摘要
缺钾及因缺钾而导致的早衰已成为当前我国棉花生产的主要限制因素,而根系的生长发育与钾素营养互相影响、关系密切。本试验在生长室内营养液培养条件下,调查缺钾对棉花幼苗根系性状的影响,测定根系游离吲哚乙酸(IAA)和乙烯释放量。结果显示,与适钾处理(0.50mmolL-1)相比,缺钾处理(0.05mmolL-1)显著抑制了根系伸长和侧根发生,而且侧根的减少主要由侧根发生区的缩短所致,侧根发生密度并无变化,似乎缺钾减慢了侧根发育的进程,但不改变可以形成侧根的中柱鞘细胞的发育状况。此外,细根(0.05～0.20mm)生长受缺钾的影响最大,绝对根长、根表面积、根体积及其占总根系的比例均显著降低;中等根(0.25～0.45mm)受到影响最小,粗根(>0.45mm)居中。由于细根的吸收活性强于中等根和粗根,因而缺钾幼苗的钾营养状况较根系生长更为恶化,处理4d和10d的整株钾积累量仅分别为适钾处理的25%左右和16%左右,而其总根长和根系总表面积分别相当于适钾处理的35.7%～38.0%(处理4d)和47.7%～50.6%(处理10d)。与适钾条件相比,缺钾使根系的游离吲哚乙酸(IAA)含量降低约50%,而乙烯释放量提高将近6倍,这可能是缺钾抑制棉花幼苗根系生长的重要原因之一。
Premature senescence caused by potassium （K） deficiency has been an important limiting factor in cotton production in China, and K uptake ability of plant from media has a close correlation with root growth and development. In the present study, cotton cultivar NuCOTN99B was sowed in sand in growth chamber, uniform cotton seedlings were transferred to 1/2-strength modified Hoagland＇s solution with low （0.05 mmol L^-1） or moderate （0.50 mmol L^-1） K^＋ at 4 d after germination to investigate the effect of K levels on the root system indicators, endogenous free indole acetic acid （IAA） content and ethylene amount released from the cotton seedlings root. The results showed that the lateral root formation of seedlings grown in low K solution for four days was significantly inhibited by about 20%. After 10 d treatment, root elongation was also significantly reduced. Furthermore, we found that the reduction of lateral root mainly resulted from short length of branched root zone, and there was no change in the density of lateral root under lower K. In addition, root system was classified into fine roots （0.05-0.20 mm）, middle roots （0.25-0.45 mm）, and coarse roots （〉 0.45 mm） according to root diameter. Total root length and total root surface area of cotton seedlings grown in low K medium for four days reduced by about 60%, and the fine root was inhibited severely, the coarse roots moderately, and the middle roots slightly. For example, the root length, root surface area and root volume of fine roots grown in low-K medium for 4 and 10 d were only approximately 10% and 25% of those in moderate-K medium, respectively. Additionally, only fine roots were constantly inhibited by low-K during treatment period in terms of the ratios of different diameter＇s roots to total roots, which resulted in the fact that the magnitude of K deficiency in cotton seedling was higher than that of inhibition of root growth, because the uptake activity in fine roots is higher than that in middle and coarse roots. For example, the accumulated K of seedlings grown in low-K solution for 4 d and 10 d were 25% and 16% of that grown in moderate-K solution, respectively; whereas the total root length and total root surface area were 35.7-38.0% （4 d） and 47.7-50.6% （10 d）. As expected, the endogenous free indole acetic acid （IAA） content in roots grown in low-K medium was reduced by 50%, whereas the amount of ethylene release had nearly six-fold increase, which might provide an explanation to some extent for the inhibition of lateral root formation and root elongation by potassium deficiency.
出处
《作物学报》
CAS
CSCD
北大核心
2009年第4期718-723,共6页
Acta Agronomica Sinica
基金
国家自然科学基金项目(30100111和30571118)
高等学校科技创新工程重大项目培育资金项目(707008)资助
关键词
棉花
钾
根系
IAA
乙烯
Cotton （Gossypium hirsutum L.）
Potassium （K）
Root growth
Indole acetic acid （IAA）
Ethylene
