棉 花 学 报 Cotton Science 2006，18(2)：99-103
Effects of Calcium and Auxin on Lateral Roots Initiation of Cotton Seedling Abstract：Effects of Ca2+ and auxins on the root growth of cotton were studied using Gossypium Hirsutium L. cv. CCRI 29. The cotton seedlings were cultured in two layers of filter paper adhered on glass board with lower 2 cm dipped in water and grown in growth chamber at 25 ± 1 ℃ . The agar solution dissolving designed concentration of Ca (NO3)2，indolebutyric acid (IBA)，Ca(NO3)2+IBA，Ca2+ antanogists or calmodulin (CaM) antanogists was respectively pasted on the conjunction area of seedling hypocotyl and radicle. Treatments of 50mg·L-1 Ca(NO3)2 and 5 mg·L-1 IBA promoted the lateral roots initiation (LRI) by 14.8% and 29.6% ， whereas retarded the primary root elongation (PRE) by 13.4% and 8.3% respectively. 50 mg·L-1 Ca2+ +5 mg·L-1 IBA showed synergic effects as the LRI was 33% higher than CK while the PRE was close to CK and higher significantly than Ca(NO3)2 or IBA treatment solely. All the PRE ， LRI and free CAM content were inhibited by the treatments of 3-10mg·L-1 LaCl3(Ca2+ inhibitor，3-10mg·L-1 EGTA (calcium chalator) and 3-10mg·L-1 TFP (CAM antanogist). 5mg·L-1 IBA enhanced IAA in basal radicle segment，repressed IAA and GAs in appical and middle segment of radicle ， heightened CTKs content and decreased IAA/CTKs in all segments of radical. 3-10mg·L-1 TIBA reduced CTKs in whole radicle，IAA 和 IAA/CTKs in basal and middle segment，while increased IAA content and IAA/CTKs in radicle apical，which might be contributed to its restrainment on LRI and enhancement on PRE.
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