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all, in all irrigation treatments except RDI
0
, the leaf micronutrients (Fe, Mn and Zn)
content was higher than their threshold values (57.8-69.4 ppm Fe, 52.7-76.3 ppm
Mn and 25.9-28.5 ppm Zn) required for optimum productivity of 'Kinnow' mandarin
[27]. Similar trend of micronutrient concentration in leaves was observed 'Nagpur'
mandarin [19] under DI. However, [25] concluded that water stress has no signifi cant
affect on Fe, Mn, Cu and Zn concentration of leaves in citrus. This difference from
the present observation might be due to higher micronutrients concentration in their
soil that supported the availability of the nutrients to plants even under water stress
condition, as compared to the soil in the present study. Moreover, the concentration of
micronutrients in leaves decreased from 2010 to 2011 due to their reduced availability
in soil over time.
19.3.4 LEAF WATER CONTENT AND STEM WATER POTENTIAL
The mean RLWC and LWC in EFGP were significantly affected under various irriga-
tion treatments (Table 3). The maximum values for RLWC and LWC were observed
with FI, whereas the minimum values were observed with RDI
0
.
Irrigation treatments affected y and S
y
of the plants signifi cantly (Table 4). The
mean values for
at EFGP were from −0.8 to −1.4 MPa and −0.7 to −1.1 MPa in
2010 and 2011, respectively. The higher values of y with lower S
ψ
in 2011 than that
in 2010 was caused by higher amount of rainfall (82.2 mm), and lower temperature
(mean, 31 °C) in conjunction with lower evaporation rate (6.95 mm/day) during EFGP
in 2011 compared with rainfall (8.8 mm), mean temperature (33 °C) and evaporation
rate (10.01 mm/day) in 2010. The trees with FI exhibited the highest y with lowest S
y
,
whereas the trees with RDI
0
exhibited the lowest values.
ψ
TABLE 3
Relative leaf water content (RLWC), leaf water concentration (LWC), mid-day stem
water potential (Ψ) and water stress integral (SΨ) of 'Kinnow' mandarin under regulated deficit
irrigation (RDI) and full irrigation (FI) during 2010 and 2011.
Leaf water relation factors
2010
2011
Mean
Treat-
ments
RLWC
(%)
LWC
(%)
Ø
(MPa)
SØ
(MPa
day)
RLWC
(%)
LWC
(%
Ø
(MPa)
SØ
(MPa
day)
RLWC
(%)
LWC
(%)
Ø
(MPa)
SØ
(MPa
day)
RDI
0
75.6
c
66.8
c
-1.4
c
45.8
a
78.2
c
68.2
c
-1.1
c
39.2
a
76.9
c
67.5
c
1.25
c
42.5
a
RDI
50
83.5
b
70.6
b
-1.2
b
29.3
b
84.6
b
73.7
b
-0.8
b
24.1
b
84.0
b
72.1
b
1.00
b
26.7
b
FI
93.7
a
78.4
a
-0.8
a
18.9
c
94.2
a
79.6
a
-0.7
a
16.2
c
93.9
a
79.0
a
0.75
a
17.6
c
Data in one column followed by different letter are significantly different at
P <
0.05
,
as per separation by
Duncan's multiple range test.
RDI
0
= No irrigation at early fruit growth period (EFGP); RDI
50
= Irrigation at 50% crop evapotranspiration at
EFGP.
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