LIBRO-CONGRESO-CITRUS

almost disappeared and total yield in four years reached to an acceptable level. Also index of alternate
bearing was calculated for all treatments and results showed that treatment 6 had the lowest and control
had the highest index among other treatments. So, as in treatment 6 (urea spraying with autumn nitrogen
application and spring pruning), alternate bearing almost was balanced and total yield increased and in
each year reached to an acceptable amount. Use of this treatment in citrus plantings in north of Iran could
be economical and profitable.
S06P15
Possibility of adjusting alternate bearing cycle in satsuma mandarin (Citrus unshiu) in north of Iran
Asadi Kangarshahi A. 1 and Akhlaghi Amiri N. 2
1 Mazandaran Agricultural and Natural Resources Research Center, Soil Science, Iran; and 2 Mazandaran Agricultural and Natural
Resources Research Center, Seed and Plant Breeding, Iran. kangarshahi@gmail.com
Alternate bearing is one major problem in some citrus varieties like satsuma mandarin. An alternate
bear tree does not produce a regular crop in consequence years. Reduced fruit quality in “on year” and
decreased quantity in “off year” cause economic loss to producer. To evaluate possibility of reducing this
disorder, an experiment was conducted in randomize complete block design with 5 treatments: 1. Control;
2. Optimum using of chemical fertilizers (based on leaf analysis and annual yield prediction); 3. Optimum
using of chemical fertilizers and NAA spraying (300 mg L -1 during June drop in on years); 4. Optimum using
of chemical fertilizer and 2,4-D spraying (50 mg L -1 during June drop in on years) and 5. Optimum using of
chemical fertilizer and sucrose spraying with 4 replications in 4 consecutive years on satsuma mandarin
mature trees. Control trees had the most alternate bearing during 4 years, as showed one “on” year, two
consecutive “off” years and one “on” year, respectively. On the other hand, other 4 treatments reduced
number of “off” years to one, during 4 years. Treatment 2 had the highest yield in “off” year and the
lowest yield in “on” year. The smallest and lightest fruit in first, second and fourth years was allocate to
control. During 4 years, the lowest total yield was recorded in control plants. In conclusion, treatment 2
by reducing yield in “on” year, increasing yield in “off” year and reduce number of “off” years compare to
control and treatments 3, 4 and 5 by reducing number of “off” years and increasing fruit size in on years
caused adjusting alternate bearing cycle, increase total yield in consecutive years, decrease fruit losses and
improve marketability in satsuma mandarin.
S06P16
Reproductive behavior of plants of ‘Valencia’ sweet orange under two soil moisture conditions
Laskowski L.L.
Universidad Lisandro Alvarado (UCLA), Agronomía - Cs. Biológicas, Venezuela. llaskowski@ucla.edu.ve
Drought in the tropics impose cessation of reproductive growth in citrus. In Venezuela has been established a
minimum requirements of 1200 mm of precipitation per year to maintain a profitable citrus farm. Otherwise,
irrigation is absolutely necessary to sustain productivity. During this investigation we evaluated the fruit
set, growth and fruit quality in plants of ‘Valencia’ sweet orange (Citrus sinensis) subject to the application
of deficient irrigation. Plants of 8 years of experimental orchard at the University Lisandro Alvarado, Lara,
Venezuela, were used. Starting from the first sprouting induced by the rains applied two irrigation treatments:
50 and 100% of the water requirement, considering the losses by evapotranspiration. In each plant were
selected four branches of 30 nodes and each month we proceeded to determine: number of flowers, fruit
number and diameter. After reaching fruit maturity, we took between 20 and 15 fruits of each plant to
determine: fresh mass, skin thickness, volume of juice, ° Brix, TSS and juice acidity. As a result, the fruits of
plants under 100% irrigation during the first 11 daa increased growth rate and shown higher percentage of
abscission compared to 50% irrigation. Next, until the end of study (244 daa), fruit set, fruit diameter and
quality were similar in both treatments and were comparable to reported for variety. The quality of the juice
shown to be significantly more palatable under deficient irrigation. In conclusion, the 50% decrease in the
amount of irrigation water considering the weekly evaporation losses did not affect plant productivity and
fruit quality under the environmental conditions studied.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 103
S06