Water:
- Apart from soil, water is an important essential natural land resource affecting growth and production of fruit crops.
- Fruit trees require irrigation water for maintaining adequate growth, fruit quality and yield, particularly in dry months. However, availability of water is always a limiting factor in fruit cultivation, particularly in arid and semi arid conditions. Even in high rainfall (>1500 mm) areas, sufficient moisture may not be available in the root zone during the dry months and crops may suffer from drought at any stage due to erratic rainfall pattern and for the want of irrigation water.
- In order to ensure the supply of requisite quantity of water at critical stages of growth and development of fruit crops, efficient management of water is required. In rain fed areas, three essential components of water management are:
- In situ moisture conservation
- Water harvesting
- Efficient utilization of conserved/harvested water through improved cultural practices
In situ soil moisture conservation:
- Mulching is known to conserve soil moisture, be it mulching with organic or inorganic material. This aspect of moisture conservation has been discussed in Chapter 4.
Water harvesting:
- Two natural water resources that can effectively be harvested are rainfall and low (as low as 1 to 30 l/min) water springs and rivulets.
- About 10 to 14 per cent of total rainfall, depending on soil and rainfall characteristics may be lost as surface runoff.
- Water harvesting can be done through in situ rainwater harvesting and water harvesting in farm ponds.
- In situ rainwater harvesting: In fruit plantations, rain water can be harvested in the tree basin areas by certain soil working techniques such as:
- Preparation of tree basins: Well prepared tree basins prior to rains aid in water infiltration, and subsequent frequent shallow hoeing not only remove the competitive weeds but also prevent evaporation losses of moisture from the soil by forming dry soil mulch over the sub soil.
- For arid and semi-arid regions, soil working techniques like ‘Crescent Bund with Open Catchments Pits’ (plate 15.1), ‘Trench Systems’, ‘V-ditch’ (plate 15.2) etc. provide satisfactory in-situ harvest of rain water. These techniques are found to be useful for conserving soil moisture in the root zone of trees for the dry months.
  Plate 15.1(left); Plate 15.2 (right)
Water harvesting through farm ponds:
- The run-off water from orchards and water flowing from other sources like spring and small streams that though cannot serve as water source for irrigating crops due to their meager flow rates but, can be effectively stored in suitable small or big reservoirs.Small ponds may also be used as water reservoirs in which water is stored during lean period and used when required by crops. The provision of a small pond in one corner of the orchard to collect runoff water during high intensity rains and its utilization as life saving irrigation or during critical periods of the crop is an age old practice.
- Small ponds are ideal for growers who have scattered land holdings. In addition, they do not require elaborate management skills and resources.
- Ponds, however, vary in shape, size and mode of construction. Orchard ponds can be divided in to three categories:
- Dugout small ponds on flat lands (Plate 15.3)
- Ponds constructed by making barriers constructed in low lying areas or natural depressions or small streams (Plate 15.4)
- Dugout ponds constructed by making barriers constructed on lands with mixed topography
- Suitable sealants may be used to check/reduce seepage losses in ponds (see Plate 15.3). Ponds may be lined with polyethylene sheet (covered with soil or bricks or round boulders to protect it against UV sun light), silpauline sheet (UV resistant), bitumen, cement and concrete lining, RCC, etc. The cost and longevity of structure will depend upon the lining material used.
- Larger ponds can be made by damming the upper catchment area of a creek. Water harvesting in larger ponds is practiced on community basis (Plate 15.5). It involves proper planning and sincere participation of the inhabitants of the catchment and command areas. It may form a part of integrated watershed management involving participatory approach.
  Plate 15.3 : Small dug out pond on flat land Plate 15.4: Pond made by constructing barrier Plate 15.5: Large pond with black polythene sheet used as sealant
- The water conserved/harvested from natural resources must be used very efficiently for fruit crops.
- The water should be possibly be used through pressurized irrigation system e.g. drip irrigation.
- Drip irrigation system is ideal for fruit crops, because it enable to achieve higher water use efficiency and also help in maximizing crop production within limited water resource.
Climatic Constraints:
- Plant productivity depends upon the absorption of light energy by the green tissues and the conversion of that energy into biomass via photosynthesis. Fruit yield has been shown to be linearly related to light interception (Palmer, 1989; Lakso, 1994).
- Although high light interception is needed for high yields per unit land area, shade can have an adverse effect on fruit quality, fruit set and flower initiation.
- Shading can arise from within or between tree sources, including windbreaks. Fruit size, red skin colour, soluble solids concentration are all reduced by shading. This seems to be a general phenomenon among perennial tree fruits and has been reported for apples, citrus, red raspberry, kiwifruit, cherries, peaches and grapes (Palmer, 1989).
- Shading can also result in a reduction of flower initiation and fruit set. These effects of shade could be mediated via a direct effect of light on carbohydrate supply or through effects on the red/far red ratio.
- In some environments, excessive amounts of light falling on the fruit can result in downgrading of the fruit due to sunburn.
- For high yield and, in particular, high fruit quality, the orchard needs to combine both high light interception and good light distribution within the tree (Wünsche et al. 1996).
|
Participants