LLAVALLOL, ARGENTINA
Instituto Fitotecnico de Santa Catalina (FCAyF, UNLP)
CIGEN (UNLP, CONICET, CIC)
Yield of waxy and high quality protein maize hybrids developed in Argentina --Corcuera,VR, Naranjo,CA It is commonly believed that waxy maize hybrids, as well as quality protein ones, yield less than their normal counterparts. This premise is set upon the lower density of their starch, soft endosperm, and consequently lower grain weight. During 1990, a maize breeding program aimed at obtaining waxy maize hybrids, as well as quality protein ones, in Argentina, was initiated at the Instituto Fitotécnico de Santa Catalina in Llavallol. Since then, several inbreds have been developed and tested. Crosses among the best inbreds were done, and finally during the growing season 2001/02, numerous single-cross hybrids were first tested at this location, situated at 35°S and 58°W. The hybrids tested can be classified into three categories: waxy hybrids, quality protein hybrids and double recessives combining modified starch with quality protein. The single-crosses, as well as their parental inbreds, were arranged in a 3 replicate complete randomised block design field trial. Each plot consisted of a single row of 5.5 m, sown at a density of 71,500 plants/ha (see Figures 1 and 2). At maturity, each plot was hand harvested, and many ear and kernel traits were measured. Some of these traits are summarized in Tables 1, 2 and 3 according to the type of hybrid. Potential yield was calculated as the product of ears/plant x grams of kernels/ear x plants/ha. Yields ranged from 8.9 to 20.9 tons/ha, 1000-kernel-weights varied from 200 to 350 grams, and 91 to 171 grams of kernels/ear were obtained (see Figures 3 to 5). Generally, lower yields are consistent with lower 1000-kernel-weights, smaller ears and/or a lower number of ears/plant. Thus, the yield of individual plants is an important factor to be considered, and comes not only from specific ear traits, but also from prolificity. It must be said that the parental inbreds used to develop these single-cross hybrids were selected among other traits because of their high prolificity. New trials at multiple locations must be made to verify the surprisingly good preliminary results obtained. By breeding, high yielding parentals may be selected, and choosing the most appropriate single-crosses among them will make it possible to develop high yielding modified starch or quality protein maize hybrids adapted to our growing conditions.

Table 1. Waxy maize hybrids.
 
Hybrid No Number of rows Kernels/row 1000-kernel-weight Grams of kernels/ear No. Ears/Plant Potential Yield(1)
3123 16 34 300.0 grams 102.1 "1.7" 12.0
3166 16 17 330.0 grams 134.7 "1.7" 16.0
3167 14 27 310.0 grams 107.0 "2.0" 14.1
3168 14 36 350.0 grams 149.1 "1.9" 18.4
3170 16 33 350.0 grams 147.1 "1.6" 15.8
3172 12 38 340.0 grams 146.8 "1.5" 15.2
3173 14 31 310.0 grams 131.3 "1.6" 14.1
3175 18 33 265.0 grams 136.3 "1.8" 15.9
3176 16 34 340.0 grams 170.2 "1.8" 20.9
3177 16 30 270.0 grams 113.8 "1.5" 11.7
3178 disordered disordered 380.0 grams 90.2 "2.0" 12.5
3179 15 36 210.0 grams 81.8 "1.7" 9.0
3180 16 36 310.0 grams 125.9 "1.5" 12.4
3182 14 31 310.0 grams 119.6 "1.2" 9.4
3184 14 36 320.0 grams 159.2 "1.5" 15.5
3185 16 36 320.0 grams 146.2 "1.7" 16.6
3186 16 31 290.0 grams 140.4 "1.6" 14.8
3187a 16 33 330.0 grams 130.9 "1.7" 13.7
3187b 16 35 350.0 grams 134.3 "1.7" 16.2
3190 16 30 270.0 grams 118.4 "1.3" 10.0
3192 16 33 330.0 grams 171.0 "1.3" 14.1
3196 14 37 320.0 grams 132.4 "1.2" 10.7
3197 16 30 310.0 grams 121.8 "1.5" 12.1
(1) Tons/hectare corrected at 15% moisture content in kernels.

Table 2. High quality protein maize hybrids.
 
Hybrid No. Number or rows Kernels/row 1000-kernel-weight Grams of kernels/ear No. Ears/Plant Potential Yield(1)
3126 18 32 230.0 grams 119.2 "1.3" 10.8
3145 14 28 290.0 grams 96.1 "2.0" 14.9
3146 14 32 290.0 grams 129.3 "2.0" 18.4
3147 16 27 250.0 grams 91.3 "1.4" 8.9
3148 16 32 260.0 grams 127.6 "1.6" 13.8
3150 14 28 200.0 grams 99.0 "1.7" 10.6
3151 14 31 280.0 grams 120.5 "1.6" 13.0
(1) Tons/hectare corrected at 15% moisture content in kernels.

Table 3: Modified starch and quality protein (double recessives) maize hybrids.
 
Hybrid No. Number of rows Kernels/row 1000-kernel-weight Grams of kernels/ear No. Ears/plant Potential Yield(1)
3159 14 35 280.0 grams 129.5 "2.0" 17.1
3160 14 36 345.0 grams 115.3 "1.9" 14.7
3161 16 33 280.0 grams 140.3 "1.7" 16.4
3163 14 36 300.0 grams 140.1 "1.7" 16.4
3164 18 31 330.0 grams 162.0 "1.3" 13.8
3165 16 32 280.0 grams 135.7 "1.1" 9.9
3198 14 27 340.0 grams 111.4 "1.3" 10.0
3199 14 35 340.0 grams 145.0 "1.7" 18.8
(1) Tons/hectare corrected at 15% moisture content in kernels.

Figures 1-5.  Waxy and Quality Protein Hybrids. Left: 2001/02 field trial. Upper right: original waxy inbred. Center: waxy hybrid. Bottom right: quality protein maize hybrid.
 
 
 
 


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