Post harvest Management of Horticultural Crops (2+1)

Methods for Judging maturity

Computational methods
1. Calendar date

It is one of the commonly used indices of maturity and is reasonably accurate provided flowering and weather during growing season is normal. But standardization requires study for many seasons for given variety, location, rootstock etc.

Eg. Mango harvesting period – April to July



2. DFFB(Days From Full Bloom)

It is reliable but varies greatly from year – to - year and location –to- location. In such case the optimum date of harvest can be predicted by doing night temperature correction for 15 days fallowing full bloom. For every 10F variation from an average night temperature, a correction of one day is made in the standard figure from full bloom.

Eg. Mango 110 -125 day (Var. Alphonso and Pairi ), Banana 99 - 107 days in dwarf Cavendish



3. Heat units/Day degree

Optimum maturity is computed by the sum of mean daily temperature, above base temperature ( 10oC/50oF for apple)for a period concerned. The number of degree-days to maturity is determined over a period of several years. 10oC /50oF is the temperature at which growth occurs for apple and base temperature varies with crop.

The degree day is based on a growth-temperature relation. However this heat units work only within limited temperature. Heat units are not useful for photoperiod sensitive species.
A Heat unit is calculated by - (daily mean temp – base temp) X No. of Days (flowering to harvest)
Base temperature for tomato, spinach and pumpkin is 150, 20 and 130C respectively.

Crop	Cultivars	Base temp	Degree Days
Apple	Red delicious	18oC	1659-1705
Grape	Thompson seedless	10 oC /50oF	1600-2000
	Bangalore Blue		3562
	Gulabi		3508
Mango	Banganapalli	18oC	1426
Banana	-	9.8oC	1930
Asparagus	-	10 oC /50oF	120-410
Peas	Early Wisconsin	4.4 oC /40oF	1319
	Alaska		1200