共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
氮素形态, 光合作用, 光呼吸 总被引:2,自引:0,他引:2
Under high light conditions, ammonium nutrition has a negative effect on plant growth. This suggests that the adverse effects of ammonium nutrition on plant growth may be related to carbon gain, photosynthesis, and photorespiration. However, there is no consistent evidence of a specific mechanism that could explain the plant growth reduction under ammonium supply. It is generally accepted that during the light reaction, a surplus of nicotinamide adenine dinucleotide hydrogen phosphate (NADPH) is produced, which is not completely used during the assimilation of CO2, Nitrate reduc- tion in the leaf represents an additional sink for NADPH that is not available to ammonium-grown plants. Nitrate and ammonium nutrition may use different pathways for NADPH consumption, which leads to differences in photosynthesis and photorespiration. The morphological (i.e., cell size, mesophyll thickness, and chloroplast volume) and enzymic (i.e., ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPCase), and glutamine synthetase/glutamate synthetase (GS/GOGAT)) differences that develop when plants are treated with either nitrate or ammonium nitrogen forms are related to photosynthesis and photorespiration. The differences in photorespiration rate for plants treated with nitrate or ammonium are related to the conversion of citrate to 2-oxoglutarate (2-OG) and photorespiratory CO2 refixation. 相似文献
4.
5.
6.
《Communications in Soil Science and Plant Analysis》2012,43(7-8):843-850
Abstract Samples of seven controlled‐release fertilizers, Nutricote Total 13–13–13, Nutricote Total 18–6–8, Osmocote Plus 15–9–12, Osmocote 13–13–13, Polyon 18–6–12, Polyon 14–14–14, and Plantacote 14–8–15, were placed in leaching columns containing acid‐washed sand. Samples of all leachates were analyzed weekly to determine release rates of ammonium‐nitrogen (N), nitrate‐N, phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and iron (Fe). Release rates for P from all products were slower than those for NH4‐N, NO3‐N, and K. Release of Mg, Mn, and Fe was very poor, with less than 50% of the total amount of each of these elements ever being released from the prills for some products. Nutricote products released Fe and Mn more effectively than did Osmocote or Plantacote. 相似文献
7.
我国东部七省(闽,浙,赣,湘,鄂,苏,皖)生态系统对酸沉降的临界负 … 总被引:1,自引:1,他引:0
本文介绍了生态系统对酸沉隆的临界负荷的概念及一般确定过程。叙述了用MAGIC区域数学模型求算临界负荷的方法,包括计算单元的选择、采样点的布设及样品的采集、土壤参数的确定、地表径流和地表水参数的研究以及临界负荷的计算方法。 相似文献
8.
遥感,地图,地理信息系统一体化应用 总被引:6,自引:0,他引:6
遥感、地图和地理信息系统三者呈“你中有我,我中有你”的相辅相成关系。三者一体化应用使地球科学得以进展,又能在资料开发、环境保护、自然灾害监测评价等方面发挥重要作用。一体化应用的基础是掌握三者的学科-技术特性与相通关系。 相似文献
9.
10.
11.
Soraya Ruamrungsri Takuji Ohyama Takamitsu Konno Taro Ikarashi 《Soil Science and Plant Nutrition》2013,59(4):809-820
Narcissus cv. “Garden Giant” bulbs were grown in N, P, K, Ca, Mg, or Fe-deficient solutions and compared with bulbs grown in the control solution containing all these nutrients. Plants were sampled at 4 stages: (I) at planting, (II) at sprouting, (III) after flower senescence and/or after visible deficiency symptoms developed, and (IV) at lifting. Observation of visible deficiency symptoms showed that leaves of narcissus displayed chlorosis in the —N, —Mg, and —Fe treatments, while roots were most susceptible to Ca-deficient conditions. Root tips in the —Ca treatment showed brown in followed by root rot. In the —N treatment, shoot growth was markedly retarded and leaves were small and yellow. On the other hand, visible deficiency symptoms were not evident in the —P treatment except for early senescence. K deficiency symptoms were also not evident. Narcissus flowers were not affected by the mineral deficiencies and mineral contents in full-bloom flowers were not different between samples. In the control plants, there was a large accumulation of N in the roots at sprouting and the content decreased thereafter. Large amounts of K accumulated in roots more than in any other organs. On the other hand the Ca content was high in the tunic and Ca in the scales was hardly mobilized thoughout the growth period. A large proportion of each element eventually accumulated in new inner scales whereas only a small fraction in the old outer scales. The -N, -Ca, and -Mg treatments severely depressed dry matter accumulation, unlike the -P, -K, and -Fe treatments. The -N treatment did not affect the concentration of other minerals, but the -P treatment tended to decrease N, K, Ca, and Mg concentrations. On the other hand, the -K treatment increased Ca and Mg concentrations. -Ca caused an increase in Mg concentration and -Mg raised Ca concentration. These results may be due to compensation effects of cation absorption for the maintenance of the cation/anion balance. 相似文献
12.
13.
14.
关于冻害,寒害,冷害和霜冻 总被引:22,自引:5,他引:17
1国内外冻害、寒害、冷害、霜冻用法不一关于冻害、寒害、冷害和霜冻的概念和用法国内外不一。50年代国内关于冻害、寒害、冷害和霜冻用法较明确,只有霜与霜冻最初有些不分。前苏联农业气象学介绍到我国,鉴用苏联的用法,霜冻指在较温暖季节出现温度0℃以下的低温冻... 相似文献
15.
Kouassi N’Guessan Louis Berenger Yao Koffi Marcellin Sangare Naminata Trokourey Albert Metongo Bernard Soro 《Journal of Soils and Sediments》2019,19(2):929-944
Journal of Soils and Sediments - Trace metals accumulate in the food web and can pose high risks to human health and aquatic biota. We investigated seasonal and spatial variations of Cu, Zn, Pb,... 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(13-14):2193-2204
Abstract The fractionation of heavy metals in previously sludge‐amended soil is important to evaluate their behavior in the environment in terms of mobility and availability to crop plants. A surface soil that received two types of sludges at two different rates, plus fertilizer only and no treatment (control), having been fallow for nine years, was used in this study. The contents of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) fractions in previously sludge‐amended soils were governed by the total content of these metals in the sludges applied and by the rate of sludge application. The contents of these metals were higher for soils that received the Chicago sludge as compared to that receiving the Huntsville sludge. Furthermore, soils that received 20 Mg/ha/yr of sludge for five years generally had higher levels of these metals than those receiving a single dose at the 100 Mg/ha application rate. The percentage of the total content in the water soluble and exchangeable forms was very low (≤1%) regardless of sludge application. The application of sludges tended to reduce the residual fraction and to increase the organic and carbonate fractions. Overall, the predominant forms of the metals in the sludges were as the Cd‐, Ni‐, Pb‐, and Zn‐carbonate and Cu‐organic fractions. 相似文献
17.
18.
19.
《Communications in Soil Science and Plant Analysis》2012,43(5):457-471
Abstract Yields were evaluated three years after applied treatments to determine if responses that were not evident during earlier years eventually occurred. Potassium sulfate was applied to established, non‐irrigated, K deficient trees on fine textured soil by banding, placing in augered holes, adding to the backfilled trenches, and by injecting into the soil. Trenches were dug in the fall beside trees to break roots and ammended during backfilling with K2SO4, dolomite lime or combinations of the two. Additional trees received a heavy compost mulch in the early fall. Trenching treatments were generally detrimental. Trenching alone reduced yield and leaf Ca but increased fruit soluble solids content. Trenching plus K2SO4, trenching and lime, all soil amendments, and mushroom compost elevated leaf K from deficient or below normal to the normal range, but decreased leaf Mg. Most K application techniques eventually increased yield, but simple surface applications of K2SO4 in a narrow band were as effective as other more costly procedures. Mulching treatments appear to be as effective as K additions and produce quicker yield responses. Mushroom composts and alfalfa increased leaf N and yield in two years. Mushroom compost doubled yield even three years after a single application. 相似文献
20.
烟草氮,钾,氯营养化学与产量,品质的关系 总被引:14,自引:0,他引:14
近30年来,烟草科学研究得到了飞速发展。本文依据该期间有关研究资源,就烟草氮、钾、氯的营养化学及如何正确合理施用相应氮、钾、氯肥以提高烟草产量、品质两方面分别进行了较为详细的论述。 相似文献