What do you mean by 'vegetative zero' please? I can't find a definition :-)

Vegetation zero is the degree of temperature (°C) where a phenological stage or a stage of development of the plant begins,

For example, flowering starts when the temperature reaches 15 °C (this is explained only to you),

Normally each stage (phenological or developmental) has a threshold, but I do not know whether it is the average or maximum or minimum temperature or the sum or cumulation? And for how many days?

I did not find a precise definition, and above all, specific thresholds, that's why I'm looking for examples.

Can be the term (zero vegetation) is not the same used in other countries.

Cordially.

I only found one here at: The Government of Canada’s terminology and linguistic data bank. Maybe it is just a 'regional' jargon. It seems that 'vegetation zero' and 'zero of vegetation' are exchangeable. [ http://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&index=alt&srchtxt=ZERO%20VEGETATION ]

1) Subject field(s):

Atmospheric Physics

Plant Biology

Plant and Crop Production

2) CONT

The plant has an important response to temperature. The vegetation zero is located at 6°C: potato is thus very sensitive to frost. Tuber formation is best under low temperatures (< 18°C) and short days (12 h) whereas vegetative growth is best when temperatures are high (> 25°C) and days long (between 14 h and 18 h).

Okay, but I still don't think 'vegetative zero' is a botanical term. There's nothing on online searches. It is better to say 'temperature-driven-phenology' or use a term like 'vernalisation' – the induction of a plant's flowering process by exposure to the prolonged cold of winter, or by an artificial equivalent :-)

Thank you very much