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Irrigating between rain events

Spring and fall can be very challenging for farmers: you will need professional tools to get optimal irrigation amounts and timing so your plants will not get stressed

Irrigation in seasons in transition – spring and fall – is a challenging task. Critical plant phenological stages, such as flowering, fruit set and fruit maturation – usually occure during these seasons. Thus, maintaining optimal watering conditions can significantly improve the obtained yields. This is not an easy task: irrigation should be well suited to the rapidly changing weather conditions and rain events that may occur during these periods. Combination between forecasted weather as well as monitored plant and soil data is providing a powerful tool to determine the optimal irrigation amounts and irrigation timing.

Monitoring the forecasted VPD values can assist in better understanding of the plant water demand: High VPD values or high relative increase in VPD values may induce plant stress due to higher water demand. In addition, monitoring soil moisture is essential to optimize plant water availability and to monitor water consumption. Overall, the plant data (trunk and fruit size) is providing a rapid and efficient tool to evaluate the plant’s response to the applied watering strategy under the given weather conditions.

In this example, the trunk size was well responding to higher VPD values and low soil moisture by higher contractions and decreased growth rates. The combination between low water availability and high VPD values during this phenological stage, induced the described stress conditions during the highlighted period (red rectangle).

Irrigation timing and quantity should be established, mainly based in the upcoming conditions (e.g., VPD relative changes) and not just retroactively reacting to the stress (when it is usually too late). Sufficient soil moisture, mainly under forecasted high VPD values or alternatively high relative increase in VPD values, is essential to decrease plant stress and enhance plant/ fruit growth, sometimes even during the rainy season.

 

 

VPD (Vapor Pressure Deficit)

The difference between the current air humidity and the fully saturated air, affecting the rate of transpiration from the leaf. If it is too high, it means the ambient air is so dry that the plant will transpire too rapidly

Daily:

over 4 – high value

under – regular for the season

Nightly:

over 0.6 – high value

under – regular for the season

 

 

Oshri Rinot (Ph.D), Agronomist, SupPlant

 

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