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India: Use of Growing Degree Day (GDD) in Horticulture

India is the mile stone in the horticulture map of the world being the second largest producer of fruit in world, contributing 10 per cent of the total world production.  Even with high production we are unable to a fetch good price in the markets. Up to 40 percent of fruit and vegetables go waste due to their perishable nature and the non availability of post harvest infrastructure and lack of management. So in order to tackle these problems we can plan according to harvest date by using degree day.

What is the Growing degree day?
The heat units (degrees) accumulated over the growing season for a particular crop is defined as growing degree day it also known as degree day.

Principles of degree days
Plant and Insect development are very dependent on temperature. As an organism develops over a growing season, its development is closely related to the daily accumulation of heat. A certain amount of heat is required to provide enough energy for the organism to move to the next development stage, the amount of heat required remains constant from year to year, but depending on weather conditions, the amount of actual time can vary. Each organism has a minimum base temperature or threshold below which development does not occur.

Use of degree day
1.    The GDD helps horticulturists predict saying that it’s ahead of the date of
maturity or blooming period of a plant.
2.    GDD is also used to predict pest outbreaks during the growing season.

Easy to calculate
To calculate GDD, first determine the average temperature for the day. This is usually done by taking the maximum and minimum temperatures for the day, adding them together and dividing by 2. The base temperature is then subtracted from the average temperature to give a daily GDD. If the daily GDD calculates to a negative number it is made equal to zero. Each daily GDD is then added up (accumulated) over the growing season.

(DD) = Average daily temp. - Base Temp. = (max. + min.) / 2 - Base temp.
If answer is negative, assume 0.

Example: Calculate DD Base 17.9 for Kesar mango given 37degrees max. And 20 degrees min.
Avg. = (37+20) / 2 = 28 degrees
DD base 17.9 = 28- 17.9= 10.6 degrees.

But look what happens given a maximum of 10 degrees and a minimum of 6 degrees:
Avg. = (10+06) / 2 = 8
DD base 17.9 = 16 – 17.9 = -1.9 degrees.

In the first example 10.6 degrees is accumulated  for 1 day. Starting from opening of the flowers do this calculation everyday until the value remains 0 that is your harvesting date. Trials have been done at the Essar Agrotech, Vadinar Jamnagar Gujarat, India. Kesar mango requires 780-796 heat units for maturation. In the Konkan region of Maharastra Power in 1997 it was observed that Kesar mango requires 773-799 heat units for maturation.

Heat requirements of various fruits and vegetables




Contact:
Ganesh Mandalik
Essar Agrotech Pvt. Ltd
Vadinar, Gujarat
India
Email: ganumandlik@yahoo.com 
Tel: +919909992313



Publication date: 1/7/2010


 


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