GIS支持下的巴西陆稻IAPAR-9再生稻合理布局气候区划

根据巴西陆稻IAPAR-9生长发育对气候条件的要求,结合其在广西的引种试验结果,分析确定了广西种植巴西陆稻再生稻的气候区划指标;利用数理统计分析方法,建立气候区划指标的空间推算模型,并采用GIS技术推算出广西lkm×lkm网格点上的有关气候要素值,利用GIS的空间分析和多层复合方法,对广西的巴西陆稻再生稻进行气候区划,为广西巴西陆稻再生稻的合理布局提供科学依据。     

GIS技术在划分巴西陆稻"IAPAR9"适宜种植区域中的应用

用贵州多年引种巴西陆稻 (IAPAR9)的试验资料与当地的气候资源进行对比分析 ,找出影响生育的关键气象因子和指标 ,并采用GIS技术推算出贵州不同地理背景下 1km× 1km网格点上的有关气候要素值 ,对巴西陆稻的适宜种植区域进行划分     

巴西陆稻在亚热带丘陵山区的生态气候适应性

通过对１９９８年巴西陆稻的分期播种试验，不同海拔高度和不同土壤条件下的品种对比试验有机肥可以结合气象条件进行分析，得出巴西陆稻具有较强的抗旱，耐盆瘠能力，在本地区种植高度以４００－８００ｍ为宜；分蘖力弱，保证基本苗是提高产量的关键。     

北亚热带边缘引种油橄榄气候适应性及开发价值的研究

通过在武都白龙江河谷地带引种油橄榄的试验研究，分析了油橄榄引种栽培的气候生态条件，评价了油橄榄在北亚热带边缘引种缘栽培的气候适宜性程度及其开发前景。     

山东紧凑型玉米引种的气候诊断分析

介绍了莱州市自然生态环境和紧凑型玉米的光、热、水气象条件，论述了高产稳产引种的关键气候要素；依据农业气候相似原理，运用加权聚类方法，进行了紧凑型玉米向国内、外引种的气候诊断分析。     

亚热带丘陵山区引种山楂的气候适应性分析

在亚热带丘陵山区引种北方山楂试验基础上，调研山楂经种地山东秦安气候资料，分析了山楂南引后的气候适应性，得出亚热带丘陵山区具有引种山楂的气候优势，生长季节长，春季回温早，升温慢，积温高，秋温适宜，秋雨明显，使山楂树体扩展快，坐果率高，果形大，丰产性能好。     

我国甘蔗的气候生产力特征分析

根据广西柳州９县１９５２～１９９０年甘蔗逐年产量和７县２５年含糖量资料，在采用方差分析和滑动相关分析确定影响甘蔗产量和品质的关系发育期及气候影响因素的基础上，建立气候影响方程，并提出气候产量和气候含糖量的影响指数（Ｃｙ与Ｃｓ）。结合甘蔗产区３８站１７年气象整编资料，对我国蔗区作出气候生产力分析和区划，为今后扩大甘蔗种植面积提高单产和品质提供切实有效的分析数据。     

贵州高原水稻引种生态气候指标研究

从水稻品种与生态气候方面入手，详细研究了增产幅度与气候变差、高度变差、生育期变差的相互关系，得出了水稻引种的生态气候指标。初步认为：当水稻引种地与原产地的气候变差小于７．０时，水稻品种的适应性较好，引种较易成功；贵州高原水稻引进品种增产幅度与原产地的海拔高度有关，高差越小，增产幅度越大；引进水稻品种生育期变差在７ｄ左右时，引种较易成功。     

湖北省烤烟生产的气候分区

根据湖北各产烟县市1961—2000年的气象资料，应用系统聚类方法，将全省烤烟种植区划分为5类气候区，并对其气候特点及适宜移栽期进行了分析。通过与国内外优质烤烟区气候条件对比分析，探讨确定了省内优质烤烟的生产区域，其中以咸丰、利川和五峰的气候条件最为优越，为全省及县域内烤烟布局调整和相关技术措施的调整和改进提供依据。     

徽成盆地栽培银杏的气候分析

根据徽成盆地银杏生长发育与气象条件的平行观测资料，分析了银杏主要生育期的农业气象指标和气候条件，并进行了气候分区，评价了银杏在徽成盆地栽培的气候适宜程度及其开发利用前景。     

Differences in soil organic carbon stocks and fraction distributions between rice paddies and upland cropping systems in China

Purpose

A large body of research suggests that rice (Oryza sativa L.) cropping facilitates soil organic carbon (SOC) storage, while the stability of the sequestered carbon is still not well understood. The objective of this study was to determine the differences in SOC stocks and fraction distributions between rice paddies and upland cropping fields and their variation in different rice cropping areas.

Materials and methods

Data from the national soil survey were analyzed to assess the differences in SOC contents between paddy and upland cropping fields at the regional scale. In addition, three pairs of rice and upland cropping systems were selected in Heilongjiang [single rice vs. single corn (Zea mays L.) cropping], Jiangsu [rice-wheat (Triticum aestivum L.) vs. corn-wheat cropping], and Jiangxi (double rice vs. double corn cropping) provinces, representing the major cropping patterns in China. Physical fractionation techniques were used to investigate the differences in SOC stocks and distribution among different pools between rice-based cropping systems and non-rice cropping systems in China.

Results and discussion

SOC concentrations were, on average, 74.9% higher at the regional scale and 56.8% higher at the field scale in paddy than in upland cropping fields. Carbon proportion of particulate organic matter within microaggregates increased from 14.4% in upland cropping soils to 25.3% in paddy soils at the Heilongjiang site and from 12.4 to 25.5% at the Jiangxi site. Meanwhile, the free silt and clay-associated carbon was significantly greater in paddy than in upland cropping soils at the both sites. Nevertheless, SOC distribution did not markedly differ between paddy and upland cropping fields at the Jiangsu site where rice was rotated with winter wheat annually.

Conclusions

As compared to upland cropping or rice-upland crop rotation, continuous rice cropping, such as single and double rice cropping, could favor SOC stabilization by occlusion within microaggregates and adsorption to the silt and clay outside microaggregates, which may promote the long-term storage of SOC in paddies.     

南方红壤稻田与旱地土壤有机碳及其组分的特征差异

大量研究证明稻田土壤比旱地土壤更具固碳潜力,但至今对稻田土壤固碳机制的认识尚不甚清楚。本研究于2007年利用两个开垦年代相似,近20多年分别一直种植双季稻和双季玉米的长期定位试验,来比较不同种植模式下土壤有机碳及其组分的差异。结果表明,水田土壤总有机碳和总氮的浓度分别是旱地的2.2倍和2.5倍。与试验前相比,水稻种植显著提高了土壤有机碳的含量,增幅达到30.8%,而旱地的前后差异不显著。在所有团聚体粒径水平上,水田有机碳的浓度均显著高于旱地。其中53～250μm微团聚体相差最大,水田是旱地的近3倍。水田微团聚体保护碳（iPOM_m）在土壤中的浓度是旱地的4.2倍,微团聚体保护碳在总有机碳中的比重也显著高于旱地,达到25.5%,是旱地的2倍。水田和旱地iPOM_m组分碳的差异能够解释其总有机碳差异的42.8%。上述结果可以增强我们对稻田土壤固碳机制的了解,为稻田土壤碳管理提供理论依据。     

Tropical Rice Cultivars from Lowland and Upland Cropping Systems Differ in Iron Plaque Formation

In iron toxic wetlands, ferric hydroxide is commonly deposited on rice roots. This study aims to to evaluate the differences in iron plaque formation in rice cultivars from different cropping systems. Thirty days old seedlings of Brazilian rice cultivars from the lowland cropping system (‘BRS Atalanta’ and ‘Epagri 107’) and upland cropping system (‘Canastra’) or both systems (‘BRSMG Curinga’) and the cultivar ‘Nipponbare’ were exposed to iron excess [4 mM iron sulfate heptahydrate (FeSO₄.7H₂O)] for seven days in nutrient solution. It was observed iron plaque formation and ruptures of the root epidermal cells. The lowland cultivars showed higher Fe content in iron plaque. Iron stain was detected in the root hairs, epidermis, hypodermis, and exodermis. The root exodermis may be contributed to prevent the deposit of iron in the cortex of the lowland cultivars and in the cultivar ‘BRSMG Curinga’. It was observed in plants with iron plaque formation significant reductions in the shoot content of phosphorous, manganese and magnesium due to different causes. The differences in iron plaque formation among the cultivars might be an indicative of variations in exodermis selectivity, root oxidative capacity, and iron nutrition mechanisms.     

Inclusion of upland crops in rice‐based rotations affects chemical properties of clay soil

In the Mekong Delta, alluvial clay soils have been used intensively over many generations for rice monoculture. Currently, farmers are confronted by problems of declining land productivity. Rotations comprising rice and upland crops can increase soil quality, but appropriate cropping systems for paddy soils have received relatively little attention. We therefore established a multiyear field experiment to evaluate the long‐term effects of cropping systems with different rotations on soil chemical quality. Systems laid out in a randomized complete block design with four replications were as follows: (i) traditional rice monoculture with three rice crops per year (R‐R‐R), (ii) rotation with two rice crops and maize (R‐M‐R), (iii) rotation with two rice crops and mung bean (R‐Mb‐R) and (iv) rotation with one rice crop and two upland crops – mung bean and maize (R‐Mb‐M). We hypothesized that systems with rotations of upland crops and their temporary beds improve chemical quality of paddy rice soil. Soil chemical parameters were determined to better understand and evaluate the sustainability of the cropping systems. Results showed an improvement in soil chemical quality for cropping systems with rotations of rice and mung bean or maize grown on temporary beds (R‐M‐R, R‐Mb‐R and R‐Mb‐M), particularly the content of soil organic carbon and a presumed hydrolysable labile carbon fraction compared with rice monoculture. Less pronounced improvements in EC, CEC and total acidity were also found with inclusion of upland crops. Cropping systems of rice with upland crops improved rice grain and straw yield in subsequent season in contrast with rice monoculture.     

Changes in soil microbial properties with no-tillage in Chinese cropping systems

No-tillage (NT) has revolutionized agricultural systems because it has potential benefits including soil conservation and reduced production costs though saving in fuel, equipment, and labor. Soil quality is of great importance in determining the sustainability of land management systems, and soil microbial properties are becoming increasingly used to assess the effect of farming practices on soil quality due to their quick response, high sensitivity, ecological relevance, and capacity to provide information that integrates many environmental factors. In China, research and application of NT have developed quickly since 1970s. Numerous studies have been conducted in this country to evaluate the effect of NT on soil microbial properties. From these studies, it is evident that NT can lead to an increase in soil microbial size or activity or both and a consequent increase in soil microbial biomass in upland cropping systems. However, there are still several issues that remain unaddressed or inadequately specified. Further investigations are needed (1) to determine the effect of NT on soil microbial diversity by using molecular biological techniques in both upland and rice-based cropping systems; (2) to fully understand the changes of soil microbial properties with NT in rice-based cropping systems, especially for double rice cropping systems; and (3) to clarify the relationship between rhizosphere microbial properties and crop growth in NT rice cropping systems.     

Effect of fungi associated with roots on the growth of continuously cropped upland rice

Pyrenochaeta sp. enriched on and in roots of upland rice through its continuous cropping, was shown to have an ability to inhibit the growth of upland rice in quartz or partially sterilized soil. It was established that the microorganism produced some substance inhibiting the growth of seedlings of upland rice or/in roots of the plant. The results suggested that Pyrenochaeta sp. produced this inhibitor even on/in roots of upland rice continuously cropped on the field, and may play a role in the appearance of upland rice soil sickness.     

不同氮水平对桂中地区晚稻生长性状与产量的影响

为探讨桂中双季稻区的水稻氮肥施用效应,为当地水稻生产合理施用氮肥提供理论依据;2008—2009年在广西来宾市兴宾区进行了氮水平对早稻生长性状、产量以及氮肥农学效率影响的大田试验研究。结果表明,施氮对桂中稻区晚稻的生长发育具有促进作用,能明显地改善水稻的产量结构,提高水稻产量。与不施氮相比,2年晚稻施氮处理的株高与有效穗分别平均提高10.33%、37.18%,单穗总粒数与千粒重分别平均提高17.06%、7.17%,产量平均提高37.00%。但当氮肥施用量>325.5kg/hm2时,随着氮肥的继续施用,晚稻氮肥农学效率大幅度降低,农业成本增加,环境污染严重。可见,在桂中稻区早稻施氮163.5～325.5kg/hm2时,既能稳定水稻高产,确保当地粮食安全,又能保证肥料资源得到高效利用,是桂中地区晚稻一个比较合理的施肥水平。     

Using different versions of the Rothamsted Carbon model to simulate soil carbon in long-term experimental plots subjected to paddy–upland rotation in Japan

We validated the Rothamsted Carbon (RothC) model against 14 experimental plots subjected to different paddy–upland rotation patterns, including continuous paddy rice cropping and different periods (short, medium, and long term) of upland conversion, in Akita prefecture, northern Japan. We ran the model using the original version of the RothC model, the paddy-soil version of the RothC model (which uses a reduced carbon decomposition rate), and alternating the use of the original and the paddy-soil versions for years with summer upland cropping and paddy rice cropping, respectively. The best simulation pattern was provided by the alternate use of the two versions. In comparison with the original RothC model, alternate use of the two versions showed a smaller root mean square error in all experimental plots and a smaller absolute value of the mean difference in 10 plots with continuous paddy rice cropping and short- and medium-term upland conversion. Alternate use of the two versions had a lower root mean square error and lower absolute value of the mean difference in long-term upland conversion plots compared to the values for the paddy-soil version and showed better performance than the paddy-soil version when straw was applied. The model performance from alternating use of the two versions compared well with the performance reported in previous studies. Alternating the use of the two model versions provides a good technique for simulating changes in soil organic carbon with time, even with a paddy–upland rotation pattern. In addition, this technique will enable a more accurate inventory of Japanese greenhouse gases and help land managers better manage soil fertility in a paddy–upland rotation system.     

耕作改制对砂姜黑土中锰的影响

研究砂姜黑土旱改水对土壤中Mn含量、赋存形态和有效性的影响结果表明,砂姜黑土中Mn存在于粘土矿物、晶形氧化铁、无定性氧化铁、氧化锰态、有机物和碳酸盐中比例分别为27.19%~46.26%、10.48%~21.65%、2.76%~12.28%、17.39%~26.53%、10.61%~24.57%和0.16%~8.35%。旱改水实施水旱轮作后砂姜黑土中全Mn含量极显著降低,平均降幅为8.77%,但伴随土壤pH值的趋中性,土壤中Mn由植物有效性较低的晶形铁结合态逐渐向植物有效性较高的氧化锰态、无定形铁态和有机态转化,活化了土壤中的Mn,提高了Mn的有效性和可移动性。