Decision guides · Citrus (Nagpur mandarin)
Water stress: the sign on the tree, the sign in the soil, the sign from the satellite
Water stress shows in three places, and the three do not show at the same time. First in the soil (moisture runs out), then on the leaves (wilting at midday, recovering by evening), and last from the satellite (greenness and the water index fall). So when the satellite warning arrives the stress may already be days old; treat it as a prompt to check at once.
Last checked (AI-assisted): 15 Oct 2026. Checked on 15 Oct 2026 against published ICAR, state agricultural university and FAO guidance with AI assistance. Not yet reviewed by an agronomist or tested with farmers. No spray, pesticide, fertiliser or irrigation amount is given here; for those, test your soil and ask your KVK or an agronomist.
The sign in the soil
A hand-span down the soil is dry and crumbly; no ball forms. With drip, the wet band narrows. The earliest sign and the cheapest check.
The signs on the leaves, in order
First: young leaves wilt at midday and recover by evening. Second: leaves wilt all day, curl a little, turn a pale grey-green. Third: old leaves yellow and drop, small fruit drops. Fourth: twig tips die back.
Water given at the first sign does no harm. Reaching the third sign can cost fruit in that bahar.
Bahar stress and accidental stress
The stress given to take a bahar is deliberate and timed; the first and second signs are expected there. Accidental stress is water missing during fruit filling or flowering; that is what to avoid.
What the satellite shows
The weekly message can carry two things: greenness fell (NDVI/NDRE down) and the leaf water index fell (NDWI down). Both down with no rain makes water stress likely.
The satellite passes about every 5 days and cannot see through cloud. Its warning never replaces the soil check; it is a reminder bell.
What to do when the warning comes
Check soil moisture. If dry and no bahar stress is under way, irrigate normally, not a flood. If the soil is moist but leaves still wilt, look for root trouble or waterlogging; more water is harmful there.
What to check in your field or orchard this week
- Walk the orchard between 2 and 4 pm: are young leaves wilting?
- A hand-span down: does the soil form a ball?
- Did the satellite message show both greenness and the water index falling?
A Watch message says only what changed and what to check. It never names a product, a fertiliser or an irrigation amount.
Questions
Should I irrigate only when the satellite warns?
No. The satellite sees late and not through cloud. Check soil moisture regularly; the satellite warning is an extra reminder.
Leaves wilt but the soil is wet. Why?
Waterlogging, rotting roots, or an extremely hot day. Do not add water; check drainage and roots and ask the KVK.
How many days of stress can a tree take?
It depends on soil, age and season; no figure is given here. The rule: check the soil at the first or second sign, never let the third arrive (bahar stress excepted).
Want a weekly message for your field?
Call us to join. Free to watch. What changed in your field or orchard, every week, with the date and the source.
Sources
- FAO Irrigation and Drainage Paper 56 (Allen et al., 1998): crop response to water stress · www.fao.org/4/x0490e/x0490e00.htm
- ICAR-CCRI Nagpur, month-by-month guidelines for citrus growers: irrigation and water stress through the year · ccri.org.in/calendar-of-operations/
- Gao (1996): NDWI, a normalized difference water index for remote sensing of vegetation liquid water (near-infrared and shortwave-infrared; not the McFeeters open-water index) · doi.org/10.1016/S0034-4257(96)00067-3
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- Weather and irrigation: how the five-day forecast changes the watering schedule
- What is satellite farming? What a satellite sees in your orchard, and what it cannot
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- Nagpur orange season and GI tag: when ambia and mrig bahar fruit reach the market
- How to see a satellite image of your own field for free: Copernicus Browser, NASA Worldview and ISRO Bhuvan
- NDVI full form and meaning: what NDVI is and what it tells you about an orange orchard
- Cotton in Vidarbha: what to check, and when, from sowing to picking
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How we compute this and what the limits are: the methods page