【作者】 张立桢； 曹卫星； 张思平； 周治国；

【Author】 ZHANG Li-zhen~(1.2), CAO Wei-xing~1, ZHANG Si-ping~2, ZHOU Zhi-guo~1 (1. Key Laboratory of Crop Growth Regulation, MOA, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; 2. Key Laboratory of Cotton Genetic Improvement, MOA, Cotton Research Institute, CAAS, Anyang, Henan 455112, China)

【机构】 南京农业大学农业部作物生长调控重点开放实验室； 中国农业科学院棉花研究所农业部棉花遗传改良重点实验室；

【摘要】 结合田间根钻取样和图像扫描分析,研究了不同棉花品种根系长度、直径和表面积动态及0～100cm深和0～40cm宽范围内的空间分布特征。该方法与常规直尺测量结果相比相关系数r²达到0.899（n=1318）。棉花平均根长密度（RLD）在花铃期为1.21～1.27mm·cm^-3,吐絮后降至1.04～1.12mm·cm^-3,收花时为0.76mm·cm^-3。棉花根平均直径在不同基因型间存在显著差异,抗虫杂交棉的根直径最粗,平均为0.52mm;早熟类型品种根直径较细,平均为0.36mm。在土壤深度上根直径的差异不显著,但距棉行距离越远,根的平均直径越小。提出了根表面积指数（RAI）的概念,与地上部叶面积指数具有相似的含义和生物学意义,且呈较好的指数相关关系（r²=0.779）。RAI在生理发育时间（PDT）小于等于40前,其增长动态符合LOGISTIC生长规律（r²=0.849）,在PDT大于40后,呈线性递减趋势（r²=0.57～0.895）,且杂交抗虫棉的RAI在全生育期内均明显高于其它类型品种,而早熟类型品种相对略低。RAI空间分布特征表现为,开花前在浅根层内（0～30cm）分布最多,花铃期以中层根系（40～60cm）为主,吐絮后主要以深层（70～100cm）和距棉行较远的行间较多。研究结果为制定合理的施肥、灌溉措施提供了理论依据,并量化了棉花根系的时空变化,为进一步提高生长发育模拟模型的精度奠定了基础。更多还原

【Abstract】 By integrating root auger and image analysis methods for root sampling and measurement in the cotton field, this study investigated dynamic characteristics of root growth and spatial distribution as root length, diameter and area within 0～100 cm depth and 0～40 cm width soil. The experiments conducted in experiment station located in Anyang city, Henan province in 2001 and 2002. The roots performance experiment for different genotypes in field conducted in 2001 with 4 cotton cultivars such as middle season hybrid CCRI 29 with Bt, middle season variety CCRI 35 without Bt, middle season variety CCRI 32 with Bt and early season variety CCRI 37 with Bt. Plant density was 60000 plants per hectare. The experiment of 2002 conducted in pool with American middle season variety 33B with Bt. The soil is loam. Weather dada collected from nearby weather station for calculation of cotton physiological development time （PDT）. Computation of PDT also integrated thermal effectiveness, photoperiod effectiveness, genetic effectiveness and its interactions. Root sample was collected from 3 or 4 placements away from cotton row 0 cm, 15 cm, 25 cm and 35 cm, root samples were collected from 10 cm of 0～100 cm soil depth on each placement. The roots were sampled by a root auger with size of volume 316.73 cm³. soil core with was washed for collection all cotton root in the samples. Cleaned roots was scanned to a black and white image with 200 pdi. The DT-SCAN software was used to calculate root length, root diameter and root surface area. Compared with the rule measurement method for root length density （RLD）, image analysis method for RLD showed advantages and credentials (r² =0.899,n = 1318. The re- suhs indicated that RLD of cotton averaged 1.21～1.27 mm·cm^-3 during flowering and boll stage, 1.04～1.12 mm·cm^-3 after boll open, 0.76 mm·cm.（-3） during harvest period. Root diameter was significantly different among genotypes （P=0.022）, with the thickest root diameter of 0.52 mm in insect resistant hybrid cultivar and thinnest root diameter of 0.36 mm in early matured cultivar. The root diameter was not significantly different within soil layers, but was significantly thinner with the placements away from cotton row. In consideration of significant differences in root length and diameter among layers, placements or genotypes, root area index （RAI） was proposed with similar biological meaning as leaf area index. The RAI and LAI was exponentially related with r² of 0.799. The dynamic course of RAI fit a logistic growth pattern （r² = 0.849） with physiological development time （PDT） when the PDT was smaller than 40, and exhibited a linear decreasing pattern （r²= 0.570～0.895） at PDT greater than 40. The maximum value of RAI was highest in insect-resistant hybrid cuhivar, but lowest in early matured cultivar. The RAI distribution was greater within top soil layer （0～30 cm） before flowering, within mid layer （40～60 cm） during flowering and boll stage, within deep layer （70～100 cm） and at placements away from cotton row after boll opening.更多还原