Decomposition and phosphorus release from organic residues as affected by residue quality and added inorganic phosphorus

The combined use of organic residue and inorganic fertiliser-phosphorus (P) is appropriate in meeting both the short and long-term P requirement of crops. To assess the influence of added inorganic fertiliser-P on the processes of decomposition and P release from the residue and the relationships with quality, prunings of Gliricidia sepium, Leucaena leucocephela, Senna siamea, Acacia mangium and Paraserienthus falcataria were incubated without and with added inorganic fertiliser-P for 56 days. Soil was added only as inoculum. Decomposition rate and amounts of acid extractable-P (P release) were in the same order: G. sepium >S. siamea > L. leucocephela >P. falcataria > A. mangium. Unlike the other residues, A. mangium released no P despite the loss of half its mass during the 8 weeks of incubation. The residue P content correlated with P release. However, decomposition rate did not correlate with residue P content but with the lignin, polyphenol and cellulose content, and ratios to P. These ratios were negatively correlated with P release suggesting that lignin and polyphenol contents influence P release more when the residue-P content is low. Results suggest that rate of decomposition influences the release of P. The critical residue P content for P release was estimated to be 0.12% < P < 0.19%. Added P had no effect on decomposition and P release from the residues.     

宝天曼植物群落物种多样性研究

对宝天曼保护区植物群落物种多样性进行了研究。结果表明 ,物种丰富度指数、多样性指数和均匀度指数在群落梯度上的分布趋势基本一致 ,较好地反映了不同植物群落类型在物种组成方面的差异。草本层物种丰富度指数明显高于乔木层和灌木层 ,草本层物种丰富度指数在群落梯度上的变异最大 ,灌木层次之 ,乔木层最小。乔木层物种多样性指数小于灌木层和草本层 ,草本层和乔木层物种多样性指数在群落梯度上的变异程度明显大于灌木层。灌木层物种均匀度指数大于乔木层和草本层 ,草本层和乔木层均匀度指数在群落梯度上的变异程度大于灌木层。物种丰富度指数和多样性指数的较大值出现在高海拔和低海拔群落 ,较小值多出现在中等海拔群落。物种均匀度指数的较小值多出现在中等海拔群落 ,但其较大值在各海拔群落都有分布。草本层物种丰富度指数和多样性指数的较高值多分布在低海拔群落 ,较小值多分布在中等海拔群落 ;乔木层和灌木层的各种指数以及草本层的物种均匀度指数在海拔梯度上的分布规律不明显     

园林植物病虫害系统控制的几点思考

分析了园林植物病虫害系统控制的重要性,针对园林病虫害系统控制的特殊性,从园林健康方面,提出了园林植物病虫害系统控制需注意的几个主要问题:园林工作者要具有园林健康意识,注重园林植物病虫害系统控制的科学性和前瞻性;建立本地区的园林植物病虫害和天敌以及小环境的系统网络体系,重视园林植物病虫害系统控制的目标化;乡土树种的合理利用和优质苗木的选育;进一步探索园林健康及病虫害系统控制的论证。     

Controlling sprouting in potato tubers using ultraviolet-C irradiance

Legislation limiting the use of chlorpropham (CIPC), the major potato sprout suppressant, has led to a need for new technologies to extend storage life of tubers. Ultra violet C (UV-C) has been used postharvest to reduce disease incidence on many crops, yet its use and efficacy as a sprout suppressant has not been investigated. The aim of this project was to identify the optimum dose and treatment timing of UV-C treatment on potato tubers as an alternative method of sprout suppression to reduce the dependence on chemical sprout suppressants. Up to six potato cultivars over two seasons were treated with varying doses of UV-C ranging from 0 to 30 kJ m⁻² either at harvest or at first indication of dormancy break. The tubers were stored at 9 °C and sprout growth and incidence assessed. Treatment with moderate UV-C doses (5–20 kJ m⁻²) suppressed sprout length and sprout incidence in a range of cultivars. Periderm DNA damage and programmed cell death were not detected in response to any of the UV-C doses. The inactive ABA metabolite, ABA-GE, increased in response to 10 or 20 kJ m⁻² within 72 h of treatment. Multivariate analysis showed a negative relationship between ABA metabolites and sprout growth/incidence during storage. This study found that UV-C reduced sprout growth in potato with no deleterious effects on tuber quality. This suggests potential for further development as an alternative or supplement to conventional sprout suppressant technologies.     

Agronomic performance of an IR64 introgression line with large leaves derived from New Plant Type rice in aerobic culture

Aerobic culture is a promising water-saving technology in irrigated rice ecosystems, but the vulnerability of plants to fluctuations in soil moisture constrains leaf expansion and yield. The objective of this study was to examine whether an aboveground architecture with large leaves and reduced tillering is associated with vigorous leaf growth in aerobic rice culture. In a series of field experiments, we evaluated the agronomic performance of an IR64 introgression line, YTH323 (IR84640-11-27-1-9-3-2-4-2-2-2-B), with fewer tillers and larger leaves than IR64, derived from New Plant Type rice, under various water and nitrogen conditions. In flooded culture, YTH323 yielded the same as IR64 and 38% more than IR65564-44-51 (a New Plant Type rice) (9.0 vs. 6.6 t ha⁻¹). In aerobic culture, in contrast, it yielded 81% more than IR64 in slightly dry soils (5.1 vs. 2.8 t ha⁻¹). YTH323 had a higher leaf area index than IR64 and IR65564-44-51 under slightly dry soil conditions and under a range of nitrogen conditions. The higher and more stable yield of YTH323 in aerobic culture was attributable to greater early vigor, high specific leaf area, a high ratio of leaf weight to total biomass, and larger leaves, along with the characteristics of high-yield cultivars such as high responsiveness to fertilizers and good grain filling. We conclude that genetic modification of the aboveground architecture of IR64, a typical tropical lowland rice cultivar, to reduce tiller and leaf number improves adaptation to aerobic culture.     

Inhibiting soil loss and runoff from small plots induced by an individual freeze-thaw cycle using three rangeland species

This study investigated the role of three rangeland species viz. Agropyron trichophorum, Medicago sativa, and Lolium prenne on mitigating of effects of a freeze-thaw (FT) cycle on runoff generation and soil loss from small experimental plots. Small plots (0.5 × 0.5m) were prepared in three replicates for control (i.e., under a FT cycle only) and treatments (i.e., individually planted with the study species and subject to a FT cycle). The treated plots were then placed at a slope of 20% and subjected to simulated rainfall with intensity of 70 mm h⁻¹ and 30 min duration. The results of the study showed a significant effect (P < 0.05) of the plants on controlling runoff and soil loss after a FT cycle. Also, the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the plants. Time to runoff increased by 54, 111 and 10%, runoff volume decreased by 27, 68 and 0.4% and soil loss changed by −34, −62, and +6.5% in the plots planted with A. trichophorum, L. prenne and M. sativa, respectively. The results of the current study indicated that L. prenne had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.     

土壤重金属污染及对生物体影响的研究进展

重金属污染是当今社会世界性的环境生态问题。由于人类社会城市化进程加剧、工业生产中"三废"的不合理排放以及现代农业中各种农药化肥的大量使用,导致土壤中重金属的含量剧增,污染问题严重,其中尤以重金属镉、汞、铅等在生物体内的富集与抗生性的研究日益受到关注。笔者综述了土壤重金属污染及对生物体影响的研究进展,以期为土壤重金属综合治理与污染修复提供科学依据。     

Effects of natural protease inhibitors on high protease activity flours

Wheat grain damaged by wheat bug (Eurygaster spp.) contains the bug salivary secretion which hydrolyses the gluten needed for the dough quality of breadmaking due to its proteolytic activity. Since the protease inhibitors are widespread throughout the plant kingdom, the possibility of using some plants, especially food and feed legumes to decrease the proteolytic activity of flours milled from bug damaged wheats was investigated. The proteolytic activity was considerably inhibited by pefabloc-SC and EDTA-Na₂, suggesting that bug protease(s) included serine and metallo proteases. Extracts from cones of hops, seeds of grass pea, red kidney bean and sunflower caused reduction in the activity of bug protease(s). Effects of hop extract on electrophoretic, rheological properties of high protease activity flours milled from different bread wheat cultivars damaged by the bug were also studied. The dough development time and stability values of high protease activity flours increased considerably with hop extract at the lowest addition level (10:1, flour to hop extract ratio). The doughs supplemented with the hop extract had higher maximum resistance and lower extensibility values as compared to their controls. These results suggested that hop extract had improving effects on high protease activity flours due to the bug damage.     

植物样品采集·制备·储存及消解过程中存在问题分析

结合目前单位所承接的植物样品检测任务的实际情况,分析了植物样品的野外采集、加工制备及消解过程中会遇到的几个问题,为准确测定植物样品中重金属元素以及客观评价植物重金属污染提供了保障。     

新式墙面绿化在广州和深圳的应用研究

新式墙面绿化对日益缩减的城市绿化环境至关重要,通过实地调查广州和深圳30个新式墙面绿化场所,分析其种植形式、植物种类、植物配置与景观效果,总结出深圳和广州新式墙面绿化的植物应用现状和景观效果,并讨论其发展前景。