scholarly journals Assessment of Pruning and Controlled-release Fertilizer to Rejuvenate Huanglongbing-affected Sweet Orange

2019 ◽  
Vol 29 (6) ◽  
pp. 933-940 ◽  
Author(s):  
Tripti Vashisth ◽  
Taylor Livingston
Keyword(s):  
Controlled Release ◽  
Sweet Orange ◽  
Root Density ◽  
High Rate ◽  
Control Treatment ◽  
Area Index ◽  
Controlled Release Fertilizer ◽  
Shoot Ratio ◽  
Canopy Volume ◽  
Root To Shoot Ratio

Previous research has shown that Huanglongbing {HLB [causal agent Candidatus Liberibacter asiaticus (CLas)]}-affected sweet orange (Citrus sinensis) trees have a reduced root-to-shoot ratio, potentially due to the high rate of root death. The diminished root system cannot support the existing aboveground canopy and a cycle of imbalance begins. As a result, the tree enters into a continuous carbohydrate stress cycle and, eventually, the tree declines. Therefore, the goal of this study was to evaluate pruning as a strategy to adjust the root-to-shoot ratio to improve growth and productivity of HLB-affected trees. In Jan. 2015, a 3-year trial was initiated on a 14-year-old grove of ‘Hamlin’ sweet orange on Swingle citrumelo (Citrus paradisi × Poncirus trifoliate) rootstock that was symptomatic of HLB and produced less than 180 lb of fruit per tree. The four pruning treatments were as follows: 1) 0% pruning (no canopy removal), 2) 25% pruning (canopy removed), 3) 50% pruning (canopy removed), and 4) 80% pruning (canopy removed). In a split-plot design, two sources of fertilizer were evaluated in combination with the pruning: 1) conventional fertilizer [CNV (dry granular)] applied at 200 lb/acre nitrogen (N) in five split applications per year, and 2) controlled-release fertilizer (CRF) applied at 150 lb/acre N, split in three applications per year. Within each pruning treatment, half of the trees received CNV and the other half received CRF. The fertilizer treatments were applied in each of the 3 years; however, pruning was performed only once in the beginning of the experiment. The trees that were pruned produced new vegetative growth that looked healthy with no visual HLB symptoms (initially); however, the trees remained positive for CLas throughout the study as determined by quantitative real-time polymerase chain reaction. The 80% pruned trees grew vigorously over the course of 3 years but remained significantly smaller in canopy than control trees (0% pruning) for both CRF and CNV treatments. The 25% and 50% pruned tree canopies grew back and were similar in canopy size as 0% pruning (control) treatment by the end of year 2. At the end of the study, the use of CRF on 25% pruned trees resulted in a significantly higher leaf area index as compared with trees receiving CNV. A significant positive linear correlation was observed between canopy volume and root density; the root density decreased with intensive pruning. A significant positive correlation was also observed between canopy volume and yield, and a negative correlation between canopy volume and fruit drop. There were no significant increases in yield resulting from any pruning or fertilization treatments compared with controls (0% pruning). However, with the use of CRF, the amount of N and frequency of application were reduced. Overall, our results indicate that pruning did not improve the productivity of HLB-affected trees over the course of 3 years. Therefore, severe pruning is not a viable option to rejuvenate the HLB-affected trees.

scholarly journals Foliar Sprays of Citric Acid and Malic Acid Modify Growth, Flowering, and Root to Shoot Ratio ofGazania(Gazania rigensL.): A Comparative Analysis by ANOVA and Structural Equations Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Majid Talebi ◽  
Ebrahim Hadavi ◽  
Nima Jaafari
Keyword(s):  
Citric Acid ◽  
Plant Height ◽  
Malic Acid ◽  
Foliar Application ◽  
Structural Equations ◽  
Control Treatment ◽  
Fresh Weight ◽  
Structural Equations Modeling ◽  
Shoot Ratio ◽  
Root To Shoot Ratio

Foliar application of two levels of citric acid and malic acid (100 or 300 mg L−1) was investigated on flower stem height, plant height, flower performance and yield indices (fresh yield, dry yield and root to shoot ratio) ofGazania. Distilled water was applied as control treatment. Multivariate analysis revealed that while the experimental treatments had no significant effect on fresh weight and the flower count, the plant dry weight was significantly increased by 300 mg L−1malic acid. Citric acid at 100 and 300 mg L−1and 300 mg L−1malic acid increased the root fresh weight significantly. Both the plant height and peduncle length were significantly increased in all applied levels of citric acid and malic acid. The display time of flowers on the plant increased in all treatments compared to control treatment. The root to shoot ratio was increased significantly in 300 mg L−1citric acid compared to all other treatments. These findings confirm earlier reports that citric acid and malic acid as environmentally sound chemicals are effective on various aspects of growth and development of crops. Structural equations modeling is used in parallel to ANOVA to conclude the factor effects and the possible path of effects.

scholarly journals Production and Postproduction Performance of Two New Guinea Impatiens Cultivars Grown with Controlled-release Fertilizer and No Leaching

1996 ◽  
Vol 121 (5) ◽  
pp. 820-825 ◽  
Author(s):  
Darren L. Haver ◽  
Ursula K. Schuch
Keyword(s):  
Controlled Release ◽  
New Guinea ◽  
Light Level ◽  
High Rate ◽  
Controlled Release Fertilizer ◽  
Light Levels ◽  
High Moisture Level ◽  
Leaf N Content ◽  
New Guinea Impatiens

The objectives of this study were to determine 1) the minimum controlled-release fertilizer (CRF) rate and the lowest constant medium moisture required to produce the highest quality plants and 2) if this production system affected quality of these plants under two postproduction light levels. Two New Guinea impatiens (Impatiens sp. hybrids) `Illusion' and `Blazon' (Lasting Impressions Series) differing in salt tolerance were grown for 42 days with a CRF at three rates (3.3, 6.6, or 9.9 g/pot) and two medium moisture levels (low or high) without leaching. The high moisture level (tension setpoints of 1 to 3 kPa) and 6.6 g of CRF/pot produced optimum biomass. Low medium moisture (tension setpoints of 4 to 6 kPa) reduced leaf area, leaf number, leaf N content, root, stem, and leaf dry masses as CRF rate increased from low to high for `Illusion'. Similar results in `Blazon' were observed as CRF rates increased from 3.3 to 6.6 g. Biomass decreased no further at the high rate of 9.9 g/pot. Biomass increased in both cultivars under high medium moisture when CRF rates increased from 3.3 to 6.6 g. Biomass of `Illusion' decreased at 9.9 g/pot, although no symptoms of salt sensitivity were observed (i.e., leaf tip burn). `Blazon' maintained a similar biomass when amended with 9.9 or 6.6 g CRF/pot, although electrical conductivity (EC) in the medium was 5.9 dS·m-1 in the upper half and 4.1 dS·m-1 in the lower half of the medium at the end of production. Growth of `Illusion' responded more favorably to postproduction light levels that were similar to those of production regardless of treatment imposed during production. Similar biomass responses occurred for `Blazon' regardless of the postproduction light level.

scholarly journals Fertilization and Liming Effects on the Growth and Nutrition of Bareroot Jeffrey Pine Outplanted on an Eastern Sierra Nevada Surface Mine

2002 ◽  
Vol 17 (1) ◽  
pp. 23-30 ◽  
Author(s):  
R.F. Walker
Keyword(s):  
Controlled Release ◽  
Sierra Nevada ◽  
Seedling Survival ◽  
Volume Growth ◽  
High Rate ◽  
Control Treatment ◽  
Surface Mine ◽  
Growing Seasons ◽  
Jeffrey Pine ◽  
Eastern Sierra Nevada

Abstract Two controlled-release fertilizer formulations, High N 22-4-6 + Minors and Forestry Dry Site 21-6-2 + Minors, and dolomitic lime were evaluated for their capacity to enhance establishment and nutrition of bareroot Jeffrey pine (Pinus jeffreyi) on an eastern Sierra Nevada surface mine. All amendments were applied at outplanting to the backfill of augered planting holes using a low rate of 8 g and a high rate of 16 g for the two fertilizers and a single 26 g rate for lime. Seedlings without fertilizer or lime served as the control treatment. Survival was unaffected by fertilization regardless of formulation and rate, while height, diameter, and volume growth were increased significantly after three growing seasons. The response to High N exceeded that to Dry Site, and the 16 g application was more stimulatory than 8 g. Liming decreased seedling survival and growth throughout the study. Fertilization increased N, P, and K foliar concentrations while depressing the concentrations of several micronutrients and Al. The influence of the lime amendment on seedling nutrition was sporadic and marginal. These results indicate that controlled-release fertilization at outplanting is a viable means of elevating seedling performance on eastern Sierra Nevada surface mines and similar harsh sites, while the liming approach used here was counterproductive to achieving reforestation objectives. West. J. Appl. For. 17(1):23–30.

scholarly journals Growth of Tree Species in Response to Controlled-release Fertilizer Sources and Application Rates in a Commercial Nursery Setting

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 603b-603
Author(s):  
Allen D. Owings ◽  
Edward W. Bush
Keyword(s):  
Controlled Release ◽  
Visual Quality ◽  
Application Rate ◽  
The Other ◽  
Control Treatment ◽  
Red Maple ◽  
Shoot Height ◽  
Controlled Release Fertilizer ◽  
Application Rates ◽  
Quality Ratings

A study was initiated at Bracy's Nursery, Amite, La., in Apr. 1997 to evaluate the influence of seven controlled-release fertilizer sources and three top-dressed application rates in production of 4-gal (15.7-L) containers of `LaFeliciana' peach and swamp red maple. The fertilizers tested were Osmocote Plus 15-9-11, Osmocote Plus 16-8-12, Woodace 20-5-10, Woodace 20-4-11, Customblen 24-4-6, Nutricote (Type 270) 17-7-8, and Nutricote (Type 360) 17-6-8. Application rates were 1.75, 2.25, and 2.75 lb N per cubic yard. The experiment was completely randomized within blocks (species) and each treatment was replicated five times. A control treatment was also included. For `LaFeliciana' peach, Nutricote and Osmocote yielded the superior results when shoot height and visual quality ratings were determined in October (6 months after initiation). Increases in application rate did not significantly increase shoot height or visual quality ratings in most cases. For swamp red maple, shoot height was not affected by fertilizer source or application rate. Caliper ranged from 19.2 to 23.0 mm but was only slightly influenced by fertilizer source and application rate. Visual quality ratings were significantly higher for Osmocote Plus 16-8-12 when compared to some of the other fertilizer sources.

scholarly journals The nitrogen topdressing mode of indica-japonica and indica hybrid rice are different after side-deep fertilization with machine transplanting

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaodan Wang ◽  
Yaliang Wang ◽  
Yuping Zhang ◽  
Jing Xiang ◽  
Yikai Zhang ◽  
...  
Keyword(s):  
Single Dose ◽  
Controlled Release ◽  
Nitrogen Uptake ◽  
Dry Matter ◽  
Hybrid Rice ◽  
Dry Matter Accumulation ◽  
Area Index ◽  
Quick Release ◽  
Significant Difference ◽  
Spikelets Per Panicle

AbstractDetermination of the optimal fertilization method is crucial to maximize nitrogen use efficiency and yield of different rice cultivars. Side-deep fertilization with controlled-release nitrogen, in conjunction with machine transplanting and subsequent topdressing, was applied to Indica–japonica hybrid rice ‘Yongyou1540’ (YY1540) and indica hybrid rice ‘Tianyouhuazhan’ (TYHZ). Four nitrogen treatments were applied in 2018 and 2019: traditional nitrogen application with quick-release nitrogen (T1), single-dose deep fertilization at transplanting with 100% controlled-release nitrogen (T2), and deep fertilization of 70% controlled-release nitrogen and topdressing of 30% quick nitrogen at tillering (T3), or at panicle initiation (T4). Side-deep fertilization reduced the fertilizer application frequency without causing yield loss, T4 enhanced the yield of YY1540 by increasing the number of productive tillers and number of spikelets per panicle compared with T1, T2 and T3. The yield of TYHZ showed no significant difference among treatments. The T4 treatment decreased the number of tillers at the tilling peak stage and increased the percentage productive tillers and number of differentiated spikelets. Compared with the other treatments, T4 increased dry matter accumulation and leaf area index during panicle initiation and grain ripening, and contributed to enhanced nitrogen uptake and nitrogen utilization in YY1540. On average, nitrogen uptake and utilization in YY1540 were highest in T4, but no significant differences among treatments were observed in TYHZ. Dry matter accumulation and nitrogen uptake from panicle initiation to heading of YY1540 were correlated with number of spikelets per panicle, but no significant correlations were observed for TYHZ. Supplementary topdressing with quick-release nitrogen at the panicle initiation stage was required to increase yield of indica–japonica hybrid rice, whereas single-dose deep fertilization with controlled-release nitrogen is satisfactory for the indica hybrid cultivar.

scholarly journals Influence of Atomization Nozzles and Spraying Intervals on Growth, Biomass Yield, and Nutrient Uptake of Butter-Head Lettuce under Aeroponics System

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 97
Author(s):  
Mazhar H. Tunio ◽  
Jianmin Gao ◽  
Imran A. Lakhiar ◽  
Kashif A. Solangi ◽  
Waqar A. Qureshi ◽  
...  
Keyword(s):  
Root Growth ◽  
Nutrient Uptake ◽  
Nutrient Solution ◽  
Biomass Yield ◽  
Chemical Properties ◽  
Cultivated Plants ◽  
Growth Ratio ◽  
Shoot Ratio ◽  
Droplet Sizes ◽  
Root To Shoot Ratio

The atomized nutrient solution droplet sizes and spraying intervals can impact the chemical properties of the nutrient solution, biomass yield, root-to-shoot ratio and nutrient uptake of aeroponically cultivated plants. In this study, four different nozzles having droplet sizes N1 = 11.24, N2 = 26.35, N3 = 17.38 and N4 = 4.89 µm were selected and misted at three nutrient solution spraying intervals of 30, 45 and 60 min, with a 5 min spraying time. The measured parameters were power of hydrogen (pH) and electrical conductivity (EC) values of the nutrient solution, shoot and root growth, ratio of roots to shoots (fresh and dry), biomass yield and nutrient uptake. The results indicated that the N1 presented significantly lower changes in chemical properties than those of N2, N3 and N4, resulting in stable lateral root growth and increased biomass yield. Also, the root-to-shoot ratio significantly increased with increasing spraying interval using N1 and N4 nozzles. The N1 nozzle also revealed a significant effect on the phosphorous, potassium and magnesium uptake by the plants misted at proposed nutrient solution spraying intervals. However, the ultrasonic nozzle showed a nonsignificant effect on all measured parameters with respect to spraying intervals. In the last, this research experiment validates the applicability of air-assisted nozzle (N1) misting at a 30-min spraying interval and 5 min of spraying time for the cultivation of butter-head lettuce in aeroponic systems.

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