Propagation and Seedling Cultivation of the Endemic Species Nothofagus alessandrii Espinosa in Central Chile

Nothofagus alessandrii is an endemic and endangered species from the Maule Region of Central Chile. The forests it once dominated have been severely degraded and fragmented by human activities, and it is estimated that only 350 ha remain. Yet, available information for propagation and nursery plant cultivation of this species is conspicuously lacking. Future efforts to restore this ecosystem type will rely, in large part, on advancing the capacity to propagate and cultivate this highly threatened species. To this end, we studied the response (germination process and nursery growth) of viable seeds of N. alessandrii to different pre‐germination treatments, sowing times, and slow‐release fertilizer. The highest germination percentages were obtained with cold stratification for periods of 30 and 45 days (84.9 and 82.6%, respectively). Sowing time was also relevant, with seeds obtaining highest germination rates (53%) when sowing during spring season (September) as well as the best growth rates. Both cold stratification and GA₃ treatments can provide adequate germination percentage and similar seedling quality. After one nursery season, no clear effect of slow‐release fertilizer on plant growth was observed. The results of this study provide important baseline information for propagation and nursery techniques for restoration programs of N. alessandrii.     

Improvement of soil acidification and ammonium nitrogen content in tea plantations by long-term use of organic fertilizer

• Soil acidification is common in some Chinese tea plantations, which seriously affected growth of tea trees. Hence, it is essential to explore soil remediation in acidified tea plantations for sustainable development of the tea industry. We sought to determine how different fertilizers affect acidified soil and their N transformation in tea plantations.
• Different fertilizers were used on acidified tea plantation soils for 4 years (2017–2021), and changes in soil pH, indices related to soil N transformation and tea yield were analysed to construct interaction networks of these indices and find which had the largest influence on fertilization.
• Long-term use of sheep manure reduced soil acidification, increased soil pH, enhanced the number and intensity of N-fixing and ammonifying bacteria, urease, protease, asparaginase and N-acetamide glucose ribosidase activity and nifH gene expression. This treatment reduced the number and intensity of soil nitrifying and denitrifying bacteria, nitrate reductase and nitrite reductase activity, while the expression of amoA-AOA, nirK, nirS, narG and nosZ in turn increased ammonium N content of the soil, reduced nitrate N content, and enhanced tea yield. Topsis index weight analysis showed that ammonium N content in the soil had the largest impact among fertilization effects.
• Long-term use of sheep manure was beneficial in restoring the balance of the micro-ecosystem in acidified soil. This study provides an important practical basis for soil remediation and fertilizer management in acidified tea plantation soils.

     

Methane flux from rice/wheat agroecosystem as affected by crop phenology, fertilization and water level

Methane flux was measured for a rice/wheat agroecosystem of Gangetic Plains, with and without application of chemical fertilizer and wheat straw (WS). Three treatments of control, fertilizer application and fertilizer + WS application, were established in a completely randomized block design and measurements were made for two consecutive years (1993 and 1994). CH₄ measurements during growth of the rice crop period showed that there were significant difference in flux rates during the two years. Maximum emission occurred at the time of anthesis and minimum at the seedling stage. The flux rates were significantly higher for fertilizer or fertilizer + WS treatments. The effects of the treatments were similar across phenological stages and years. In the subsequent wheat crop and fallow period, the soils consumed CH₄. There were significant differences in CH₄ uptake rates between the two years. Fertilizer treatments reduced CH₄ uptake in both the years. The results suggested that tropical agroecosystems may consume substantial amounts of CH₄ and that the methane output can be reduced by lowering the submergence level in rice paddies.     

Assessing Cross-disciplinary Efficiency of Soil Amendments for Agro-biologically, Economically, and Ecologically Integrated Soil Health Management

Preventive and/or manipulative practices will be needed to maintain soil's biological, physiochemical, nutritional, and structural health in natural, managed, and disturbed ecosystems as a foundation for food security and global ecosystem sustainability. While there is a substantial body of interdisciplinary science on understanding function and structure of soil ecosystems, key gaps must be bridged in assessing integrated agro-biological, ecological, economical, and environmental efficiency of soil manipulation practices in time and space across ecosystems. This presentation discusses the application of a fertilizer use efficiency (FUE) model for assessing agronomic, economic, ecological, environmental, and nematode (pest) management efficiency of soil amendments. FUE is defined as increase in host productivity and/or decrease in plant-parasitic nematode population density in response to a given fertilizer treatment. Using the effects of nutrient amendment on Heterodera glycines population density and normalized difference vegetative index (indicator of physiological activities) of a soybean cultivar 'CX 252', how the FUE model recognizes variable responses and separates nutrient deficiency and toxicity from nematode parasitism as well as suitability of treatments designed to achieve desired biological and physiochemical soil health conditions is demonstrated. As part of bridging gaps between agricultural and ecological approaches to integrated understanding and management of soil health, modifications of the FUE model for analyzing the relationships amongst nematode community structure, soil parameters (eg. pH, nutrients, %OM), and plant response to soil amendment is discussed.     

Field evaluation of the response of Aedes albopictus (Stegomyia albopicta) to three oviposition attractants and different ovitrap placements using black and clear autocidal ovitraps in a rural area of Same,Timor‐Leste

Known oviposition attractants or stimulants were compared, singly and in combination, using inexpensive autocidal ovitraps designed to trap emerging adults, in a rural area of Timor‐Leste during the dry season. In this area, the dengue vector Aedes albopictus (Stegomyia albopicta) Skuse (Diptera: Culicidae) was abundant, but Aedes aegypti (Stegomyia aegypti) L. was not detected. The attractants were: (a) a compound found in Aedes eggs (dodecanoic acid); (b) components of nitrogen, phosphorous and potassium‐based (NPK) fertilizer, and (c) infusions of discarded cigarette butts. A solution of ammonium phosphate and potassium nitrate was significantly more attractive to gravid Ae. albopictus than water only. Dodecanoic acid and cigarette butt infusions were not significantly more attractive than the control; however, they attracted various other Diptera and many non‐culicid larvae developed in ovitraps in which these substances were used; thus, the presence of eggs or larvae of other species may have deterred Aedes oviposition. Significantly more Aedes eggs were found in ovitraps under vegetation than in ovitraps placed inside houses or against external walls. Clear‐sided ovitraps in which black mesh was placed over a black ring floating on the water surface collected significantly fewer eggs than black ovitraps with identically placed mesh and rings.     

Bt抗虫棉秸秆还田对土壤养分特征的影响

【目的】研究转基因作物秸秆或残茬还田可能对土壤养分特性造成的影响。【方法】以不同抗虫水平Bt棉花和常规棉花(泗棉3号)为研究材料,分别在经过一、二个生长周期后将秸秆机械粉碎后原位还田,40 d后测定分析土壤中Bt蛋白含量及肥力相关的养分含量变化。【结果】Bt棉秸秆还田后,所有品种棉花土壤中Bt蛋白含量与还田前无显著增加,且转Bt基因棉与非转基因棉还田对土壤Bt蛋白含量的影响并无显著差异。同时,棉秸秆还田可显著提高土壤有机质、速效磷、碱解氮、速效钾、全氮、全磷和全钾含量,提升土壤pH值;增加幅度在不同抗虫水平Bt棉花间及与非转基因常规棉花品种间皆无显著性差异。【结论】秸秆还田对土壤肥力的提升与Bt棉的抗虫水平无关。“转Bt基因”不成为Bt棉秸秆还田提高土壤肥力的限制性因素,其秸秆还田不会对土壤肥力质量产生负面影响,可使土壤养分含量增加,有效提升土壤肥力。秸秆原位还田简单、无害又提升肥力,有条件作为转Bt基因植物秸秆无害化处理的理想方式。