Find in Library

The application of methods based on measurements of photosynthesis efficiency is now more and more popular and used not only for the evaluation of the efficiency of herbicides but also for the estimation of their phytotoxicity to the cultivated crop. These methods enable to determine also dif­fe­ren­ces in the sensitivity of cultivars and/or hybrids to individual herbicides. The advantage of these methods consists above all in the speed and accuracy of measuring.In a field experiment, the sensitivity of several selected grain maize hybrids (EDENSTAR, NK AROBASE, NK LUGAN, LG 33.30 and NK THERMO) to the herbicide CALLISTO 480 SC + ATPLUS 463 was tested for a period of three years. The sensitivity to a registered dose of 0.25 l . ha−1 + 0.5 % was measured by means of the apparatus PS1 meter, which could measure the reflected radiation. Measurements of sensitivity of hybrids were performed on the 2nd, 3rd, 4th, 5th and 8th day after the application of the tested herbicide, i.e. in the growing stage of the 3rd–5th leaf. Plant material was harvested using a small-plot combine harvester SAMPO 2010. Samples were weighed and converted to the yield with 15 % of moisture in grain DM.The obtained three-year results did not demonstrate differences in sensitivity of tested hybrids to the registered dose of the herbicide CALLISTO 480 SC + ATPLUS 463 (i.e. 0.25 l . ha−1 + 0,5 %). Recorded results indicated that for the majority of tested hybrids the most critical were the 4th and the 5th day after the application; on these days the average PS1 values were the highest at all. In years 2005 and 2007, none of the tested hybrids exceeded the limit value 15 (which indicated a certain decrease in the efficiency of photosynthesis). Although in 2006 three of tested hybrids showed a certain decrease in photosynthetic activity (i.e. EDENSTAR and NK AROBASE on the 3rd day and NK LUGAN on the 2nd–4th day after the application), no visual symptoms of damage of plants were found out. It could be concluded that the herbicide CALLISTO 480 SC + ATPLUS 463 (when applied in the registered dose of 0.25 l . ha−1 + 0.5 %) did not damage hybrids under study and did not show any statistically significant effect on the grain yield. This means that the manufacturer’s statement that this herbicide, if applied in the registered dose of 0.25 l . ha−1 + 0.5 %, is very tolerant to grain maize seedlings in the growth stage of 3–5 leafs, was correct. The most suitable date of measurements of differences in sensitivity to and/or potential phytotoxicity of the preparation CALLISTO 480 SC + ATPLUS 463 seemed to be the fourth day after the application because the measured average PS1 values were the highest in all hybrids under study. When evaluating the pooled three-year yields of grain (converted to 15% of moisture content) by means of variance analysis, a statistically significant effect of the year and the hybrid on the grain yield was found out. On the other hand, however, there was no statistically significant difference in the grain yield between control and the variant treated with the registered dose of the herbicide CALLISTO 480 SC + ATPLUS 463, i.e. 12.08 t . ha‑1 and 11.50 t . ha−1, respectively (grain moisture content 15%). When comparing pooled three-year yields of all hybrids under study, there were statistically significant differences between yields of the hybrid NK THERMO on the one hand and hybrids EDENSTAR and NK AROBASE on the other.