LIBRO-CONGRESO-CITRUS

S10P20
Phosphorus deficiency decreases nutrient use efficiency of citrus
Zambrosi F.C.B., Mattos Jr. D., Quaggio J.A., and Boaretto R.M.
Instituto Agronômico (IAC), Solos, Brasil. zambrosi@iac.sp.gov.br
The evaluation of the effects of P availability on the efficiency of nutrient absorption and utilization by citrus
rootstocks is required to extend the knowledge on plant responses to P deficiency. Thus, seedlings of citrus
rootstocks ‘Rangpur’ lime, ‘Swingle’ citrumelo, ‘Cleopatra’ and ‘Sunki’ mandarins were grown on nutrient
solution with 0.0125; 0.05; 0.2 and 0.8 mmol L-1 of P. After 100 days of P treatments, the rootstocks were
harvested and then separated into leaves, stem and roots to estimate plant dry weights, and N, K, Ca, Mg,
S and B concentrations. The nutrient accumulation by the citrus rootstocks was proportional to P supply
in the nutrient solution. Regardless of treatment, the following pattern of nutrient accumulation by the
rootstocks was observed: ‘Rangpur’ lime > ‘Swingle’ citrumelo > ‘Sunki’ mandarin > ‘Cleopatra’ mandarin. The
lowest P concentration in the nutrient solution significantly decreased the efficiency of nutrient absorption
and utilization compared to 0.2 and 0.8 mmol L-1 of P. The ‘Rangpur’ lime was the most efficient rootstock
in nutrient utilization for growth, while ‘Swingle’ citrumelo was the least efficient in nutrient absorption.
The results demonstrate that low-P availability decreased the accumulation, efficiency of absorption and
utilization for growth of N, K, Ca, Mg S and B by the plants, suggesting that the adequate management of P
fertilization is critical to improve nutrient use efficiency in citrus orchards.
S10P21
Enhancement yield, fruit quality and nutritional status of Washington Navel orange trees by
application of some biostimulants
El-Shazly S.M. 1 , and Mustafa N.S. 2
1 Faculty of Agriculture, Alexandria University, Alexandria, Egypt. 2 Agricultural and Biological Division, National Research Center, Cairo,
Egypt. samyshazly55eg@yahoo.com
The effect of biostimulants [potassium humate, yeast extract and amino green II (amino acids mixture)]
on yield, fruit quality and nutritional status of Washington Navel orange trees were evaluated under field
conditions. Potassium humate was applied at 10 and 20 g/tree as soil application. In addition, yeast extract
at 0.2 and 0.4% and amino green II at 0.25 and 0.5% were applied as foliar application. The obtained data
revealed that all biostimulants increased total yield compared to control. The highest yield was obtained
with trees received potassium humate at 20 g/tree. Fruit weight, fruit juice %, total soluble solids (TSS), total
sugars and vitamin C contents were markedly increased with biostimulants treatments compared to control.
Moreover, high values of such characters were obtained with trees treated with potassium humate at 20g/
tree and active dry yeast at 0.4%. Biostimulants treatments enhanced leaf chlorophyll content and leaf mineral
contents of N, P, K, Ca and Mg. It was concluded that biostimulants treatments had a promotional effect on
yield, fruit quality and nutritional status of Washington Navel orange trees. In this respect, potassium humate
at 20 g/tree and active dry yeast at 0.4% were considered promising treatments.
S10P22
Calcium, magnesium and potassium levels in the soil and in the leaf of orange trees on different
rootstocks and soil conservation systems in the northwest of Paraná State, Brazil
Gil L. G. 1 , Auler P. A. M. 2 , and Pavan M.A. 1
1 Instituto Agronônico do Paraná (IAPAR), Área de Solos, Brasil; and 2 Instituto Agronônico do Paraná (IAPAR), Área de Fitotecnia, Brasil.
lggil@iapar.br
This study aimed to determine the effects of soil preparation, Brachiaria brizantha mowing, and rootstocks on
soil nutrient availability and leaf Ca, Mg and K contents of orange trees, on a Typic Haplorthox originated from
the Caiua Sandstone. The experimental plots were defined by soil preparation: no-tillage (NT), strip-tillage
(ST) and conventional tillage (CT); the subplots by mowing management between tree rows: conventional
(CM) and mulching (MM), and the subsubplots by rootstocks: Rangpur lime and Cleopatra mandarin. Leaf
XII INTERNATIONAL CITRUS CONGRESS 2012 - 169
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