淹水厌氧培养对水稻土中酶活性的影响

An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease （P ≤ 0.05） of fluorescein diacetate （FDA） and /3-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited （P ≤ 0.05） arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation （W1 and W2 treatments） significantly increased （P ≤ 0.05） FDA, alkaline phosphatase, and /3-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas /3-D-glucosidase activity decreased. A significant difference （P ≤ 0.05） was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however,/3-D-glucosidase and urease were usually not significant （P ≤ 0.05）. No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.     

长江中游水稻土潜育作用的特点

The gleyization of representative paddy soils in the middle reaches of the Yangtze River was characterized, taking oxidation-reduction potential(Eh), the amount of active reducing substances and the forms of iron and manganese as the parameters. The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an average. The degree of gleyization of different horizons was graded as ungleyed, slightly gleyed, mildly gleyed and gleyed. The Eh of the four grades was > 500, 300-500, 100-300 and < 100 mV, respectively, and the corresponding amount of active reducing substances was < 1, 1-7, 7-30 and > 30 mmol_c kg^-1, respectively. The amount of ferrous iron of the four grades was < 0.5, 0.5-5, 5-25 and > 25 mmol kg^-1, respectively. The extent of gleyization of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horizon was less than 30 cm, 30-60 cm or more than 60 cm.     

稻作区保护性耕作和小麦种植对土壤养分的影响

该文采用4个处理：常规犁耕-休闲(DTF)、常规犁耕-小麦(DTW)、保护耕作-休闲(CTF)和保护耕作-小麦(CTW)，分析了10年后稻作区保护性耕作和小麦种植对土壤养分的影响。结果表明：在CTW处理下，土壤全N分别较DTF、DTW和CTF处理高10.03%、26.81%和23.17%。土壤碱解N也呈现相同的趋势；土壤全P，CTW处理下较DTF、DTW和CTF处理分别高12.93%、15.86%和21.36%。在0～10 cm土深，CTW处理下土壤有效P分别是DTF和DTW处理下的4.5和2.1倍；土壤全K在4种处理中与全N和P有类似的趋势；与处理DTF相比，Ca₂-P、Ca₈-P、Al-P、Fe-P、O-P和Ca₁₀-P在CTW下的含量迅速增加；代换态、易还原结合态、碳酸盐结合态、有机质结合态和无定形态Fe、Mn和Cu在CTW处理下含量降低，而残渣态Fe、Mn和Cu则增加。代换态和易还原锰结合态Zn在CTW处理下的含量增加，而相应地，无定形态和有机质结合态Zn则显著降低。而且，在有效Fe、Cu和Mn降低的同时，有效的Zn增加；稻作区，保护性耕作和小麦种植不仅增加表土层土壤养分的含量，而且可通过影响P、Fe、Mn、Zn和Cu的形态，缓解Fe和Mn对作物的毒害。     

The effect of soil flooding on the transformation of Fe oxides and the adsorption/desorption behavior of phosphate

As repeatedly reported, soil flooding improves the availability of P to rice. This is in contrast with an increased P sorption in paddy soils. The effects of soil flooding on the transformation of Fe oxides and the adsorption/desorption of P of two paddy soils of Zhejiang Province in Southeast‐China were studied in anaerobic incubation experiments (submerging with water in N₂ atmosphere). Soil flooding significantly increased oxalate‐extractable Fe (Fe_ox), mainly at the expense of dithionite‐soluble Fe (Fe_DCB), as well as oxalate‐extractable P (P_ox), but decreased the ratio of P_ox/Fe_ox. Flooding largely increased both, P adsorption and the maximum P adsorption capacity. The majority of newly sorbed P in the soils was P_ox, but also more newly retained P was found to be not extractable by oxalate. Flooding also changed the characteristics of P desorption in the soils. Due to a decrease of the saturation index of the P sorption capacity, P adsorbed by flooded soils was much less desorbable than that from non‐flooded soils. There are obviously significant differences in the nature of both, the Fe_ox and P_ox fractions under non‐flooded and flooded conditions. The degree of the changes in Fe_ox, P_ox, P adsorption and P desorption by flooding depended on the contents of amorphous and total Fe oxides in non‐flooded soils. Our results confirm that the adsorption and desorption behavior of P in paddy soils is largely controlled by the transformation of the Fe oxides. The reasons of the often‐reported improved P availability to rice induced by flooding, in spite of the unfavorable effect on P desorbability, are discussed.     

旱直播稻田杂草群落演替规律及化学除草的研究

北方地区的旱直播稻田杂草群落属于水旱共生型复合群落，具有2个杂草发生高峰期，第1次高峰期为旱生型杂草，第2次高峰期以水生及湿生型杂草为主导群落．用百草枯除苗前大草，秧苗3叶期用“快杀稗＋苯达松”茎叶处理，杂草综合防效可达95％以上．     

两系法籼粳亚种间杂交稻产量因素与产量关系的研究

为了选育产量因素高度协调的籼粳亚种间杂交稻，有必要对其穗料结构进行理论分析。通过对２４个两系法籼粳亚种间组合的产量因素与产量的遗传相关分析，得出以下结论：亚种间杂交稻单株粒重显著高于品种间杂交稻，２４个组合中有６个组合与汕优６３比有正向竞争优势；产量因素中，每穗总颖花粉，每穗实粒数和千粒重与单株粒重的遗传相关系数为正值并达显著水平。     

新辟红壤性稻田适宜施钾量研究

以耕型砂岩红壤开辟的新稻田为供试土壤，以杂交水稻——华联二号为供试作物，研究了新辟红壤性稻田不同施钾水平对早、晚稻的生育和营养特性、产量及土壤供钾能力的影响，并由此提出了新辟红壤性稻田早、晚稻的适宜施钾量。     

稻作制与有机肥及地下水对水稻土硫素状况的影响Ⅰ．全硫和有效硫含量

为探明耕作、施肥、灌溉等农艺措施对水稻土硫素状况的影响，研究了在长期定位试验条件下稻作制、有机肥用量及地下水位对水稻土全硫及有效硫含量的影响。结果表明，不同稻作制间，耕层土壤全硫含量以稻－稻－冬泡最高，稻－稻－冬绿次之，稻－稻－冬油最低；有效硫含量则以冬绿处理最高，冬泡处理最低；不同有机肥施用水平之间，耕层土壤全硫含量为常量有机肥处理最高，高量有机肥处理居中，化肥处理最低。高地下水位能提高土壤中全硫含量，但不利于土壤硫的有效化。     

预测二化螟的生物学参数和数学模型

本文研究了种植杂交稻后,二化螟的发育历期、积温、期距、繁殖能力、种群生存率和为害量等参数,并组建了预测模型.     

汕优63生长后期及其再生稻的光合产物分配规律研究

应用＾１４Ｃ示踪技术，研究了杂交中稻汕优６３生长后期及其再生稻光俣产物的分配规律。结果表明，头季后期的光合产物一半以上运往头季穗部，８．２％－１０．１％分配到再生稻穗部。分配到再生节位的光合物以倒２，３节位最多，主要运往茎和鞘中。再生稻的光合物主要输往穗部，并以倒２，３，４节位再生穗的分配比例最大。