scholarly journals Timing Citrus and Avocado Foliar Nutrient Applications to Increase Fruit Set and Size

1999 ◽  
Vol 9 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Carol J. Lovatt
Keyword(s):  
Foliar Application ◽  
Persea Americana ◽  
Flower Initiation ◽  
Cumulative Yield ◽  
Phenological Stages ◽  
Inflorescence Development ◽  
Nutrient Demand ◽  
Washington Navel ◽  
Foliar Nutrient ◽  
Hass Avocado

The goal of this research was to identify the role essential nutrients play in the physiology of tree crops, and then to apply the nutrient as a foliar fertilizer to stimulate a specific metabolic process at phenological stages when nutrient demand is high. This approach has proven successful. A single winter prebloom foliar application of nitrogen as low-biuret urea [0.16 kg N/tree (0.35 lb N/tree)] to 30-year-old `Washington' navel orange (Citrus sinensis L. Osbeck) trees during flower initiation significantly increased yield and fruit number per tree for each of 3 consecutive years (P ≤ 0.05). The number of commercially valuable largesize fruit also increased significantly with yield increases (r2 = 0.88). Sodium tetraborate applied foliarly to `Hass' avocado (Persea americana Mill.) trees at the cauliflower stage of inflorescence development (elongation of inflorescence secondary axes, pollen and ovule development) increased the number of pollen tubes reaching the ovule, ovule viability and cumulative yield (P ≤ 0.05). Additional examples are presented.

Properly Timed Foliar Nutrient Applications Provide an Efficient Means to Meet Nutrient Demand to Increase Flowering, Fruit Set, and Size of Citrus and Avocado

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 556f-557 ◽  
Author(s):  
Carol J. Lovatt
Keyword(s):  
Persea Americana ◽  
Cumulative Yield ◽  
Inflorescence Development ◽  
Ongoing Research ◽  
Horticultural Crops ◽  
Nutrient Demand ◽  
Washington Navel ◽  
Foliar Nutrient ◽  
Essential Nutrient ◽  
Hass Avocado

The goal of our research is to identify the role that specific essential nutrient elements play in the physiology of horticultural crops and then to apply the nutrient as a fertilizer to the foliage at key times in the phenology of the tree, i.e., a time when the demand for the nutrient is likely to be high, in order to stimulate a specific physiological process. This approach proved successful in the following completed studies. A single winter prebloom application of nitrogen as low-biuret urea made to the foliage of 30-year-old `Washington' navel orange (Citrus sinensis L. Osbeck) trees at the time of irreversible commitment to flowering significantly increased yield and fruit number per tree for each of three consecutive years. In addition, the number of commercially valuable fruit with diameters of 6.1 to 8.0 cm significantly increased as yield increased (r2=0.88). Applications of boron as sodium tetraborate to the foliage of a commercial orchard of `Hass' avocado (Persea americana Mill.) trees at the cauliflower stage of inflorescence development (gametogenesis) increased the number of pollen tubes reaching the ovule, ovule viability and cumulative yield (P ≤ 0.05). Additional examples from ongoing research also will be presented.

scholarly journals Properly Timed Soil-applied Nitrogen Fertilizer Increases Yield and Fruit Size of `Hass' Avocado

2001 ◽  
Vol 126 (5) ◽  
pp. 555-559 ◽  
Author(s):  
Carol J. Lovatt
Keyword(s):  
Fruit Size ◽  
Persea Americana ◽  
Double Dose ◽  
Cumulative Yield ◽  
Phenological Stages ◽  
N Application ◽  
Large Size ◽  
Tree Phenology ◽  
Hass Avocado ◽  
Applied Nitrogen

To protect groundwater from potential nitrate pollution, `Hass' avocado (Persea americana Mill.) growers in California divide the total annual soil-applied nitrogen (N) fertilizer (N at 56 to 168 kg·ha-1) into small applications made during the period from late January to early November. However, no research had been conducted to test the efficacy of this fertilization practice, and there was concern that the amount of N in the individual applications may be too little to meet the demand of the tree at some stages of its phenology. The research presented herein addressed the question of whether yield of `Hass' avocado could be increased by doubling the amount of N currently applied during specific stages of tree phenology. The control in this experiment was the practice of annually applying N as NH4NO3 at 168 kg·ha-1 (168 trees/ha) in six small doses of N at 28 kg·ha-1 in January, February, April, June, July, and November. From these six application times, five were selected on the basis of tree phenology and additional N as NH4NO3 at 28 kg·ha-1 was applied at each time for total annual N of 196 kg·ha-1. Two phenological stages were identified for which N application at 56 kg·ha-1 in a single application (double dose of N) significantly increased the 4-year cumulative yield (kilograms fruit per tree) 30% and 39%, respectively, compared to control trees (P ≤ 0.01). In each case, more than 70% of the net increase in yield was commercially valuable large size fruit (178 to 325 g/fruit). The two phenological stages were when shoot apical buds have four or more secondary axis inflorescence meristems present (mid-November); and during anthesis to early fruit set and initiation of the vegetative shoot flush at the apex of indeterminate floral shoots (about mid-April). When the double dose of N was applied at either of these two stages, the kilograms and number of large size fruit averaged across the 4 years of the study was significantly greater than the control trees (P ≤ 0.01). Averaged across the 4 years of the study, only the November treatment increased yield compared to the control trees (P ≤ 0.05). Application of the double dose of N at flower initiation (January), during early-stage gynoecium development (February), or during June drop had no significant effect on average or cumulative yield or fruit size compared to control trees. Application of the double dose of N in April significantly reduced the severity of alternate bearing (P ≤ 0.05). Yield was not significantly correlated with leaf N concentration. Time and rate of N application are factors that can be optimized to increase yield, fruit size, and annual cropping of `Hass' avocado. When the amounts of N applied were equal (196 kg·ha-1), time of application was the more important factor.

scholarly journals Properly Timing Foliar-applied Fertilizers Increases Efficacy: A Review and Update on Timing Foliar Nutrient Applications to Citrus and Avocado

2013 ◽  
Vol 23 (5) ◽  
pp. 536-541 ◽  
Author(s):  
Carol J. Lovatt
Keyword(s):  
Foliar Application ◽  
Total Yield ◽  
Persea Americana ◽  
Nitrate Contamination ◽  
Soil Conditions ◽  
Negative Consequences ◽  
Runoff Water ◽  
Nutrient Demand ◽  
Tree Phenology ◽  
Fertilizer Rates

Foliar fertilization efficiently meets the nutrient demand of tree fruit crops during periods when soil conditions (low or high temperatures, low or excess soil moisture, pH, salinity) render soil-applied fertilizers ineffective, when nutrients (e.g., phosphate, potassium, and trace elements) become fixed in the soil, and when tree nutrient demand is high. Applying nutrients directly to leaves ensures that the metabolic machinery of the tree is not compromised by low availability of an essential nutrient. It should be noted that phloem mobile nutrients applied to the foliage are translocated to all tree parts, even feeder roots. Because foliar application of fertilizers can reduce nutrient accumulation in soil, runoff water, surface water (streams, lakes, ocean), and groundwater (drinking water supply), where they contribute to salinity, eutrophication, or nitrate contamination, with negative consequences to the environment and humans, it is highly desirable to replace soil-applied fertilizers at least in part with foliar-applied fertilizers. However, not all nutrients are taken up through leaves and, even if taken up, some nutrients are not phloem mobile. In addition, although foliar fertilizer rates are typically lower than soil fertilizer rates, application can be more costly. The goal has been to time the application of foliar fertilizers to key stages of citrus (Citrus sp.) and avocado (Persea americana) tree phenology when demand for the nutrient is likely to be high and especially when soil conditions are likely to compromise nutrient uptake by roots. This approach has proven successful for increasing yield, fruit size, and grower income even when the tree is not nutrient deficient by standard leaf analysis. Winter prebloom foliar-applied low-biuret urea was previously documented to increase total yield of both navel and ‘Valencia’ oranges (Citrus sinensis). Adaptation of this treatment to ‘Nules’ Clementine mandarin (Citrus reticulata) increased the yield of commercially valuable size fruit in two experiments. Foliar application of boron or low-biuret urea to ‘Hass’ avocado trees at the “cauliflower” stage of inflorescence development increased total yield; potassium phosphite applied at this stage of tree phenology increased the yield of commercially valuable size fruit.

scholarly journals Inflorescence and Flower Development of the `Hass' Avocado (Persea americana Mill.) during “On” and “Off” Crop Years

1998 ◽  
Vol 123 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Samuel Salazar-García ◽  
Elizabeth M. Lord ◽  
Carol J. Lovatt
Keyword(s):  
Flower Development ◽  
Persea Americana ◽  
High Yield ◽  
Reproductive Condition ◽  
Inflorescence Development ◽  
Apical Buds ◽  
Secondary Axis ◽  
Primary Axis ◽  
Hass Avocado ◽  
Flowering Process

Inflorescence and flower development of the `Hass' avocado (Persea americana Mill.) were investigated at the macro- and microscopic level with three objectives: 1) to determine the time of transition from vegetative to reproductive growth; 2) to develop a visual scale correlating external inflorescence and flower development with the time and pattern of organogenesis; and 3) to quantify the effect of high (“on”) and low (“off”) yields on the flowering process. Apical buds (or expanding inflorescences) borne on summer shoots were collected weekly from July to August during an “on” and “off” crop year. Collected samples were externally described and microscopically analyzed. The transition from vegetative to reproductive condition probably occurred from the end of July through August (end of shoot expansion). During this transition the primary axis meristem changed shape from convex to flat to convex. These events were followed by the initiation of additional bracts and their associated secondary axis inflorescence meristems. A period of dormancy was not a prerequisite for inflorescence development. Continued production of secondary axis inflorescence meristems was observed from August to October, followed by anthesis seven months later. In all, eleven visual stages of bud development were distinguished and correlated with organogenesis to create a scale that can be used to predict specific stages of inflorescence and flower development. Inflorescence development was correlated with minimum temperature ≤15 °C, whereas yield had little effect on the timing of developmental events of individual inflorescence buds. However, the high yield of the “on” year reduced inflorescence number and increased the number of vegetative shoots. No determinate inflorescences were produced during the “on” year. For the “off” year, 3% and 42% of shoots produced determinate and indeterminate inflorescences, respectively.

scholarly journals Foliar-applied GA3 Advances Fruit Maturity and Allows Off-season Harvest of ‘Hass’ Avocado

HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 257-261 ◽  
Author(s):  
Samuel Salazar-García ◽  
Luis E. Cossio-Vargas ◽  
Isidro J.L. González-Durán ◽  
Carol J. Lovatt
Keyword(s):  
Gibberellic Acid ◽  
Foliar Application ◽  
Fruit Size ◽  
Inflorescence Development ◽  
Avocado Fruit ◽  
Negative Effect ◽  
Effect On Yield ◽  
Hass Avocado ◽  
Vegetative And Reproductive Growth ◽  
Prohexadione Calcium

Michoacán and Nayarit are, respectively, the largest and second largest avocado-producing states in Mexico. The main harvest of the ‘Hass’ avocado in both states is concentrated during November to December, which saturates the market and reduces the price of fruit and grower income. The goal of this research was to manipulate vegetative and reproductive growth of the ‘Hass’ avocado with properly timed foliar-applied plant bioregulators (PBRs) to shift the date of flowering and harvest to the period before or after the main harvest. Effects of canopy sprays of gibberellic acid (GA3) or prohexadione calcium (a gibberellic acid biosynthesis inhibitor) applied at different stages of tree phenology on inflorescence development, time of anthesis, date of legal maturity for harvest of ‘Hass’ avocado fruit, yield, and fruit size were quantified. No PBR treatment influenced the time of anthesis. A single or double foliar application of GA3 (50 mg·L−1) ≈4 months (July) before the expected date of main harvest (November) resulted in ‘Hass’ avocado fruit reaching legal maturity (mesocarp dry matter 21.5% or greater) 24.8 to 28.2 d earlier than those of untreated control trees with no negative effect on yield or fruit size.

scholarly journals Inflorescence Development of the `Hass' Avocado: Commitment to Flowering

1999 ◽  
Vol 124 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Samuel Salazar-García ◽  
Elizabeth M. Lord ◽  
Carol J. Lovatt
Keyword(s):  
Low Temperature ◽  
Developmental Stage ◽  
Persea Americana ◽  
Inflorescence Development ◽  
Apical Buds ◽  
Secondary Axis ◽  
Primary Axis ◽  
Hass Avocado ◽  
Old Trees

The developmental stage at which the shoot primary axis meristem (PAM) of the `Hass' avocado (Persea americana Mill.) is committed to flowering was determined. Three-year-old trees were subjected to low-temperature (LT) treatments at 10/7 °C day/night with a 10-h photoperiod for 1 to 4 weeks followed by 25/20 °C day/night at the same photoperiod. Before LT treatment, apical buds of mature vegetative shoots consisted of a convex PAM with two lateral secondary axis inflorescence meristems lacking apical bracts each associated with an inflorescence bract. Apical buds did not change anatomically during LT treatment. However, the 3- and 4-week LT treatments resulted in inflorescences at 17% and 83% of apical buds, respectively. Trees receiving 2 weeks or less LT, including controls maintained at 25/20 °C, produced only vegetative shoots. Apical buds of 2-year-old trees receiving 3 weeks at 10/7 °C plus 1 week at 20/15 °C produced 100% inflorescences. GA3(100 mg·L-1) applied to buds 2 or 4 weeks after initiation of this LT treatment did not reduce the number of inflorescences that developed. `Hass' avocado apical buds were fully committed to flowering after 4 weeks of LT, but were not distinguishable anatomically from those that were not committed to flowering.

scholarly journals Use of GA3 to Manipulate Flowering and Yield of `Hass' Avocado

2000 ◽  
Vol 125 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Samuel Salazar-García ◽  
Carol J. Lovatt
Keyword(s):  
Early Stage ◽  
Persea Americana ◽  
Yield Reduction ◽  
Alternate Bearing ◽  
Concomitant Increase ◽  
Vegetative Shoot ◽  
Inflorescence Development ◽  
Initial Development ◽  
Shoot Number ◽  
Hass Avocado

Avocado trees (Persea americana Mill.) bearing a heavy crop produce a light “off” bloom the next spring. This results in a light crop and a subsequent intense “on” bloom the year after. The objective of the study was to quantify the effects of GA3 canopy sprays applied to `Hass' avocado trees during the months preceding an “off” or “on” bloom on inflorescence and vegetative shoot number and yield. The experiment was initiated approximately seven months before an anticipated “off” bloom in an attempt to increase flowering intensity and yield. GA3 (25 or 100 mg·L-1) was applied to separate sets of trees in September (early stage of inflorescence initiation), November (early stage of inflorescence development), January (initial development of the perianth of terminal flowers), March (cauliflower stage of inflorescence development; only 25 mg·L-1), or monthly from September through January (only 25 mg·L-1). Control trees did not receive any treatment. GA3 (100 mg·L-1) applied in September reduced inflorescence number in both years, but not yield. GA3 (25 or 100 mg·L-1) applied in November before the “on” bloom reduced inflorescence number with a concomitant increase in vegetative shoot number and 47% yield reduction compared to control trees. This treatment might provide avocado growers with a tool to break the alternate bearing cycle by reducing yield in an expected “on” crop year to achieve a higher yield the following year. GA3 (25 mg·L-1) applied in November or January stimulated early development of the vegetative shoot of indeterminate inflorescences. January and March applications did not affect the number of flowering or vegetative shoots produced either year. GA3 (25 mg·L-1) applied in March at the start of an “off” bloom increased 2-fold the production of commercially valuable fruit (213 to 269 g per fruit) compared to the control.

scholarly journals Nitrogen Fertilization Strategies for the ‘Hass’ Avocado that Increase Total Yield Without Reducing Fruit Size

2016 ◽  
Vol 26 (4) ◽  
pp. 426-435 ◽  
Author(s):  
Jaime E. Salvo ◽  
Carol J. Lovatt
Keyword(s):  
Shoot Growth ◽  
Important Determinant ◽  
Total Yield ◽  
Fruit Size ◽  
Fertilizer Application ◽  
Persea Americana ◽  
Phenological Stages ◽  
Tree Phenology ◽  
Hass Avocado ◽  
N Demand

Effects of nitrogen (N) fertilizer application times and rates on ‘Hass’ avocado (Persea americana) yield and fruit size were determined to resolve whether a single dose of soil-applied N [1x N (25 lb/acre)] at each of the five key stages of tree phenology (January, April, July, August, and November) (control) was as efficacious as soil-applied 2x N (50 lb/acre) at one or two key stages or soil- or foliar-applied 3x N (75 lb/acre) at only one stage. All trees received soil-applied N at 125 lb/acre as ammonium nitrate (NH4NO3) annually; trees receiving 2x or 3x N received the remaining N divided evenly at the same phenological stages (months) as trees receiving five 1x N applications. The importance of supplying N during the summer, when June drop, exponential fruit growth, vegetative shoot growth, and floral initiation occur, was determined by testing soil-applied 0.8x N in July plus August only (40 lb/acre N as NH4NO3 annually). Application time proved an important determinant of total yield. Yield of commercially valuable size (CVS) fruit was correlated with total yield (r = 0.80, P < 0.0001). Four-year cumulative total yields were equal for trees receiving soil-applied 1x N at five key phenological stages and trees receiving soil-applied 2x N in April and 18.75 lb/acre N at the four other stages (months). However, trees receiving soil-applied 2x N in April plus November and only 8.3 lb/acre N in the three other months, in particular July and August, had significantly lower 4-year cumulative total yields (P = 0.0362). Additional evidence of the importance of meeting avocado tree N demand in the summer is that trees receiving only 40 lb/acre N split in July plus August produced 4-year cumulative total yields equal to trees receiving 25 lb/acre N at the five key phenological stages; lower annual N would reduce fertilizer expense and protect the environment.

scholarly journals Standardizing the Hydrogel Application Rates and Foliar Nutrition for Enhancing Yield of Lentil (Lens culinaris)

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 420 ◽  
Author(s):  
Shashidhar K. Shankarappa ◽  
Samuel J. Muniyandi ◽  
Ajay B. Chandrashekar ◽  
Amit K. Singh ◽  
Premaradhya Nagabhushanaradhya ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Seed Yield ◽  
Lens Culinaris ◽  
Foliar Application ◽  
Winter Season ◽  
Growth Period ◽  
Growth And Yield ◽  
Flower Initiation ◽  
Foliar Nutrition ◽  
Pod Development

Lentil (Lens culinaris) is an important winter season annual legume crop known for its highly valued seed in human and animal nutrition owing to its high lysine and tryptophan content. Shortage of water during the crop growth period has become the major impediment for cultivation of pulses in rice fallow in particular. Under such conditions, the application of hydrogel can be a potential alternative to improve photosynthetic efficiency, assimilate partitioning, and increase growth and yield. A field experiment was conducted from November to February during 2015–16 to 2017–18 on clay loam soil that was medium in fertility and acidic in reaction (pH 5.4) at Central Agricultural University, Imphal, Manipur. The experiment was laid out in split plot design with three replications. There were three hydrogel levels in total in the main plot and foliar nutrition with five different nutrient sprays in sub-plots, together comprising 15 treatment combinations. The data pooled over three years, 2015–2018, revealed that application of hydrogel at 5 kg/ha before sowing recorded a significantly greater number of pods per plant (38.0) and seed yield (1032.1 kg/ha) over the control. Foliar application of nutrients over flower initiation and pod development had a positive effect on increasing the number of pods per plant eventually enhanced the seed yield of lentil. Foliar application of either 0.5% NPK or salicylic acid 75 ppm spray at flower initiation and pod development stages recorded significantly more pods per plant over other nutrient treatments. Further, the yield attributed improved because of elevated growth in plant. Significantly maximum seed yield (956 kg/ha) recorded in the NPK spray of 0.5% remained on par with salicylic acid 75 ppm (939 kg/ha) over the rest of the treatments.

Note. Effect of Storage Temperature on the Shelf Life of Hass Avocado (Persea Americana)

2004 ◽  
Vol 10 (2) ◽  
pp. 73-77 ◽  
Author(s):  
K. Perez ◽  
J. Mercado ◽  
H. Soto-Valdez
Keyword(s):  
Weight Loss ◽  
Shelf Life ◽  
Respiration Rate ◽  
Ethylene Production ◽  
Storage Temperature ◽  
Persea Americana ◽  
Co2 Production ◽  
Hass Avocado ◽  
Storage Temperatures

The effect of storage temperature on the shelf life, weight loss, respiration rate and ethylene production of Hass avocado (Persea americana Mill) was studied. Two batches of green mature avocado fruits, classified as ‘‘super extra’’ were stored at 10 and 20 C (first batch) and at 7 and 25 C (second batch). The avocado shelf lives were 22, 8, 32 and 6 days at 10, 20, 7 and 25 C, respectively. Based on the data of the first assay Q10 was calculated as 2.75, with this value the predicted shelf life at 7 and 25 C were 29.8 and 4.8 days, respectively. That meant shelf life was underestimated 7 and 20% at 7 and 25 C, respectively. Weight loss was linear at both the storage temperatures, it was 4.3% in fruits at 20 C for 8 days and 3.0% at 10 C for 22 days. The maximum CO2 production at 20 C was reached during the second day of storage, while at 10 C it was reached at the 17th day (176.17 15.98 and 74.73 7.32 mL/kg h, respectively). The maximum ethylene production at 20 C was reached the second day of storage, and at 10 C the 6th day (239.06 54.55 and 28.00 8.12 mL/kg h, respectively).

Sign in / Sign up

Export Citation Format

Share Document