Temperature influences postdispersal predation of weed seeds          下载免费PDF全文

Shahrzad Noroozi  Hasan Alizadeh  Hamid Rahimian Mashhadi 《Weed Biology and Management》2016,16(1):24-33

Temperature is a key factor for the living organisms on earth. It influences weed management practices, either directly or indirectly. Field experiments were conducted to determine the effect of temperature on the postdispersal seed predation of four important weed species (Cuscuta compestris, Stellaria media, Taraxacum officinale and Veronica persica) in two lucerne fields in Mashhad and Chenaran, north‐eastern Iran. These two cities have the same climate: temperate and cold alpine but the temperature varies between them. Wire mesh cages were used to determine the relative importance of birds in predation and pitfall traps were used to detect the species and the activity density of invertebrate predators. The results showed that the predation preference of different weed species was significantly different between and within fields. Seed predation fluctuated widely throughout the sampling periods, matching the periodic forage harvest and regrowth cycle of lucerne. Despite the level of seed predation fluctuating, it declined toward the last sampling periods. Using wire mesh exclusion cages showed no significant effect of birds on weed seed predation in both fields. Ants, crickets and carabid beetles were the invertebrate seed predators that were caught in the pitfall traps. There were significant correlations between the mean temperature and predator activity densities and also between the predated seeds and the mean air temperature in both locations. The results of this study indicate the significant effect of temperature on postdispersal weed seed predation. Therefore, with respect to climate change and increasing global warming, it would be possible to focus on postdispersal seed predation in weed management in the future.  相似文献   

Impacts of cropping system and management practices on the assembly of weed communities          下载免费PDF全文

J Barroso  Z J Miller  E A Lehnhoff  P G Hatfield  F D Menalled 《Weed Research》2015,55(4):426-435

Understanding how weed communities assemble as a function of biotic and abiotic filters and transform through time has important implications for the sustainable management of agronomic systems. In a three‐year study, we evaluated weed community responses to lucerne (Medicago sativa, perennial) vs. continuous spring wheat (Triticum aestivum, annual, CSW) and weed management practices where weeds in the CSW system were managed with three contrasting approaches (herbicide, tillage or sheep grazing). Our results indicated no differences in weed diversity between the perennial and annual crops or across the different management practices in CSW. However, there were differences in weed community composition. Lucerne, with the exception of the establishing year, impeded the growth and reproduction of several annual weeds, including Amaranthus retroflexus, Thlaspi arvense, Lamium amplexicaule and Chenopodium album, but favoured perennial broad‐leaved weeds such as Taraxacum officinale and Cirsium arvense. The replacement of herbicide treatments in pre‐plant and post‐harvest in CSW with soil tillage or sheep grazing selected for different weed communities beyond the second year of establishment. The weed species driving the differences in CSW systems were Androsace occidentalis, more common in CSW managed chemically; Asperugo procumbens, more common in CSW managed with tillage; and T. officinale and Lactuca serriola, more common in CSW managed with sheep grazing. Understanding how cropping systems modify weed communities is a necessary step to shift from reactive weed control programmes to predictive management strategies.  相似文献   

吉林西部人工草地水分生产函数模型初探   总被引：1，自引：0，他引：1  

贾小丰  卢文喜  马洪云  曾献奎 《节水灌溉》2008,(8)

水分生产函数模型用以描述作物产量与水分因子之间的数学关系。确定合适的作物水分生产函数模型对建立与完善节水灌溉系统具有十分重要的意义。选常用的Jensen、Minhas、Blank、Stewart及Singh模型,依据在吉林省松原市前郭县草原管理站进行的苜蓿非充分灌溉试验中所获得的资料,采用多元回归分析方法求出各模型的参数,并对这5种模型进行了对比和筛选,得出了Jensen模型是最适宜于吉林省松原地区苜蓿的水分生产函数模型的结论。还探讨了Jensen模型水分敏感指数在苜蓿全生育期的变化规律,并指出了其在实践应用中的意义。  相似文献   

甘农1号杂花苜蓿寒地栽培技术   总被引：6，自引：4，他引：6  

曹致中  贾笃敬 《草业科学》1992,9(1):47-48

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新疆苜蓿蚜虫的种类、分布及识别   总被引：1，自引：0，他引：1  

赵莉  王林波  范菊兰 《新疆农业科学》2004,41(4):216-218

通过对和田、喀什、阿克苏、库尔勒、乌鲁木齐、昌吉等地州(市)苜蓿田的蚜虫调查,并查阅了相关资料,整理出新疆苜蓿田常见11种蚜虫,其中蚜科9种,它们是豆蚜(苜蓿蚜)Aphis craccivora、乌苏黑蚜A.craccivorausuana、棉蚜A.gossypii、棉黑蚜A.atrata、刀豆黑蚜A.robiniae canavaliae、苜蓿无网蚜Acyrthosiphon kondoi、京豌豆蚜A.pisivorum、豌豆蚜A.pisum、桃蚜Myzuspersicae;斑蚜科2种,它们是灰彩斑蚜Therioaphis cana、三叶草彩斑蚜T.trifolii.并对这些蚜虫的分布和危害特征进行了描述,列出了识别鉴定的检索表.  相似文献   

Efficacy of different temperate pasture species to reduce nitrogen leaching from cattle urine applied in different seasons: A soil lysimeter study     

Brendon G. Welten  Stewart F. Ledgard  Amanda A. Judge  Mike S. Sprosen  Alec W. McGowan  Moira M. Dexter 《Soil Use and Management》2019,35(4):653-663

A soil lysimeter field study assessed the efficacy of different pasture species to reduce nitrogen (N) leaching loss from cow urine deposited in different seasons. A single application of cow urine (¹⁵N‐labelled; equivalent to 622 kg N ha^?1) was applied in three different seasons (summer, autumn or winter) to three pasture species monocultures (perennial ryegrass, plantain or lucerne) on a free‐draining volcanic soil and monitored over 362 days. Leachate analyses revealed consistently large leaching losses of inorganic‐N from lucerne (>200 kg N ha^?1) across different urine application times due to the relatively low plant growth rates during winter (<15 kg DM ha^?1 day^?1) that led to low total recovery of urine‐N by lucerne plants (<20% of the applied urine‐¹⁵N). Conversely, plant uptake of the urine‐N was higher by plantain (ranging from 30% to 45% of that applied) driven by moderately higher winter plant growth rates (30 to 60 kg DM ha^?1 day^?1). Plantain exhibited large seasonal variation in its efficacy to reduce urine‐N leaching relative to ryegrass (ranging from 15% to 50% reduction for summer or winter urine applications, respectively) with an overall reduction of 39% in the total amount of inorganic‐N leached across the three seasons (53 vs. 87 kg N ha^?1 leached relative to ryegrass). This study has demonstrated the potential benefit of using plantain to reduce N leaching losses from urine deposited in the summer to winter grazing period. However, further research is required to quantify the effects of plantain on annual N leaching losses from grazed pastoral systems.  相似文献   

Effects of contrasting seasonal growth patterns on composition and persistence of mixed grass‐legume pastures over 5 years in a semi‐arid Australian cropping environment          下载免费PDF全文

R. C. Hayes  G. D. Li  M. R. Norton  R. A. Culvenor 《Journal of Agronomy and Crop Science》2018,204(3):228-242

Perennial grass‐based pastures are uncommon in phased cropping rotations in south‐eastern Australia, where rainfall often limits production and persistence. The high reliance on pure legume‐based pastures limits overall pasture productivity and has adverse effects on environmental parameters such as weed incursion and ground cover. A field experiment was monitored over 5 years to examine the relative productivity of the temperate perennial grasses, phalaris (Phalaris aquatica) and cocksfoot (Dactylis glomerata) and determine whether contrasting seasonal activity enhances their persistence when grown in mixtures with lucerne (Medicago sativa) and annual legumes. Phalaris swards were shown to increase cumulative aboveground biomass by up to 96% and 32%, and in year 5 reduce annual grass emergence by between sevenfold and threefold compared to annual legume and lucerne/annual legume mixed swards, respectively. Only swards that included phalaris maintained ground cover above 70% in each autumn of the experimental period. Swards based on the highly summer dormant cocksfoot cultivar, Kasbah, were generally less productive over all, despite the cocksfoot showing a high level of persistence and good recovery following drought. Grass‐based swards that included lucerne were observed to produce ~35% greater legume biomass than a sward sown only to annual legumes. Cumulative legume biomass was greatest in lucerne swards in the absence of perennial grasses. The experiment was unable to demonstrate a consistent benefit in production and persistence associated with contrasting seasonal growth patterns. However, mixtures containing a range of functional types were consistently shown to enhance productivity over the duration of the experiment compared to less diverse swards. The potential to substantially increase forage productivity and ground cover, while reducing incursion by annual grass weeds, by including well‐adapted perennial grasses in mixtures with lucerne and annual legumes should be utilized.  相似文献   

Volatile losses of sulphur from oven drying lucerne (Medicago sativa L.): Effects of sulphur,nitrogen, phosphorus and potassium supply     

N.J. Grundon  C.J. Asher 《Journal of plant nutrition》2013,36(9):833-845

Lucerne was grown in nutrient solutions at adequate and “deficient”; levels of sulphur, nitrogen, phosphorus or potassium. Volatile losses of sulphur were then measured when shoots and roots were oven dried at 80°C for 48 hours.

Small but significant losses of sulphur occurred during oven drying. Losses from shoots ranged from 4.2 to 13.9 μgS/g dry weight, which represented from 0.38 to 0.66% of the total sulphur content of the shoot. Losses from roots ranged from 12.0 to 47.8 μgS/g dry weight, representing 0.82 to 1.77% of the total sulphur content of the root. Decreases in supply of nitrogen, phosphorus, potassium or sulphur generally decreased the amount of volatile sulphur lost by oven drying shoots. Losses from roots generally decreased when supply of sulphur decreased, but increased when nitrogen and potassium supply decreased, and were generally unaffected by phosphorus supply.

The organic sulphur concentration in the tissue was linearly correlated with absolute losses of sulphur (r = 0.799** for shoots; r = 0.822** for roots), the amount of sulphur lost per unit dry weight (r = 0.469* for shoots; r = 0.381* for roots) and the percentage of the total sulphur released as volatile sulphur (r = 0.937** for shoots; r = 0.970** for roots). By contrast, the total sulphur concentration in the tissue was linearly correlated only with the amount of sulphur lost per unit dry weight ( r = 0.704** for shoots; r = 0.723** for roots).  相似文献   

Physiological Effects of Waterlogging on Two Lucerne Varieties Grown Under Glasshouse Conditions     

L. J. Irving  Y.-B. Sheng  D. Woolley  C. Matthew 《Journal of Agronomy and Crop Science》2007,193(5):345-356

Two lucerne (Medicago sativa) varieties, an anecdotally waterlogging‐intolerant old New Zealand variety, Grasslands Wairau, and a reputedly waterlogging‐tolerant new variety, Pioneer 54Q53, were subjected to waterlogging stress and a range of physiological and agronomic measurements performed. Waterlogging stress was characterized by measurement of soil oxygen depletion and soil carbon dioxide accumulation. Both varieties exhibited strong responses to waterlogging stress, including reduction in leaf soluble protein concentration, photosynthetic rate and tap root weight, but also exhibited differences in response, notably a decrease in carboxylation efficiency and in the steady‐state quantum yield of electron flow through PSII (ΦPSII) in Wairau, but not in Pioneer. Implications for understanding of waterlogging effects on photosynthesis, and for field management of lucerne on wet soils are discussed.  相似文献   

弃耕地苜蓿耗水规律及灌溉制度研究   总被引：10，自引：0，他引：10  

范文波刘换芳  朱保荣王振华 《水土保持学报》2003,17(3):165-166,173

通过对弃耕地苜蓿生长过程中水分变化的研究,发现在苜蓿生长的苗期、分枝期和花期,日平均耗水强度依次表现出递增的趋势,结实期则有所下降;水分变化与生长过程具有相似的变化规律。初步给出了弃耕地苜蓿生长过程中灌溉制度。  相似文献