NaCl胁迫对两种南瓜幼苗离子含量的影响

NaCl胁迫7d明显抑制了两种南瓜——黑籽南瓜（Cucurbita ficifolia Bouche．）和白籽南瓜（Cucurbita moschata Duch．）幼苗地上部和根系的生长，使地上部相对含水量明显下降。随NaCl胁迫浓度（150、300和500mmol／L）的提高，两种南瓜幼苗根、茎和叶片中Na^＋含量明显增加，K^＋含量明显下降。Na^＋和K^＋含量在两个南瓜品种各器官中的分布规律分别是：根〉茎〉叶片和茎〉叶片〉根。NaCl胁迫后黑籽南瓜根、茎和叶片Na^＋含量远低于白籽南瓜，而叶片游离脯氨酸含量、可溶性糖含量和地上部相对含水量明显高于白籽南瓜。表明两者在渗透调节方式、离子的吸收和运输能力上有差异，黑籽南瓜耐盐性较强。

Effects of NaCl Stress on Cation Contents in Seedlings of Two Pumpkin Varieties

Effects of different concentration NaClstress on cation contents of pumpkin cultivars(Cucurbita ficifolia and Cucurbita moschata) usu-ally used as rootstocks of cucumber was studied. Theresults showed that, in both cultivars treated with 150,300 and 500 mmol/L NaCl for 7 d, increasing salinitycaused in increasing retardation of shoot and rootgrowth, and reduction of shoot relative water content(Table 1). With increasing NaCl concentration, Na+content increased while K+ content decreased distinctlyin roots, stems and leaves of both cultivars. And Na+and K+ contents in different organs were in the ordersroots>stems>leaves and stems>leaves>roots respec-tively (Fig.3). There were less Na+ in root, stem andleaf (Fig.3), more free proline and soluble sugar inleaves (Figs.1, 2), and higher shoot relative water con-tent (Table 1) in C. ficifolia than in C. moschata. Sothere are differences between C. ficifolia and C.moschata in osmotic adjustment mechanisms and se-lective absorption and transportation of differentcations, and the salt tolerance of C. ficifolia is higherthan C. moschata.