зард

зард: yellow

Лимӯ ва банан ранги зард дорад.
Lemons and bananas are yellow.
Меваи помидор дар аввал сабз буда, дар вақти пухтанаш (вобаста ба навъҳояш) ранги сурх, норинҷӣ ва зард ба худ мегирад.
The fruit of the tomato is at first green, and when it ripens (according to its kind) it takes on a red, orange or yellow colour.

Bonus:
Synonym: лимӯранг

In Tajik when saying the colour of something you usually use the verb “to have”, as you can see in the first sentence. We could translate that sentence, “Bananas and lemons have a yellow colour”.

зарди тухм: egg yolk, the yellow of the egg
зарди тиллоранг: golden yellow
зардолу: apricot

Tajik has some fun colour words:
каб-кабуд: very blue
сап-сафед: very white
сип-сиёҳ: very black
суп-сурх: very red
заб-зард: very yellow

If you need to review colours you can do it at Memrise: Tajik Colours. (You need to log in, but it is free.)

сабз

сабз: green

Барои чӣ либосҳои сабз напӯшидед?
Why didn’t you wear green clothes?
Меваи помидор дар аввал сабз буда, дар вақти пухтанаш ранги сурхро ба худ мегирад.
The fruit of a tomato being green at the beginning, takes on a red colour when it ripens.

Bonus:
Баҳор омад, садои булбул омад,
Насими фораму бӯйи гул омад.
Либоси сабзро саҳро ба бар кард,
Кулоҳи сап-сафед олу ба cap кард.
Мирзо Турсунзода

Spring came, the voice of the nightingale came,
A pleasant breeze and the smell of flowers came.
The field put on green clothes,
The plum tree put on a very white hat.
Mirzo Tursunzoda

кабуд

кабуд: blue

Модарам чашмони кабуд дорад.
My mother has blue eyes.
Осмон беабр ва кабуд буд.
The sky was cloudless and blue.

Bonus:
чойи кабуд: green tea
пиёзи кабуд: green onions
(Don’t get hung up on the fact that in these cases we would translate кабуд to mean green. It is better to learn language without always translating back to your native language anyway.)

кабудпӯш: somebody wearing blue clothes for mourning (blue is a mourning colour)

Tajik has some fun colour words:
каб-кабуд: very blue
сап-сафед: very white
сип-сиёҳ: very black
суп-сурх: very red
заб-зард: very yellow

If you need to review colours you can do it at Memrise: Tajik Colours. (You need to log in, but it is free.)

сиёҳ

сиёҳ: black

Мӯи шимпанзе сиёҳу сахт мебошад.
The hair of a chimpanzee is black and hard.
Дар кишвари Дания лолаи сиёҳро парвариш мекунанд.
In Denmark they grow black tulips.

Bonus:
абри сиёҳ: black cloud, rain cloud
рӯзи сиёҳ: black day i.e. sad day, day of disaster
тахтаи сиёҳ: blackboard
сип-сиёҳ: very black
If you need to review colours you can do it at Memrise: Tajik Colours. (You need to log in, but it is free.)

сафед

сафед: white

Ранги сафед аз бисёр рангҳо иборат аст – зард, норинчӣ, сурх, сабз, кабуд ва гулобӣ.
White is composed of many colours – yellow, orange, red, green, blue and purple.
Роҳи сафед!
Safe journey! (Literally – white road)


Bonus: 
Do you know what тиллои сафед is? You can use google image search to find out.
There is a cool way to say “very white” in Tajik – сап-сафед. There are also cool ways to say “very blue”, “very red” etc.
If you need practice with colours you can learn them here: Memrise – Tajik Colours