Zhang Yuping

Absorption, Distribution, and Translocation of Nitrogen at Growth Stages in Oilseed Rape Plant

The differences of concentration and distribution of nitrogen in crop depend on organs and growth stages, and nitrogen redistribution in different organs will be occurred at different stages; these differences are related to the transfer of growth center. Consequently, the high crop yield depends not only on the high amount of nitrogen absorption, but also on the high efficiency of nitrogen redistribution. The objective of this study was to reveal the law of nitrogen absorption, distribution, and translocation in oilseed rape plant at different growth stages using two winter oilseed rape cultivars with the 15N labeling method in sand culture under Hoagland complete nutrient solution conditions. The results (average value from the two cultivars) indicated that 83.5% of nitrogen absorbed at the seedling stage, and 67.3% of nitrogen absorbed at the stem elongation stage, were distributed to leaves; 79.1% of the nitrogen absorbed at flowering stage was contained in leaves and stems, with 42.8% of it in the leaves. However, 42% of the nitrogen absorbed at siliquing stage was distributed to siliquae which is just the organ directly distributed the highest proportion of nitrogen absorbed at this stage. The nitrogen absorbed at four growth stages (seedling, stem elongation, flowering, and siliquing) translocated from the vegetative to the reproductive organs at 34.4%, 44.3%, 41.2%, and 31.7%, i.e. 203.2, 325.8, 218.0, and 82.0 mg plant-1, respectively. The translocated nitrogen from vegetative organs to the total nitrogen in seed accounted for 65.1%; among with 25.8% absorbed at the stem elongation stage, 16.9% absorbed at flowering stage, 15.9% absorbed at seedling stage, and 6.4% absorbed at siliquing stage, respectively. The proportion of nitrogen loss, after being absorbed at the four growth stages, was 24.0%, 10.5%, 11.7%, and 7.3 %, i.e. 141.6, 79.2, 43.2, and 16.2 mg plant-1, respectively. To sum up, nitrogen absorbed by roots at the earlier growth stages in oilseed rape was mainly translocated to leaves first, and then to the reproductive organ at the later growth stages.

油菜NO 3 – 的吸收、分配及氮利用效率对低氮胁迫的响应

目的n 探究油菜NO3– 的吸收、分配和对低氮胁迫的响应及其氮利用效率，为理解油菜在不同低氮胁迫下相关生理变化及其氮素利用效率提供科学依据。 n 方法n 以常规油菜品种814为研究材料，采用砂培试验，在正常供氮水平 (10 mmol/L) 和低氮胁迫水平 (3 mmol/L、1 mmol/L) 下，研究油菜的根系特性、蒸腾作用对低氮胁迫的响应及其氮素吸收效率，并研究油菜NO3– 的运输分配与同化对低氮胁迫的响应及其氮素利用效率。 n 结果n 与正常供氮处理 (10 mmol/L) 相比，低氮胁迫处理 (3 mmol/L、1 mmol/L) 的油菜NO3– 含量、全氮含量均显著下降，但 (NO3–) 叶/根、(全氮(%)) 叶/根显著升高，植株根系干物质重、根系吸收面积均显著下降，但根冠比显著升高。油菜植株在低氮胁迫下气孔导度和蒸腾速率显著增加，一方面促进植株对NO3– 的捕获，另一方面也促使更大比例的NO3– 分配在植物的地上部分，但植株的水分散失加剧，水分利用效率显著下降。低氮胁迫处理油菜根和叶中NR、GS活性与正常供氮处理之间的差异不显著或有增加，其叶绿素含量、光合速率均显著下降，但光合氮素利用率显著升高。 n 结论n 在低氮胁迫条件下，油菜植株的氮素和干物质累积均显著下降，但NO3– 在植株的地上部分分配比例的增加以及光合氮素利用率的升高促使植株的氮素利用效率显著提高。

Effects of different nitrogen management models on agronomic characters and nitrogen fertilizer utilization efficiency of early rice.

Using on Luliangyou996 as provided material, choosing middling fertility field for experiment, setting up 5 treatment levels, which are: fertilizer model without N, farmers-familiar fertilizer model(150 kg/hm2,according to N), the optimal-nutrient management model(120 kg/hm2), super-high-yield and high-efficient model(150 kg/hm2), super- high-yield model(180 kg/hm2), various forms of nitrogen nutrition on agronomic characters and nitrogen use efficiency on early rice were studied. The results showed that: super high yield and high efficient model could promote root growth, increase chlorophyll content of leaves, enhance the formation and accumulation of photosynthetic products, enhance the nutrient absorptivity of rice, compared to the farmers familiar fertilizer models which are treated at the same nitrogen fertilization level, its yield increased 5.61%, nitrogen use efficiency increased by 9.06 percentage points, relativly increased 34.49%. It showed that super high yield and high efficient model can improve the yield of rice,can be expected to effectively improve the nitrogen utilization, reduce nitrogen losses, decrease the pollution caused by fertilizer application.

Effects of organic fertilizers on yield and quality of rice grains and nitrogen use efficiency.

A field plot experiment was conducted to study effect of organic fertilizers on yield and quality of rice grains and nitrogen use efficiency.The results showed that,the rice yield is much higher under the facility treatments of 20% pig manure and 10% pig manure decomposed organic fertilizer and 20% biogas fertilizer instead of pure fertilizer treatments.Compared with CK treatments the rice yield respectively increased by 103.49%,81.62% and 74.64% under the three treatments and increased by 38.67%,23.77% and 19.02% than that of the pure fertilizer treatments.The 20% pig manure decomposed organic fertilizer instead of 20% nitrogen fertilizer had the highest nitrogen use efficiency of 32.64% which was 2.66% higher than pure chemical fertilizer.And both that of 20% pig manure and 10% pig manure decomposed organic fertilizer were higher compared to the pure fertilizer treatments with the growth of 1.12% and 1.04%.According to the results,we organic fertilizer can increase the rice yield and nitrogen fertilizer use efficiency.Furthermore,compared with pure fertilizer treatment,replacing the same proportion of chemical fertilizer by either 10% of the straw,or 20% of the pig manure,or 30% of the pig manure organic fertilizer or 20% biogas could lower chalk whiteneww.And replacement of the same proportion of chemical nitrogen fertilizer by either 20% of pig manure or 20%,or 10% or 30% of pig manure decomposed fertilizer could improve the rice gel consistency,10% of the straw instead of 10% chemical fertilizer treatment had a lower amylase content.In conclusion,organic fertilizers could improve the appearance quality of rice and cooking quality.