The following points highlight the irrigation requirements of popular fruits, vegetables and spices.
1. Irrigation Requirement of Mango:
Regular watering is recommended till establishment. First irrigation is required just after planting and regular watering is needed until tree establishment. The irrigation should be given at 10-15 days interval during the fruit development period. While, during flowering with holding of irrigation is beneficial.
The water requirement of plant depends on age, soil type and climate. Under conventional irrigation systems, weekly irrigation is essential. With micro-irrigation the requirement is restricted to one-third of the water required for conventional method. Fertigation (application of fertilisers with drip irrigation) in mango is being promoted to get higher nutrient and irrigation use efficiency.
Success Story of Micro-Irrigation in Mango in Arid North West India:
Gujarat has an area of 1.42 m ha and production of 1.12 m tonnes with low productivity (7.891 ha-1). Some farmers are coming forward to adopt high density planting (HDP) and fertigation. Company like Reliance Industry has established a big mango orchard (180 ha) in Jamnagar where the hi-tech mango culture has been adopted.
This kind of favourable development is expected to help to enhance mango productivity in the State. Kesar is a famous mango variety of Gujarat. Progressive farmer Mr. M. Hirpura converted the poor hilly area at the foot hill of Girnar Hill into a mango orchard in 2002. Initially spacing adopted was 25 × 25 ft which was later reduced to 12 × 12 ft. Varieties grown were Kesar (mainly), Alphonso and Amrapalli. The per hectare plant population was 688 and maximum yield (16.2 t/ha) was obtained at sixth year of planting.
2. Irrigation Requirement of Pomegranate:
Pomegranate can be grown in dry area with minimum water requirement, once it is established in the field. However, to obtain good quality and quantity of fruit yield, timely irrigation is required. Pomegranate can give flower and fruit (called bahar) thrice in a year if climatic conditions are congenial for plant.
The water requirement of plant depends on the desirable bahar or season to season. For Mrigbahar, irrigation should be started during second week of May followed by regular irrigation until the onset of monsoon. For good growth of fruit without cracking, regular irrigation is needed even after completion of monsoon period.
In Gujarat, the farmers mostly take ambebahar (Feb – March), for this regular weekly irrigation is needed from March to July. In general, check basin system of irrigation is followed to irrigate plants. For arid and semi-arid conditions, micro-irrigation system should be followed to economize water. Drip irrigation with mulch save 44% water in comparison to check basin system. While, Patil et al. (1982) found 64% water saving when mulch is used with drip irrigation.
Behina (1999), during an irrigation experiment in Iran, observed that in drip irrigation water requirement can be reduced upto 66% compared to surface irrigation of water and yield can be increased upto 24.5%. Maintenance of continuously high soil water potential, minimizes fluctuations in soil water content during the irrigation cycle. Yield increase by adoption of drip over conventional irrigation methods in pomegranate is by 36% to 37%.
3. Irrigation Requirement of Sapota (Manilkarazapota):
Sapota can be grown under semiarid condition of Gujarat in India. It can survive fairly better with little supply of water during critical growth periods. Weekly irrigation is required for good vegetative growth during early stage. After the establishment of tree, sapota needs irrigation twice in a month in summer and once in a month in winter. Micro-irrigation system is also beneficial especially under water scarce condition with 40% water saving.
4. Irrigation Requirement of Banana (Musa Paradisiaca):
Water requirement of banana is very high as it is a moisture loving plant. Banana requires ample and frequent irrigations throughout the year. Water deficit adversely affect crop growth and yields. Normal furrow and basin system of irrigation are followed to irrigate banana plants if water availability is not a constraint.
Water requirements per year vary between 1200 mm in the humid tropics to 2200 in the dry tropics. For rainfed production, average rainfall of 2000 to 2500 mm per year, well-distributed, is desirable, but banana often grows under less rainfall. Drip irrigation can be a better option in arid areas through which water quantity can be reduced and yield can be increased, because water use efficiency with drip irrigation is very high compared to other surface irrigation systems.
Drip irrigation system not only saves the water by 40-50%, the yield of drip irrigated plants is also higher. Studies carried out using farm level data also suggest that drip irrigation increases water use efficiency, productivity and reduces cost of cultivation for different operations. Significant amount of saving in electricity use due to drip irrigation has also been observed using field data.
Importantly, these field based studies found that the investment in drip irrigation technologies is economically viable for farmers even at 15 percent discount rate, without availing subsidy from government. When rainfall and irrigation water is limited, it is advantageous to reduce the depth of each water application rather than to extend the irrigation interval. Yield increase by adoption of drip over conventional irrigation methods in banana is 14.5 to 52%.
5. Irrigation Requirement of Ber (Ziziphus Mauritiana):
Ber is a drought hardy species and require little irrigation, however, irrigation increase the production. In dry and hot condition of Gujarat and Rajasthan, irrigation twice in a month should be applied in the month of November, December and January. If water resources are very limited in that case, one irrigation in a month, can give satisfactory result. In arid region, pitcher irrigation is also followed. In ber, most critical period for irrigation is during the emergence of new flush and fruit development. Irrigation during fruiting season helps to increase fruit set and also enlarges fruit size.
6. Irrigation Requirement of Date Palm (Phoenix Dactylifera):
In general, water demand of date palm is high but it can withstand prolonged drought period as well as excessive irrigation. It can grow easily in low rainfall areas with supplemental irrigation. During early stage, frequent irrigation of light intensity must be given in every alternate day.
The irrigation frequency can be reduced after off shoots have established in soil. Mulching with black polythene organic materials may reduce the water demand of crop. In dry arid conditions, 2-3 irrigations amounting to 8-12 acre inch in rapid succession should be given, and thereafter, 4-6 acre inch per irrigation may be required.
7. Irrigation Requirement of Vegetables:
For optimum yield, onion requires 350 to 550 mm water. Onion, in common with most vegetable crops, is sensitive to water deficit. For high yield and good bulb development the onion crop should be irrigated immediately after, transplanting, and thereafter, frequent and light irrigations at every 2 to 4 days are needed for high yield of good quality produce. However, over-irrigation leads to reduced growth.
The crop is most sensitive to water deficit during the yield formation period, particularly during the period of rapid bulb growth which occurs about 60 days after transplanting. Irrigation should be discontinued as the crop approaches maturity to allow the tops to desiccate, and also to prevent a second flush of root growth. Last irrigation is provided at 10-15 days before harvesting, which reduces storage losses.
A field experiment conducted in south Gujarat during 1989 to 1991 to explore the feasibility of adoption of mini sprinkler irrigation system for onion crop during rabi season shows a considerable increase of yield and water saving over the method of flood irrigation. In drip and micro-sprinkler irrigation, right quantity of water is applied in the vicinity of root zone which helps in maintaining optimum water potential in plant system favouring photosynthesis, which consequently resulted in better growth and higher yield attributes of the onion.
b. Tomato (Solanum Lycopersicum L.):
Total water requirements after transplanting, of a tomato crop grown in the field for 90 to 120 days, are 400 to 600 mm, depending on the climate. Frequent irrigation is needed for optimum growth, fruiting and yield. Heavy irrigation provided after a long spell of drought causes cracking of the fruits. Hence, it should be avoided. Generally, open furrow method of irrigation is followed.
For high yield and good quality, the crop needs a controlled supply at 8-12 days interval of water throughout the growing period. Highest demand for water is during flowering. Under water-limiting conditions, some water savings may be made during the vegetative and ripening periods, water supply should preferably be directed toward maximizing production per ha rather than extending the cultivated area under limited water supply.
When water supply is limited, the application of water should be concentrated during periods of flowering and fruit development. In general, a prolonged severe water deficit limits growth and reduces yields, which cannot be corrected by heavy watering later on.
c. Brinjal (Solanum Melongena L.):
A light irrigation is given on the first and third day after transplanting. Thereafter, irrigation is given at an interval of 8-10 days during winter and 5-6 days during summer. Irrigate the field after every third or fourth day during the summer season, and after, 12 to 15 days during the winter season.
During an experiment in Karnataka by Bhogi et al. (2010) found that there is substantial amount of water saving by drip irrigation system (4-9 1 plant -1) as compared to furrow irrigation system. This may be due to the fact that maximum amount of water was stored in the root zone and deep percolation losses were minimum at lower irrigation levels. These results are in agreement with the findings of Sivanappan (1979) in brinjal, tomato, chilli, bhendi and sweet potato, Gorantiwar et al. (1994) and Katti (1998) in bhendi.
d. Watermelon (Citrullus Lanatus Thunb.):
Under conditions of high evaporation, irrigation intervals may be as short as 6 to 8 days. Water requirements for the total growing period for a 100-day crop range from 400 to 600 mm. In spring-summer crop, frequency of irrigation is very important as water stress during fruit development leads to fruit cracking. Mulching of the hills after sowing reduces moisture loss at the time of emergence and prevents crust formation.
In dry climates with moderate evaporation and little rain, the watermelon produces an acceptable yield (15 t ha-1) with one heavy irrigation in the beginning of the growing period when soil water over the full root depth is brought to field capacity.
The flowering period and the fruit filling are the most-sensitive periods to -water deficit. Where evaporation is high and rainfall is low, frequent irrigation with an interval from 7 to 10 days may be necessary. Frequency of irrigation is reduced when the fruits reach near maturity while it is completely stopped at harvesting stage.
The most common method is by furrow. Under conditions where crop water requirements are high and the soils are light textured, drip irrigation has been successfully applied with a reduction in overall water demands.
8. Irrigation Requirement of Spices, Medicinal and Aromatic Crops:
a. Fenugreek (Trigonella Foenumgraecum L.):
Water requirement of fenugreek depends upon soil depth, texture, evaporation and cropping intensity. Irrigation needs to be given just after sowing to help in seed germination. Five irrigations are sufficient for successful harvesting of crops through flood irrigation. Now- a-days, drip irrigation is successful to save water and also to give high germination, plant height and crop yield.
Lai et al. (2013) observed that different irrigation methods significantly influenced number of pods plant-1, number of seeds pod-1, test weight of seed, seed yield plant-1 seed, straw and biological yields of fenugreek. Irrigation with drip method gave the highest number of pods per plant, length of pod, seed per pod, test weight (16.26 g) and seed yield per plant (6.69 g) and seed yield per ha (2043.96 kg) which were significantly higher over control. Similar findings were also reported by Ghetia (1995) in groundnut and Desai et al. (1993) in onion.
In order to find out the relative economics of Sprinkler Irrigation Method (SIM) over Flood Irrigation Method (FIM) in fenugreek crop, a three year trial was conducted in North Gujarat. The study shows that under the conditions of normal water availability, the use of SIM can result in 29 percent water saving along with 35 percent yield increase. Importantly for farmers, the net income per mm of water used rose from Rs.2.80 with surface method to Rs.9.57 with sprinkler method of irrigation.
Mehta et al. (2010) observed that application of irrigation at 1.0 irrigation water/cumulative pan evaporation ratio resulted in 10 and 38% higher fenugreek seed yield over 0.8 and 0.6 irrigation water/cumulative pan evaporation ratio, respectively. Seghatoleslami et al. (2013) also noted that fenugreek plants were more sensitive to irrigation and soil moisture supply than to fertilization under semi-dry conditions.
The results showed that the highest biomass (120.8 g m -2) and seed (36.39 g m-2) yield were obtained with irrigation interval of 5 days. Between two irrigation interval 10 and 15 days, no significant differences were observed. Dutta and Chatarjee (2006) found highest gross returns, net returns and benefit – cost ratio with application of irrigation water/cumulative pan evaporation ratio, (IW/CPE) of 0.8. Simultaneous emergence and rapid growth of weed leads to severe weed-crop competition for light, moisture, space and nutrients, and hence, fenugreek field should be weed free at initial stage of crop establishment by employing available weed control system.
b. Cumin (Cuminum Cyminum L.):
Cumin is a rainfed crop and requires less irrigation compared to other spice crops but supplemental irrigation is needed in dry years. First irrigation should be given just after seed sowing for easy germination of seeds. Second irrigation should be applied one week after first irrigation. Then after, irrigation may be given at 15-20 days interval. Last irrigation at the time of seed formation is very necessary.
Sabzevar et al. (2011) observed proper irrigation had significant effect on number of umbels per plant, number of lateral shoots, biological yield and seed yield. Highest cumin yield was obtained when crop was irrigated four times (seed germination, stem elongation, flowering and seed formation). These results agree with Rahimian (1992) who showed that the highest yield was obtained from complete irrigation for cumin.
c. Corriander (Coriandrumsativum Sativum Linn.):
Generally, 4-6 irrigations are given depending on type of soil and climate. First irrigation should be given within 30-35 days from the date of sowing, second after 50-60 days, third after 70-80 days, fourth after 90-100 days, fifth after 105-110 days and sixth after 115-125 days.
Lakpale (2007) noted that the number of branches significantly increased with the increase in number of irrigation. Significantly highest branches and dry biomass were recorded in coriander under irrigation schedule of 0.8 IW/CPE. However, it was at par with the irrigation schedule at 0.6 IW/CPE and three irrigations at 35, 60 and 85 days after sowing.
A field experiment was conducted at Junagadh by Mathukia et al. (2013) to evaluate methods of irrigation (drip, mini-sprinkler and flood irrigation) and levels of irrigation (0.4, 0.6 and 0.8 Pan Evaporation Fraction (PEF)) in coriander.
The results revealed that mini-sprinkler and drip irrigation significantly improved growth and yield attributes viz., plant height, branches/plant, umbels/plant and test weight, and thereby, increased seed and stalk yields along with higher net returns, B: C ratio and water use efficiency over flood irrigation. Similarly, irrigation at 0.8 PEF enhanced growth and yield parameters.
d. Isabgol (Plantago Ovata Husk)
Immediately after sowing, light irrigation is essential. The seeds germinate in 6-7 days. If the germination is poor, second irrigation should be given. Thenafter, the crop should be irrigated 30 and 70 days after sowing. Last irrigation is given when the maximum spikes occur at milk stage.
e. Dillseed (Anethumgraveolens L.):
Presowing irrigation is beneficial to allow seed to germinate early. During prolonged periods of drought, crop requires supplemental watering. Soil should be moist during growth period but soil must not become waterlogged.
Field and laboratory experiments were carried out in order to investigate the influence of 3 sowing dates and 4 irrigation disruption treatments at different growth stages on the seed yield and quality of dill. Irrigation disruption during stem elongation (I1) and umbel appearance (I2) had no significant effect on mean seed weight, germination, mean germination time (MGT) or SDW of harvested seeds.
However, water deficit during seed filling (I3) reduced seed vigour significantly. Although irrigation disruption at this stage (I3) had no considerable effect on the seed yield of dill, it reduced seed quality and vigour, especially at later sowings (S2 and S3). Therefore, it was recommended that for producing high quality dill seeds, it is necessary to provide sufficient water during seed filling.
Khamssi (2014) showed that the different irrigation treatments had no considerable effect on grain yield of dill. The highest and lowest essential oil content was obtained under irrigation disruption during stem elongation and well watered treatments, respectively. It seems that the essential oil content of dill can be increased partly by a moderate water deficit during vegetative stage.