Phosphorus nutrition of spring wheat (Triticum aestivum L.). 3. Part 2, Aust. J. Agric. Res., 1997, 48, 869-81.. Effects of plant nitrogen status and genotype on the calibration of plant tests for diagnosing phosphorus d

1997 ◽  
Vol 48 (6) ◽  
pp. 883 ◽  
Author(s):  
D. E. Elliott ◽  
D. J. Reuter ◽  
G. D. Reddy ◽  
R. J. Abbott

The influence of plant nitrogen (N) status and plant genotype on plant test criteria for diagnosing phosphorus (P) deficiency in wheat was examined in 2 glasshouse experiments. Criteria for both total and labile P in leaf blades of standard physiological age are, to only a minor extent, affected by variations in N supply and by genotypic diversity Interactions between N and P supply had marked and complex effects on shoot and root yield, P and N uptake in shoots and concentrations in leaf blades, and on the distribution of P and P fractions within wheat shoots. Thus, whilst the external P requirement (i.e. P level required for 90% maximum shoot yield) more than doubled as N supply was raised, variations in N supply had only minor effects on internalP requirement (i.e. the tissue P concentration required for 90% maximum shoot yield). On the other hand, the external P requirement for root yield varied markedly with plant age and N supply. N deficiency increased total P concentrations in leaf blades at all P levels, primarily by increasing the concentration of the labile P fraction. Also, N concentrations increased to adequate levels in the shoots of P-deficient plants but only at the 2 lower levels of applied N. Plant N status also affected the shape of diagnostic relationships between relative shoot yield and P concentrations in young and mature leaf blades by constricting P concentration in the adequate-luxury zone and increasing the slope of the relationship in the zone of deficiency. Whilst the asymptotic grain yield and external requirement for P for the tall cultivar (Halberd) was substantially less than for the semi-dwarf cultivars (Condor and Durati), consistent P cultivar interactions on shoot yield and P uptake during vegetative growth, were largely absent. For leaf blade classes examined, the shape of the diagnostic relationship for total and labile P was essentially similar for each cultivar. As a result, differences in estimated critical P concentrations for total and labile P between the cultivars for leaf blades during vegetative growth, or criteria for grain, glumes, and straw at maturity, were relatively small.

1995 ◽  
Vol 35 (2) ◽  
pp. 239 ◽  
Author(s):  
PJ Hocking

Edible-oil linseed (Linola, CSIRO Australia) was grown in a sand culture experiment in a glasshouse to develop tissue tests for assessing the nitrogen (N) status of the crop. Seven rates of N, provided as nitrate, were used to obtain critical N concentrations. Plants were tissue-tested at 3 developmental stages: early tillering (TL), flower buds visible (BV), and the start of flowering (SF). Suitable tissues for tests based on nitrate-N were the upper half of the main stem and the whole main stem. Leaves were unsuitable as their nitrate-N concentration was unresponsive to N supply until well above the rate for maximum growth. For tests based on total N, suitable tissues were upper stem, upper leaves, total stem, total leaves, and whole shoot. Critical N supply rates for vegetative growth at TL, BV, and SF, respectively, were 85, 145, and 145 mg/L. The critical N supply rate for seed yield was 65 mg/L. Excessive N supplies (350, 700 mg N/L) reduced both seed oil percentage and seed yield. Critical nitrate-N concentrations in fresh, upper stem tissue for vegetative growth decreased from-0.26 to 0.16 mg/g fresh weight (FW) between stages TL and BV. A critical nitrate-N concentration for seed yield could only be obtained for fresh stem tissue at TL, and this value was 50% lower than that for vegetative growth. Critical nitrate-N concentrations [mg/g dry weight (DW)] in dried stem tissue for vegetative growth at TL, BV, and SF, respectively, were 2.3, 1.7, and 0.7 (upper stem); and 2.1, 1.1, and 0.6 (whole stem). Critical nitrate N values (mg/g DW) for seed yield at TL, BV, and SF were 1.1, 0.8, and 0.3 (upper stem); and 1.0,0.7, and 0.2 (whole stem). Critical total N concentrations (% DW) for vegetative growth at TL, BV, and SF, respectively, were 3.0, 2.3, and 2.2 (upper stem); 5.3, 5.8, and 4.5 (upper leaves); 2.2, 1.7, and 1.6 (whole stem); 5.5, 4.9, and 4.5 (total leaves); and 4.5, 3.1, and 2.7 (whole shoot). Corresponding total N values (% DW) for seed yield at TL, BV, and SF, respectively, were 2.9, 2.2, and 2.0 (upper stem); 5.2, 4.8, and 4.3 (upper leaves); 2.1, 1.4, and 1.4 (whole stem); 5.2, 4.4, and 4.2 (total leaves); and 4.3,2.8, and 2.6 (whole shoot). The upper stem is the preferred tissue when testing for nitrate-N, and the whole shoot is the most convenient tissue for total N. Tissue testing for N status of Linola needs to be matched closely to plant age or stage of development because of the decline in critical N concentrations between early tillering and flowering.


2021 ◽  
Vol 12 ◽  
Author(s):  
Bi Zheng Tan ◽  
Dugald C. Close ◽  
Peter R. Quin ◽  
Nigel D. Swarts

Optimizing the utilization of applied nitrogen (N) in fruit trees requires N supply that is temporally matched to tree demand. We investigated how the timing of N application affected uptake, allocation, and remobilization within 14-year-old “Gala”/M26 apple trees (Malus domestica Borkh) over two seasons. In the 2017–2018 season, 30 g N tree−1 of 5.5 atom% 15N–calcium nitrate was applied by weekly fertigation in four equal doses, commencing either 4 weeks after full bloom (WAFB) (pre-harvest) or 1-week post-harvest, or fortnightly, divided between pre- and post-harvest (50:50 split). Nitrogen uptake derived from fertilizer (NDF) was monitored by leaf sampling before whole trees were destructively harvested at dormancy of the first season to quantify N uptake and allocation and at fruit harvest of the second season to quantify the remobilization of NDF. The uptake efficiency of applied N fertilizer (NUpE) was significantly higher from pre-harvest (32.0%) than from the other treatments (~17%). The leaf NDF concentration, an indicator of N uptake, increased concomitantly only when pre-harvest N was applied. Pre-harvest treated trees allocated more than half of the NDF into fruit and leaves and stored the same amount of NDF into perennial organs as the post-harvest treatment. Subsequent spring remobilization of NDF was not affected by the timing of N fertigation from the previous season. A seasonal effect of remobilization was observed with a decrease in root N status and a reciprocal increase in branch N status at fruit harvest of season two. These findings represent a shift in the understanding of dynamics of N use in mature deciduous trees and indicate that current fertilizer strategies need to be adjusted from post-harvest to primarily pre-harvest N application to optimize N use efficiency. This approach can provide adequate storage N to support early spring growth the following season with no detriment to fruit quality.


1997 ◽  
Vol 48 (6) ◽  
pp. 869 ◽  
Author(s):  
D. E. Elliott ◽  
D. J. Reuter ◽  
G. D. Reddy ◽  
R. J. Abbott

In 2 glasshouse experiments, the effects of variations in phosphorus (P) level on concentration and distribution of total and labile P within wheat plants were examined to compare the sensitivity of various plant tests for assessing the P status of wheat. Total P was distributed unevenly within the plant: shoots had higher total P concentrations than roots, and concentrations in grain were markedly higher than in glumes or straw. Within wheat shoots, the concentration of total and labile P varied with stage of plant growth and the type and physiological age of the plant part analysed. In general, leaf blades had higher concentrations than their subtending sheaths. During the vegetative phase, the highest P concentrations were measured in immature tissues and the concentrations decreased progressively in older plant parts, except at luxury supply where total P was invariably higher in old leaf blades. Critical total P concentrations (CTPC) estimated for whole shoots decreased with advancing plant age beyond Zadoks Scale 13·5. Circumstantial evidence suggests that this may be caused by stems of lower P concentration progressively constituting a larger proportion of shoot biomass with increasing age. Critical concentrations defined for leaf blades of known physiological age also decreased with plant age beyond Zadoks Scale 13·5 for both labile and total P. These decreases may result from either an increase in the size of the sampled individual leaf blades as plants age or shifts in distribution of P within the shoot from the main culm to developing tillers (or reproductive structures). Total P is the preferred and easier method of analysis, and in most cases, diagnostic and predictive CTPC were similar in defined individual leaf blades. The estimated critical value for the labile P: total P ratio of about 30% appeared to be independent of leaf age or stage of plant ontogeny. These data suggest that the existence of P deficiency in wheat can be confirmed by analysing whole shoots or recently matured leaf blades for total P. In the period up until early tillering, the P test criteria are constant but thereafter must be related to stage of growth.


2011 ◽  
Vol 62 (11) ◽  
pp. 992 ◽  
Author(s):  
Jiayin Pang ◽  
Mark Tibbett ◽  
Matthew D. Denton ◽  
Hans Lambers ◽  
Kadambot H. M. Siddique ◽  
...  

Developing new perennial pasture legumes for low-P soils is a priority for Australian Mediterranean agro-ecosystems, where soil P availability is naturally low. As legumes tend to require higher P inputs than non-legumes, the ability of these plants to fix N2 under varying soil P levels must be determined. Therefore, the objective of this study was to investigate the influence of soil P supply on plant N status and nodule formation in 11 perennial legumes, including some novel pasture species. We investigated the effect of applying soil P, ranging from 0 to 384 μg P/g dry soil, on plant N status and nodulation in a glasshouse. Without exogenous P supply, shoot N concentration and N : P ratio were higher than at 6 μg P/g soil. Shoot N concentration and N : P ratio then changed little with further increase in P supply. There was a close positive correlation between the number of nodules and shoot P concentration in 7 of the 11 species. Total nodule dry weight and the percentage of plant dry weight that consisted of nodules increased when P supply increased from 6 to 48 μg P/g. Without exogenous P addition, N : P ratios partitioned into a two-group distribution, with species having a N : P ratio of either >70 or <50 g/g. We suggest that plants with a high N : P ratio may take up N from the soil constitutively, while those with a low N : P ratio may regulate their N uptake in relation to internal P concentration. The flexibility of the novel pasture legumes in this study to adjust their leaf N concentrations under different levels of soil P supplements other published evidence of good growth and high P uptake and P-use efficiency under low soil P supply and suggests their potential as pasture plants in low-P soils in Australian Mediterranean agro-ecosystems warrants further attention.


OENO One ◽  
2019 ◽  
Vol 53 (2) ◽  
Author(s):  
Sylvain Vrignon-Brenas ◽  
Metay Aurélie ◽  
Leporatti Romain ◽  
Gharibi Shiva ◽  
Fraga Alana ◽  
...  

Aim: Nitrogen is a major element conditioning grapevine growth, yield and aromatic profiles of berries and wines. Different tools can be used in order to detect differences in N status of the plant, including direct measurements of soil, plant nitrogen status (eg. petiole; must), or indirect observations of plant nutritional status such as leaf transmittance or reflectance (eg. SPAD; NDVI). However, the relationships between these indicators of nitrogen status and the overall plant functioning over vintages remain poorly known. The present study aimed at quantifying key vegetative and reproductive responses to plant nitrogen status over two successive seasons under different nitrogen supply levels.Methods and results: Potted plants of Sauvignon Blanc grafted onto SO4 were grown outdoors in 2017 and 2018 with no water limitation. Four mineral nitrogen fertilization levels (equivalent to 0 kg of N ha-1 or 0U, 20U, 40U, 80U) and one organic nitrogen fertilization level (40U) were imposed in 2017. These treatments were doubled in 2018 to increase the degree of nitrogen supply and consequently, the range of observed effects on plant growth and yield. Plant nitrogen status (SPAD) was monitored weekly during both growing cycles. Yield components were determined over the two seasons. Lastly, plant carbon status was addressed through dynamic measurement of plant development and photosynthesis, and destructive measurement of dry matter accumulation and carbon storage in annual and perennial organs at flowering, veraison and harvest.The SPAD values progressively decreased under lower N supply (0N) during the first year (from 31 to 16) and they were more than halved between the maximum and the minimum N treatments straight after budburst in year two (40 for 160N and 19 for 0N). Then, the differences in SPAD values among treatments were maintained up to harvest (2018). The gradient of N status resulted in a gradient of berry numbers per inflorescence (from 180 to 34 berries/inflorescence for 80N and 0N, respectively in 2018) and of individual berry dry matter at harvest (from 0.13 to 0.41 g for 160N and 0N, respectively in 2018). Quantitative relationships between N status and the relative reductions (% of reduction per %SPAD decrease) in terms of C gain (leaf area, photosynthesis), C growth (shoot, berry, trunk and root dry matter) and C storage (trunk and root) were fitted at flowering, veraison and harvest. The reduction in C gain under lower N supply was mainly related to the decrease in total leaf area before flowering (-1.64%). Although the photosynthesis rate tended to decrease under N deficiency over the season, it only poorly contributed to the reduction in C gain. The whole plant C growth was inhibited when N status decreased (-1.13% at harvest), due to the inhibition of shoot dry matter before veraison (-1.81%) and to a lower extent, to the lower dry matter in berries (-0.80%), trunks (-0.42%) and roots (-0.84%) at harvest. Part of the reduction in root dry matter was related to the lower starch reserves (-0.31%) at harvest. Interestingly, starch reserves tended to be higher under organic N supply than mineral N supply.Conclusion: The present results provided a general framework of carbon gain and use over time (within and between seasons) as impacted by N supply levels and form. Such a framework will be useful when building a model of the pluri-annual dynamics of carbon balance related to yield elaboration in grapevines.


HortScience ◽  
2008 ◽  
Vol 43 (7) ◽  
pp. 2151-2154 ◽  
Author(s):  
Guihong Bi ◽  
Carolyn F. Scagel

Rooted liners of Hydrangea macrophylla (Thunb.) Ser. ‘Berlin’ were fertigated with different rates of nitrogen (N) from July to Sept. 2007 and leaves were sprayed with 15N-labeled urea in late October to evaluate urea uptake and 15N translocation by hydrangea leaves in relation to plant N status. Four plants from each N fertigation rate were harvested before they were sprayed with urea and 2, 5, 10, and 15 days after urea spray. Increasing rate of N fertigation increased plant N content in October before being sprayed with urea. Leaves rapidly absorbed 15N from urea spray. The highest rate of 15N uptake occurred during the first 2 days after urea spray and then decreased. Export of 15N from leaves occurred rapidly after uptake and the highest rate of 15N export occurred during the first 2 days after urea spray and then decreased. During the first 5 days after urea spray, the rate of 15N uptake by leaves and export from leaves decreased with increasing rate of N fertigation. On a whole plant basis, the total amount of 15N from foliar 15N–urea spray increased with increasing rate of N fertigation; however, the percentage of 15N exported from leaves and the percentage of N that derived from foliar 15N–urea spray decreased with increasing rate of N fertigation. Results suggest that hydrangea plants with lower N status in the fall are more efficient in absorbing and translocating N from foliar urea than plants with higher N status.


2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Fangwei Yu ◽  
Shenyun Wang ◽  
Wei Zhang ◽  
Hong Wang ◽  
Li Yu ◽  
...  

Abstract The members of myeloblastosis transcription factor (MYB TF) family are involved in the regulation of biotic and abiotic stresses in plants. However, the role of MYB TF in phosphorus remobilization remains largely unexplored. In the present study, we show that an R2R3 type MYB transcription factor, MYB103, is involved in phosphorus (P) remobilization. MYB103 was remarkably induced by P deficiency in cabbage (Brassica oleracea var. capitata L.). As cabbage lacks the proper mutant for elucidating the mechanism of MYB103 in P deficiency, another member of the crucifer family, Arabidopsis thaliana was chosen for further study. The transcript of its homologue AtMYB103 was also elevated in response to P deficiency in A. thaliana, while disruption of AtMYB103 (myb103) exhibited increased sensitivity to P deficiency, accompanied with decreased tissue biomass and soluble P concentration. Furthermore, AtMYB103 was involved in the P reutilization from cell wall, as less P was released from the cell wall in myb103 than in wildtype, coinciding with the reduction of ethylene production. Taken together, our results uncover an important role of MYB103 in the P remobilization, presumably through ethylene signaling.


Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 939
Author(s):  
Yoko Watanabe ◽  
Kiyomi Hinata ◽  
Laiye Qu ◽  
Satoshi Kitaoka ◽  
Makoto Watanabe ◽  
...  

To elucidate changes in the defensive traits of tree seedlings under global environmental changes, we evaluated foliar defensive traits of the seedlings of successional trees, such as beech, oak, and magnolia grown in a natural-light phytotron. Potted seedlings were grown under the combination of two CO2 concentrations (360 vs. 720 ppm) and two nitrogen (N) treatments (4 vs. 15 kg N ha−1 yr−1) for two growing seasons using quantitative chemical analyses and anatomical method. We hypothesized that the effects of CO2 and N depend on the successional type, with late successional species providing greater defense of their leaves against herbivores, as this species exhibits determinate growth. Beech, a late successional species, responded the most to both elevated CO2 concentration (eCO2) and high N treatment. eCO2 and low N supply enhanced the defensive traits, such as the high leaf mass per area (LMA), high carbon to N ratio (C/N ratio), and increase in the concentrations of total phenolic and condensed tannin in agreement with the carbon–nutrient balance (CNB) hypothesis. High N supply decreased the C/N ratio due to the high N uptake in beech leaves. Oak, a mid–late successional species, exhibited different responses from beech: eCO2 enhanced the LMA, C/N ratio, and concentration of total phenolics of oak leaves, but only condensed tannin increased under high N supply. Magnolia did not respond to all treatments. No interactive effects were observed between CO2 and N supply in all species, except for the concentration of total phenolics in oak. Although the amounts of phenolic compounds in beech and oak varied under eCO2 and high N treatments, the distribution of these compounds did not change. Our results indicate that the changes in the defensive traits of forest tree species under eCO2 with N loading are related to the successional type.


1997 ◽  
Vol 122 (3) ◽  
pp. 459-464 ◽  
Author(s):  
Catherine S.M. Ku ◽  
David R. Hershey

Poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch `V-14 Glory') grown as single-pinched plants and received constant fertigation of Hoagland solution with N at 210 mg·L-1 of 100% NO3-N or 60% NO3-N : 40% NH4-N; P at 7.8 and 23 mg·L-1; and leaching fractions (LFs) of 0, 0.2, or 0.4. The P at 23 mg·L-1 used in this study was about half the P concentration typically provided from a 20N-4.4P-16.6K fertilizer at 200 mg·L-1 N fertigation. The total P applied via fertigation ranged from 51 mg at the 0 LF to 360 mg at the 0.4 LF. The leachate P concentration ranged from 0.2 to 46 mg·L-1. With P at 7.8 mg·L-1, the percentage of total P recovered in the leachate was 6% to 7%. At 23 mg·L-1 P fertigation, however, the total P recovered in the leachate with 60% NO3-N treatment was 2-times greater than with 100% NO3-N treatment. This result is attributed to a lower substrate pH, which resulted from NH4-N uptake and nitrification processes with 60% NO3-N fertigation. The P concentration in the recently matured leaves with 7.8 mg·L-1 P fertigation was in the normal range of 0.3% to 0.6%. Fertigation P can be reduced by up to 80% and still be sufficient for producing quality poinsettias. Reducing the fertigation P concentration is beneficial because it reduces P leaching, reduces fertilizer costs, and reduces luxury consumption.


1973 ◽  
Vol 9 (2) ◽  
pp. 113-120 ◽  
Author(s):  
M. J. Jones

SUMMARYMaize was grown for three years at three levels of nitrogen, 56, 112 and 224 kg. N ha.−1, involving altogether nine different timing and splitting treatments. Measurements were made of grain yield, plant nitrogen status and total-N-uptake, and, in one year, movement of nitrate-N in control plot soils. Where only 56 kg. N ha.−1was applied, its time of application made very little difference to yield; at higher rates of nitrogen an unsplit application as late as seven weeks was very inefficient, but only at the highest rate did a split application give any appreciable yield increase over an unsplit application to the seed bed. Consideration of the soil nitrate-N data and the long-term pattern of rainfall distribution leads to the conclusion that leaching is unlikely to be a serious problem in the nitrogen nutrition of early-planted maize.


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