Controlled-release fertilizer is one of the best fertilizer management strategies for improving the yield and nitrogen use efficiency of transplanted seedling rice. Wet direct-seeded rice has gradually replaced transplanted seedling rice since it saves labor. In addition, it is conducive to mechanization promotion. However, the effects of controlled-release fertilizers on wet direct-seeded rice remain largely unknown. A two-year field experiment aimed to compare the effects of controlled-release blended fertilizer at two rates (basal N to tiller N ratio = 7:3 (CRBF+U), CRBF alone), urea at two rates (basal–tiller ratio of 4:6 (U40), 6:4 (U60)) and a control (no N fertilizer) on the ammonia volatilization (AV) loss, nitrogen runoff loss, accumulation, transport, utilization and yield of rice. The nitrogen runoff loss in wet direct-seeded rice paddy fields was concentrated from sowing to the three-leaf and one-leaflet stage, and the loss rat was lowest after CRBF+U (11.41–12.94%). AV loss rate was lowest after CRBF (3.41%), followed by CRBF+U (3.55–3.89%). CRBF+U increased nitrogen accumulation by extending the duration of rapid nitrogen growth and accelerating maximum nitrogen growth. CRBF+U also increased the nitrogen transport rate of stems, sheaths and leaves from full heading to maturity, and intensified the increase in nitrogen in panicles, increasing the harvest index, agronomy utilization rate and apparent utilization rate of nitrogen. Finally, the grain number per panicle, seed-setting rate and actual yield of rice were significantly improved. In conclusion, CRBF+U can reduce nitrogen runoff loss and AV loss and can improve the yield and nitrogen use efficiency of wet direct-seeded rice.

为探讨不同类型氮肥按不同基蘖肥比例配施对直播稻田径流氮流失、氨挥发及氮肥利用率的影响,本研究开展了田间小区试验,设置了7个施氮处理,即不施氮肥的空白对照(CK)、普通复合肥(基肥)与尿素(分蘖肥)基蘖肥配比4∶6(U40)和6∶4(U60)、控释掺混肥(基肥)与尿素(分蘖肥)基蘖肥配比7∶3(C70)和10∶0(C100)、海藻多糖尿素基蘖肥配比4∶6(H40)和6∶4(H60),每个处理设置3个重复.结果表明:径流氮流失量主要集中在基肥施入后,以铵态氮(NH+4-N)为主,与U60处理相比,C100、H60、U40、C70和H40处理总氮流失量分别减少了7.20％、13.36％、24.30％、26.41％和35.92％;不同氮肥之间的氨挥发损失量和损失率呈现出普通复合肥与尿素配施处理＞海藻多糖尿素处理＞控释掺混肥与尿素配施处理;与U60处理相比,U40、H60、H40、C70和C100处理的氨挥发总损失量分别降低了7.89％、20.81％、27.84％、42.08％和47.00％,C70、C100处理降低效果显著(P＜0.05);与U60、C100和H60处理相比,U40、C70和H40处理径流的总氮流失量分别降低了24.30％、20.70％和26.04％.氮肥后移的U40、C70和H40处理的径流氮流失及氨挥发损失均有所降低,且不影响产量;C70处理产量和氮肥农学利用率均为最高,分别为9116.67 kg·hm-2和29.64 kg·kg-1,且氮肥表观利用率为41.99％.研究表明,C70和C100处理均能显著降低稻田径流氮流失,减少氨挥发损失,提高氮肥利用率和直播稻产量.综合考虑产量及环境影响,以控释掺混肥(基肥)与尿素(分蘖肥)按基蘖肥比7∶3配施更值得推广.

水稻直播条件下,苗期防涝排水会增大稻田氮素流失风险,适当调整氮肥基施和追施的比例,可降低这种风险.在N、P2O5、K2O用量分别为180、75、105 kg?hm-2的条件下,以江汉平原稻田氮肥习惯施用比例(基肥、分蘖肥、穗肥比例为6:4:0)为对照(CK),另设7个氮肥基追比的处理(基肥、分蘖肥、穗肥的比例分别为:T1,4∶6 ∶0;T2,4:4∶2;T3,4∶2∶4;T4,2∶6∶2;T5,2∶4∶4;T6,0∶8∶2;T7,0∶6∶4),开展田间试验,实测不同处理下氨挥发损失、氮径流损失和水稻成熟期的产量.结果表明:T7处理总氮径流流失最小(8.79 kg·hm-2),T3处理的氨挥发损失最小(11.90 kg? hm-2),T7处理总的氮素损失最小(22.89 kg·hm-2),T4处理的产量最高(9 270.0 kg·hm-2)、T5处理的产量次之(9 150.0 kg·hm-2).综合考虑氮素损失和水稻产量,推荐基肥、分蘖肥、穗肥中氮素的施用比例为2∶ 6∶ 2或2∶ 4∶ 4.

为研究不同氮肥基追比对直播稻产量、氮素利用率的影响,以深两优332为供试材料,采用田间小区试验,设置8个不同氮肥基追比处理,基肥:分蘖肥:穗肥比例分别为0:8:2(T1)、0:6:4(T2)、2:6:2(T3)、2:4:4(T4)、4:6:0(T5)、4:4:2(T6)、4:2:4(T7)、6:4:0(农民习惯施肥,T8),以不施氮肥(T0)为对照(CK),以期筛选出最适合直播稻的氮肥施用方法.结果表明:分蘖盛期、拔节期以T5处理的干物质积累量最高,明显高于T8处理,分别比T8处理高11.03％、4.04％,且拔节期T5处理干物质积累量显著高于T1、T2处理,分别比T1、T2处理高9.19％、11.96％;孕穗期以T6处理的干物质积累量最高,比T5处理高6.12％;成熟期以T5处理的干物质积累量最高,比T8处理高12.68％.与T8处理相比,氮肥基施40％可以增加直播稻在分蘖盛期、拔节期的干物质积累量,同时与T8处理相比,氮肥适量后移作穗肥施用(T6处理)可增加直播稻孕穗期干物质积累量.在产量上,T5、T6、T7处理之间不存在显著差异,但T5处理与其他5个处理及CK之间均存在显著差异,且T5处理的产量比T8处理高7.68％,比T1、T2处理高27％～30％.由此可以看出,氮肥适量基追配施以及氮肥适当后移可以显著提高直播稻的产量.在氮肥吸收利用方面,T5处理和T6处理的氮肥吸收利用利率和农学利用率不存在显著差异,但T5处理与其他处理间均存在显著差异,且T5处理的氮肥吸收利用率和农学利用率分别比T8处理高7.61％、15.04％,分别比T1处理高21.79％、73.68％,分别比T3处理高14.02％、23.47％,氮肥适当后移可以提高直播稻氮肥利用率.通过比较直播稻氮肥不同基追肥配施下干物质量、产量以及氮肥利用率可以得出,基肥:分蘖肥:穗肥为4:6:0和4:4:2为直播稻的较佳施肥方法.

【Objectives】 Nitrogen loss from agricultural soils is an environmental concern worldwide and the purpose of this paper is to investigate the impact of the types of nitrogen fertilizers and planting methods on reducing nitrogen loss from surface runoff and ammonia volatilization from paddy field. 【Method】 The experiment was conducted in a field with the rice established either from machine transplanting (MTR) or direct drill (DSR). Added to these were four nitrogen fertilizations: conventional fertilization (FFP), slow-controlled fertilizer combined with urea (CRF) and seaweed polysaccharide nitrogen fertilizer (HTN), with no nitrogen application as control (CK). In each treatment, we measured nitrogen loss from the surface runoff and ammonia volatilization. 【Result】 Nitrogen lost from surface runoff was dominated by ammonium nitrogen (NH4+-N), with the loss from the drainage prior to the planting accounted for approximately 52% of the total nitrogen loss from the surface runoff. The impact of fertilizers on total nitrogen loss from the surface runoff was ranked in the order of FFP > HTN > CRF, the same as the loss rate and intensity of ammonia volatilization (AV) for both MTR and DSR. Compared with FFP, CRF and HTN each in combination with MTR reduced the AV loss during the whole growth season by 12.5% and 4.3% respectively, with their associated AV intensity reduced by 43.1% and 17.8% respectively; when combining each with DSR, they reduced AV loss rate by 23.2% and 12.2% respectively, with their associated AV intensity reduced by 53.3% and 26.8% respectively. Compared with FFP, CRF and HTN increased the yield by 9.31% and 4.70%, respectively, for rice planted using MRT, and 9.25% and 4.91%, respectively, for rice planted using DSR. 【Conclusion】 During the whole growth season, planting rice using DSR increased the AV flux, nitrogen loss rate and AV intensity than planting with MTR. The impact of fertilizers on nitrogen loss from the surface runoff was ranked in the order of FFP > HTN > CRF. When the amounts of all applied nutrients were the same, selecting an appropriate nitrogen fertilizer with a rational combination with basal fertilization and tillering-stage dressing can not only reduce nitrogen loss, but also improve nitrogen use efficiency and ultimate yield.

The improvement of grain quality in aromatic rice is very important for farmer to increase their income. Present study was conducted with a two-year field experiment and three aromatic rice cultivars in order to study the effects of exogenous alpha-ketoglutaric acid on yield formation, grain quality characters and the biosynthesis of 2-acetyl-1-pyrroline (2-AP, key component of aromatic rice's fragrance) in aromatic rice. At heading stage, 0.50 mmol L-1 (T1) and 1.00 mmol L-1 (T2) alpha-ketoglutaric acid solutions were overhead sprinkle to aromatic rice plants, respectively while the treatment which was overhead sprinkled with distilled water was set as control (CK). The results showed that 17.34%-33.04% and 21.39%-34.74% higher grain 2-AP contents were recorded in T1 and T2 treatments, respectively. Compared with CK, T1 and T2 treatments significantly reduced the transcript level of gene BADH2 which is related to the 2-AP biosynthesis in aromatic rice. 3.86%-7.51% higher grain protein contents and 1.15%-3.37% higher head rice rates were also recorded in alpha-ketoglutaric acid treatments than CK. Moreover, T1 and T2 treatments remarkably decreased the chalky rice rate, chalkiness and grain amylose content. However, there was no remarkable difference in grain yield and related trails (effective panicle number, grain number per panicle, seed-setting rate and 1000-grain weight) among CK, T1 and T2 treatments. In conclusion, application of exogenous alpha-ketoglutaric acid enhanced 2-AP biosynthesis and improved grain quality of aromatic rice.

为改进江汉平原地区中稻氮肥施用方法.采用田间小区试验,设置当地常规施肥(FFP)、缓控释肥与尿素配施(CRF)、海藻多糖氮肥替代(HTN)及不施氮对照(CK)4个氮肥管理,研究不同氮肥运筹对机插稻、直播稻氮素吸收、转运及氮肥利用率的影响.结果表明:水稻分蘖前期机插稻的干物质积累量FFP处理比CRF、HTN处理分别高41.83％、19.89％,直播稻CRF处理比FFP处理高4.84％;分蘖盛期-拔节期机插稻干物质积累量、氮素积累量占总干物质积累量、氮素积累量的比例比直播稻分别高12.58％～17.21％、15.24％～67.24％;拔节期-成熟期各处理的干物质积累量表现为CRF>HTN>FFP,且直播稻的干物质积累量占总干物质积累量的比例比机插稻高12.72％～17.61％,CRF处理机插稻和直播稻的穗部干物质积累分别比FFP处理增加了19.71％和14.82％,HTN处理分别增加了13.10％和3.93％.在氮素的积累、转运、利用上机插稻与直播稻具有相似性,均表现为CRF>HTN>FFP,CRF处理下机插稻和直播稻氮肥表观利用率分别比FFP处理增加了38.02％和34.57％,HTN处理分别增加了11.82％和13.33％.缓控释肥与尿素配施、施用海藻多糖氮肥,都有利于提高杂交中稻氮素的积累、转运和利用,同时氮肥适当后移有助于直播稻的氮素吸收.

[目的]湖北平原湖区6—7月降雨较多,因此,需合理利用降雨资源,确定雨后田间适宜蓄水深度.[方法]结合湖北平原湖区生产实际,针对中稻机插秧和直播2种播种方式,在中稻分蘖期进行了不同蓄水深度(4、8、12和16 cm)测坑试验.[结果]当模拟机插稻蓄水深度4 cm、直播稻蓄水深度8 cm时,水稻叶片的光合速率最高,10～20 cm土层的根系干质量最大,产量最高;对模拟机插稻,蓄水深度8、12、16 cm的处理,产量较4 cm处理分别降低3.75％、9.49％和11.97％;对直播稻,蓄水深度4、12、16 cm的处理,其产量较8 cm处理分别降低5.03％、12.87％和16.45％.[结论]在本试验所研究的蓄水深度下,模拟机插稻与直播稻在分蘖期适宜的蓄水深度分别为4 cm和8 cm.当遭遇大暴雨导致农田排水不畅时,在允许水稻减产12％左右的情况下,分蘖期机插稻蓄水上限为16 cm,直播稻蓄水上限为12 cm.