جستجوی مقالات مرتبط با کلیدواژه "برش" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

Grazing and harvesting are two major ways of utilizing natural and artificial grasslands. Current research was aimed at studying the effects of shoot cutting frequency on total phytomass, above-ground phytomass, underground phytomass, the condition of tillering, and the tolerance of four halophytes (P. distans, A. littoralis, A. lagopoides and J. articulates) against cutting. This experiment was carried out in a completely randomized design with 7 replications. Four mentioned species and four different cuttings were considered as treatments. Seedlings of four species in growth stage were collected from grasslands of Inchebroon, located in north of Agh-ghala, and were cultivated in the pots. During the growth period, aerial parts of the species were cut at 6 cm above the soil surface of pots in four cutting treatments including once every week, once every two weeks, once every four weeks, and control treatment. Results indicated that total phytomass, above- ground phytomass and underground phytomass of A. littoralis, A. lagopoides and J. maritimus reduced as a response to the stress of cutting compared with control treatment. Consequently, these three species cannot retrieve total phytomass in comparison with control treatment. Total phytomass of P. distans remained stable in all treatments; therefore this species is able to retrieve phytomass loss completely. Repeating cutting decreased the number of shoots in four species. According to the results, in one-year experimental conditions, P. distans was identified as a high-tolerant species against cutting while A. littoralis, A. lagopoides and J. maritimus showed a medium tolerance.

This study aimed to evaluate effects of clipping on some growth characteristics of Panicum antidotale. A completely randomized design with 4 treatments including once a week (frequent), every two weeks (moderate), every four weeks (low) and control (unclipped) was carried out in 11 replicates. Shoots were clipped at a height of 7 cm in all treatments. The result showed no significant effects of clipping treatments on total biomass, above-ground and below ground biomass and also number of shoots and roots. Therefore, this species can be considered as tolerant to clipping.

We studied the effects of shoot clipping frequency on biomass production, biomass allocation and shoot number on two range species (Agropyron elongatum (Host) Beauv., and Festuca ovina L.). Plants were grown during a 15-week experiment in experimental garden. The above ground parts were clipped at a height of 7 cm following four treatments: frequent (every one week), moderate (every two weeks), low (every four weeks) and unclipped (control). Total biomass and root mass of A. elongatum were reduced by frequent defoliation until 40% whereas F. ovina maintained a similar production for two plant components (above-ground and roots biomass) when clipped. The latter one was able to compensate for the biomass loss even after five consecutive clippings. The changes in biomass production patterns of A. elongatum were accompanied with variations in biomass allocations. Biomass allocated to roots was significantly lower for A. elongatum in clipped plants than in control plants. The shoot mass and root mass fraction of F. ovina were similar among clipping treatments. Shoot number was significantly increased until 30% for A. elongatum and F. ovina in clipped plants than in control plants. Finally, in the experimental conditions, F. ovina was the most tolerant species to clipping, while A. elongatum showed moderate tolerance.