百花山香草植物资源

香草,是指具有芳香气味和药用价值的草本植物。在调查的基础上,介绍了北京百花山主要的香草植物资源的分布、生物学特性、应用部位和途经,为将来的开发利用奠定基础。     

Nitrogen mineralization from ‘AU Golden' sunn hemp residue

The tropical legume sunn hemp (Crotalaria juncea L.) cultivar ‘AU Golden’ has the potential to provide substantial nitrogen (N) to subsequent crops to reduce recommended application rates of synthetic N fertilizers. A mineralization field trial was conducted to measure mass decomposition and N and carbon (C) amounts remaining from sunn hemp residue following three planting dates (May, June, and July) during the 2013 growing season at the Tennessee Valley (TVS) and Coastal Plain (WGS) locations of AL. Residue from June and July plantings contained 50.0% and 61.1% N at WGS and 41.5% and 66.5% N at TVS by the end of their respective incubation periods compared to residue from the May planting, which contained 21.1% N at WGS and 47.8% at TVS. In order to create a more synchronous relationship between ‘AU Golden’ residue N mineralization and crop demand, termination must be delayed until approximate planting of the following crop.     

Improving local technologies to manage speargrass (Imperata cylindrica) in southern Benin

Abstract

Speargrass (Imperata cylindrica) is difficult to control in the tropics. Farmers allocate most of their time and labour to weeding speargrass. We investigated in a joint experiment concluded with farmers, how effectively grain legumes suppress speargrass, and the relationships between speargrass suppression, legume grain yield, and subsequent maize yield. Without management, speargrass shoots and rhizomes increased with 31 and 17% per month, respectively. The integration of deep ridging, deep hoe weeding and shading suppressed speargrass more effectively than farmers' practices. Creeping varieties of cowpea that produced most biomass were most successful in suppressing speargrass and in enhancing subsequent maize yields, but erect cowpea cultivars produced more grain. Farmers traded off cowpea yield against speargrass suppression to bridge the hungry gap. They preferred the erect cowpea cultivar wan. The need to forego a harvest and the fact that pigeonpea is not consumed in the area makes pigeonpea presently unsuitable for integration into the cropping system.     

Rock phosphate-enriched organic fertilizer with phosphate-solubilizing microorganisms improves nodulation,growth, and yield of legumes

ABSTRACT

Phosphorus availability from rock phosphate (RP) can be increased via composting with organic fertilizer and phosphate-solubilizing microorganisms (PSMs) in the soil. Incubation and pot experiments were conducted to investigate the comparative efficacy of RP-enriched organic fertilizer with PSMs vs. diammonium phosphate (DAP) as a control to enhance the production of legumes. In incubation studies, RP-enriched organic fertilizer with PSM₂ significantly increased soil aggregate stability (37%) and P-release (2.35 folds) as compared to control, whereas, in pot study, the number and dry weight of nodules plant^?1, shoot length, number of pods plant^?1, and grain yield of chickpea increased by 23%, 13%, 17%, 15%, and 15% with RP-enriched organic fertilizer + PSM₂ compared to control. Similarly, nitrogen and phosphorus contents in straw (11 and 42% respectively) and grains (11 and 13% respectively) and protein contents (16%) of chickpea were also increased. A similar trend was observed regarding the growth and yield parameters of lentil. The use of RP-enriched organic fertilizer with PSM could produce results similar to that of DAP for the optimum production of legumes.     

Quantifying aggregate stability of a clay soil under annual forage crops

This study explored the influence of 10 annual forage legumes belonging to the Lathyrus and Vicia genera on wet aggregate stability (WAS) and dispersion ratio (DR) indices of a clay soil. Five Lathyrus and five Vicia species were sown in autumn. Seed‐to‐seed and row‐to‐row distance was maintained at 5 cm and 20 cm, respectively. The experiment was planned in a randomized block design with three replications. After 90 d following seed harvest, soil cores were collected from two depths (0–15, 15–30 cm) in each plot and WAS and DR were determined. Annual forage legumes increased WAS of the soil but decreased the DR index. The WAS and DR values were affected at level of p < 0.001 by genus, species, and soil depth. Values of WAS and DR of the control plots without plant on the average were found to be 44.5% and 9.3% for 0–15 cm, and 41.2% and 10.1% for 15–30 cm, respectively. For 0–15 cm depth, the highest WAS (77.7%) and the lowest DR (6.4%) values were found in L. sphaericus L. (wild) plots. For 15–30 cm depth, the highest WAS value (62.6%) was obtained in L. annuus L. (wild) plots and the lowest DR value (6.7%) was in L. sativus L. (Gurbuz‐2001) plots.     

柠条人工林下草本植被特征与土壤特性相关性研究

为探索黄土丘陵沟壑区最佳的柠条（Caragana Korshinskii）平茬措施,本研究以该区柠条人工林为研究对象,对其进行4种不同方式的平茬措施,分析在不同平茬措施的柠条林下草本植被特征与土壤特性的相关关系。结果表明：隔行平茬措施下草本生物量最大,柠条林下各土层土壤含水量与草本地上生物量密切相关,且以负相关关系为主;草本植物多样性各指数均与土壤含水量呈负相关关系,40～80 cm土层的土壤含水量与Simpson指数的相关性显著（P<0.05）,与Shannon-wiener指数的相关性极显著（P<0.01）;土壤养分各指标与草本植物多样性没有显著相关性,在0～60 cm土层内,土壤碱性越大,草本生物量越大,20～40 cm土层土壤有机质越小,草本生物量越大。综合以上结果,在该区域采取柠条隔行平茬措施最佳。     

三种豆科作物与玉米间作对玉米生产力和种间竞争的影响

合理的种间配置是间作系统中作物获取高产,种间相互作用发挥优势的关键。本研究设置蚕豆/玉米(M/F)、大豆/玉米(M/S)和豌豆/玉米(M/P) 3种豆科作物与玉米间作模式,以及相应单作种植,通过测定单间作条件下作物产量、生物量,明确3种豆科作物与玉米间作对间作玉米生产力和间作作物种间资源竞争力的影响。结果表明,3种间作模式均具有间作优势,土地当量比(LER)均大于1,两年平均土地当量比分别为1.38 (M/F)、1.19 (M/S)、1.26 (M/P);两年结果均是M/S中玉米产量最高,至收获期,与大豆间作的玉米产量可达单作玉米产量的93.6% (2017)和71.2% (2018);M/S中玉米的穗粒数显著高于M/F和M/P中;地上部生物量及采样期平均生长速率均表现为M/S>M/P>M/F;共生期内大豆相对于玉米的资源竞争力(A_sm)随共生期推进逐渐降低,而蚕豆相对于玉米的竞争力(A_fm)和豌豆相对于玉米的竞争力(A_pm)逐渐升高;玉米单独生长时期3种间作模式玉米的补偿效应(CE)无显著差异,各间作模式两年平均CE值均小于1;因此,在本试验条件下,甘肃河西走廊灌区玉米与大豆间作是保证间作玉米稳产的有效措施。     

Mycorrhiza‐soil fertility effects on regrowth,nodulation and Nitrogenase activity of siratro (Macroptilium atropurpureum (DC) Urb.)

Siratro (Macroptilium atropurpureum (DC) Urb.) is a vigorous perennial forage legume with good potential for improving pastures in the extensive neotropical regions of the world. It is well adapted to a wide range of soil and climatic conditions. The objective of these studies was to determine effects of Glomus fasciculatum colonization, rigorous defoliation, and soil fertility treatments to a Psammentic Paleustalf (Eufaula) soil on growth, regrowth, nodulation, and nitrogenase activity (C₂H₂ red.) of Siratro inoculated with Rhizobium leguminosarum Frank. Top growth increased significantly with soil K and P amendment and with mycorrhiza colonization. Nodulation and nitrogenase activity were correlated with highly significant increases from G. fasciculatum, P treatments and K additions to 300 mg K kg^‐1 soil. Growth and peduncles of nonclipped plants increased about 4 fold from 90 to 225 day age with mature seed yield increasing about 10 fold; nodule mass and nitrogenase activity levels approximately doubled. Regrowth response of plants defoliated at 45 day intervals, following their initial 90 day age, was somewhat constant between clippings for magnitude of regrowth 12.3–13.8g, development in number of peduncles 4.0–6.8, seed yield 1.4–2.6g, nodulation 2.9–3.7g, and nitrogenase activity 73.9–95.8μ mol C₂H₄g^‐1 nodule. Multiple regression for nitrogenase = 0.55 g top wt. + 0.63 g nodule wt. + 1.91 day age ‐ 0.07 peduncle no., R² = 0.85 and C.V. = 14.3%. Favorable tripartite symbiosis with both effective Rhizobium and endophyte mycorrhiza were essential for high levels of symbiotic nitrogen fixation.