GrainGenes

ITEMS FROM ARGENTINA

CÓRDOBA NATIONAL UNIVERSITY

College of Agriculture, P.O. Box 509, 5000 Córdoba, Argentina.

Spikelets per spike number improvement in bread wheat after six cycles of recurrent selection. [p. 17]

Ariel Masgrau and Ricardo Maich.

In the central, semiarid region of Argentina, wheat grain yield and its components have great variability due to drought stress conditions and warm temperature during the critical periods of heading and flowering. Four S1-derived families per cycle (C0 to C6), with similar flowering dates, were cultivated during 2004. Our objective was to evaluate, in a semiarid environment under rainfed conditions, the genetic progress for grain yield and some of its components after six cycles of recurrent selection. A significant increase of the number of spikelets/spike (11 %) was observed at the most advanced cycle (C6). However, grain yield did not increase, probably because of tiller inhibition and a prolonged drought stress after flowering.

Spikelet analysis comparing six cycles of recurrent selection. [p. 17-18]

S.P. Gil, C.S. Perrone, M.M. Cernana, and R.H. Maich.

The goal of our work was to evaluate the plant-breeding effects of six cycles of recurrent selection on the number of floret primordia and fertile florets in bread wheat.

The plants were grown at the Experimental Farm of the College of Agriculture (31 29'S and 64 00'W), Córdoba, Argentina, during three consecutive years: 2001, 2002, and 2003. We compared the C0 (initial), C1, C2, C3, C4, and C5 (intermediate), and C6 (more advanced) cycles. Five main shoot spikes from each of the 12 S-derived families/population were divided in thirds (lower third, spikelets 4 and 5; middle third, spikelets 9 and 10; and upper third, subterminal spikelet) were studied. Data were evaluated with ANOVA and Duncan s Multiple Range Test (p <= 0.05).

The results of the analysis, regardless of the degree of significance, pointed out that the intermediate cycles C3 and C4 had higher mean values than the others, whereas the more advance C6 cycle did not show the behavior expected.

C3-00-42: An autochthonous and strong short-cycle wheat with highlighted agronomic performance. [p. 18]

G. Manera, D. Ortega, and R.H. Maich.

During 2004, the experimental, the short-cycle wheat line C3-00-42 was evaluated in a farmers field. We also evaluated the following commercial, short-cycle cultivars: Klein Flecha, Klein Chaj, ProInta Gaucho, and Baguette Premium 13. This comparative yield test was made under the technical supervision of Tecnocampo (Monte Cristo, Córdoba, Argentina). Randomized blocks with three repetitions were used. Each parcel occupied a 2,100 m^2^ area. Seeding under no-till on soybean stubble was done on 30 May, 2004. The land was previously chemically fallowed and fertilized with 120 kg urea/ha. At that time, 120 mm of useful water was stored in the land until a depth of 160 cm was measured. A notable 50-mm precipitation occurred during July and another 33 mm in October. This last precipitation happened more than 15 days after flowering (29 September, 2004), during grain filling. The phenologic agronomic age is less important, because the number of seeds/area already was established (20 days before and 10 days after heading). A mechanical harvest was made on 8 November, 2004, with a yield-monitoring system. The values obtained from the system were compared with means obtained on a self-weight chute. Seed yield values with 14 % humidity are expressed.

The good agronomic performance of experimental line C3-00-42 is not correlated with the qualitative profile of the current short-cycle wheats, which is not common (Table 1). Finally, because there is no preharvest loss due to the tenacious glumes that protect the grain, the farmer or contractor has some flexibility of deciding when to harvest and may anticipate planting a second crop of soybean or corn.

Information collected by the Wheat Genetic Subject Group, Faculty of Agricultural Sciences, National University of Córdoba. Argentina.

Bread-making quality of two genotypes versus six commercial cultivars of wheat developed for the semiarid regions of Argentina. [p. 19-20]

M.E. Dubois and Z. Gaido.

Argentina, as a wheat-exporting country, should compete with others whose quality is classified into different classes and types according to end use, thus promoting diversity and guaranteeing quality. In Argentina, agroecological diversity differentiates quality, but there is limited knowledge and information about the relative wheat quality of the different regions.

We evaluated the bread-making quality of new genotypes of bread wheat compared to six commercial cultivars. The two better genotypes were obtained by recurrent selection for yield (C1-00-83 and C3-00-42). The six commercial cultivars were ProINTA Imperial, Klein Don Enrique and Martillo, Buck Halcón, Buck Sureño, and Buck Raudal. All wheats were evaluated in the field of the College of Agriculture, located in the Argentine central semiarid region (31 29' S and 64 00' W), in 2003. A randomized block design with four replications was used. Quality of the grain and flour and experimental panification were determined.

The bread-making quality of the C3-00-42 corresponded to a strong wheat (W = 385 x 10^-4^ J), very tenacious, high water absorption, and good loaf volume. The genotype C1-00-83 represents the best values for protein, gluten, and loaf volume of all those analyzed, with a high flour yield, and a very strong (W = 349 x 10^-4^ J), balanced (P/L 0.61), and the least mixing time (Table 2).

Table 2. Bread-making quality of two genotypes versus six commercial wheat cultivars after recurrent selection.

The genotype C3-00-42 presents similar baker characteristics to Buck Sureño, categorized by the National Commission of Seeds into Group 1, which are used for flours or manufactured products that require strong wheats with a W > 350 and protein > 12 %. The excellent baking characteristics of C1-00-83 place it in Group 2 (Wheats for Traditional Panification with more than 8 h of fermentation), better than Buck Raudal and ProINTA Imperial, which also belong in group 2.

These two analyzed genotypes that were developed for the semiarid region present excellent baking characteristics and offer different industrial qualities, which responds to the demand of national and international markets for certain quality and industrial that allow the elaboration of products of more acceptance on the part of the consumer.

Integral genetic progress in hexaploid triticale (X Triticosecale Wittmack) after three cycles of recurrent selection. [p. 20-21]

R. Maich and D. Manero de Zumelzoe.

Our objective was to determine the genetic progress in grain yield and other nine associated physical and physiological characters after three recurrent selection cycles in hexaploid triticale. The selection criterion was sustained on a selection index constituted by eleven traits.

Ten S1:2 selected progenies were analyzed for each one of the following recurrent selection cycles: C0, C1, C2, and C3. The material was sown under rainfed conditions on 19 May, 2004 at the Experimental Farm of the College of Agriculture (Córdoba National University), Córdoba, Argentina (31°29' S, 64°00'W). The experimental unit consisted of 1-row plots with two replications, 1.3-m long, 0.20-m spacing, and a seeding rate of 150 grains/m^2^. The traits measured were number of spikes (number/plot), grain and biological yield (g/plot), harvest index (%), 1,000-kernel weight (g), grain (number/plot), grain and biomass yield (g/spike), harvest index/spike (%), and straw yield (g/spike). Analyses of variance were computed for all traits considering the cycle of selection as variation source. Significant differences between mean values were determined using Duncan s Multiple Range Test.

We observed significant statistical differences between mean values only for harvest index/spike, a physiological grain yield component calculated as the ration between grain yield and spike biomass. Genetic progress of 14 % (C3 with respect to C0), which implicated an annual rate of 2.3 %, was observed. For the other characters (except straw yield/spike), positive tendencies, even if not statistically significant, through the first three cycles of recurrent selection in hexaploid triticale, were observed.

Taking into account that 2004 was an atypical period with dry environmental conditions, these results promise a repeat of the experiment in 2005 and a continuation of this genetic breeding program.

Morphological changes to the root system in wheat associated with six cycles of recurrent selection. [p. 20]

Gabriela Melchiorre and Laura Torres.

Our objective was to determine the wheat seedling aerial and root system morphological changes measured at the end of six cycles of recurrent selection performed under rainfed condition. For each one of the four S1 families derived from each cycle (C0-C6), we made two moist paper rolls containing 25 seeds each. The seeds were germinated for 8 days under controlled conditions (8/16 h photoperiod and 20°C). We measured the seedlings for length of the first leaf (cm) and number and length of the seminal root. The results were classified as large (I), medium (II, III, and IV), and small (V). Root and aerial dry weight also were estimated. The regression coefficients between the dependent variables and the number of recurrent selection cycles (C0-C6) were calculated. Significant linear regression coefficients for root number and radical and aerial dry weight were obtained. With respect to the seminal root number, the lowest value was 0.06 roots/cycle. The dry weight decreased 0.004 g/cycle, whereas the weight of the first leaf decreased 0.01 g/cycle. These results suggest that the plant idiotype that best responds to drought conditions is that one with a less profuse root system, which allows the plant greater water availability during flowering.

Publication. [p. 20]

• Ortega D, Manera G, Astolfi G, Argenti R, and Maich R. 2004. Progeso genético en trigo cultivado en secano. Agrisciencia XXI:89-92 (In Spanish).