Critical nitrate-nitrogen and total nitrogen concentrations for vegetative growth and seed yield of Linola (edible-oil linseed) as affected by plant age

1995 ◽  
Vol 35 (2) ◽  
pp. 239 ◽  
Author(s):  
PJ Hocking
Keyword(s):  
Seed Yield ◽  
Vegetative Growth ◽  
Edible Oil ◽  
Plant Age ◽  
Main Stem ◽  
Stem Tissue ◽  
Total N ◽  
N Supply ◽  
Nitrate N ◽  
N Status

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.

Assessment of the nitrogen and potassium status of irrigated Brussels sprouts (Brassica oleracea L. var. gemmifera) by plant analysis

1996 ◽  
Vol 36 (7) ◽  
pp. 887 ◽  
Author(s):  
CMJ Williams ◽  
NA Maier
Keyword(s):  
Total Yield ◽  
Leaf Age ◽  
Plant Analysis ◽  
Total N ◽  
Brussels Sprouts ◽  
Critical Concentrations ◽  
N Supply ◽  
Nitrate N ◽  
N Concentration ◽  
N Status

Four field experiments were carried out during 1992-93 (sites 1 and 2) and 1993-94 (sites 3 and 4) to assess the effects of nitrogen (N), at rates up to 600 kgha, and potassium (K), at rates up to 300 kgha, on total N, nitrate-N and K concentrations in petioles of the youngest fully expanded leaves (P-YFEL) of Brussels sprouts (Brassica oleracea var. gemmifera). The experiments were located in commercial plantings in the Mt Lofty Ranges, South Australia. Plant samples were collected at 2-4-week intervals from 4 to 28 weeks after the plants were transplanted. Temporal or seasonal variation, and the effects on concentrations of total N, nitrate-N and K of sampling leaves next in age (YFEL-1 to YFEL+2) to the index leaf, were also studied. Total N concentration in P-YFEL was more sensitive to variations in N supply than nitrate-N at all sites. Total N and nitrate-N concentrations in petioles also varied with the age of the leaf sampled. Total N concentrations in petioles of leaves sampled 4-16 weeks after transplanting decreased with increasing leaf age. In contrast, nitrate-N concentrations in petioles sampled 4-8 weeks after transplanting increased with leaf age. Potassium concentrations in petioles did not vary consistently between leaves of different age. From 4 to 6 weeks after transplanting, relationships between total N or nitrate-N concentrations in P-YFEL and relative total yield were not significant (P>0.05), therefore, critical concentrations could not be determined. Linear and quadratic models were used to study the relationships between total N and nitrate-N concentration in P-YFEL and relative total yield during 8-28 weeks after transplanting. Total N concentrations accounted for a greater amount of variation in relative total yield at 10, 12, 14, 16, 18, 20, 24 and 28 weeks after transplanting compared with nitrate-N. Coefficients of determination (r2) were in the range 0.52-0.93. Relationships between nitrate-N concentration in P-YFEL and relative total yield were only significant 8, 10, 14 and 16 weeks after transplanting and 9 values were in the range 0.49-0.82. Critical concentrations for total N decreased from 3.13-3.44% at 10 weeks to 1.22-1.38% at 28 weeks after transplanting. This decrease highlights the importance of carefully defining sampling time to ensure correct interpretation of plant test data. Potassium concentrations also decreased between 4 and 28 weeks after transplanting. Critical concentrations were not determined for K, because the crops at all sites did not respond significantly (P>0.05) to applied K. Based on sensitivity (as indicated by the range in tissue concentrations in response to variations in N supply) and on the correlations between total N and nitrate-N concentrations and relative total yield, we concluded that total N was better than nitrate-N as an indicator of plant N status and yield response of Brussels sprouts. We suggested that growers sample P-YFEL several times during the growing season, starting 10 weeks after transplanting. Plant analysis can be used to monitor N status and to detect N deficiencies which may arise during the growing season of Brussels sprouts which may be up to 9 months duration. Growers can adjust their fertiliser N program to ensure deficiencies are quickly corrected.

Diagnostic nitrogen concentrations for tomatoes grown in sand culture

1988 ◽  
Vol 28 (3) ◽  
pp. 401 ◽  
Author(s):  
DO Huett ◽  
G Rose
Keyword(s):  
Critical Values ◽  
Sand Culture ◽  
Nutrient Concentrations ◽  
Total N ◽  
Nitrate N ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Petiole Sap ◽  
N Status ◽  
Leaf N

The tomato cv. Flora-Dade was grown in sand culture with 4 nitrogen (N) levels of 1.07-32.14 mmol L-1 applied as nitrate each day in a complete nutrient solution. The youngest fully opened leaf (YFOL) and remaining (bulked) leaves were harvested at regular intervals over the 16-week growth period. Standard laboratory leaf total and nitrate N determinations were conducted in addition to rapid nitrate determinations on YFOL petiole sap. The relationships between plant growth and leaf N concentration, which were significantly affected by N application level, were used to derive diagnostic leaf N concentrations. Critical and adequate concentrations in petiole sap of nitrate-N, leaf nitrate-N and total N for the YFOL and bulked leaf N were determined from the relationship between growth rate relative to maximum at each sampling time and leaf N concentration. YFOL petiole sap nitrate-N concentration, which can be measured rapidly in the field by using commercial test strips, gave the most sensitive guide to plant N status. Critical values of 770-1 120 mg L-I were determined over the 10-week period after transplanting (first mature fruit). YFOL (leaf + petiole) total N concentration was the most consistent indicator of plant N status where critical values of4.45-4.90% were recorded over the 4- 12 week period after transplanting (early harvests at 12 weeks). This test was less sensitive but more precise than the petiole sap nitrate test. The concentrations of N, potassium, phosphorus, calcium and magnesium in YFOL and bulked leaf corresponding to the N treatments producing maximum growth rates are presented, because nutrient supply was close to optimum and the leaf nutrient concentrations can be considered as adequate levels.

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
Keyword(s):  
Vegetative Growth ◽  
N Uptake ◽  
Physiological Age ◽  
Root Yield ◽  
P Deficiency ◽  
Plant Nitrogen ◽  
N Supply ◽  
P Concentration ◽  
Labile P ◽  
N Status

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.

Determination of critical nitrogen concentrations of zucchini squash (Cucurbita pepo L.) cv. Blackjack grown in sand culture

1991 ◽  
Vol 31 (6) ◽  
pp. 835 ◽  
Author(s):  
DO Huett ◽  
E White
Keyword(s):  
Growth Rate ◽  
Growth Period ◽  
Sand Culture ◽  
Total N ◽  
N Supply ◽  
Nitrate N ◽  
Fruit Harvest ◽  
Petiole Sap ◽  
Leaf Nitrate

A gamma x quadratic response surface model was used to predict the growth rate over the 14-week growth period of zucchini squash (Cucurbita pepo L.) cv. Blackjack in sand culture with nitrogen (N) levels of 2, 7, 14, 29 and 43 mmol/L. Growth rate relative to maximum was plotted against tissue N concentration every 2 weeks, to derive diagnostic petiole sap; leaf nitrate-N and leaf total-N in youngest fully opened leaf, youngest fully expanded leaf and oldest green leaf; and total N in bulked leaf samples. Critical concentrations corresponding to 90% maximum growth rate for deficiency and toxicity are presented. Petiole sap and leaf nitrate-N were much more responsive than leaf total N concentrations over the 2-14 mmol N/L range where positive growth responses were recorded. At 2 mmol N/L, plants were severely N-deficient and growth rate was low (1.6 g/plant.week at fruit set). Tissue nitrate concentrations were negligible, while leaf total N concentrations exceeded 2.6%. Salt toxicity occurred at 29 and 43 mmol N/L, and at the highest N level, tissue N concentrations were sometimes reduced so that concentration ranges for adequacy and toxicity overlapped. Critical tissue N concentrations always exceeded (P<0.05) levels recorded in plants receiving a marginally deficient N level (7 mmol/L). Critical petiole sap and leaf nitrate-N concentrations were much more variable between sampling periods than leaf total N concentrations. Adequate concentration ranges (values between critical concentrations for deficiency and toxicity) were determined for the pre-fruit harvest (weeks 2-6) and fruit harvest (weeks 8-14) growth stages where values were common for consecutive weeks within each sampling period. It was only possible to determine adequate concentrations over the entire growth period for bulked leaf total N (4.30440% prefruit harvest and 4.15-4.45% fruit harvest). Concentrations of potassium (K), phosphorus and sulfur were affected (P<0.05) by N application level, with the largest effect being recorded for K. This confirms the importance of optimising N supply when determining critical levels of these nutrients for zucchini squash. Determination of petiole sap nitrate-N concentrations in the field can be used to distinguish between a deficient and an adequate N supply, but the large variation in values between sampling periods renders this technique less reliable than leaf total N. Tissue N concentrations which exceed critical deficient levels can be interpreted as such because they were recorded when growth was depressed at high N levels. This will rarely occur under field conditions.

Assessment of the nitrogen status of field-grown canola (Brassica napus) by plant analysis

1997 ◽  
Vol 37 (1) ◽  
pp. 83 ◽  
Author(s):  
P. J. Hocking ◽  
P. J. Randall ◽  
D. De Marco ◽  
I. Bamforth
Keyword(s):  
Brassica Napus ◽  
Dry Matter ◽  
Stem Elongation ◽  
Dry Weight ◽  
Growth Stages ◽  
Total N ◽  
Plant Parts ◽  
Nitrate N ◽  
Matter Production ◽  
N Status

Summary. Field trials were conducted over 2 seasons at Greenethorpe and Canowindra in the Cowra region of New South Wales to develop and calibrate plant tests for assessing the nitrogen (N) status of canola (Brassica napus). Plants were tested at 3 and 7 growth stages up to the start of flowering at Greenethorpe and Canowindra, respectively. The petiole of the youngest mature leaf (YML) was the most suitable plant part to sample for tests based on nitrate-N. Suitable plant parts for tests based on total N were the YML petiole or lamina, or the whole shoot. There was good agreement between the 2 sites in the just-adequate fertiliser N rates (rates giving 90% of maximum yield) and the critical N concentrations in the plant parts tested. Critical nitrate-N concentrations in the fresh YML petiole for dry matter production at the time of sampling the plants decreased from 1.62 to 0.14 mg nitrate-N/g fresh weight between the 4–5 leaf rosette stage (4–5 RS) and the start of flowering (SF). Critical nitrate-N concentrations in the dry YML petiole decreased from 16.5 to 0.8 mg/g dry weight between 4–5 RS and SF. Critical total N concentrations decreased from 4.5 to 2.0, 7.2 to 5.0 and 6.2 to 2.8% dry weight, in the YML petiole, YML lamina, and whole shoot, respectively, between 4–5 RS and SF. Critical nitrate-N and total N concentrations for assessing potential seed yield were similar to those for dry matter production at the time of sampling for each of the growth stages. The critical total N concentrations obtained for the YML petiole and lamina, and the whole shoot before the start of stem elongation are likely to be less precise than the critical nitrate-N concentrations in the YML petiole because of the limited response of total N concentrations to increasing rates of fertiliser N. However, total N in the YML petiole or lamina, or in the whole shoot may be a better indicator of N status for plants sampled after the start of stem elongation as nitrate-N concentrations become low and more variable, and it is harder to identify the YML. The decline in critical N concentrations must be taken into account when interpreting the results of plant tests for diagnosing the N status of canola, as sampling needs to correspond to the plant growth stage for which a particular critical N concentration has been obtained.

scholarly journals Rate of Nitrogen Fertigation During Vegetative Growth and Spray Applications of Urea in the Fall Alters Growth and Flowering of Florists' Hydrangeas

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 472-477 ◽  
Author(s):  
Guihong Bi ◽  
Carolyn F. Scagel ◽  
Richard Harkess
Keyword(s):  
Plant Growth ◽  
Vegetative Growth ◽  
Plant Biomass ◽  
Quality Characteristics ◽  
Plant Performance ◽  
N Content ◽  
Leaf Quality ◽  
Total N ◽  
N Status ◽  
Spray Applications

Plants of Hydrangea macrophylla ‘Merritt's Supreme’ were fertigated with 0, 70, 140, 210, or 280 mg·L−1 nitrogen (N) from July to Sept. 2005 and sprayed with 0% or 3% urea in late October to evaluate whether plant N status during vegetative growth influences plant performance during forcing. In late November, plants were manually defoliated, moved into a dark cooler (4.4 to 5.5 °C) for 8 weeks, and then placed into a greenhouse for forcing. After budbreak, plants were supplied with either 0 N or 140 mg·L−1 N for 9 weeks. Plant growth and N content were evaluated in Nov. 2005 before cold storage and plant growth, flowering, and leaf quality parameters were measured in late Apr. 2006. Increasing N fertigation rate in 2005 significantly increased plant biomass by ≈14 g (26%) and plant N content by ≈615 mg (67%). Spray applications of urea (urea sprays) in the fall had no influence on plant biomass but significantly increased plant N content by ≈520 mg (54%). In general, plants grown with 210 and 280 mg·L−1 N during 2005 had the greatest growth (total plant biomass, height), flowering (number of flowers, flower size), and leaf quality (leaf area, chlorophyll content) during forcing in 2006. Urea sprays before defoliation increased plant growth, flowering, and leaf quality characteristics during forcing in 2006. Providing plants with N during the forcing period also increased plant growth, flowering, and leaf quality characteristics. Urea sprays in the fall were as effective as N fertilizer in the spring on improving growth and flowering. We conclude that both vegetative growth and flowering during forcing of ‘Merritt's Supreme’ hydrangea are influenced by both the N status before forcing and N supply from fertilizer during forcing. A combination of optimum rates of N fertigation during the vegetative stage of production with urea sprays before defoliation could be a useful management strategy to control excessive vegetative growth, increase N storage, reduce the total N input, and optimize growth and flowering of container-grown florists’ hydrangeas.

Assessment of the nitrogen status of onions (Allium cepa L.) cv. Cream Gold by plant analysis

1990 ◽  
Vol 30 (6) ◽  
pp. 853 ◽  
Author(s):  
NA Maier ◽  
AP Dahlenburg ◽  
TK Twigden
Keyword(s):  
Field Experiments ◽  
Soluble Solids ◽  
Marketable Yield ◽  
Total N ◽  
Scale Thickness ◽  
Plant Parts ◽  
N Supply ◽  
Nitrate N ◽  
Allium Cepa L ◽  
N Rates

Three field experiments were carried out during 1987-88 (1 site) and 1988-89 (2 sites) with Cream Gold onions grown on siliceous sands, to investigate the effect of nitrogen (N), at rates up to 475 kg N/ha on total-N, nitrate-N, potassium (K) and phosphorus (P) concentrations in youngest fully expanded blades (YFEB), bulked blades, necks and developing bulbs. The plant samples were collected when the largest bulbs were 25-30 mm in diameter. Nitrate-N concentrations were in the order WEB> bulked blades>necks = developing bulbs. For total-N the order was YFEB = bulked blades>necks> developing bulbs. Nitrate-N was more sensitive to variations in N supply than total-N in all tissues sampled. Potassium concentrations were in the order bulked blades > YFEB > necks > bulbs. At N rates <75 kg N/ha, P concentrations were in the order YFEB = bulked blades > bulbs > necks. Coefficients of determination (r2) for the relationships between nitrate-N and total-N concentrations and relative marketable yield of bulbs were in the range 0.73-0.98. At sites 1 and 3, the relationships between total-N and relative marketable yield were 'C-shaped' or showed the Piper-Steenbjerg effect. Critical concentrations (values at 90% relative marketable yield) for nitrate-N varied between plant parts (375-590 mg/kg) and sites (590-940 mg/kg for YFEB). Critical total-N concentrations also varied between the different plant parts (1.2-2.9%) but less so between sites (2.4-2.9% for YFEB) compared with nitrate-N. Based on sensitivity (as indicated by the range in tissue concentrations in response to variations in N supply) and on the correlations between nitrate-N and total-N concentrations and per cent relative marketable yield, we concluded that nitrate-N and total-N concentrations in YFEB were suitable indicators of the N status of onion plants. The YFEB is easily identified, and compared with bulked blades, necks or bulbs, samples of 50-100 can be collected without destroying plants and will also not result in excessive plant material to dry. Based on the variation in critical values between sites (reproducibility), total-N is preferred to nitrate-N. Correlations between nitrate-N and total-N concentrations in YFEB and bulb quality attributes (scale thickness, glucose concentration, fructose concentration, soluble solids and dry matter) were poor (72 values 10.48) and of little predictive value.

Critical sulfur concentrations in oilseed rape (Brassica napus) in relation to nitrogen supply and to plant age

1998 ◽  
Vol 38 (5) ◽  
pp. 511 ◽  
Author(s):  
A. Pinkerton
Keyword(s):  
Oilseed Rape ◽  
Seed Yield ◽  
Critical Values ◽  
Sand Culture ◽  
Culture Experiment ◽  
Total N ◽  
N Supply ◽  
S Deficiency ◽  
Time Required ◽  
Time Critical

Summary. Oilseed rape was grown in a sand culture experiment in a glasshouse to derive values for plant testing for the diagnosis of sulfur (S) deficiency and for the prediction of seed yield. Five rates of S, combined factorially with 4 rates of nitrogen (N), maintained constant throughout the experiment, were used to determine critical concentrations of S fractions and ratios (total S, St; sulfate-S, SO4; total N/total S, N/St; SO4/St). The most satisfactory indices of rapeseed S status for diagnosis or prediction were St and SO4. Whole shoots and youngest fully expanded leaves exhibited similar critical values in plants at the rosette stage, and critical values (St = 0.20–0.25%; SO4 = 230–460 mg/kg) changed little with time. Critical values for N/St changed with time, required 2 analyses, and gave no indication of the degree of deficiency when used to predict yield. Critical values of SO4/St depended on N supply, so 3 analyses were needed. It is argued that high critical values reported previously for prediction of seed yield have been obtained when there was a decline in soil-available S and plants relied on S taken up during early growth.

Determination of critical nitrogen concentrations of lettuce (Lactuca sativa L. cv. Montello) grown in sand culture

1992 ◽  
Vol 32 (6) ◽  
pp. 759 ◽  
Author(s):  
DO Huett ◽  
E White
Keyword(s):  
Dry Matter ◽  
Growth Period ◽  
Sand Culture ◽  
N Application ◽  
Total N ◽  
N Supply ◽  
Nitrate N ◽  
N Concentration ◽  
Nitrate Concentrations ◽  
Petiole Sap

A gamma x cubic response surface model was used to predict the dry matter yield of lettuce cv. Montello over the 8-week growth period in sand culture with nitrogen (N) levels of 2, 5, 11, 18 and 36 mmol/L. At 1, 2, 3, 5, 7 and 8 weeks after transplanting, dry matter yield relative to maximum was plotted against tissue N concentration to derive diagnostic concentrations of petiole sap nitrate-N and leaf total N in youngest fully opened leaf (YFOL), youngest fully expanded leaf (YFEL) and oldest green leaf (OL), and total N in bulked leaf samples. Critical concentrations corresponding to 90% maximum yield are presented. Growth was consistently depressed at 2 mmol N/L due to N deficiency, and at 36 mmol N/L due to salt toxicity. Petiole sap nitrate concentrations were more responsive than leaf total N concentrations to N application levels. Leaf N concentrations at N application levels of 18 and 36 mmol/L were often similar. Critical leaf total N concentrations in YFOL and YFEL decreased from 2 weeks after transplanting to maturity, whereas the opposite trend occurred for petiole sap nitrate concentrations. Critical total N concentration ranges in YFEL were 0.30-0.95 g/L for petiole sap nitrate-N, and 4.00-5.30% for leaf total N concentration. Critical leaf total N and petiole sap nitrate concentrations clearly differentiated between inadequate and adequate N application rates. Critical values in most cases, differentiated toxic concentrations. Nitrogen application levels of 2 and 36 mmol N/L reduced (P<0.05) potassium, calcium and magnesium concentrations in all leaves. This confirms the importance of optimising N supply when determining critical levels of these nutrients for lettuce. Petiole sap nitrate-N concentrations, which can be determined rapidly in the field, can be used to distinguish between a deficient and an adequate N supply. The marked increase in critical concentration over the growth period requires consecutive determinations to verify the N status of lettuce.

scholarly journals Evaluation of Chlorimuron as a Growth Regulator for Peanut

1995 ◽  
Vol 22 (1) ◽  
pp. 62-66 ◽  
Author(s):  
Wayne E. Mitchem ◽  
Alan C. York ◽  
Roger B. Batts
Keyword(s):  
Growth Regulator ◽  
Vegetative Growth ◽  
Lateral Branch ◽  
Internode Length ◽  
Main Stem ◽  
Stem Length ◽  
Vine Growth

Abstract Chlorimuron was evaluated as a growth regulator on peanut. Treatments included chlorimuron at a total of 8.8 g ai/ha applied once at 60,75, or 90 d after emergence (DAE) or in equal portions applied twice at 60 and 75, 60 and 90, or 75 and 90 DAE or three times at 60, 75, and 90 DAE. Daminozide at 950 g ai/ha applied 75 DAE was included as a comparison. In a year with excessive vine growth, daminozide and all chlorimuron treatments except 8.8 g/ha applied 90 DAE reduced cotyledonary lateral branch and main stem length at harvest 9 to 20 and 12 to 24%, respectively, due to suppression of internode length. Sequential applications of chlorimuron generally suppressed growth more than single applications. No improvement in row visibility at harvest was noted. In a dry year with limited vegetative growth, neither chlorimuron nor daminozide affected cotyledonary lateral branch or main stem length at harvest. Chlorimuron at 2.9 g/ha applied 60, 75, and 90 DAE reduced yield 18% at one of four locations; no other treatment affected yield. Chlorimuron at 8.8 g/ha applied 60 DAE or 4.4 g/ha applied 60 and 75 DAE reduced the percentage of fancy pods and extra large kernels at one or more locations. No treatment affected the percentage of total sound mature kernels. Results suggest chlorimuron has little to no potential for use as a growth regulator.

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