Optimization of citrus nursery production in soilless culture under controlled environment

Figures (2) Tables (6)

Figure 1.
Daily water usage per plant of Tango mandarin grafted on C35 throughout the experiment. The daily usage values were normalized by dividing the recorded volume by the number of days elapsed between each sampling (i.e. sampling frequency of either 3 or 4 days, twice a week).
Figure 2.
Plots of measured daily actual evapotranspiration ($ {ET}_{A} $) versus estimated $ {ET}_{A} $in (a) regular shading and coir, (b) regular shading and mix, (c) extra shading and coir, and (d) extra shading and mix scenarios. The solid line represents the trendline, and the dashed line represents a 1:1 relationship.

Table 1.

Details of each treatment combination.

Treatment combination	Linear equation	R²	Projected trunk diameter (mm)
1	D_t = 0.134 × t + 3.126	0.97	9.6^a
2	D_t = 0.095 × t + 3.300	0.96	7.9
3	D_t = 0.115 × t + 3.283	0.98	8.8^a
4	D_t = 0.082 × t + 3.499	0.98	7.4
5	D_t = 0.106 × t + 3.323	0.97	8.4^a
6	D_t = 0.089 × t + 3.276	0.97	7.6
7	D_t = 0.091 × t + 3.354	0.97	7.7
8	D_t = 0.086 × t + 3.195	0.97	7.3
^a Trees with a salable trunk diameter.

Table 2.

Trunk growth rate in the treatments and the projected trunk diameter on target selling date.

	Height (cm)	Diameter (mm)	Total leaf area (cm²)	Leaf count
Shade
Extra	39.7 ± 1.8^a	4.64 ± 0.06^a	678.0 ± 68.0^a	48 ± 6^a
Regular	35.0 ± 2.2^a	4.84 ± 0.07^a	682.2 ± 83.2^a	70 ± 7^a
Substrate
Coir	38.6 ± 1.6^a	4.90 ± 0.07^a	764.8 ± 62.8^a	62 ± 5^a
Mix	36.1 ± 1.6^a	4.58 ± 0.07^b	595.5 ± 62.8^a	56 ± 5^a
Fertigation
Flow-through	37.4 ± 2.2^a	4.79 ± 0.07^a	728.5 ± 83.2^a	66 ± 7^a
Recirculating	37.3 ± 1.8^a	4.69 ± 0.06^a	631.8 ± 68.0^a	53 ± 6^a
Means followed by different letters represent significant differences based on Tukey-Kramers' LSM (p < 0.05).

Table 3.

Means and standard errors of growth parameters affected by different shade levels, substrates, and fertigation systems.

Substrate	Height (cm)	Diameter (mm)
Coir	4.7 ± 0.9^a	0.74 ± 0.05^a
Mix	1.3 ± 1.1^b	0.22 ± 0.06^b
Means followed by different letters represent significant differences based on t-test (p < 0.05).

	Average daily evapotranspiration rate per plant (L)	Potential daily water saving per plant (L)
	Average daily evapotranspiration rate per plant (L)	LF from this study	LF 0.2	LF 0.5	LF 0.8
Reg. shade	0.20	0.11	0.05	0.20	0.80
Extra shade	0.14	0.14	0.04	0.14	0.56