ВЛИЯНИЕ СРЕДСТВ ХИМИЗАЦИИ НА ОПТИЧЕСКИЕ СВОЙСТВА АГРОЦЕНОЗА ЯРОВОГО ЯЧМЕНЯ С ПОДСЕВОМ МНОГОЛЕТНИХ ТРАВ

Abstract

The purpose of the research was to study the effect of mineral fertilizers and plant protection system on the vegetation index NDVI and its seasonal dynamics in agrocenoses of spring barley with overseeding of perennial grasses in the North-West of Russia. The data obtained indicate that against the background of the deficiency of the main elements of mineral nutrition in the second half of the growing season of spring barley, a significant phytomass of perennial grasses is formed in the crop, which account for 36.7%. This leads to a smaller decrease in the NDVI index (by 0.06) than in the fertilized variants (0.20). The value of NDVI index reflects not only the state of cultivated plants and weed infestation of crops, but also the level of development of crops, growing under vegetation. The influence of mineral nutrition developed during the period of maximum values of the index, which were recorded 6-8 weeks from the sowing date and 26-30 weeks from the beginning of the year. Under the influence of average doses of fertilizers, the NDVI index increased by 0.09...0.2 (on average 0.13), under the influence of high doses – by 0.13...0.26 (on average 0.18). The influence of plant protection system was expressed by a decrease in the phytomass of weeds (by 49.4...68.9%), at the same time the mass of spring barley and perennial grasses increased (by 1.7...18.5% and by 11.7...43.5% respectively). Carrying out the whole complex of protective measures led to a decrease in the NDVI index values by 0.01...0.06, depending on the phytosanitary situation in the agrocenosis. The most reliable forecast of the yield of spring barley can be implemented in the period from 5 to 7 weeks from the beginning of the emergence of barley shoots, especially against the background of the use of plant protection products that eliminate the influence of harmful organisms on the formation of the crop and the optical properties of crops