Short-season genotypes have a shorter growing period than that of normal genotypes and are planted to specific production conditions. The short-growing season national programme was started in the 1997/1998 season to test hybrids for adaptation and to determine whether cultivation practices had to be adapted.
Since short-season cultivars are usually planted at a much higher density than other cultivars, and are mostly cultivated under conditions of sufficient water supply, it was decided that from the 2007/2008 growing season only short-growing cultivars under irrigation would be tested. The adaptability of commercial genotypes to a wide range of yield potential is evaluated in these short-growing season trials.
The mean grain yield in hot environments was 14,58t/ha. The minimum was 13,26t/ha at Vaalharts and the maximum was 16,05t/ha at Orania. PAN3P-502R, BG3492B, PAN3Q-240 and DKC62-80BRGEN were the four best-performing hybrids, with a yield of 16,09t/ ha, 15,99t/ ha, 15,57t/ ha and 15,55t/ ha respectively. The mean grain yield under cool to temperate conditions was 12,47t/ ha, with a minimum of 9,47t/ ha at Delmas and a maximum of 15,88t/ha at Winterton.
BG3492B, PAN3Q-740BR, BG3792BR and BG3292 were the four best-performing hybrids under irrigation, yielding 13,64t/ ha, 13,46t/ ha, 13,41t/ha and 13,33t/ ha respectively. Twenty-four genotypes entered by seed companies were used throughout the trial period. The yield potential and adaptability of the genotypes were the criteria for measuring genotype performance.
Various seed companies
Environmental conditions differ from year to year, which means that more reliable conclusions can be drawn from multi-seasonal data than from that of only one season. Yield potential in the hot regions varied from 13,26t/ha at Vaalharts to 16,05t/ha at Orania. For the cool to temperate regions, it varied from 9t/ ha, 47t/ha at Delmas to 15,88t/ha at Winterton.
The seed companies participating in the trial were Klein Karoo, Pannar, Monsanto and Link Seed.
The trials were conducted in, among others, Bethlehem, Bergville, Delmas, Hopetown, Orania and Ventersdorp. As in all the other trials, the information and observations included fertiliser and pesticide quantity, time and method of application, planting, plant emergence and harvesting dates, as well as spacing and net plot size. The number of days to 50% pollen shed, 50% silking and number of plants/ ha were also recorded.
Researchers were requested to report the incidence of any diseases immediately to ensure that the necessary follow-up and data collecting could be done. A standard of 40 plants per plot was prescribed throughout. A total of 26 plants in each of two plant rows was recommended for a row spacing below 1,5m, while 46 plants in a single plant row was recommended for a row spacing above 1,5m. Using suitable herbicides and insecticides, including systemic soil insecticides, was allowed.
The summer rainfall season in South Africa is from November to April; grain production mainly depends on sufficient rainfall during this period. The late start of the 2013/2014 summer rainfall season reflected in lower vegetative activity than in 2012.
Above-normal rainfall was recorded over most parts of South Africa during this season. Two exceptions to this pattern were central KwaZulu-Natal and surroundings, and the extreme western Free State and eastern Northern Cape, where some areas received below 75% of the long-term average.
Table 1 shows the yield of 24 short-growing maize hybrids tested on 16 different irrigated sites. Yield potential in the hot region varied from 13,26t/ha at Vaalharts to 16,05t/ha at Orania. In the cool to temperate region, yield varied from 9,47t/ha at Delmas to 15,88t/ ha at Winterton.
Results of the 2011/2012, 2012/2013 and 2013/2014 National Cultivar Trial series were summarised in the recent ARC report. These multi-seasonal trials show the genotypes’ performance during these years. For fair comparison, only genotypes entered in the National Cultivar Trials for maize since 2011/2012 were included.
Tables 2 and 3 show the mean grain yield of 14 genotypes at 39 locations. The highest was at Hopetown (17,75t/ ha) and the lowest at Delmas (9,56t/ha). The genotype producing the highest mean yield was BG3492B with 14,86t/ha.
Phone the ARC on 012 427 9700.