INCUBATION-TEMPERATURE AFFECTS CHANGES IN CUCUMBER SEED PROTEINS AND MINERAL-CONTENT

Suboptimal soil temperatures retard germination of cucumber (Cucumis s ativus L.) seed leading to uneven stands and reduced yield. This proje ct was undertaken to determine how concentration of minerals (N, NO2-, NO3-, P, HPO4-2, K, SO4-2, Ca, Fe, Mg, Mn, and Na) and density of pro tein bands in seed of the cvs. 'Arkansas Little Leaf and 'Earlipik 14' changed during germination and radicle elongation. Seed were incubate d in distilled water in petri dishes at 13.9, 15.6 and 20 degrees C. S eed were analyzed for mineral content and proteins prior to incubation and then at intervals up to 168 hr. At 20 degrees C, at least 90% of seed of both cultivars germinated by 48 hr. The content of N, P, HPO4- 2 and SO4-2 in 'Earlipik 14' seed were significantly less at 13.9 or 1 5.6 than at 20 degrees C. This suggests leakage of minerals occurred a t suboptimal temperatures. After 24 hr incubation at 20 degrees C the density of the 70.1 Kda protein band in gets did not increase, while d ensity of 37.4, 43.4, and 50 Kda protein bands increased in seed of bo th cultivars. Ar the other temperatures density of protein bands in ge ls increased until 120 hrs. The data suggests that low cucumber germin ation rates at suboptimal temperatures were related to: 1) leakage of minerals, and/or 2) the lack of formation or denaturation of proteins associated with germination and radicle elongation.