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1.
基于DNDC模型模拟江汉平原稻田不同种植模式条件下温室气体排放 总被引:3,自引:0,他引:3
稻田被认为是温室气体CH_4和N_2O的主要排放源之一。湖北省江汉平原地区水稻常年种植面积约8×105 hm2,占湖北省水稻种植面积的40%左右。研究江汉平原地区稻田温室气体排放特征,对于评估区域稻田温室气体排放以及稻田温室气体减排具有重要意义。目前,DNDC模型已被广泛应用于模拟和估算田间尺度的温室气体排放,DNDC模型与地理信息系统(Arc GIS)结合,可进行区域尺度的温室气体排放模拟与估算。本研究以湖北省典型稻作区江汉平原为研究区域,运用DNDC模型模拟和估算江汉平原稻田区域尺度的温室气体排放。设置大田定点观测试验,监测中稻-小麦(RW)、中稻-油菜(RR)、中稻-冬闲(RF)3种种植模式下稻田温室气体CH_4和N_2O的周年排放特征。通过田间观测值与DNDC模拟值的比较进行模型验证,并利用获取DNDC模型所需的气象、土壤、作物及田间管理等区域数据,模拟江汉平原稻田不同种植模式下温室气体CH_4和N_2O的排放量。田间试验表明,江汉平原稻田RW、RR和RF模型的CH_4排放通量为-2.80~39.78 mg·m-2·h-1、-1.74~42.51 mg·m-2·h-1和-1.57~55.64 mg·m-2·h-1,N_2O周年排放通量范围分别为0~1.90 mg·m-2·h-1、0~1.76mg·m-2·h-1和0~1.49 mg·m-2·h-1;CH_4排放量RW和RR模式显著高于RF模式,N_2O排放量为RF显著低于RW和RR模式。模型验证结果表明,不同种植模式温室气体排放实测值与模拟值比较的决定系数(R2)为0.85~0.98,相对误差绝对值(RAE)为8.29%~16.42%。根据DNDC模型模拟和估算的结果,江汉平原区域稻田CH_4周年的排放量为0.292 9 Tg C,N_2O周年的排放量为0.009 2 Tg N,不同种植模式稻田CH_4排放量表现为RWRRRF,N_2O排放量表现为RWRFRR,增温潜势(GWP)表现为RWRRRF。不同地区稻田CH_4排放量表现为监利县荆门市公安县天门市仙桃市洪湖市松滋市汉川市潜江市石首市荆州市江陵县赤壁市嘉鱼县,N_2O排放量表现为监利县荆门市公安县洪湖市仙桃市天门市汉川市潜江市松滋市荆州市江陵县赤壁市石首市嘉鱼县。本研究结果表明DNDC模型能较好地应用于模拟江汉平原稻田温室气体排放,RR和RF模式相比RW模式可有效减少温室气体CH_4和N_2O的排放。 相似文献
2.
Evaluation of 'quick and dirty' DNA extraction methods for marker-assisted selection in rice (Oryza sativa L.) 总被引:2,自引:0,他引:2
Six simple methods for extracting DNA from rice seedlings were evaluated for marker‐assisted selection (MAS). The assessment of each method was based on PCR amplification of SSR markers, DNA yield and purity, time and cost. Based on these criteria, two methods were selected as being superior to other methods. The best two methods included the standard method developed at the International Rice Research Institute (IRRI), which utilizes a sodium dodecyl sulfate extraction buffer followed by chloroform/isoamyl alcohol extraction and a previously published method using sodium hydroxide and Tris. These two methods produced nearly identical PCR amplification results. The sodium hydroxide method is considerably simpler, quicker and cheaper than the standard IRRI method, and may be particularly useful for many applications of MAS or high‐resolution mapping. This method was also adapted into an effective high throughput method utilizing 96‐well plates emphasizing its versatility. 相似文献
3.
On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable
areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the
continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives.
Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine
here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa,
where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were
readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by
the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The
new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces
so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them
along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces
or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used
to test the significance of the differences between individual years. In all states, this revealed a significant reduction
in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across
years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of
whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for
mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily
replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the
highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a
diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was
little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact
on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties
into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining
diversity. 相似文献
4.
Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an exotic species native to the USA, damaging cotton and other plant families. The
feeding potential of different development stages of Cryptolaemus montrouzieri Mulsant, a biological control agent against mealybugs, was investigated on different development stages of P. solenopsis. Fourth instar grubs and adults of C. montrouzieri were the most voracious feeders on different instars of mealybug. The number of 1st instar nymphs of mealybug consumed by 1st, 2nd, 3rd and 4th instar larvae and adult beetles of C. montrouzieri was 15.56, 41.01, 125.38, 162.69 and 1613.81, respectively. The respective numbers of 2nd and 3rd instar nymphs of mealybug consumed were 11.15 and 1.80, 26.35 and 6.36, 73.66 and 13.32, 76.04 and 21.16, 787.95 and 114.66.
The corresponding figures for adult female mealybugs were 0.94, 3.23, 8.47, 12.71 and 73.40, respectively. The results indicate
that C. montrouzieri has the potential to be exploited as a biocontrol agent in North India; inoculative releases of 4th instar larvae and adults may provide instant control of P. solenopsis. Field experiments should be conducted to determine the efficiency of the ladybird on this mealybug. 相似文献
5.
为探究转Cry2A*基因水稻品系根系特性,为抗虫转基因水稻的栽培调控提供技术支撑,通过盆栽试验,以常规粳稻与其转Cry2A*基因水稻品系、常规籼稻与其转Cry2A*基因水稻品系为试验材料,探究施氮、不施氮处理下转Cry2A*基因水稻品系的根系特性。结果表明:转Cry2A*基因水稻品系的根长、根表面积、根体积在成熟期不施氮处理下显著低于亲本对照,在施氮处理下与亲本对照无显著差异;KY(Cry2A*)的根系活跃吸收面积在花期显著高于亲本对照,而MH86(Cry2A*)的根系活跃吸收面积与其亲本对照无显著差异;与不施氮处理相比,施氮能显著提高KY(Cry2A*)的根直径,对MH86(Cry2A*)的根直径无显著影响。本研究结果表明,转Cry2A*基因水稻根系特性与其亲本之间存在一定差异,且这种差异在不施氮处理条件下更为明显。 相似文献
6.
稻鸭、稻鱼复合生态系统土壤微生物多样性特征分析 总被引:2,自引:0,他引:2
21世纪以来,由于其良好的生态环境效应、及市场对绿色安全稻米的需求,稻田种养复合生态系统的应用范围不断扩大,模式多种多样,在我国南方地区主要以稻田养鸭、养鱼、养虾为主。同时对稻田种养复合生态系统的机理及其效应也进行了较为广泛的研究。相关研究表明:稻鸭共生可利用鸭子的活动、觅食产生中耕除虫的效果[1,2],减少农药对环境的污染;稻鸭共生有利于稻田通风透光,改善水稻群体结构;提高土壤肥力[3~5];还能减少稻田中的产甲烷菌数量,减少甲烷排放[6~9]等方面作用。然而对于稻田养鸭、养鱼后对土壤微生物数量及多样性方面的研究还很少,甘德欣等[10]研究表明稻田养鸭后能增加土壤微生物的数量,但对土壤微生物 相似文献
7.
Harpreet Kaur Virk Guriqbal Singh Gursahib Singh Manes 《Journal of plant nutrition》2018,41(9):1184-1196
A field experiment was conducted to study the effect of different planting methods (Happy Seeder sowing, Straw Chopper + Zero Tillage sowing, and conventional sowing) and nitrogen (N) levels (0%, 75%, 100%, and 125% of recommended N) on the emergence, growth, symbiotic parameters, productivity, and profitability of soybean sown after wheat harvest. Growth and symbiotic parameters were significantly better under Happy Seeder sowing and Straw Chopper + Zero Tillage sowing than conventional sowing. The seed yield, nutrient uptake, and economic returns were significantly higher under Happy Seeder sowing than other methods. The growth parameters, symbiotic parameters, biological, straw, and seed yields were increased significantly up to 100% recommended N level. The nutrient uptake increased significantly up to 100% recommended N level. Therefore, sowing with Happy Seeder after combine harvested wheat along with 100% recommended N would best optimize soybean yield and profitability. 相似文献
8.
Daljit Singh Virk 《Journal of Crop Improvement》2017,31(1):1-24
The analysis of residuals computes general adaptabilities (GAs) and specific adaptabilities (SAs) of genotypes similar to combining ability analysis. The residual analysis is simple and robust being based on the first-degree statistics, and is assumption-free. A unique statistic of ratio of variances (VR) of residuals for individual genotypes allows comparing their stability. The residuals analysis of genotype × environment (GE) interactions was performed for grain yield (t ha?1) of 25 rice (Oryza sativa L.) genotypes, including two developed by marker-assisted selection for root traits quantitative trait loci (QTL), tested across 16 sites. Results were compared with the linear regression analysis for (i) full set of 16 sites showing adequacy of linear model and (ii) subset of nine-poor sites showing inadequacy of linear model. There was agreement between the two analyses for situation (i) but not for situation (ii) when the regression analysis fails because of nonlinearity but the residual analysis retains its validity. 相似文献
9.
Yuling Han Wei Ma Baoyuan Zhou Akram Salah Mingjian Geng Cougui Cao Ming Zhan Ming Zhao 《作物学报(英文版)》2021,(1):168-180
Straw return is an effective way to improve crop grain yield and potassium(K)use efficiency by increasing soil K content.However,the effects of straw return on soil K supplying capacity,replacement of K fertilizer,and K-use efficiency under maize(Zea mays L.)–rice(Oryza sativa L.)cropping systems are little studied.A two-year field experiment was conducted to determine the physiological determinants of K-use efficiency under straw return with four K fertilization rates.Sr33(straw returned plus 33%of K fertilizer applied)and Sr67(straw returned plus 67%of K fertilizer applied)increased annual crop yields by 1.5%and 3.2%and increased agronomic K-use efficiency by respectively 2.9 and 1.3-fold on average in the two years,compared with the conventional practice S0K100(no straw returned plus normal amounts of K fertilizer applied).The Sr33 and Sr67 treatments resulted in significantly greater equilibrium K concentration ratios(CR0 K)and specifically exchangeable K(KX)values according to quantity/intensity(Q/I)relationship analyses,indicating improvement of the potential soil K supply capacity.However,the Sr67 better maintained the soil exchangeable K level and K balance.The results suggested that K released from maize and rice straw can replace about half of chemical K fertilizer,depending on the available K content in maize–rice cropping system production. 相似文献
10.
村级生态农业的模糊综合评判 总被引:2,自引:0,他引:2
本文基于生态农业系统的模糊性,在专家调查的基础上,对鄂中丘陵区具有代表性的5个村的生态农业建立进行了模糊综合评判。评价中建立了各子目标的隶属函数,计算了各村子目标及综合的隶属不同类别的隶属芭。评价结果显示:扬港村属于较高水平的生态农业类型,星火等另外4个村属中等水平生态农业类型。 相似文献