Spraying 3.0% urea was more effective for fruit quality than 2.0%.

nitrogen · quality: general · Citrus sinensis (sweet orange)Positive and negative results

4 papers in the same direction as this claim · 3 in the opposite direction · 1 reporting no difference from an alternative

1. no effect
   Nitrogen rates of 168, 224 or 280 kg N per ha per year did not significantly affect fruit nutrient status, juice quality or nutrient concentrations in the spring flush of orange.

   Fruit nutrient accumulation of four orange varieties during fruit development¹ · 2000

   Opposite direction

2. no effect
   Protoplast yield, quality and growth did not differ between cryopreserved and non-cryopreserved sweet-orange callus.

   Cryopreserved callus, a source of protoplasts for citrus improvement · 2000 · compared with non-cryopreserved callus

   Opposite direction

3. no effect
   Nitrogen rate and fertigation frequency did not affect fruit size or juice quality.

   Optimum nitrogen rate for fertigated young navel orange trees in arizona · 2007

   Opposite direction

4. no effect
   Among fertilized treatments, nitrogen rate had no significant effect on fruit quality.

   Development of Best Management Practices for Fertigation of Young Citrus Trees, 2002 Report · 2002 · compared with fertilized treatments

   No difference from an alternative

5. positive
   Fruit from urea phosphate-treated Valencia orange trees had the highest ratings for fruit flavour, compared with potassium nitrate foliar sprays.

   The Effect of Nutritional Treatments on Post-Harvest Quality and Flavour of Valencia Oranges · 1982 · compared with potassium nitrate foliar sprays

   Same direction

6. positive
   Suitable nitrogen, phosphorus and potassium improved orange output and quality.

   Impact of Different Levels of Nitrogen Fertilization on Oranges Output and Quality · 2015

   Same direction

7. positive
   Without added P, N showed a trend toward lower juice quality.

   NUTRITIONAL REQUIREMENTS OF CITRUS CONVERTED FROM FLOOD TO A PRESSURIZED IRRIGATION SYSTEM · 1992

   Same directionAbout lacking this nutrient, so it counts the other way round

8. positive
   Nutrient application improved sweet orange TSS, TSS: acidity ratio and total sugars.

   Effect of nutrients level on quality parameters of sweet orange under western Maharashtra conditions · 2024

   Same direction

application · quality: general · Citrus sinensis (sweet orange)Positive and negative results

7 papers in the same direction as this claim · 2 in the opposite direction

1. no effect
   The orange zinc application did not affect fruit size or quality.

   PROPERLY TIMED FOLIAR FERTILIZATION CAN AND SHOULD RESULT IN A YIELD BENEFIT AND NET INCREASE IN GROWER INCOME · 2010

   Opposite direction

2. negative
   Fruit quality was altered and off-flavor detected after bloom spray in Washington Navel orange trees.

   Responses of Orange and Grapefruit Trees to Maleic Hydrazide · 1952

   Opposite direction

3. positive
   Frequent foliar iron sprays prevented yield and quality losses.

   FOLIAR TREATMENTS AS A STRATEGY TO CONTROL IRON CHLOROSIS IN ORANGE TREES · 2002

   Same direction

4. positive
   Spraying at 30 DAFB significantly improved the external quality and coloring of citrus fruit.

   Ca(NO3)2 canopy spraying during physiological fruit drop period has a better influence on the tree character and fruit quality of Newhall navel orange (Citrus sinensis Osbeck) · 2017

   Same direction

5. positive
   Higher-dose drill-based OTC injection improved juice quality more than lower-dose drill-free injection, with cultivar-dependent responses.

   Systemic Delivery of Oxytetracycline by Drill-Based and Drill-Free Trunk Injection for Treatment of Huanglongbing in Young Sweet Orange Trees · 2025 · compared with lower doses by drill-free injection

   Same direction

6. positive
   Late-summer oil spray was less likely to reduce Valencia orange juice quality than other application times.

   Timing oil spray on valencias: Study indicates influence of application timing on effect of pest control oil spray on yield and juice of Valencias · 1956 · compared with any other time of the year

   Same direction

7. positive
   Soil ZnSO4 150 g with foliar ZnSO4 0.50% (T10) was the most effective treatment for quality parameters of sweet orange

   Effect of soil and foliar application of zinc on quality parameters of sweet orange Var. Nucellar (Citrus sinensis L. Osbeck) · 2018

   Same direction

8. positive
   Fluroxypyr retained fruit sensory attributes relative to other treatments or untreated fruit.

   Postharvest treatment of navel oranges with fluroxypyr, 2-methyl-4-chlorophenoxyacetic acids, and 2,4-dichlorophenoxyacetic maintains physiological quality during ambient storage · 2024 · compared with MCPA 2,4-D, or untreated fruit

   Same direction

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