Physiological role of epicuticular waxes for plants and their practical significance

Abstract

The purpose. To specify the features of dynamics of formation of a layer of epicuticular waxes on leaves of weeds of different sorts during their organogenesis under different conditions of vegetation of plants and determination of role of such layer in use of herbicides. Methods. Probes were carried out in laboratories of herbology of IBCSB and IPP of NAAS in 2014–2018. The cultivated area of microplot — 1 m2, registration plot — 0,5 m2. Frequency of experiments — 7-fold. On plots they kept 50 plants of one sort of weeds for 1 m2. All alternatives of experiments were realized both in conditions of open ground and under the polymerous transparent film (sheltered ground) where conditions of vegetation were more stable. The square of leaves for analysis was determined by method of “notchings” (A.A. Nichiporovich). For determination of amount of epicuticular waxes on leaves they used “washing off” method. After sampling leaves of plants for analysis the plot were sprayed with herbicide Betanal expert k.e. (phenmedipham — 91 g/l + desmedipham — 71 + ethofumezat 110 g/l) in rate of application of 1,0 l/hectare and dose of importation of working fluid of 210 l/hectare. Results. Analysis proved that on the surface of green seed-lobe of different sorts of weeds used in experiments, epicuticular waxes were almost absent. To the time of formation of 4 leaves at juvenile plants intensity of formation of layer epicuticular waxes increased. Their average amount at plants of white goosefoot was 0,24 g/m2, or on 50% more than in the previous records, at plants of asperous jointweed — 0,26 g / m2, or on 24% more in comparison to previous indexes, at sprouts of amaranth — 0,31 g/m2, or on 35% more than in the phase of 2 leaves. In phases of formation of leaves and accumulation of more powerful layer of epicuticular waxes sprouts of weeds manifested phase resistance to action of herbicide. Conclusions. Epicuticular waxes are essential obstruction in diffusion of acting matters of herbicides in tissue of mesophyll of leaves. The augmentation in 5,6 times of amount of waxes on leaves of plants of asperous jointweed during their development coincided with the level of recession of efficiency of herbicide on 62%, r=0,723. At plants of amaranth at augmentation of accumulation of epicuticular waxes from 0,09 up to 0,72 g/m2 the level of efficiency of herbicide decreased from 100 to 35%, r=0,886.