact Factor -
Article: Genetic changes in durum wheat yield components and associated traits in Italian and Spanish varieties during the 20th century
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ABSTRACT: Twelve field experiments comparing 24 durum wheat varieties from three periods—old (<1945), intermediate (1950–1985) and modern (1988–2000)—were carried out in order to ascertain the advances made in durum wheat yield components and related traits in Italian and Spanish germplasm. Grain yield improvements were based on linear increases in the number of grains per m2 and harvest index, while grain weight and biomass remained unchanged. Yield per plant increased at a rate of 0.36 and 0.44% y–1 and the number of grains per m2 improved by 39% and 55% in Italian and Spanish varieties, respectively. The mean rate of increase in the number of grains per m2 was 0.55% y–1. Plants per m2, spikes per plant and grains per spike contributed 20%, 29% and 51%, respectively, to the increase in the number of grains per m2. The enhance of the number of grains per m2 was due to the greater grain set in the modern varieties, since the number of spikelets per spike remained Twelve field experiments comparing 24 durum wheat varieties from three periods—old (<1945), intermediate (1950–1985) and modern (1988–2000)—were carried out in order to ascertain the advances made in durum wheat yield components and related traits in Italian and Spanish germplasm. Grain yield improvements were based on linear increases in the number of grains per m2 and harvest index, while grain weight and biomass remained unchanged. Yield per plant increased at a rate of 0.36 and 0.44% y–1 and the number of grains per m2 improved by 39% and 55% in Italian and Spanish varieties, respectively. The mean rate of increase in the number of grains per m2 was 0.55% y–1. Plants per m2, spikes per plant and grains per spike contributed 20%, 29% and 51%, respectively, to the increase in the number of grains per m2. The enhance of the number of grains per m2 was due to the greater grain set in the modern varieties, since the number of spikelets per spike remained unchanged. Harvest index increased overall by 0.48% y–1 (0.40 and 0.53% y–1 in Italian and Spanish varieties, respectively). Plant height was the trait that suffered the most dramatic changes (it decreased at a rate of –0.81% y–1, with little difference between the varieties of the two countries), as consequence of the presence of the Rht-B1 dwarfing gene. Harvest index and plant height, which were the traits that most contributed to discriminating between periods, remained unchanged from 1980 to 2000. The higher rates of improvement in Spain are discussed in the context of the contrasting strategies followed to improve durum wheat yield in the two countries.Euphytica 01/2007; 155:259-270. · 1.55 Impact Factor -
Article: Breeding effects on the genotype x environment interaction for yield of bread wheat grown in Spain during the 20th century
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ABSTRACT: This study evaluates the changes caused by breeding in the genotype × environment interaction of the bread wheat varieties most widely cultivated in Spain during the 20th century. A set of 27 varieties was tested in 8 environments representative of the bread wheat growing areas in the country. Minimum temperature and thermal time from sowing to heading were the main environmental traits determining genotype × environment (GE) interactions for yield. Landraces were the least productive and showed specific adaptation to environments with low minimum temperatures before heading and high relative air humidity after heading. Yield consistency was low in landraces due to large environmental effects on the number of spikes and grain weight. Old-bred varieties (released between 1945 and 1955) were the first step towards breeding for wide adaptation due to the lower dependence of their final spike number and grain weight on water availability during grain filling. Differences in the adaptation pattern of the varieties introduced since the 1960s were caused by their growth habit. Winter types were more widely adapted than spring ones, mostly because they had a more consistent number of grains per spike. Grain weight of winter varieties was enhanced in environments with high relative humidity during grain filling. Spring varieties had more grains per spike in environments with high minimum temperatures and thermal time before heading. The number of grains per spike was the yield component that most closely followed the pattern of adaptation observed for grain yield.Field Crops Research 01/2012; 126:79-86. · 2.47 Impact Factor
