This blog contains comprehensive information about the irrigation practice in grapes, challenges faced by growers and ways to overcome them.

In India, the majority of grapes are produced in semi-arid, dry regions with low rainfall and substantial evapotranspiration losses. As a result, additional irrigation is required. The amount of water that vines need depends on their stage of development.

Challenges in Irrigation management in grape cultivation

• Without irrigation, grape vines cannot grow normally in arid and semi-arid climates where evapotranspiration surpasses rainfall. The primary variety of grapes grown in India, the Thompson Seedless grape, requires 450–600 mm of irrigation in addition to monsoon rainfall in Madhya Pradesh and Maharashtra. 
• As a result of a recent decline in rainfall in several key grape-growing regions, existing irrigation sources like open wells and bore wells have entirely dried up. As a result, producers are compelled to transport water in tankers over distances of up to 30 kilometers in order to maintain their vines. This costs approximately Rs. 1200–1500 per day per hectare, depending on the transit distance.
• Some vineyards have seen 100% output losses as a result of
  •  the lack of rainfall, 
  • the inaccessibility of irrigation water, and 
  • the high expenses associated with transporting water.  

• On the other side, excessive watering also lowers yields when there is an unlimited water supply and no adequate irrigation schedule. The bunch number/vine is significantly decreased by excessive irrigation during the bud differentiation stage. The quality is further reduced by berry cracking and fruit rot caused by heavy irrigation after veraison (veraison is the onset of the ripening of the grapes.)

The control of soil water availability is an important vineyard management technique since it significantly impacts grapevine growth. 

Insufficient soil moisture causes:

• The vine to be under water stress conditions.
• Decreases fruit harvests and vine growth.
• Can have a favorable or negative impact on fruit quality depending on when and how much stress is applied.

Irrigation practice in grapes

Irrigation intervals and stages:

• Following fertilizer and pruning, vines are immediately irrigated. At 5-7 days intervals, watering is administered during the berry growth stage. 
• To enhance the quality of the fruit, water is withheld for at least 8 to 10 days before harvest. Pruning is followed by resuming irrigation.
• Depending on the soil moisture state, irrigation is administered at intervals of 10 to 12 days till winter pruning throughout the period from summer pruning to the start of the rainy season. 

When to avoid irrigation:

• After summer pruning, 45 to 50 days later, excessive irrigation should be avoided as it hinders bloom initiation by encouraging vegetative growth. 
• Similarly, excessive irrigation that occurs between the flower opening and the stage when the berries are pea-sized should be avoided since it worsens the downy mildew disease problem.

An overabundance of soil moisture can cause excessive vine growth, which can result in a shaded canopy that may be bad for the quality of the fruit and raise the probability of fungus diseases.

The main techniques for controlling soil moisture are :

• Supplemental irrigation to raise soil moisture. 
• For excessively wet soil, cover crops can be beneficial to dry out the soil.
• Mounding or raised beds to lower soil moisture and drain tiles to drain out the excess water from the farm.

Why do grapes require precision irrigation?

Water and nutrients must be delivered to grape plants precisely and on time, which calls for an effective precision irrigation system. Precision irrigation systems use less water than other irrigation techniques due to reduced runoff, deep percolation, and soil surface evaporation before and after watering events.

• Maintaining optimum soil-water balance

It is essential to maintain soil-water balance for effective irrigation management. Maintaining soil-water balance with precision irrigation can lessen the likelihood of crop loss during times of insufficient rainfall.

• About 30% cost reduction

Drip irrigation doesn’t waste anything as it evenly distributes nutrients and water to each plant’s roots. Comparing this strategy to other irrigation techniques, you can save up to 30% on water and fertilizer costs alone. Additionally, accurate water distribution guarantees little weed development, cutting down on the expense of pesticide treatment.

What is the impact of excessive moisture and over-irrigation on grapes?

Over irrigation and moisture stress impacts the overall health and productivity of vines. Vines suffer from high moisture levels in the root zone brought on by excessive irrigation or precipitation, particularly in dense soils. In such soils, a lack of aeration in the root zone results in serious physiological issues for the vine.

Reduced shoot growth and thickness are the results of severe moisture stress. Aside from this, the leaves continue to be small, and the internodes get shorter. Early leaf fall is a result of prolonged moisture stress. The canes display indications of false maturity.

Farmers in Maharashtra suffered significant losses last year, around 30 November 2021, due to unseasonal rains. Over 25 lakh hectares of flowering, mature crops were destroyed.

The severe rainfall that affected farmers in Nasik around September 15, 2021, also contributed to the fruit’s early cracking.

Impact of excessive moisture stress on grape vines at different growth stages

How Fasal manages irrigation in vineyards of grapes

• Fasal is a horticulture IoT-based platform. It gathers real-time data on conditions from on-farm sensors in order to give farmers actionable recommendations tailored to their vineyards.
• With the help of sensors installed in the Fasal system, farmers can now precisely irrigate their grape vines and reduce the likelihood of poor yields due to over- or under-irrigation.

• The Fasal system continuously monitors the microclimatic conditions on your farm using sensors and other monitoring tools, enabling you to plan irrigation in advance and lessen the impact of unpredictable weather on your grape vines.
• The Fasal system alerts farmers about any chances of rain within the following 14 days, allowing them to plan their irrigation more effectively.
• The Fasal system notifies farmers when the soil needs to be watered and assists in determining the appropriate irrigation water requirements based on precise soil moisture measurements.
• Fasal System keeps a constant track of the soil and crop health along with their optimum mineral and water needs resulting in sweeter & healthier fruit quality.