Lactuca sativa cultivar solid heart

A method of introducing a desired trait into lettuce variety Solid Heart, the method comprising:

• (a) crossing a plant of lettuce variety Solid Heart grown from seed of lettuce variety Solid Heart, wherein a representative sample of seed has been deposited under ATCC Accession No. PTA-126703, with another lettuce plant that comprises a desired trait to produce at least one F1 progeny plant, wherein the desired trait is selected from the group consisting of insect resistance, herbicide resistance, disease resistance, water stress tolerance, heat tolerance, improved shelf life, delayed shelf life, and improved nutritional quality;
• (b) selecting one or more progeny plants that have the desired trait to produce at least one selected progeny plant;
• (c) crossing at least one selected progeny plant with at least one plant of the lettuce variety Solid Heart to produce at least one backcross progeny plant;
• (d) selecting for at least one backcross progeny plant that has the desired trait and all of the physiological and morphological characteristics of lettuce variety Solid Heart when grown in the same environmental conditions to produce at least one selected backcross progeny plant;
• and
• (e) repeating steps (c) and (d) three or more times in succession to produce at least one selected fourth or higher backcross progeny plant that comprises the desired trait and all of the physiological and morphological characteristics of lettuce variety Solid Heart when grown in the same environmental conditions.

A method of vegetatively propagating a plant of lettuce variety Solid Heart comprising:

• (a) collecting tissue capable of being propagated from a plant of lettuce variety Solid Heart, a sample of seed of the variety having been deposited under ATCC Accession No. PTA-126703;
• (b) cultivating the tissue to obtain proliferated shoots and rooting the proliferated shoots to obtain rooted plantlets;
• and
• (c) optionally growing plants from the rooted plantlets.