agricultural water management 84 (2006) 202–206
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Response of Greenhouse tomato to irrigation and fertigation Gulshan Mahajan *, K.G. Singh Department of Soil & Water Enginnering, Punjab Agricultural University, Ludhiana 141004, India
article info
abstract
Article history:
A 2-year study was conducted during 2002–2004 at Department of Soil and Water Engineer-
Accepted 12 March 2006
ing, Punjab Agricultural University, Ludhiana to investigate the effect of irrigation and
Published on line 24 April 2006
fertigation on Greenhouse tomato. Drip irrigation at 0.5 Epan along with fertigation of 100% recommended nitrogen resulted an increase in fruit yield by 59.5% over control (recom-
Keywords:
mended practices) inside the Greenhouse and by 116.2% over control (recommended
Greenhouse
practices) outside the Greenhouse, respectively. The drip irrigation at 0.5 Epan irrespective
Tomato
of fertigation treatments giving a saving of 48.1% of irrigation water and resulted in 51.7%
Drip irrigation
higher fruit yield as compared to recommended practices inside the Greenhouse. Total root
Root length
length was more in drip irrigated crop as compared to surface irrigated crop. Greenhouse
Fertigation
tomato fruits founded superior than fruits of open field crop in view of fruit size, TSS
Water-use efficiency
content, ascorbic acid content and pH. Further, drip irrigation in Greenhouse crop caused
TSS content
significantly improvement in all the quality characteristics.
Ascorbic acid content
1.
Introduction
Greenhouse technology is a breakthrough in the agricultural production technology that integrates market driven quality parameters with the production system profits (Aldrich and Bartok, 1989). In the present scenario of perpetual demand of vegetables and shrinking land holding drastically, protected cultivation or Greenhouse technology is the best alternative for using land and other resources more efficiently. Greenhouses are framed structures covered with transparent or translucent material and large enough to grow crops under partial or fully controlled environmental conditions to get maximum productivity and quality produce. At present, there are more than 50 countries supporting commercial crop cultivation in green house. In India, use of green house technology started in 1980s as research activity. The green houses for commercial purposes started in 1988 and it is increasing in area because of liberalization in economy and stress on export promotion. The Greenhouse tomato is a major vegetable crop that has achieved tremendous popularity over the last century. Tomatoes, aside from being tasty are very
# 2006 Elsevier B.V. All rights reserved.
useful for our heath as they are a good source of Vitamins A and C. Cooked tomatoes and tomato products are the best source of lycopene, which is very powerful antioxidant and helpful in preventing the development of many form of cancer. Hence, this crop is gaining its importance both in developing and developed countries and efforts are being made for the quality and quantity production of tomato. In open field, fruit yield and quality are poor due to prevailing low temperature during the winter season when it is grown and also crop faces severe attack of frost due to which growth of the crop is affected and resulted lower yield. In this direction, Greenhouse is the best alternative for quality and quantity production of tomato because in addition to higher yield; the production is also free from dust, insect, disease and pest. Moreover, due to favorable environment the size of the fruit remain uniform. Water is an important input for Greenhouse tomato because irrigation is the only source for application of water to the plants in Greenhouse. Several efforts have been conducted to use irrigation as efficient as possible under protected cultivation system. The use of drip irrigation saves water and gives better plant yield and quality as it reduces the
* Corresponding author. Tel.: +91 1612400145; fax: +91 1612400945. E-mail address:
[email protected] (G. Mahajan). 0378-3774/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2006.03.003
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agricultural water management 84 (2006) 202–206
humidity build up inside Greenhouse after irrigation due to precise application of water to the root zone of the crop (Papadopoulos, 1992). In Greenhouse tomato due to indeterminate nature of crop, vegetative and reproductive stage overlaps and the plant needs nutrients even up to fruit ripening stage for better growth and fruit size, so, application method such as fertigation may be very effective in Greenhouse tomato. Since a very meager work has been carried out on drip irrigation and fertigation on tomato grown in low cost naturally ventilated Greenhouse, the present experiment was conducted to study optimum water and nitrogen requirement of drip-irrigated tomato grown in naturally ventilated Greenhouse.
2.
Materials and methods
The experiment was conducted in a natural ventilated Greenhouse at the research farm of Department of Soil and Water Engineering, PAU, Ludhiana. A semicircular shaped Greenhouse covering a floor area 6.25 16 (100 m2) with sidewall ventilation was used for the study. The orientation of the Greenhouse was east-west direction. The Greenhouse was covered with an ultra violet stabilized low-density polyethylene film having 200 mm thickness. The tomato cultivar Naveen, widely grown by the farmers in Greenhouse was used. The experiment had eight treatments (Table 1) comprised combination of two levels of water supply (1.0 Epan, and 0.5 Epan) and three N level (100, 125 and 150% of recommended dose) that were tested against check basin methods of irrigation at recommended dose of N when the crops was sown at recommended spacing of 75 cm 30 cm both inside and outside the Greenhouse in RBD design. In check-basin method (surface flooding) the irrigations were provided on the basis of 1.0 cummulative pan evaporation (Epan). The drip irrigation was done on alternate day on the basis of pan evaporation value of the previous day, while in surface irrigation method, the water depth was 50 mm. In normal sowing, the distance between the rows was 75 cm and plant to plant spacing was 30 cm. However, in paired sowing,
the row to row space between paired rows was 60 cm and row to row space between pairs was 90 cm but plant to plant spacing space was 30 cm. So, in paired sowing total as well as number of rows and plants were same. The recommended fertilizers in Greenhouse tomato were 137.0 kg N and 62.5 kg P2O5/ha. Whole of the phosphorus was basal applied (before sowing of crop) in all the treatments. In all the treatments, a basal dose of FYM @ 25 t/ha was also applied before sowing of crop. Other cultural operations were same to all the treatments and were attended regularly. The drip system consisted of polyethylene laterals of 12 mm in diameter, laid parallel to crop row and each lateral served two rows of crop. The laterals were provided with on line emitters of 3 l/h capacity at 0.3 m apart. The different levels of water supply were maintained by managing the number of holes in each lateral. In drip irrigation system, N was applied at 15 days interval in 10 equal doses of N starting from 15 days after transplanting. The first picking of Greenhouse tomato was started in the last week of February and in all 25 pickings of Greenhouse tomato were done and the last picking was ended on the first fortnight of May. Fruit weight, total soluble solids and titrable acidity were determined using standard procedure. For root length measurement, plants were harvested with most care. The sides of plants, 60 cm from each side were dug 1 m deep and the plant along with the soil was lifted. Later the roots were washed with a fine jet of water by keeping it over a set of sieves of varying pore size. The soil particles were separated from the roots. Total root density was measured using water displacement methods. Root length was estimated by modifying the method of Habib (1988). Volumetric method was used for computing the uniformity coefficient (Uc) of drip irrigation system (Eq. (1)). In all 12-inline emitter were selected in each of the lateral lines at regular interval. Water was collected in large size petridishes placed below the drippers and discharge rate was computed as l/h. Dq (1) Uc ¼ 1 q where q is the mean emitter discharge rate (l/h) and Dq, mean deviation of the emitter discharge from mean value.
Table 1 – Soil and air temperature, relative humidity and light intensity inside/outside the Greenhouse Period
November 1–15 November 16–30 December 1–15 December 16–31 January 1–15 January 16–31 February 1–15 February 16–28 March 1–15 March 15–31 April 1–15 April 16–30 May 1–15 May 16–31
Soil temperature (8C)
Air temperature (8C)
Relative humidity (%)
Light intensity (lx)
Inside
Outside
Inside
Outside
Inside
Outside
Inside
Outside
27.6 27.1 27.2 22.9 21.6 22.4 24.3 24.2 27.1 31.1 28.7 30.3 31.8 37.0
26.1 23.7 24.5 20.9 14.8 14.8 17.6 18.2 23.3 24.9 27.2 28.9 30.4 36.1
31.4 31.4 29.2 25.4 23.1 19.0 23.7 23.7 30.4 29.5 31.6 35.5 40.0 42.4
27 27.3 25.0 21.4 18.8 16.1 19.3 19.6 26.5 26.3 30.5 33.3 37.8 41.2
48.6 37.9 39.2 56.7 57.7 44.3 90.2 85.7 90.8 87.7 82.7 63.8 60.0 36.5
45.6 32.0 34.0 51.2 52.2 38.1 72.7 76.2 72.4 70.1 60.9 57.6 51.8 32.7
12855 15422 15422 10121 9920 10966 14068 13590 17480 19829 17276 21733 20590 35220
24300 25308 25308 17694 18052 32487 25997 23567 36562 33479 34637 36136 44142 56070
204 3.
agricultural water management 84 (2006) 202–206
Results and discussion
The uniformity coefficients of drip system were found to be 92.6% for the first year and 92.7% for the second year. The high values of uniformity coefficient indicate an excellent performance of irrigation system in Greenhouse in supplying water uniformly throughout the lateral lines.
3.1.
Fruit yield
In general, Greenhouse crop resulted increase in yield at all the level of irrigation and fertigation, than the surface irrigated crop that gown outside the Greenhouse, though the response was comparatively high when irrigation was applied through drip at 0.5 Epan. Higher yield under Greenhouse may be ascribed to favorable environment at the early stages of tomatoes (especially in the month of December and January, when the day and night temperature is very low) resulted better growth and cause more pickings of tomatoes especially in the early stages). Environmental data in the Greenhouse (Table 1) revealed that the soil temperature and air temperature in the Greenhouse remained an average 3.7 8C and 3.3 8C higher, respectively, in Greenhouse than the outdoor environment. The relative humidity inside the Greenhouse was 14.6 units higher inside the Greenhouse but the light intensity reduced by an average 14,232 lx (Table 1), which caused a favourable microclimate to Greenhouse tomato. These results are in conformity with Phookan and Saikia (2003) who also observed that green house crop of tomato resulted better
growth especially in the early stage and resulted more and early yield. The perusal of data in Table 2 revealed that in Greenhouse tomato when same quantity of water and nitrogen was applied through drip irrigation a significantly higher tomato yield (68.5 t/ha) was obtained as compared to 58.4 t/ha and 43.1 t/ha in check basin method of irrigation when the crop was sown both inside and outside the Greenhouse, respectively. When the quantity of water through drip irrigation was reduced, tomato yield increased further significantly as compared to check basin method of irrigation at the same level of nitrogen. When irrigation was done at 1.0 Epan, the fruit yield was statistically same at all the level of nitrogen fertigation, but found significantly inferior over the treatments when irrigation was applied at 0.5 Epan along with fertigation of 100% or 125% of recommended nitrogen. Drip irrigation at 0.5 Epan along with fertigation of 100% nitrogen resulted increase in fruit yield by 59.5% over control of recommended practices inside the Greenhouse and by 116.2% over control of recommended practices outside the Greenhouse, respectively. The increased yield under drip irrigation system might have resulted due to better water utilization (Manfrinato, 1971), higher uptake of nutrients (Bafna et al., 1993) and excellent soil–water–air relationship with higher oxygen concentration in the root zone (Gornat et al., 1973). Under control treatments, both inside and outside the Greenhouse, surface irrigation not only resulted in wastage of water in deep percolation below root zone, but also sets a chain of undesirable reaction such as leaching of available plant nutrients, and consequently
Table 2 – Effect of treatments on different parameters of Greenhouse tomato Treatments
T1 G.H.C. + Drip irrigation 0.5 Epan + 100% N T2 G.H.C. + Drip irrigation 0.5 Epan + 125% N T3 G.H.C. + Drip irrigation 0.5 Epan + 150% N T4 G.H.C. + Drip irrigation 1.0 Epan + 100% N T5 G.H.C. + Drip irrigation 1.0 Epan + 125% N T6 G.H.C. + Drip irrigation 1.0 Epan + 150% N T7 G.H.C. + Control (100% N + surface irrigated) T8 N.G.H.C + Control (100% N + surface irrigated) LSD (0.05)
Pooled fruit yield (t/ha)
Tomato size (cm3)
Root length (m)
Pooled water applied (mm)
Pooled WUE (t/ha-mm)
TSS (8 brix)
Ascorbic acid (mg/100 ml of juice)
pH
93.2
36.6
49.3
415
0.224
5.70
42.2
4.29
95.9
36.0
49.2
415
0.231
5.69
42.2
4.29
76.8
35.8
42.7
415
0.185
5.68
42.1
4.28
68.5
34.8
23.0
775
0.088
5.54
41.6
4.27
75.6
35.2
21.7
775
0.097
5.54
41.6
4.28
72.6
35.3
20.7
775
0.093
5.58
41.5
4.27
58.4
24.3
20.4
800
0.073
5.18
37.6
4.17
43.1
16.2
16.6
800
0.053
4.64
22.7
3.90
7.5
2.5
3.0
–
–
0.14
1.5
0.08
G.H.C, Greenhouse crop; N.G.H.C., non-Greenhouse crop.
agricultural water management 84 (2006) 202–206
development of soil problems and poor aeration resulted in reduced yield. These results are in accordance with the findings of Bhella (1988), who observed 70% higher tomato yield under drip irrigation as compared to surface irrigation. Bafna et al. (1993) reported such increase in tomato yield to the extent of 41%. A comparison of different levels of irrigation indicates maximum tomato yield with irrigation at 0.5 Epan, along with fertigation at 100 or 125% of recommended nitrogen. At lower level of drip irrigation (0.5 Epan), further increase in nitrogen dose (150% of recommended N) may shift the balance between vegetative growth and reproductive growth toward excessive vegetative development, thus delaying crop maturity and reducing tomato yield.
3.2.
Water-use efficiency
Drip irrigation both at 0.5 Epan and 1.0 Epan registered much higher water-use efficiency as compared to control practices both inside and outside the Greenhouse. Considering average value for all tried level of fertigation, drip irrigation at 0.5 Epan gave maximum water-use efficiency 0.21 t/ha-mm, while at 1.0 Epan, the water-use efficiency was found 0.093 t/ha-mm. The drip irrigation at 0.5 Epan irrespective of fertigation treatments giving a saving of 48.1% of irrigation water resulted in 51.7% higher fruit yield as compared to recommended practices inside the Greenhouse. Since, the rate of water loss through evaporation from soil surface was much lower under drip irrigation; hence, water-use efficiency was higher as compared to surface irrigation. Malik and Kumar (1996) and Bafna et al. (1993) also made similar observations on water-use efficiency of drip irrigation in pea and tomato crop, respectively.
3.3.
Variation in root length
Drip irrigated plants received water in shorter interval (once in 2 days), where as water applied at larger interval in surface irrigated plants as in control practices. The root length increased gradually at lower level of irrigation in drip treatments. In drip irrigation treatments, plants in 0.5 Epan treatment had more total root length than plants in 1.0 Epan. Though the crop received water at shorter interval in drip irrigation, the amount of water was applied less at 0.5 Epan. It has been reported that soil water deficit often reduces shoot growth before root growth, resulting in increased growth of roots (Kramer and Boyer, 1995). The root length of plants under drip irrigation at 1.0 Epan was less compared to treatments of drip irrigation at 0.5 Epan. Osmotic adjustment and prolonging root cell expansion (Sharp et al., 1990) had been described as a cause for increased root length in mildly stressed plants than well-watered plants (Jupp and Newman, 1987). Outside the Greenhouse, i.e. in control practices, the surface irrigation was done at larger intervals (approx. 7–10 day interval), the treatments suffered maximum water stress has stopped the root elongation as evident from root length data.
3.4.
Quality characteristics
The investigated factors significantly influenced some quality parameters of tomato. Greenhouse environment improved the
205
TSS of the tomato (5.188 brix) as compared to outside environment (4.648 brix). Soraya et al. (2001) reported that variations in the concentration of dry matter and sugars in tomato have been coupled with the conditions of climate and root medium: these concentrations increase under high temperature, CO2 concentration, high vapour pressure deficit (VPD) or high nutrient concentration. As in the Greenhouse crop, temperature, CO2 concentration, water and nutrient use efficiency increased due to favourable environment, which helped in better development of tomato in different period of development (cell division, growth and ripening phase). Such increases in dry matter or sugar concentration could be associated with variations in the balance between water and assimilate influx to the fruit, i.e. between the fluxes of the phloem and xylem saps and of fruit transpiration. Drip irrigation at 0.5 Epan in the Greenhouse caused an increase in TSS up to 5.708 brix. Similarly ascorbic acid content in the Greenhouse surface irrigated crop increased by 65.6% over the outdoor surface irrigated crop due to favorable environment, which help in better development of tomato in different phases of development. Further drip irrigation at 0.5 Epan in the Greenhouse caused an increase in ascorbic acid content of tomato by 85.9% over the outdoor surface irrigated crop due to lesser amount of water available to fruits at shorter interval which caused osmotic adjustment in the pericarp of tomato and resulted in higher ascorbic acid content and pH (Mitchell et al., 1991). In drip irrigation when water was applied in lesser amount, sugar imported by fruits via phloem become concentrated which help in increasing TSS content and pH of tomato. These results are in conformity with the study of Elkner and Kaniszewski (1995). Tomato size of the Greenhouse drip irrigated tomato at 0.5 Epan irrespective of fertigation increased by 48.5% over the surface irrigated Greenhouse crop and by 122.8% over the surface irrigated outdoor crop, respectively. Comparable results regarding total soluble solid were obtained by Steve et al. (1983) in drip irrigated tomatoes.
Acknowledgements The authors are highly thankful to Mr. Markus Mo¨ller from the Agricultural Research Organization, Israel, for his guidance and encouragement in writing this manuscript. The authors are also grateful to Dr. Ashwani Kumar, Project Coordinator, AICRP on Application of Plastics in Agriculture for providing funds and various facilities to do this work.
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