Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application

The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.     

长龄壮秧超稀植杂交稻生长和产量状况研究

[目的]了解长龄壮秧对超稀植杂交稻生长和产量的影响。[方法]设T1(30d)、T2(42d)T3(54d)3个秧龄处理,研究B优827、岗优725和D优527超稀植时的生长及产量情况。[结果]随着秧龄的延长,3个品种的最高分蘖期推迟。同一品种不同处理的单株最大茎蘖数无明显差异。岗优725的平均单株有效穗数为T1>T2>T3,其余两品种的为T2>T1>T3。3个品种T3处理的二次分蘖穗占总有效穗的比例下降,三次分蘖穗的比例增加。B优827和D优527的实收产量为T1>T2>T3,岗优725的为T2>T1>T3。不同品种对秧龄长短的反应有明显差异。[结论]秧龄对超稀植杂交稻的分蘖动态、有效穗及其组成、经济性状和产量都有一定的影响。在良好管理的基础上,合理选用品种,长龄壮秧超稀植杂交稻仍能保持高产水平。     

Spatial variation in organic carbon, nutrients and microbial biomass contents of paddy soils in a hilly red soil region

The contents of soil organic C (SOC), total N (TN), total P (TP), dissolved N (D_N), Olsen-P, and microbial biomass C, N, P (B_C, B_N, B_P) of 254 paddy soils (0–18 cm in depth) in a hilly red soil region of subtropical zone of China were studied. The results showed that the contents of SOC, TN, B_C, B_N and D_N of paddy soils at the bottom of hills were 14.6%, 13.6%, 24.6%, 20.4% and 95.8% higher than those at the foothill, respectively. The Olsen-P content of paddy soils at the foothill was 33.3% higher than that at the bottom of hills. However, the differences in TP, B_P and available P (the sum of B_P and Olsen-P) contents were not significant between the two positions. In addition, the ratios of soil C/P, B_C/B_P and B_C/SOC of paddy soils at the bottom of hills were 12.7%, 28.5% and 8.2% higher than those at the foothill, respectively, but the differences in ratios of soil C/N, B_C/B_N, B_N/TN and B_P/TP were not statistically significant between various positions. __________ Translated from Plant Nutrition and Fertilizer Science, 2007, 13(1): 15–21 [译自: 植物营养与肥料学报]     

低温锻炼对冷胁迫下甜瓜幼苗抗氧化酶活性与质膜透性的影响

以“玉金香”甜瓜(Cucumis meloL.)为材料,研究了经过10昼夜15/10、10/5℃低温锻炼与25/15℃对照处理后再经过4昼夜2℃冷胁迫处理后甜瓜幼苗抗氧化酶活性与质膜透性的变化规律。结果表明,与对照相比较,经低温锻炼的甜瓜幼苗膜系统、叶绿素和MDA含量均发生了一定变化,SOD、POD含量显著增加;在之后的冷胁迫处理过程中,经低温锻炼的甜瓜幼苗真叶中SOD、POD活性显著高于CK,而MDA含量显著低于CK。说明经较长时间的低温锻炼能使甜瓜幼苗增强对更低温度的适应性,明显提高抗寒能力,但锻炼温度的量值不同,甜瓜幼苗抗寒能力的提高程度有一定差异。     

茄种衣剂1号对茄子发芽及幼苗生长的影响

用西北农业大学园艺系研制的“茄种衣剂１号”包衣的种子，其发芽率、发芽势和发芽指数分别较对照提高２０．０％，１９５．２％和７８．６％，平均发芽天数缩短２．５ｄ，且种子包衣利于幼苗生长。用人工快速老化测定种子的耐藏性表明，人工老化处理不仅不降低包衣种子发芽，反而极明显地加速了种子萌发和幼苗生长     

耕作方式对稻田土壤有机碳转化的影响

为阐明免耕土壤碳转化过程对土壤同碳的影响,设计了4种耕作方式,包括稻草还田免耕(NTS)、稻草还田常耕(CTS)、无稻草还田免耕(NT)和无稻草还田常耕(CT),在水稻生育期分层(0~5、5~12和12~20 cm)采集稻田耕层土壤样品进行测定.结果表明,在0~5 cm土层,土壤有机碳、活性碳、热水提取碳水化合物、全酚...     

利用热力学参数对水稻土供钾状况的研究

本文在盆栽试验条件下,研究了水稻土供钾状况与几个热力学参数的关系。结果表明:土壤钾位势缓冲容量(PBC~k)、平衡活度比(AR_o~k)、钾位(Z)及钾离子在土壤中的扩散系数(D_k)单独使用难以说明水稻土供钾状况,但PBC~k、Z及D~k在衡量水稻土供钾状况时有相互补充的作用。活性钾(-△K_o)能较好地反映水稻土供钾状况。 PBC~k与土壤阳离子交换量(C·E·C)呈显著正相关,因而PBC~k可能与土壤胶体表面的电荷性质及密度有关。     

水稻持久抗瘟性生化鉴定的研究

对２个持久抗瘟性和２个感病水稻品种苗期接种稻瘟菌，分析接种前后叶片内的生化指标，结果表明：接种后感病品种过氧化物酶活性持续增加，接种９６ｈ后酶活性急剧上升，而持抗品种过氧化物酶活性增幅较少．接种前后持抗和感病水稻品种叶片蛋白质含量变化均不明显，前者蛋白质含量显著高于后者．接种后０～６ｄ内持抗品种叶片可溶性糖含量均低于感病品种，而持抗品种游离氨基酸含量高于感病品种．初步认为：接种后叶片的过氧化物酶活性可作为鉴别水稻品种抗瘟性的依据     

壳聚糖对黄瓜萌芽种子及幼苗生理生化特性的影响

以黄瓜(cucumis sativus)种子及幼苗为试材．研究了壳聚糖处理后的生理生化特性变化．结果表明：壳聚糖能够促进叶绿素合成和子叶增重．提高过氧化氢酶(CAT)、过氧化物酶(POD)和L-苯丙氨酸解氨酶(PAL)的活性，增强超微弱发光强度。     

水稻栽培技术路线、模式表与回归数模配套应用的研究

针对安徽省水稻产量结构的薄弱环节与主要技术障碍,提出高产优质高效的栽培技术路线.以此路线为纲,拟订“模式表”,选定供试栽培技术因子,多点同步进行“模式表”应用验证和正交旋转组合设计试验,供试因子零水平与其它栽培条件力求与“模式表”保持一致.试验数据经统计分析求得“回归数模”,模拟选优并参考示范验证结果修订“模式表”.“栽培技术路线指明了主要栽培技术目标和措施;在供试5项栽培措施方面“回归数模”可以指导“模式表”的灵活应用;按“模式表”栽培既可以确保“技术路线”的具体实施,又可以为“回归数模”的应用创造必要的条件.