The root √KUL was connected to gold and gold-coloured things throughout Tolkien’s life but gradually shifted in meaning. The earliest form of this root was ᴱ√KULU “gold” from the Qenya Lexicon of the 1910s (QL/49), but at this early stage it was connected to actual metallic gold as much as the colour, as opposed to ᴱQ. laure which was “magic” name of gold (LT1/100). In The Etymologies of the 1930s, ᴹ√KUL was first glossed “gold (metal)”, but was eventually revised to “golden-red” (replacing a rejected variant ᴹ√GUL), and metallic gold became ᴹQ. malta < ᴹ√SMAL “yellow” (Ety/SMAL) while ᴹQ. laure shifted in sense to “golden light” (Ety/GLAW(-R)).
Tolkien’s continued use of names like Q. Culúrien (S/38) and Q. culumalda “tree with hanging yellow blossoms (prob[ably] a laburnum)” (RC/626) indicate the continued validity of this root, though I suspect in later writings it primarily referred to a golden-red or orangish colour.
This root first appeared as ᴹ√RED “scatter, sow” in The Etymologies of the 1930s along with augmented variant ᴹ√ERÉD and derivatives like ᴹQ. erde/N. eredh “seed, germ” and ᴹQ. resta/N. rîdh “sown field, acre” (Ety/ERÉD, RED). √RED appeared again in the Outline of Phonology (OP2) from the early 1950s with the same gloss “scatter, sow” and derivatives Q. resta/S. rîdh “sown field” (PE19/91). The Quenya word resta reappeared in the 1964 phrase Q. nai elen siluva parma-restalyanna meldonya “✱may a star shine upon your book-fair, my friend” (VT49/38), which might indicate the ongoing validity of this root, but it is also quite possible that resta “✱fair” has a completely different etymology.