水分管理和氮肥运筹对水稻养分吸收、转运及分配的影响

在高产施氮量180 kg hm^-2条件下,以杂交稻冈优527为材料,通过“淹水灌溉”(W₁)、“湿润灌溉(前期)+浅水灌溉(孕穗期)+干湿交替灌溉(抽穗至成熟期)”(W₂)和“旱种”(W₃) 3种灌水及不同的氮肥运筹处理,研究水分管理和氮肥运筹对水稻养分吸收、转运、分配及产量的影响,并探讨各养分间及其与产量的相互关系。结果表明,水分管理和氮肥运筹对水稻主要生育期氮、磷、钾的累积、转运、分配及产量的影响均存在显著的互作效应,水氮互作条件下各生育期氮、磷、钾间的吸收存在显著的协同效应;抽穗期氮、磷、钾的累积与各养分在结实期转运总量间,以及结实期各养分转运间均呈极显著正相关,且氮、钾在抽穗前期的累积对促进结实期各养分向籽粒的转运和提高产量影响显著,但氮肥后移比例过重(N₄处理)及W₃处理均会导致结实期叶片和茎鞘各养分转运总量的显著降低,氮、磷、钾降幅分别达2.73%~18.00%、8.03%~19.70%、6.52%~17.02%。据产量及其与养分吸收、转运间关系的表现,W₁模式下氮肥后移量以占总施氮量的40%~60%为宜,W₂模式与氮肥运筹方式为基肥:蘖肥:孕穗肥(倒四、二叶龄期分2次等量施入)=3∶3∶4组合是本试验最佳的水氮耦合运筹模式,W₃模式下,应减少氮肥的后移量,氮肥后移量占总施氮量的20%~40%为宜。     

西南稻区不同地域和施氮水平对杂交中稻氮、磷、钾吸收累积的影响

以杂交中稻II优7号和渝香优203为材料,在西南稻区4省(市)的7个生态点采用相同的试验方案,研究了地理位置、土化特性、施氮量对植株氮、磷、钾积累和分配的影响。结果表明,不同试验地点间稻谷产量、干物质产量、氮磷钾的吸收量、收获指数和每生产1 000 kg稻谷的氮、磷、钾需要量(RAGPPG)差异显著或极显著。施肥处理对稻谷产量、干物质产量、氮的吸收量、收获指数和RAGPPG中的氮有显著或极显著影响,对RAGPPG中的磷、钾影响不显著。氮、磷、钾收获指数间和RAGPPG间均呈极显著正相关,RAGPPG和收获指数均与稻谷产量水平没有相关性。经逐步回归分析,RAGPPG和氮、磷、钾收获指数均分别与试验点所处地理位置、施肥水平及土化特性呈极显著线性关系,决定系数分别为0.5972~0.8404和0.7637~0.8804。可作为制定各地水稻高产高效相应的氮、磷、钾施肥量的科学依据。     

Nitrogen Uptake by Rice (Oryza sativa L.) Exposed to Low Water Temperatures at Different Growth Stages

The responses of nitrogen (N) uptake by rice (Oryza sativa L.) to low water temperatures at different growth stages were examined during a 3‐year field trial in northern Japan. Cool irrigation water was applied at two to three temperature levels (16–25 °C) for 20–34 days during the vegetative stage and then during reproductive growth. We measured the N uptake rate, N content and canopy radiation interception during both growth stages. Exposure to low water temperature during either the vegetative or the reproductive growth stage slowed N uptake, and the magnitude of the decrease differed between the growth stages; the decrease was greater during vegetative growth than during reproductive growth. Consequently, total N uptake at maturity was most strongly reduced by low water temperature during vegetative growth and was not affected by low water temperature during reproductive growth, even though N distribution to the panicle was greatly reduced. The variations in N uptake during the growing season among growth stages and years were explained better by the amount of canopy radiation capture than by the number of degree‐days based on water temperature. This strong dependency on canopy radiation capture improves our understanding of the factors responsible for variations in N uptake under different levels of water temperature, and this knowledge will provide an opportunity to simplify the modelling of N uptake.     

Effects of Root Zone Temperature on Root Activity of Two Potato (Solanum tuberosum L.) Clones with Different Adaptation to High Temperature

Under controlled environmental conditions, the effect of optimal (20 °C) and supraoptimal (30 °C) root-zone temperature on root activity (respiration, soluble sugar content, ethylene release, nitrogen uptake and translocation) was studied in water culture with two potato clones differing in the heat tolerance of their root systems. Root respiration was little affected by raising temperature from 20 °C to 30 °C. However, in both clones assimilate allocation to the roots was strongly depressed. In the heat sensitive clone LT-1 exposed to 30 °C root-zone temperature, concentrations of soluble sugars in the apical root zone (0–10 mm) increased with time, presumably as a result of the cessation of root growth. The rate of nitrate absorption was not significantly affected by root-zone temperature. However, the export of nitrogen (xylem exudate) was depressed in the heat tolerant clone whereas in the heat sensitive clone the export of total nitrogen and the proportion of nitrate increased. No effect of root-zone temperature on ethylene release was observed in our experiments.     

Effect of Spatial Soil Moisture Stress on Cotton Root Architecture

[Objective] This study aimed to explore the effects of spatial soil moisture stress on cotton root growth, and to analyze the corresponding changes in cotton root architecture. [Method] To produce soil moisture spatial stress, cotton spacing was set at 30 cm. The cotton was all irrigated on one side of the pole (the side sampling point). By excavating the cotton root, analysis of the main root bifurcation, which was cultivated away from the irrigation point, could be undertaken. [Result] The analyses of the cotton A (the nearest plant to the irrigation location) root system showed that soil moisture near the irrigation point was distributed uniformly. The root system architecture of the cotton cultivated near the irrigation point mostly presented a symmetrical "umbrella" pattern; the difference in root diameter between the main and lateral roots was 5–6 mm, and the average angle between them was 70°–80°, which decreased with the increase in cotton growth stage. Soil moisture spatial stress influenced the cotton plant C, which was cultivated away from the irrigation point, such that the root system architecture was asymmetrical. The roots of cotton plant C grew towards the high soil moisture zone; 48.15% of the lateral roots became thicker, which acted as a bifurcated main root. The difference in diameter between the bifurcated roots was 1–4 mm, and the average angle of the bifurcated roots along the vertical direction was between 20°–37°, which increased with the increase in cotton growth stage. [Conclusion] The results provide important information on the physiological responses of the cotton root system to the soil moisture environment.     

节水灌溉条件下氮肥密度互作对双季晚稻丰源优299肥料利用率的影响

为构建水稻高产高效节水栽培技术模式,通过大田小区试验,研究了在节水灌溉条件下施氮量和栽植密度对双季晚稻丰源优299肥料利用率的影响。结果表明：施氮量、栽植密度及氮密互作对水稻氮磷钾素吸收和肥料利用率的影响均显著。随着施氮量的增加,水稻植株氮素与磷素吸收量呈先增长后减少的趋势,吸钾量呈现出先增加后减少再增加的趋势。随着密度的增加,植株总吸氮量与总吸钾量呈现先降低后升高的趋势,总吸磷量呈现逐步增加的趋势。低氮处理的氮肥贡献率、土壤氮素依存率、氮肥农学利用率和氮肥偏生产力最高,显著高于中氮处理;高密处理提高了氮肥吸收利用率和氮肥贡献率。水稻经济产量与茎叶氮磷钾素吸收量呈极显著正相关,与氮肥贡献率呈极显著正相关。因此,合理的施氮量和栽植密度组合（N₁T₃）能够形成水稻高产高效的群体结构,提高肥料利用率,进而提高水稻生产效益。     

稻麦连作中超高产栽培小麦和水稻的养分吸收与积累特征

以2个小麦品种和2个水稻品种为材料,大田种植,稻麦连作,重复2年, 设置超高产栽培和当地高产栽培两种栽培模式,旨在探明超高产栽培小麦和水稻养分吸收与积累特征。超高产栽培中,采用实地氮肥管理及水稻轻干湿交替灌溉和小麦控制土壤水分灌溉等关键技术。与当地高产栽培(小麦产量< 8 t hm^-2,水稻产量< 10 t hm^-2)相比,超高产栽培(小麦产量> 9 t hm^-2,水稻产量> 12 t hm^-2)小麦和水稻的氮(N)、磷(P)、钾(K)总吸收量显著增加,并表现为拔节前的吸收和积累量显著降低,拔节至开花、开花至成熟的吸收积累量显著提高。超高产栽培的N、P、K的总吸收量,小麦分别为265、58和256 kg hm^-2,水稻分别为256、79和321 kg hm^-2。上述3种元素于生育中后期(拔节至成熟)的吸收量占总吸收量的比例,小麦为50%~60%,水稻为60%~-70%。超高产栽培显著提高了N、P、K偏生产力(产量/N、P、K施用量)、养分吸收的养分籽粒生产率(籽粒产量/成熟期植株N、P、K吸收量)和养分收获指数(籽粒N、P、K吸收量/成熟期植株N、P、K吸收量),降低了生产单位籽粒产量的养分吸收量(成熟期植株N、P、K吸收量/籽粒产量)。本研究结果显示,超高产栽培小麦和水稻养分吸收与积累具有生育前期较低、生育中期和后期较高的特点,且养分吸收利用效率提高。     

Management of Two Potentially Iron Toxic Benchmark Wetlands Using Integrated Approach for Rice Production in Nigeria

To manage iron toxic rainfed lowlands on a sustainable basis for rice production, a trial was conducted using an integrated approach (i.e. tolerant genotype and fertilizer nutrients). This trials involved two rice cultivars ITA 212 and Suakoko 8 in two cropping seasons (1994 and 1995) and on two potentially iron toxic soil types with excessively high active Fe contents of between 4.43 % and 5.15 %, respectively, located in two agro‐ecological zones in Nigeria. The effects of fertilizer nutrients (N, P, K, Zn, N+P, N+K, N+Zn, N+P+K, N+P+K+Zn and control) were evaluated on the grain yield (GY) and nutrient uptake (leaf analyses) of the rice plants using stepwise multiple regression analysis (SMRA). Results showed that these soils are acidic and had sub‐optimal macronutrient and micronutrient contents coupled with excessively high active Fe (Fe_H) of between 4.43 % and 5.15 %. Fertilizer nutrients N+K, N+P+K and N+P+K+Zn consistently appeared to result in higher GY compared to others on both soil types. Plant analysis of both rice cultivars showed no apparent deficiencies in elemental composition with regard to macronutrients and micronutrients. Results of SMRA showed that tissue K, Zn and Mg contents were significantly related (P < 0.01) to the GY of the two rice cultivars.     

Impact of Wood Biochar and Its Interactions with Mycorrhizal Fungi,Phosphorus Fertilization and Irrigation Strategies on Potato Growth

Biochar amendment to soil has the potential to improve soil quality and increase crop yield. Arbuscular mycorrhizal fungi (AMF ) provide beneficial plant services of stress alleviation with respect to phosphorus (P) deficiency and drought. The aim of this study was to explore interactive effects of biochar with AMF , P fertilization levels and irrigation strategies on growth of potato plants. Potato plants were amended with wood biochar of 0.74 % w/w (B+) or not (B?), fertilized with phosphorus of 0.11 mg P g^?1 soil (P1) or not (P0), irrigated with full irrigation (FI ) or partial root‐zone drying irrigation (PRD ) and inoculated with AMF of Rhizophagus irregularis (M+) or not (M?) in split‐root pots in a sandy loam soil. Plants were analysed for growth performance, P and nitrogen (N) uptake and water use efficiency (WUE ). Biochar adsorption of mineral P and N in aqueous solution was tested in subexperiment. B+ significantly decreased plant biomass production except under P0 FI M?, where B+ increased plant biomass. This growth stimulation was counteracted by treatments of P1, PRD and M+. B+ significantly decreased plant leaf area, P and N uptake and WUE , but had no significant effect on root biomass and soil pH. The positive plant growth response to AMF was substantially reduced by biochar amendment. The wood biochar had no adsorption for mineral N, and it had 0.96 % adsorption for mineral P in aqueous solution. The results suggested that the negative effect of wood biochar application on plant growth may due to the reduced plant uptake of P and N and the possibility of phytotoxic effects of wood biochar on potato growth. It was concluded that the wood biochar used in current study had negative impact on plant growth and P/N uptake and it is not recommendable to apply this wood biochar to mycorrhizal agro‐system, to soil fertilized with high rate of P or to soil suffering water deficiency.     

不同栽培和灌溉方式对冷浸田障碍因子及水稻产量的影响

为了消减冷浸型中低产田长期浸渍、泥温低、结构差、还原性物质毒害、有效养分低等障碍因子,通过田间小区试验和动态取样与室内测定,研究了不同栽培和灌溉方式对冷浸田障碍因子及水稻产量的影响。结果表明：与常规灌溉方式比较,起垄栽培结合湿润灌溉方式增加了晴朗天气条件下冷浸田土壤温度,土壤气相比例提高3 倍,土壤液相比例减少20%,土壤活性还原物质含量降低了21.9%,土壤细菌数和微生物活性分别提高128.7%和3.8%,土壤排水通气性增强,还原性物质毒害减轻,土壤有效养分提升,为微生物活动创造了优良的条件,最终使早稻增产10.8%。起垄栽培结合湿润灌溉方式是适合于冷浸田早稻增产的农水管理措施。     

磁化水灌溉对保护地土壤质量及尖椒品质的影响

[目的]探讨磁化水处理技术对长期保护地栽培土壤矿质养分、生物酶活性、物理结构等土壤理化性状及果实品质的影响,为减缓保护地栽培土壤次生盐渍化进程及土壤质量改善提供理论依据,为磁化水处理技术的应用提供理论基础。[方法]以山东省寿光市洛城镇长期保护地栽培土壤和尖椒为试材,采用田间小区试验设计,设置磁化水灌溉处理,以非磁化水灌溉处理为对照,测定0~15cm土层中土壤全量养分、有效性养分和交换性养分含量、土壤脲酶、磷酸酶、蔗糖酶和过氧化氢酶活性以及土壤容重、孔隙度、土壤颗粒以及pH等土壤理化性质和果实品质指标,分析其变化特征。[结果]结果表明：(1)磁化水灌溉提高了尖椒果实中维生素C、花青素、还原糖含量和可溶性糖含量,提高比例分别为1.76~46.85%；降低了果实中有机酸含量。(2)磁化水灌溉处理促进了Fe、Cu、N和P在叶片中的累积,其含量高于果实,而Mn和Zn含量则略低于果实中含量；Fe含量提高比例最高,在叶片和果实中平均值为57.20%,其次为全磷含量,平均值为53.49%；且磁化水灌溉处理尖椒果实和叶片矿质元素含量均高于非磁化水灌溉处理。(3)磁化水灌溉保护地栽培土壤中N、P、Mn和Zn等元素全量含量降低,为2.04%~20.61%；Fe和Cu等元素全量含量提高为4.64%-6.48%；土壤交换性K、Na和Ca等离子含量降低,为2.15%~4.95%,而交换性Mg离子含量则提高；铵态氮、硝态氮、速效磷和有机质等有效性养分含量提高。(4)磁化水灌溉保护地栽培土壤脲酶、蔗糖酶、磷酸酶和过氧化氢酶等生物酶活性均有不同幅度的提高,为0.27%~24.75%。(5)磁化水灌溉保护地栽培土壤容重降低、孔隙度增加,黏粒和粉粒等细小颗粒含量增加,而砂粒含量则有所下降。[结论]综上所述,磁化水处理技术有利于土壤物理结构的改善,对土壤有效性养分累积和供应强度以及土壤生物酶活性有明显的促进作用,从而提高尖椒果实的鲜食品质；并通过调整交换性离子含量和组成以及土壤pH的调节,减缓保护地土壤次生盐渍化的发生。     

机插稻育秧床土的培肥效应研究

床土培肥是培育水稻机插秧苗的首要措施。在不同类型床土条件下对培肥水平与床土速效氮磷钾增加的关系及育秧过程中的肥力消耗进行了分析。结果表明,通过添加速效肥料进行床土培肥,可使床土速效NPK含量迅速增加,速效氮的增加呈指数关系,高培肥处理的增幅大于低培肥处理,丘陵土的增加快于冲积土;速效磷含量随培肥水平的     

花铃期增温对棉花干物重累积的影响及其生理机制

以遗传背景相近的棉花(Gossypium hirsutum L.)品种泗棉3号和泗杂3号为材料,于2010年在南京农业大学牌楼试验站(118º50′E, 32º02′N)模拟全球温室化气候,研究花铃期增温对棉花干物质累积的影响及其生理机制。结果显示,增温2~3℃(龄期日均温33.5~35.2℃)的条件下,主茎功能叶SPAD值降低,蒸腾速率(T_r)、气孔导度(G_s)、胞间CO₂浓度(C_i)上升,但净光合速率(P_n)下降;棉铃对位叶可溶性蛋白含量大幅上升(Δ%>50%)、可溶性糖及可溶性氨基酸含量小幅下降(P<0.05)、C/N值显著下降(P<0.05);叶片POD、CAT活性大幅下降、MDA含量显著上升;泗杂3号相关指标变化幅度较泗棉3号小。说明尽管2~3℃的增温幅度较小,但在花铃期日均温(33.5~35.2℃)的条件下,植株已处于显著的热胁迫状态,光合产物累积能力受到抑制,棉铃对位叶光合产物输出能力显著下降, 棉株总干物质累积量下降20%左右;增温条件下植株水分吸收能力下降并因此受到一定程度的水分胁迫,但此条件下光合能力下降主要由非气孔因子所致,与叶片膜结构的严重受损关系密切;泗杂3号抗高温能力高于泗棉3号。     

不同水分条件及氮素处理对油茶嫁接苗养分含量的影响

为探明氮素对油茶嫁接苗在不同水分条件下叶片、根部养分含量变化,从而为油茶苗期合理施肥,提高抗性提供依据。以2 年生油茶嫁接苗为试验对象,对其在不同水分（土壤含水量分别为：28%~31%、15%~18%、9%~12%）和不同浓度氮素（0、0.375、0.75 g/株）条件下,通过生理生化试验方法,测定油茶嫁接苗叶片、根部C、N、P、K的含量。结果表明：在土壤水分胁迫条件下,施加低氮（0.375 g/株）更有利于苗木在土壤水分胁迫条件下C、N、P、K积累。在土壤水分轻度胁迫条件下,施加低氮、高氮均促进叶片、根部C、N、P积累,不能促进K的积累。在土壤水分重度胁迫条件下,施加低氮促进叶片C、N、P、K和根部C、N、K的积累,施加高氮不能促进叶片C积累,但能促进根部C、N的积累。     

水稻孕穗期在淹涝胁迫下施肥的优化选择及其作用机理

采用正交试验与对比试验相结合, 研究了N、 P、 K、 Zn、 Si肥和栽培密度各因子及其优化处理对孕穗期完全淹涝胁迫下早稻产量的影响与作用机理. 结果表明, 不同N肥和K肥水平对产量的影响达到了显著水平差异, 其各自的最适用量分别约为纯氮135 kg/hm2和纯钾120 kg/hm2; 适N高K能明显提高水稻的耐淹涝胁迫能力, N/K比宜介于1.1     

Influence of Soil Water Regimes on VA Mycorrhiza

A greenhouse trial was conducted with cassava inoculated with seven different VAM fungal species, i.e. Acaulospora longula, A. myriocarpa, Entrophospora colombiana, Glomus fasciculatum, G. manihotis, G. occultum and Scutellospora heterogama. A wet and a dry soil water regime was established to study the effect of water stress on performance of these fungi with a drought tolerant cassava clone. At harvest, N, P and K concentration was analysed in leaves, petioles, stems and roots.
In unstressed plants, five endophytes were effective whereas in stressed plants only three fungi improved growth beyond the non-mycorrhizal control. These were E. colombiana, G. manihotis and G. occultum which were most effective for P uptake under stress. Differential effects of VAM fungal species on root length and K. uptake were found. A. myriocarpa caused the greatest increase in length of feeder roots and G. occultum was one of the most effective for K uptake under both water regimes even though these fungi were not the most effective for dry matter production. Under each water regime, the concentration of N, P and K in leaves, petioles, stems and roots was influenced by the fungal species. Mycorrhizal endophytes differed in tolerance to dry soil conditions as found by root infection ratings. From the results it can be concluded that in addition to the improved P nutrition the enhanced root length and K uptake by VAM fungi may be important for drought tolerance of cassava.     

水分供应和氮素形态对水稻一些水分生理特征的影响

为探明不同水分供应和氮素形态对水稻一些水分生理特征的影响,设正常水分及50 g L^-1 PEG模拟水分胁迫及3种不同NH₄⁺-N/NO₃^--N比例（75/25,50/50,25/75）的处理,测定了水稻叶片的NO₃^-、Ca²⁺和Mg²⁺含量,叶片浸出液电导率,叶片相对含水量,叶片水分临界饱和亏以及叶片水势。结果表明,在NH₄⁺-N/NO₃^--N比例较低时,模拟水分胁迫使广陵香粳水稻幼苗吸收更多的NO₃^--N。模拟水分胁迫条件下,水稻幼苗叶片浸出液电导率随NH₄⁺-N/NO₃^--N比例的降低呈下降趋势,且在NH₄⁺-N/NO₃^--N比例为25/75时,叶片浸出液电导率低于正常水分培养条件下的叶片浸出液电导率。而在正常水分培养条件下,水稻幼苗叶片浸出液电导率随NH₄⁺-N/NO₃^--N比例的降低呈上升趋势。水分胁迫使高NH₄⁺-N/NO₃^--N处理水稻叶片相对含水量降低、水分临界饱和亏上升,但对低NH₄⁺-N/NO₃^--N处理（25/75）水稻叶片相对含水量和水分临界饱和亏影响很小。同样,低NH₄⁺-N/NO₃^--N处理削弱了水分胁迫对水稻叶片水势的降低。总体上说,低NH₄⁺-N/NO₃^--N能减轻水分胁迫对水稻水分生理的不良影响。     

氮肥形态及氮钾施用措施对水稻生长 和养分吸收的影响

为探明不同氮（NH4-N和NO3-N）源下，不同施钾水平及氮钾施用次序对水稻生长和养分吸收的影响，进行了温室盆栽试验。结果表明：在水稻生长早期（20d左右时），以NO3-N作为N源时水稻的生物产量和氮钾养分吸收量均显著高于NH4-N作N源的处理，但随着生长时期的延长，NH4-N源更能促进水稻的生长和养分吸收，因此，从整个营养生长时期来讲，铵态氮肥作为水稻N源更具有优越性。结果同时表明，氮肥施用效果与钾肥的施用水平有很大关系，在一般盆栽试验氮肥用量（纯N用量0.15 g/kg）水平下，施钾（K2O）量达到0.51g/kg时会导致水稻的生长及养分吸收量显著下降。铵钾施用次序对水稻的营养生长及养分吸收均有一定的影响，特别是施钾量较高时，铵钾在土壤中的交互作用会导致水稻因氮素供应不足而影响生长和养分吸收。     

The Effects of Prolonged Drought and Nitrogen Fertilizer on Root and Shoot Growth and Water Uptake by Winter Wheat

Winter wheat growing on a silty clay loam soil was protected from rainfall by a mobile shelter for 100 days from tillering to maturity. During this time the crop was either irrigated according to demand or grew on stored soil water. The effects of this high and low water supply, in combination with a high and low N supply, on root and shoot growth and water uptake were studied.
The crop given both N and water yielded 9.7 t/ha of grain (85 % DM), drought reduced this to 7.9 t/ha, low N to 4.3 t/ha and drought and low N to 3.8 t/ha. Yield reductions were mainly due to fewer grains being produced.
Little root growth occurred in the topsoil during the drought but there was compensatory growth in the subsoil provided that N fertilizer was given. The droughted crops rooted to 160 cm, about 20 cm deeper than the irrigated crops, but the amount of root in the deep subsoil was very small, less than 0.1 cm/cm³ ai 140–160 cm, compared with 5–9 cm/cm³ in the topsoil.
The crop demand for water at any given time was partitioned throughout the root system but atmospheric demand was only met whilst the topsoil was wet. The fertilized, droughted crop extracted all of the potentially available water to a depth of 80 cm and a mean rooting density of 1 cm/cm³ was necessary to achieve this. Uptake from below this depth was limited by root growth.
The limiting value of the potential soil water deficit was 170 mm, and weather records showed that this would be exceeded one year in ten, on average. The likelihood of yield reduction due to drought could be reduced on this soil by improving root growth below 80 cm depth, although the chances of achieving this are low as root growth was probably limited by poor soil structure.     

Temperature Regime of Azolla under Rice

The effects of different rice canopies on the temperature regime of the Azolla plants and their immediate environment were studied in a paddy field in the Philippines.
Diurnal temperature cycles were measured in the field with thermocouples. Without rice plants Azolla temperature reached of up to 41°C, which was 6°C above air temperature. The rice canopy reduced the temperature of Azolla by up to 5°C. The relationship between the temperature of Azolla and of its environment (air and floodwater) is discussed. Differences between the two planting patterns of rice were obvious. With 20 × 20 cm spacing temperatures were reduced to a greater extend and at an earlier rice crop stage than with double-narrow-row spacing. Under extremely high temperatures the nee canopy may improve the conditions for the growth of Azolla.