Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 2.39

PROGRESS IN DURUM WHEAT BREEDING FOR YIELD AND GRAIN QUALITY DURING THE 20^TH CENTURY IN ITALY

P. DE VITA*, O. LI DESTRI NICOSIA**, F. NIGRO**, C. PLATANI**, A. MAGGIO*, N. DI FONZO**

*) Enea C.R. Trisaia, 75026 Rotondella, Matera, Italy

**) Experimental Institute For Cereal Research, Section Of Foggia, 71100 Foggia, Italy

durum wheat breeding, genetic improvement, yield, grain quality

A group of 14 durum wheat (Triticum durum Desf.) varieties cultivated in Italy during the years 1900-2000 was studied. Four 25-year time periods were considered. For each period, the 2-4 most cultivated varieties were selected. Field trials were conducted at Foggia (Southern Italy) during 2000-2001 and 2001-2002 seasons. Three nitrogen levels were compared in a completely randomised block design with three replications. To understand the morphological and physiological basis for yield improvement during 100 years of selection, and to possibly assist future breeding for yield and grain quality, several traits were considered: grain yield, days to heading, plant height, physiological maturity, harvest index, test weight, weight of 1000 kernels, grain protein content, pigment content and ash content. At harvest, for each experimental plot, two sub-samples of 0.5 m each were collected to assess total dry matter and yield components (kernels m^-2, spikes m^-2, spikes length, peduncle length, spikelets/spike, kernels/spike). During the growth season, and in coincidence with the heading date, several physiological parameters were measured for each cultivar, including transpiration rate (E), photosynthetic rate (A), stomatal conductance (g) and internal CO₂ concentration (Ci). Over the years, a significant genetic improvement was observed for grain yield. A yield increase of 1.40 t ha^-1 was observed in modern vs. older cultivars, with an annual genetic gain of about 19 kg ha^-1. Based on these results we conclude that the overall potential yield of durum wheat cultivars released in Italy in the 20^th century has increased of approximately 44%. Specifically, the improved potential yield was associated to higher kernels number m^-2. Yield improvement was mostly associated to larger grain/spike ratios, partially due to the introgression into modern genotypes of dwarf genes from Norin 10. In addition, a larger number of spikes m^-2 in modern vs. older genotypes has been found to be correlated both to a reduced number of total tillers and improved tiller fertility. Early heading genotypes, with reduce plant height, have been selected over the last century with the final goal of improving both the adaptability to Mediterranean environments and the harvest index. Regarding grain quality traits, weight of thousand kernels, test weight, and pigment content did not present over time any distinctive trend. In contrast, grain protein contents showed a significant reduction in modern cultivars, which confirmed the negative relationship between protein content and grain yield (R²=-0.60 at p<0.05). This trend was remarkable for all the N levels considered. The linear regression between grain yield and maximum photosynthetic rate (A_max) was significant (R²= 0.40 at p<0.05), indicating that A_max may be considered as physiological marker to assist future selection for grain yield.