Matcha, Gyokuro are grown with covered before the harvest, while Tamaryokucha, Sencha are not.  This page explains how shaded cultivation makes influence to the tea taste (= chemical components) .

Shaded Cultivation
Shaded Cultivation
Open Field Cultivation
Open Field Cultivation

Shaded cultivation is covering tea trees for certain level and certain period before the harvest.  And those tea leaves are used for Matcha, Gyokuro.  While open field cultivation is growing tea trees in open fields without blocking sunshine.  Tamaryokucha, Sencha leaves are grown in open field.

1. Major Chemical Components

Japanese Teas have 3 major chemical components that influence the taste.  Amino acids taste umami and sweet.  Caffeine takes bitter taste.  And catechins has astringent taste. 

2. Amino Acids & Caffeine

The following charts display how the content % of Amino Acids and Caffeine change between shaded cultivation and open field cultivation before the 1st harvest.  Shaded cultivation curb the decline of Amino Acids and Caffeine.  So Matcha and Gyokuro leaves preserve more Amino Acids and Caffeine than Tamaryokucha or Sencha leaves.

Condition: Average data of 1st harvest leaves in multiple test zones.

Amino Acids

All Y axis unit: mg% of each total chemical component

Caffeine

All Y axis unit: % of each total chemical component
(Anan and Nakagawa, “Effect of Light on Chemical Constituents in the Tea Leaves”. Journal of the Agricultural Chemical Society of Japan , Vol.48, No.2, 1974, P93,
Link to the source of this research paper )

3. Catechins

In the same experiment, the content % of Free Catechins and  those of Ester Type Catechins showed the following trends.  As time goes, shaded cultivation curb the increase of Free Catechins, while Ester Type Catechins indicates the similar declining trend as open field cultivation.   This means, Tamaryokucha and Sencha have more Free Catechins than Matcha, Gyokuro.  And in total, Tamaryokucha and Sencha have more Catechins than Matcha or Gyokuro.

Condition: Average data of 1st harvest leaves in multiple test zones.

Free Catechins (EC + EGC)

Ester Type Catechins (EGCG + ECG)

All Y axis unit: % of each total chemical component
(Anan and Nakagawa, “Effect of Light on Chemical Constituents in the Tea Leaves”. Journal of the Agricultural Chemical Society of Japan , Vol.48, No.2, 1974, P93,
Link to the source of this research paper)

4.  Nutrition

With open field cultivation, sunlight generates more Vitamin C than shaded cultivation does.  Therefore, Tamaryokucha, Sencha have more Vitamin C than Matcha or Gyokuro.

(Horie et al. “Chemical Composition of Japanese Green Tea on Market”. Tea Research Journal, No.80,  1994, P25, Link to the source of this research papaer)

5. Summary

Shaded cultivation preserve Amino Acids and Caffeine, while open field cultivation creates more Catechins and Vitamin C.  Therefore, Matcha and Gyokuro have more umami, sweet, and bitter taste, while Tamaryokucha and Sencha have more astringent taste.

Which tea is your choice?