جستجوی مقالات مرتبط با کلیدواژه « non-chemical management » در نشریات گروه « گیاهپزشکی »

Cyerus rotundus is a perennial weed of the Cyperaceae family spread throughout the tropical and subtropical parts of the world. It is a C4 and fast-growing plant that replicates rapidly through the extensive underground system and tuber. This weed causes damage to more than 92 countries and 50 crop species. In this regard, it is considered as the most damaging weed in the world. The amount of damage varies depending on the crop. One of the most important characteristics of purple nutsedge is the production of the tuber. According to available studies, burial depth of tuber plays an important role in the emergence of the onset of the competition period. Among the physical properties of the soil, soil texture plays an important role on plant growth characteristics, development of underground organs, especially in tuber plants and the amount of water penetration and maintenance. So, given the importance of accurately recognizing the biology and the ability to reproduce of nutsedge in its management, this research is also intended to study the effect of burial depths and the soil texture on the growth of purple nutsedge.

In order to evaluate the effects of soil texture and burial depth on purple nutsedge vegetative characteristics, a trial was conducted at Kerman Natural Resources and Agricultural Research Center, using factorial statistical method and experimental design of randomized complete blocks at three replications. The first factor was burial depth at five levels (2, 12, 22, 32 and 42 cm) and second factor was soil texture at three levels (sandy loam, silty loam and clay loam). The traits of emergence percentage, the time of emergence, the number of produced tubers and dry weight of the underground organs were measured at 130 days after planting. For this purpose, the pots and dumps were emptied, then the underground organs were separated and placed in paper envelopes and finally, paper envelopes were placed in oven with temperature of 75°C for 72 hours. Data were analyzed using SAS v. 9.1 software. Figures are also plotted by Sigmaplot v. 12 and Excel v. 2013.
Results and Discussion The results showed that emergence time, germination percentage, underground organ dry weight and tuber numbers were affected by depth of planting and soil texture. Emergence of C. rotundus was faster in sandy soil and at a lower depth, so that the tubers grew in the sandy loam soil at a depth of 2 cm 7/7 days after planting (the shortest time), and silty loam and clay loam were ranked next lowest. Understanding ecology of germination and weed emergence plays an important role in their management. With increasing depth of sowing, the percentage of germination in the tested soil texture decreased. So that the maximum amount of germination (85%) was obtained at 2 cm depth of sandy loam soil and the lowest germination percentage was observed at depths > 32 cm in silty loam and clay loam soils and the depth of 42 cm of sandy loam soil encountered with no germination and emergence of seedling. According to the results, the underground organ dry weight of C. rotundus in the textures and depths of the soil was quite different. In sandy loam, the highest underground dry weight was obtained at the 2 cm depth and the lowest was at 42 cm depth (0) of sandy loam. The highest underground dry weight of the tuber (63.6 g) was observed at 12 cm depth and the lowest (0) was obtained at 32 and 42 cm depths. The results showed the highest tubers number was observed at 2 cm depth of sandy loam soil and the lowest was obtained at 42 cm depth of sandy loamy and 32 cm and 42 cm depth of sandy loamy. The number of tubers decreased with increasing planting depth in all three texture types. The highest percentage of tuber production in heavy textures (silty loam and clay loam) was formed in layers of 2 to 12 cm of the soil.

The results showed that with increasing depth in all three types of soil texture, all the growth characteristics of purple nutsedge significantly reduced. More than 80% of the distribution and dispresal of underground organs was formed at a depth of 2 to 12 cm. The percentage of emergence decreased by 100 % at 32 and 42 cm depths of clay loam and silty loam. It seems that, the lack of emergence at the high soil depth is due to disruption of gas exchanges and lack of light. Given the importance of tubers in reproduction of this plant, this should be considered in management strategies. The deep plowing by delaying the emergence and growth and decreasing the production of reproductive organs (rhizome and tuber) of purple nutsedge can be considered as a management option. This weed has high emergence ability in the sandy loam soils due to high permeability and porosity.

Drought is one of the most important and common environmental stresses in the country, which affect different stages of plant growth and development. Drought can affect plants growth in various ways, thereby reduces and delays germination, and decreases shoot growth and dry matter production. In the case of high water stress, it results showed great reductions in photosynthesis and disruption of the physiological processes, as well as growth stop and eventually plant death.Purple nutsedge (Cyperus rotundus L.) has been listed as the world’s worst weed based onits worldwide distribution (92 countries) and interference with over 50 crops. It causes high yield losses in fruiting vegetables and cucurbits in eastern and southeastern parts of Iran, where drought stress is a common phenomenon. Therefore, it is of utmost importance to understand the response of this noxious weed species to drought stress.
In order to study the effect of drought stress on growth and distribution of purple nutsedge, two separate experiments were carried out in a randomized complete block design with three replications in the Research Greenhouse at Birjand University in 2013. The first experiment consisted of 6 irrigation interval levels (3, 6, 9, 12, 15 and 18- day irrigation intervals) and the second one were 5 irrigation levels based on field capacity (12.5, 25, 50, 75 and 100 % FC).
ANOVA results of both experiments showed that all growth characteristics of purple nutsedge were affected by drought stress. The results of irrigation interval stress experiment showed that the maximum height (76 cm), leaf area (110.83 cm2), stem number (4.66 stemperpot), shoot dry weight (4.132 gr per plant), tuber number (7.66 tuber per pot) and total underground organs dry weight (4.435 gr per plant) were observed in 3- day irrigation interval. Also, the lowest amount of these characteristics was obtained in 18- day irrigation interval. The influence of increasing the irrigation intervals up to 18 days was obvious in reducing weed morphological characteristics. With longer irrigation intervals, weed height declined severely, and the greatest reduction in plant height (62.43% comparison to control) was obtained from 18- day irrigation interval. Irrigating plants at 12, 15 and 18- day intervals decreased 66.15, 77.84 and 88.96% in weed leaf area compared to 3- day irrigation interval (control), respectively. The maximum reduction in stem number (78.54% relative to control) was observed at 18- day irrigation interval. Increasing drought stress levels significantly decreased 62.95, 76.27, 97.57% shoot dry weight under 12, 15 and 18- day irrigation intervals regimes, respectively. . Also, increaseddrought levels, significantly reduced weed tuber number, so that no tuber produced at 18- day irrigation interval. Moreover, underground organs dry weight decreased 51.91, 65.68 and 88.48% at 12, 15 and 18- day irrigation intervals compared to control, respectively. In other experiment, the maximum height (70.33 cm), leaf area (116.33 cm2), stem number (7 stem per pot), shoot dry weight (3.701 gr per plant), tuber number (5.66 tuber per pot) and total dry weight of underground organs (513/3 gr per plant) were obtaind at 100% field capacity (control).. The results showed that plant height decreased with increasing drought levels, so the minimum plant height was observed at 25 and 12.5% FC. Increasing drought stress reduced leaf area 68.59 and 91.61% at 75% and 50% FC compared to control, respectively. The maximum reduction in stem number was observed at 25 and 12.5% FC. The weed dry matter decreased 52.90 and 88.05% compared to control at 75 and 50% FC, respectively. Tuber production was severely affected by soil water content reduction, so that no tuber was produced at 25 and 12.5% FC. Dry weight of underground organs in purpule nutsedge decreased 39.48 and 79.24% at 75 and 50% FC compared to control, respectively.
Overall different levels of drought stress in both experiments, were reduced all weed growth characteristics. Since reproductive organs such as tuber and rhizome were not produced at 18- day irrigation interval regime and 25 and 12.5% FC,, therefore it seems non-chemical control methods such as irrigation management can be effective to control this weed. Obviously repeating this research in field conditions is required to confirm these results.

Weeds causing 15 % or more damage to crops, annually. The amount of these damages depends upon different factors such as cultivar type and weeds species. Wild mustard is a cosmopolitan and most serious broad leaf weed in wheat fields which has widespread through world including Iran. Rapid emergence of wild mustard under cold condition and fast growth early in the spring are reasons that make its competitive capability along growing season with wheat. In the more global regions, soil seed bank persistence, height competitive ability, vast fecundity and herbicides resistance are chief problems in wild mustard control. Nonetheless, one of the weeds control strategies in integrated weed management systems is utilization of height competitive ability cultivars.
In order to examine competitiveness of various wheat cultivars on wild mustard and evaluation of presence of this weed species yield and its components in wheat, an outdoor pot experiment was conducted at Agricultural Research Greenhouse, College of Agriculture, Mohaghegh-e Ardabili University, during 2013-2014. Treatments comprising of 18 wheat cultivars namely: [Var1: Karkheh, Var2: Alborz, Var3: Azadi, Var4: Shahpasand, Var5: Sepahan, Var6: Flat, Var7: Ghods, Var8: Roshan, Var9: Sorkh¬tokhm, Var10: Moghan3, Var11: Alvand, Var12: MS-81-14, Var13: Yarvarus, Var14: Shahriyar, Var15: Golestan, Var16: Bam, Var17: Niknajad, Var18:Karaj3]. All mentioned cultivars were laid in the weed free (no wild mustard present) and interference condition (wild mustard present) pots and were arranged in a factorial experiment based on completely randomized design with three replications. Wild mustard seeds, were used as weed seeds source that previously have collected in Agronomic Department Laboratory of Mohagheghe Ardabili University. Each pot was filled with almost 5 Kg mixtures of (sand, farm soil and farm yard manure). Also in each pot 15 wheat seeds along with several wild mustard seeds in regular pattern had been sown. First irrigation was done immediately after sowing on the pots. In the spring after wheat seedling were established pots were thinning and 6 seedlings in each pots and only one established wild mustard was remaining. At the end of growing season, yield, yield components and weeds losses dry weight were estimated. Competitive index (CI) and Weed Interference Tolerance Index (WITI) were assessed.
All gathered data and trials that involving yield such as (spike number, seeds number per spike and thousand seeds weight), at ripening stage of all wheat in the pots were measured and weighted. Numeric observations which ascribing to wheat cultivars based on Squared Euclidean clustering analysis procedure for all cultivars categorize were used. Data were subjected to ANOVA, and means were separated using Fisher’s Protected LSD test at 0.05 probability (P ≤ 0.05).
Wild mustard dry matter weight was influenced by means of different wheat cultivars (P ≤ 0.01). This effects resulting reduction of wild mustard dry matter weight ranged 14.4 -67.4% based on cultivar types, so that Bam, Alvand and MS-81-14 cultivars in this aspect was superior cultivars. Also, collected information represented that between cultivars there are significant difference in the spike production in each pot (P ≤ 0.01). Whereas, numbers of spike in each pot varied between 22 to 43, but Golstan cultivar had maximum spike in each pots and minimum spike belonged to Sepahan and Roshan cultivars. Spike numbers also had a significantly positive correlation with decreased weed dry matter percentage. There was difference between wheat cultivars in the seed per spikes (P ≤ 0.01). There was negative correlation between seed numbers and spike numbers (P ≤ 0.01), but positive association was between this character with wild mustard dry matter percentage decline (P ≤ 0.05). Numbers of fertile spikes were important factor in grain yield (15). There are significant differences in wheat yield between eighteen cultivars (P ≤ 0.01), so that Bam, MS-81-14 and Yarvarus have highest yield and Roshan has lowest from the rest cultivars. Yield data was influenced under wheat cultivars and wild mustard interference effects and inter-act of two mentioned factors (P ≤ 0.05).
Although, large numbers of study in overall world focus on cultivar’s merits and competitor cultivars study well documented, but we credence is that cultivars election and recommendations for each specific local must be documented in repeated and long-terms studies (in time and site). But results originated of this study, well documented cultivars selections in view of more effective Weed interference tolerance index (WITI) for Alvand, Bam, MS-81-14, and Yarvarus cultivars for weed suppress such wild mustardin Ardabil conditions,and yield productionalso Bam, MS-81-14 and Yarvarus were superior cultivars from others cultivars in Ardabil regions, which appear to be implemented in integrated weed managements design options. Finally, authors must be mentioned that this conclusion merely is primarily information in cultivars selections and other works must extended and carry out in Ardabil field conditions.

Employment of solarization using the polyethylene mulch can be effective as a non-chemical approach for some control noxious weed management such as purple nutsedge (Cyperus rotundus). In order to determine the effect of different levels of polyethylene mulches including one- layer clear polyethylene film, two- layer clear polyethylene film, one- layer black polyethylene film and two- layer black polyethylene film as well as a non-mulched control on three different populations of purple nutsedge from Birjand, Kahnooj and Jiroft, a factorial experiment based on a randomized complete block design with three replications was conducted at research field of Birjand university, during a 60-day period in summer 2012. Results indicated that polyethylene mulches significantly reduced tubers number and weight, pre-tuber (tubers with a diameter less than 2 mm) number and weight, number and weight of above mulch shoots as well as number and weight of below mulch shoots in all three purple nutsedge populations. One-layer mulches (either clear or black sheets), however, did not show a remarkable preventive effect on purple nutsedge shoots growth, so that plant shoots can easily pass over the plastic sheets. Moreover, results showed that the two-layer black polyethylene mulch provided the most effective control among all three purple nutsedge populations.