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用田间试验与化学分析相结合来研究水稻不同生育期的需氮情况。试验是在浙江省分布较广的三种水稻土:黄斑坤、青紫泥和小粉土上进行。选用各种早、晚稻品种进行了三年试验,所得结果归纳如下: 1.在稻穗分化初期,检定半展开叶片或针叶中的天门冬酰胺,如有出现,表示水稻植株中氮素营养充足,无需追施氮肥;否则,应追施穗肥。检定天门冬酰胺可作为晚稻是否施用穗肥的诊断方法。 2.就早稻而言,稻穗分化期和拔节期几乎同时进行。这时施用氮肥会造成节间伸长,引起倒伏。因此氮肥须延至抽穗期使用。在试验条件下,检定叶鞘中淀粉含量A/B比[即淀粉碘反应的叶鞘长度(A)/叶鞘总长度(B)],大于0.56～0.70,表示氮营养不足,喷施尿素,可提高产量;当A/B比小于0.4～0.5,表示不需要氮素,喷施尿素,对各品种增产或减产效果均不显著。在抽穗期进行叶鞘淀粉碘反应检定,可作为早稻是否需用粒肥的诊断。 3.水稻各生长期对土壤有效氮(0.5N E_2SO_4水解)的需要是不同的。品种农垦58在分蘖期,土壤有效氮低于6.7毫克/100克土,分蘖少;但也不要超过7.3毫克/100克土。在幼穗分化期,土壤有效氮每百克干土低限为6.4毫克,高限为7.3毫克。当土壤有效氮在以上两生育期如小于低限或大于高限,则水稻生长不正常,产量很低。
Field experiments and chemical analysis were used to study the nitrogen demand during different growth stages of rice. The experiment was carried out on three paddy soils widely distributed in Zhejiang Province: Huangkuankun, Qingziju and small silt. A variety of early and late rice varieties were selected for three years and the results are summarized as follows: 1. In the early stage of rice panicle, the asparagine in semi-expanded leaves or needles was tested, if any appeared, which indicated that nitrogen nutrition Adequate, without topdressing nitrogen fertilizer; otherwise, should be topdressing spike. Asparagine can be used as a diagnostic method for applying panicle fertilizer to late rice. 2. In the case of early rice, panicle differentiation and jointing stages are almost simultaneous. At this time the application of nitrogen will cause internodal elongation, causing lodging. Therefore, nitrogen must be extended to the use of heading. Under the experimental conditions, the starch content A / B ratio (ie, the length of the sheath (A) / the total length of the sheath (B)) of the leaf sheath was tested, which was greater than 0.56-0.70, indicating insufficient nitrogen nutrition. Yield; when the A / B ratio is less than 0.4 ~ 0.5, it means no need of nitrogen and spraying urea, and the effect of increasing or decreasing yield of all varieties is not significant. Sheath Starch iodine reaction at heading stage, can be used as a diagnostic map for early rice granulation. 3. The demand of soil available nitrogen (0.5N E_2SO_4 hydrolysis) in different growth stages of rice is different. Variety Nongken 58 At the tillering stage, soil available N was less than 6.7 mg / 100 g soil, less tillers; but no more than 7.3 mg / 100 g soil. During panicle differentiation, the lower limit of soil available nitrogen per 100 grams of dry soil was 6.4 mg and the upper limit was 7.3 mg. When soil available nitrogen is less than the lower limit or higher than the upper limit during the above two growth stages, the rice is not normally grown and the yield is very low.