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V = [S × Kp × K
C
× (Ecp - ER)]/[r]
(1)
where: V = Irrigation volume (l/tree), S = Tree canopy area (m
2
), Kp= Pan factor (0.7),
Kc = Crop factor (0.6), Ecp= Cumulative class-A pan evaporation for two consecutive
days (mm), ER = Cumulative effective rainfall for corresponding two days (mm), and
r = Water application efficiency of irrigation system (» 90%). Water quantity applied
in basin irrigation method was computed using Eq. (2).
V = (F.C. - R.S.M.) × d × A
(2)
where: V = Volume of irrigation water (m
3
), F.C. = Field capacity (v/v,%), R.S.M. =
Required soil moisture (at 50% depletion of available soil moisture » 23.9% v/v) to
start irrigation, d = Depth of effective root zone (0.3 m), A = Mean canopy area of the
plants.
The black linear low-density polyethylene sheet of 400-gauge thickness with 1.0
m ´ 1.0 m size was used in mulching on each plant basin keeping the plant at the center.
The soil moisture content at 0.45 m distance from tree trunk was monitored twice
in a week at 0.30 m and 0.60 m depths through neutron moisture meter (Troxler mod-
el-4300, USA). Leaf samples (2nd - 4th leaf from tip of branches) surrounding the
trees at a height of 1.5 m to 1.8 m from the ground were collected at the end of irriga-
tion seasons and nutrient (N, P, K, Fe, Mn, Cu, and Zn) analysis was done as per the
standard procedure followed by Srivastava et al. [12]. The plant height, stem height,
canopy width, and stem (stock and scion) girth were measured for all plants and their
polled annual incremental magnitudes were compared. The canopy volume was cal-
culated using Eq. (3) [7].
Canopy volume = 0. 5233 H W
2
(3)
where: H = (plant height - stem height), and W = the canopy width [7]. The fruit
samples (10 number/ tree) were collected to evaluate the yield and quality (juice, acid-
ity and TSS) parameters in different treatments. The All the data generated were sub-
jected to analysis of variance (ANOVA) and the Least Significant Difference (LSD) at
5% probability level was obtained according to the method described by Gomez and
Gomez [5].
18.3 RESULTS AND DISCUSSION
18.3.1 IRRIGATION WATER
The monthly irrigation water applied was highest in May and lowest in December
irrespective of irrigation method and regime due to highest and lowest atmospheric
demand in respective months (Fig. 1). In whole, the annual mean depth of irrigation
water applied was 272, 408, 544 and 680 mm through drip irrigation scheduled at 40,
60, 80 and 100% of pan evaporation with plastic mulch, respectively, compared to
635 mm under basin irrigation method. The reduction of water consumption through
drip at optimum irrigation level with plastic mulch over conventional basin irrigation
method was also studied in Kinnow mandarin [6].
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