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991.
Jiyong Shi Wenting Li Xiaodong Zhai Zhiming Guo Mel Holmes Haroon Elrasheid Tahir 《Journal of plant nutrition》2013,36(20):2773-2783
AbstractA new and nondestructive method for diagnosing magnesium (Mg) deficiency based on chlorophyll concentration distribution features of cucumber leaves was proposed. Mg deficient cucumber plants and Control plants were grown under non-soil conditions with special nutrient supply. Cucumber leaves were employed to collect hyperspectral images using a visible and near infrared (VIS/NIR) hyperspectral imaging system (400–900?nm) and determine reference chlorophyll concentrations using high performance liquid chromatography (HPLC). An optimal chlorophyll concentration calibration model (Rp = 0.9087) was constructed and used to detect chlorophyll distribution maps of Mg deficient leaves and Control leaves. Results shown that chlorophyll content distributed more unevenly on Mg deficient leaves than Control leaves. The Standard Deviation (SD) value of the chlorophyll content at all the pixels on a chlorophyll distribution map was calculated for Mg deficient diagnostics. An Mg deficiency diagnostics model with satisfied performance (diagnostic rate 93.33%) was obtained. The result indicated the SD value of chlorophyll concentrations on the whole cucumber leaf could be employed to diagnose Mg deficiency nondestructively. 相似文献
992.
Seshadri Kannan 《Journal of plant nutrition》2013,36(8):1203-1212
Iron deficiency stress was induced in cultivars, PKV‐7237, Morden and EC‐68414 of sunflower (Helianthus annuus L) by first growing them in full nutrient medium and transferring to minus Fe medium after a month. The minus Fe nutrient medium was changed again at 13 and 26 days. The change in pH and the degree of chlorosis were recorded. It was found that the pH decreased rapidly in all cultivers from 6.4 to 3.8 in 5 days. The cv. Morden was found more tolerant to the stress than others. Furthermore, the flavinlike pigments as shown by the yellow coloration of the medium were more intense in PKV than in Korden, and were very much less in EC. It was also noted that the pH reduction was non‐redumptive, a feature observed even after transferring twice to fresh minus Fe medium adjusted to pH 6.4. The results of the experiments showed that as long as Fe absorbed from the pre‐stress medium was available in the root, the chlorosis was not severe; but once it was nearly depleted, chlorosis appeared and persisted for a long time. 相似文献
993.
Many producers are using foliar fertilizers on seedling cotton (Gossypium hirsutum L.) with the intent of promoting early vigor and increasing yields. However, the hypothesis that foliar feeding young cotton increases seedling vigor and yield has not been rigorously tested. We conducted 5 studies during 1990 to 1992 to investigate the value of one, two or three foliar applications of 12–48–8 fertilizer to seedling cotton. Two studies also included foliar‐applied urea. Plant height and whole‐plant phosphorous (P) and nitrogen (N) were determined two weeks after each application in two studies. Yield and P and N concentrations were not influenced by foliar fertilizers in any study. Seedling height was not influenced by applications of 12–48–8. A slight early‐season height advantage was observed with foliar‐applied urea at one location. Our results suggest that application of foliar N and P fertilizers to seedling cotton has little agronomic value. 相似文献
994.
The interaction between salinity and nitrogen (N) forms and concentration was studied with alfalfa (Medicago sativa L.) grown in pots with fine sand under greenhouse conditions. Salinity (0–100 mM NaCl) caused a substantial reduction in carbon assimilation rate, stomatal conductance, water use efficiency, and leaf area, while transpiration rate was least affected. Salinity effects were considerably moderated by additional N supply, varied with form, concentration, and stage of plant growth. The photosynthesis was reduced more in ammonium‐ than in nitrate‐fed plants, while the transpiration rate was relatively lower in nitrate‐fed plants grown either with or without NaCl. The plants also responded differently to salinity and N levels at two harvests. This indicated a change in plant behaviour with age. The promotive effect of N on photosynthesis and other parameters in saline as well as in non‐saline conditions may be attributed to the enhanced synthesis and availability of carbon assimilatory enzymes and cofactors required for optimal photosynthesis. 相似文献
995.
《Journal of plant nutrition》2013,36(8):1347-1353
ABSTRACT The findings of an experiment using serially harvested young tomato plants grown in water culture are reported, showing the dramatic influence of sulfur status of the nutrient medium on transport of molybdenum in xylem sap. On average for the five harvests taken over a 14 d growth period, the molybdenum (Mo) concentration in the sap was approximately 11 times greater in the absence of sulfate in the nutrient medium. Restoring sulfate to the nutrient medium without sulfur (S) on day four of the experiment depressed the Mo concentration of the sap at the next harvest (taken three days later) to a value similar to that in plants receiving sulfate from the onset of the growth period and, similarly, raised the S concentration as well. Rates of transport of Mo as measured by root pressure exudates were slightly less spectacular, as S deficiency depressed the rate of exudation. The results support the concept that sulfate and molybdate compete for the same carrier and transport sites in uptake, and that sulfate deficiency leads to excess Mo uptake. The findings are of little consequence for plant cultivation, as plants are tolerant to elevated Mo concentrations, but are relevant to animal nutrition—particularly that of ruminants, which are susceptible to excess Mo and Mo-induced copper (Cu) deficiency. 相似文献
996.
Hitoshi Moro Tatsuji Saito Naoki Yaguchi Tsuyoshi Sato 《Archives of Agronomy and Soil Science》2013,59(12):1807-1813
To evaluate the relationship between the potassium (K) status in the microbial community and the exchangeable K concentration in soils, the effects of K addition on microbial activity were assessed in cultivated Andisols not having received K fertilizer. Potassium limitation was not observed in the microbial community, even in a soil amended with only nitrogen (N) and phosphorus (P) but not K since 1938, though crop plants in this soil showed severe K deficiency symptoms. Furthermore, in a soil amended with NP + compost, microbial activity was limited by K only after limitation of carbon (C) and N. These results suggest that soil microorganisms demand more C and N than K, even in soils with low K availability, and also that the soil microbial community is less susceptible to K deficiency than are crop plants. 相似文献
997.
998.
Noboru Murayama 《Soil Science and Plant Nutrition》2013,59(1):134-141
Introduction Absorption of nitrogen by the rice plant in relationship to its growth, and its movement within the plant as a whole have recently been made quite clear1),2. The recent advance in the analysis of the processes of rice plant growth, clarified that feature of nitrogen movement is quite different according to the portion of the rice plant. Togari3 and this writer4 reported that leaf blade is invariably higher in nitrogen concentration and quantity than leaf sheath or culm, and nitrogen moving to the ear at maturing stage is mainly derived from the leaf blade. Tanaka5 went still further, making it clear that individual leaves are different in their mode of nitrogen metabolism, which can be divided into three groups according to their position on the stem. 相似文献
999.
Nitrogen mineralization and immobilization of rice residue in Maahas clay soil under lowland and upland conditions were investigated by using 15N-labelled rice straw. The mineralization of residue-nitrogen was taking place even though the net mineralization was depressed by incorporation of rice residue. There were some significant differences in the pattern of nitrogen transformation between lowland and upland soil conditions. The nitrogen transformation measured by mineralization of soil nitrogen and rice-residue nitrogen and the nitrogen immobilization into rice residue were more active under lowland conditions than under upland conditions, during the earlier period of residue decomposition. 相似文献
1000.
Hitoshi Obata Atsuo Shimoyama Masanao Umebayashi 《Soil Science and Plant Nutrition》2013,59(4):933-936
Under Zn deficiency, some major deficiency symptoms were observed on rice plants, i.e., reduction of young leaf elongation and development of necrosis on the expanded leaves. To clarify the former phenomena, the physiological role of Zn was studied from the standpoint of protein synthesis (Kitagishi and Obata 1986; Obata et al. 1994, 1996) and metabolism of auxin (Takaki and Arita 1986; Domingo et al. 1992). In contrast, the direct cause of the latter phenomenon has not yet been studied. 相似文献