LLAVALLOL, ARGENTINA
Instituto Fitotecnico de Santa Catalina
Universidad Nacional de la Plata and CIGEN (CONICET-CIC-UNLP)

Evaluation of yields in precommercial waxy and double recessive hybrids developed in Argentina

— Corcuera, VR; Bernatené, EA; Salerno, JC; Tomas, P; Naranjo, CA

Since 1990 a Maize Quality Breeding Program aimed to develop high quality starch and high quality protein hybrids has being conducted within the IFSC-CIGEN. Waxy maize is valuable for food, papers, adhesives and textile industries, whilst quality protein maize has a great importance for monogastrics and human nutrition.

During the growing season of 2003–04, multilocation trials were conducted in Llavallol (35°S, 58°W), Castelar (35°S, 56°W) and Pergamino (33°S, 60°W). All of these are located in the province of Buenos Aires or in Esperanza (province of Santa Fe) (31°S, 61°W). All the field trials were sown according to a complete randomized blocks design with three replicates. The experimental unit or plot consisted of a row of 5.5 m length, and the sowing density was 71,500 plants/ha. Kernel weight per ear (in grams) (KWE), number of ears per plant (EP), and yield (Kg/ha) were the variables measured in each location. Yield was calculated as kernel weight per plot × 2,857.1 in all the locations except Llavallol. There, potential yield was calculated as plant density × EP × KW. Ear weight (EW) in grams, cob percentage, 1,000 kernels weight in grams (W1,000), number of rows per ear (ER) and number of kernels per row (K/R) were also measured in Llavallol. Least significant differences (LSD) analysis was performed. Waxy and double recessive (DR) hybrids differed in their average yields and KWE in all locations (see Tables 1 and 2). Average yields ranged from 4,286 kg/ha to 12,634 kg/ha for all the hybrids tested (see Table 1). The wide range of variation is surely influenced by environment factors defined by the different sowing dates used in the various locations, as well as by the different methods used to estimate yields. Undoubtedly the one used in Llavalol tends to overestimate yields. The trials in Castelar and Llavallol were sown on October 20th, the trial in Pergamino was sown on October 25th, and the one in Esperanza was sown on December 15th. This late sowing date promoted a reduction of the vegetative phase duration, inducing a shorter cycle and consequently a yield decrease due to smaller and lighter ears (see Table 2 and Figure 1). Yield parameters results, measured in each hybrid tested in Llavallol, may be seen in Table 3. DR hybrids have heavier kernels than waxy maizes, which is reflected in their W1,000 and EW. The yields observed in Castelar and Pergamino (on average 9,425 and 9,328 kg/ha, respectively, with tops at 11,147 and 14,764 kg/ha) constitute a strong proof of the excellent agronomic performance of this germplasm that we hope could soon be released for commercial use.

Table 1: Average yields according to hybrid type and location.

Average values followed by same letters do not differ significantly.

Table 2: Yield in multilocation tests.

Average values followed by the same letters do not differ significantly.

Table 3: Yield parameters evaluated in Llavallol.

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