【作者】 黄见良；

【导师】 邹应斌； 彭少兵；

【作者基本信息】 湖南农业大学 ， 作物栽培学与耕作学， 2003， 博士

【摘要】 中国氮肥消耗量占世界总量的30％，中国稻田氮肥用量高于世界平均水平的70％，但水稻的氮肥利用率低于一些主要产稻国家。提高中国稻田氮肥利用率，不仅有利于增加水稻的施肥效益，而且可以减少稻田氮肥过量施用所带来的环境影响。本项研究于2002年旱季和2003年旱季在菲律宾国际水稻所，以及2001年和2002年在中国湖南两个不同的生态气候区的大田条件下进行。采用田间试验，结合¹⁵N示踪技术和水稻液培试验，系统地研究了氮肥施肥时期、氮肥用量和施用方法对水稻的生长发育、稻谷产量及氮肥利用率的影响，客观分析和确立了测定水稻氮肥吸收利用率的适宜方法。主要的研究结果如下： （1） 水稻自移栽至幼穗分化始期，肥料氮素对水稻的生长发育影响较大，植株吸收的氮素60％以上来自肥料。至成熟期，水稻地上部积累氮素，有40％来自肥料，其中20％来自幼穗分化始期追肥，来自分蘖期和基肥各10％左右； （2） ¹⁵N分别标记基肥、分蘖期追肥和幼穗分化始期追肥的研究表明，水稻对基肥吸收的持续时间长达30天，对分蘗期追肥吸收的持续时间为14天，对幼穗分化始期追肥吸收的持续时间仅为10天。幼穗分化期水稻对氮素吸收速率最大，在此时期追肥后水稻氮素的最大吸收速率达9.5 kgN hm^-2 d^-1，其中对¹⁵N标记肥料的最大吸收速率为5.4～6.4 kgN hm^-2 d^-1； （3） 水稻对不同时期施用的氮肥其吸收利用率相差较大。在热带地区，¹⁵N示踪法测定的水稻对幼穗分化期追肥的的吸收利用率为59％，对分蘖期追肥和基肥的吸收利用率分别为26％和24％，差减法测定值分别为67％、54％和45％； （4） 只要选择某一时期不施氮处理作为对照区，除基肥以外差减法测得的氮肥吸收利用率与¹⁵N示踪法的测定结果相接近，但如果用全生育期均没有施用氮肥的空白区作为对照，由于施肥的激发效应而偏高导致差减法测定值偏高； （5） 水稻与某些旱地作物相似，在抽穗后植株组织中的氮素存在着挥发损失，在分蘖期吸收的¹⁵N至成熟期通过这一途径损失的氮素占原吸收总量的16％，幼穗分化期吸收的氮素至成熟期通过这一方式损失其吸收总量的13％； （6） 不同的叶绿素仪对同组水稻叶片样品测定值之间存在偏差，最大偏差达2.7个读数单位，在进行实时实地氮肥管理时，应考虑这种偏差带来的影响，试验前有必要对各台仪器进行标准化处理或调节补偿值; （7）中国杂交稻汕优63在热带生态气候条件下的生物产量与热带釉稻IR72相当，氮肥的吸收利用率与差异不显著。因此可以认为，品种不是导致中国稻田氮肥利用率低的主要原因; （8）在中国湖南亚热带与菲律宾热带生态气候条件下进行的相同设计的试验进行比较分析表明，中国稻田的氮肥吸收利用率并不如先前报道的那样低，汕优63在中国湖南亚热带生态气候条件下的氮肥吸收利用率平均为65%，而在菲律宾国际水稻所的吸收利用率为50%。但中国稻田氮肥的农学利用率和生理利用率极显著低于热带地区; （9）在中国应用实时实地氮肥可以降低氮肥用量30%一50%，水稻产量稳中有升，氮肥的农学利用率可以由农民的习惯施肥法的4k泌ralnk扩N提高到13一巧kgGralnug-，N。因此，实时实地氮肥管理模式在中国稻田氮肥管理中具有重要的指导意义。更多还原

【Abstract】 Nowadays, about 30% of world nitrogen (N) fertilizer is consumed by China. Average rate of N application for rice production in China is higher and fertilizer-N use efficiency (NUE) is lower compared with that in other major rice growing countries. Therefore, it is profitable not only on the profit of rice production, but also on the help to release farming environmental stress. The field experiments were conducted in 2001 and 2002 at Hunan site in China, and in 2002 dry season (DS) and 2003DS at IRRI farm in Philippines. The objectives are: (1) to determine the effect on rice growth by fertilizer-N application timing, rates and methods; (2) to identify the hypothesis on the causes of low NUE of irrigated rice in China; (3) to compare the recovery efficiency estimating by 15N dilution method and ’difference method’ through frequently sampling; and (4) to test the effect on improving NUE of irrigated rice in China through real-time nitrogen management and Site-Specific Nutrient Management (SSNM). The results showed as followings:1. At rice earlier growing season, fertilizer-N was the most important contribution to the rice nitrogen, it accounted for 60% from total nitrogen (TN) from transplanting to panicle initiation (PI); At maturity, 40% of nitrogen derived from fertilizer, among them, fertilizer-N (FN) uptake at PI contributed 20%, and mid-tillering (MT) or basal contributed 10% respectively;2. The 15N uptake rate was greatest while FN applied at PI, and absorbed the approximate maximum amount in 9 days after fertilization; The highest uptake rate based on total N accumulation was 9.5 kgN hm-2 d-1, and 5.4~6.4 kgN hm-2 d-1 from 15N-fertilizer at PI. The rice plant reached the maximum 15N accumulation in 14 days after FN topdressing at MT, but 30 days after FN applied as basal;3. The difference of nitrogen recovery use efficiency (RE) was significant among various FN application stages. RE were 59%, 26%, and 24% determined by 15N dilution method when FN applied at PI, MT and basal, and which were 67%, 54%, and 45% estimating by ’difference method’ respectively;4. RE determined by ’difference method’ were always overestimated due to priming effect if using the blank plots as control. And it was found that if set a proper control for ’difference method’, the measurement value is highly close to the determination value that is estimated by I5N dilution method when fertilizer was topdressing at MT or PI.5. It was found that, rice plant existed a pathway to lose nitrogen by volatilization from plant tissues at later growing season. According to the I5N balance at maturity, the nitrogen loss proportion was 16% from 15N uptake at MT, and 13% from I5N uptake at PI;6. The differences in SPAD readings were statistically significant among the six meters and the difference between two meters was as large as 2.7 units. Such magnitude of discrepancy should be considered when different SPAD meters are used in a same study;7. It was found that the difference of biomass production and nitrogen uptake by rice was insignificant between Chinese hybrid rice Shanyou63 and tropical indica rice IR72 under tropical ecosystem conditions. Therefore, it was to say, variety is not the main cause to contribute the low RE of irrigated rice in China;8. Comparison was done to the RE, agronomic use efficiency (AE), and physiological use efficiency (PE) between tropical ecosystem at IRRI farm, in Philippines, and in sub-tropical ecosystem at Hunan site, in China. The results showed that RE was 65% at Hunan site, higher than that at IRRI site. But the AE and PE in China was significantly lower than that at IRRI site due to poor yield response to fertilizer application at Hunan, China;9. Among different nitrogen management strategies, real-time nitrogen management and SSNM could reduce N application rate but maintain the grain yield or increased the grain yield in some cases, compared with that under fanner’s practice at Hunan, China. Therefore, the AE and PE were significantly improved simultaneously u更多还原