Influence of wheat residue management on irrigated corn grain production in a reduced tillage system

Management of wheat (Triticum aestivum L.) residues for corn (Zea mays L.) planting is an important issue in southern parts of Iran where these two irrigated crops are consecutively grown. Concerns have been raised in recent years over the burning of the crop residues by farmers in these areas. A 2-year (2001–2002) field experiment was conducted as a randomized complete block design with three replications. The treatments consisted of irrigated corn planted, after burning wheat residues followed by conventional tillage (CT), after residue removal followed by CT, after soil incorporation of 0, 25, 50, 75, and 100% of residue followed by chisel plow, disk harrow, and row crop planter equipped with row cleaner. The CT operations consisted of mollboard plowing followed by two times disk harrowing. Treatments had significant effects on corn grain yield, biological yield, and leaf area index. The highest grain yield (15.73 t ha⁻¹) and grains per ear (709.3) were obtained when 25–50% of wheat residues were soil incorporated and the seeds were sown with planter equipped with row cleaner in both years as compared with conventional tillage practices. It is recommended that complete residue removal or burning should be avoided; hence for successful corn production after wheat, residue management techniques that reduce residue level in the row area should be implemented.     

市郊菜园土壤污染及治理

针对衡阳市郊菜园土壤受到污染的实际，分析了主要污染源，提出了控制与治理污染的措施。     

Analysis of flowering,stigmas yield and qualitative traits of saffron (Crocus sativus L.) as affected by environmental conditions

Saffron is well known for its use as a condiment spice, as a dye and traditional medicine. Saffron is experiencing an increasing interest mainly due to its peculiar and manifold properties of the metabolic pool of its stigmas, mainly crocetin esters and picrocrocin. This species is cultivated in environments with very different climatic conditions and with very different corm rates from place to place, passed down over the centuries. The aim of this study was therefore the evaluation of the influence of rainfall, temperature and corm density on flower phenology, stigmas yield and main compositional characteristics of two saffron corms provenience. Flowering beginning in saffron seems to be influenced by the combination of temperature and soil moisture, whilst its flowering calendar proves independent of corm provenance, environment and plant density. On the contrary, the studied factors exert a strong effect on both total stigmas yield and qualitative characteristics: colder environment resulted in a higher flower production, but lower quality of stigmas. Flower number was positively correlated with the stigmas yield, but negatively with its unitary weight. The content of crocetin esters and picrocrocin has been evaluated according to the spectrophotometric ISO normative, which ranked the samples into three qualitative decreasing categories (I–III). The spectrophotometric data showed positive correlation with the unitary stigmas weight and negative with stigmas production.     

土壤容重对生姜生长及产量和品质的影响

以莱芜大姜为试材,研究了容重分别为1.49(CK)、1.36(T1)、1.20(T2)g·cm-3的3种土壤对生姜生长及产量、品质的影响。结果表明,容重较小的土壤,其孔隙度较大,最大持水量较高,有利于生姜植株的生长和产量的提高。生长末期T2的株高、茎粗、分枝数和叶片数分别比CK增加17.9%、14.0%、35.2%和36.1%,单株根、茎、叶、根茎鲜质量分别比CK提高43.3%、24.4%、28.1%和35.2%,收获时CK、T1、T2的产量分别为2534.1、3017.7和3326.8kg·(667m2)-1,处理间差异极显著。此外,生姜根茎干物质、淀粉及挥发油含量随土壤容重降低而降低,而蛋白质、游离氨基酸则相反,粗纤维、可溶性糖及VC含量则基本不受土壤容重的影响。     

Optimizing the lighting regime for Alstroemeria with respect to photoperiod and fluence rates

The Alstroemeria cultivars Diamond, King Cardinal and Libelle were grown for 18 months under five lighting regimes with, and without, soil cooling. The aim was to optimize the daily investment of light energy from artificial sources with respect to photoperiod and photosynthetic fluence rates and to elucidate possible links between reactions to photoperiod and root-zone temperature. The more photons (photosynthetically active radiation, PAR) that were supplied to the plants per day (8, 11 and 13 mol m⁻²), the higher was the total production of flowering stems. The total yield from regimes with 13 mol m⁻² day⁻¹ was higher when the light was spread over 20 and 16 h compared to 12 h. In treatments with soil cooling, the plants flowered continuously under all combinations of photoperiods and photosynthetic fluence rates, and the summer and autumn recession in flower production that occurred for non-cooled ‘King Cardinal' and ‘Diamond' was the same under all lighting regimes. It is concluded that it might be more cost-effective to spread the daily investment of light over 20 rather than 16 or 12 h when the total energy budget and CO₂ costs are taken into consideration.     

A strain of Bacillus subtilis stimulates sunflower growth (Helianthus annuus L.) temporarily

Preliminary studies showed that a Bacillus subtilis strain stimulates plant growth. We investigated how inoculating seeds of a sunflower cultivar (Helianthus annuus L.) with this strain stimulated plant growth, soil properties and emissions of greenhouse gasses, i.e. carbon dioxide (CO₂) and nitrous oxide (N₂O), when cultivated in a greenhouse. Unfertilized sunflowers or fertilized with urea served as controls. After one month, root length and fresh and dry root weight of the sunflower was significantly higher in the bacteria amended plant than in the urea and unfertilized plants. However, at harvest, no positive effect was observed. The number of seeds per plant and seed weight was not significantly different between the treatments, but total plant N was significantly higher in urea-amended plants than in unfertilized plants. The CO₂ production rate was not affected by treatment, but the N₂O emission rate was significantly higher in soil amended with urea plus bacteria soil compared to the unfertilized treatments. It was found that the B. subtilis strain used in this study had a positive, but only temporarily effect on growth of the sunflower cultivar used.     

新疆喀纳斯景区表层土壤磁学特征及环境意义

为探究环境磁学方法在景区土壤污染监测中的可行性,以新疆5A级景区喀纳斯为研究区域,采集表层土壤样品72个,并对其进行系统的环境磁学分析。结果表明:喀纳斯景区土壤磁性矿物平均含量较高,磁学矿物主要由亚铁磁性矿物构成,并含有少量的不完全反铁磁性矿物。磁晶颗粒主要为粗颗粒多畴,同时存在较少的超顺磁颗粒。磁参数空间分布表明,磁性矿物含量参数(χLF、SIRM、SOFT、HIRM)在湖口旅游区表现出高值,新村、老村和旅游接待地呈现相对低值;其他参数(χFD%、S-ratio、SIRM/χLF)空间分布规律与含量磁性参数基本呈相反趋势;研究区的磁性高值点分布与景区人类活动密集区、建筑物及道路的分布具有一致性;湖口旅游区较高的磁性值主要与较强的自然成土作用有关,其他区域的磁性高值点主要受旅游活动的影响。因此,借助土壤磁学方法能够有效区分和圈定景区土壤人为污染范围,为景区土壤污染防治和旅游规划提供参考依据。     

乌江流域茶园土壤理化性状对茶叶品质影响的研究

对乌江流域主要茶场茶园土壤理化性状、茶叶生化成份测定结果表明：不同母岩发育的土壤理化性状各不相同，其对应的茶叶品质也不相同。土壤理化性状及茶叶品质优劣依序为硅质黄壤＞砂页岩黄壤＞第四纪粘质黄壤＞小黄泥＞黄棕壤     

施用磷肥对环境的影响探讨

磷肥的施用与环境质量密切相关。本文讨论了过量施用磷肥加剧了农业非点源污染,农业非点源磷的累积增加了水体富营养化的风险,同时,磷肥中的重金属随磷肥的施用进入土壤环境,对土壤环境质量和农产品品质以及人体健康也有一定的影响。