【目的】本文基于幼苗图像分析建立鉴定水稻耐深播相关特性的方法,鉴定旱直播条件下水稻耐深播的农艺性状。【方法】以不同中胚轴伸长能力的18份水稻品种和稗草、马唐的种子,设置3cm、5cm、7cm、9cm和11cm深度的砂培试验,观察出苗情况并在播种后第15天摄取幼苗照片,采用图像分析技术提取幼苗生长相关的表型指标。【结果】在人工标记幼苗胚芽鞘节等部位前提下,通过图像分析可一次性测定中胚轴长度和累积绿叶投射面积;当播种深度为3cm时,短中胚轴水稻品种能在播后第6天前后出苗,长中胚轴品种能在播后第5天出苗;播种深度为5-7cm时,短中胚轴品种不能正常出苗,长中胚轴品种能在播后第7-10天出苗;在同等播种深度下长中胚轴品种第15天幼苗叶面积高于短中胚轴品种,在7cm以上播种深度下差异极为明显;稗草和马唐都具有幼苗中胚轴伸长能力,种子能从5cm或3cm深度下正常出苗。【结论】基于幼苗图像分析技术,本试验建立了水稻旱直播耐深播相关指标的表型检测方法,识别幼苗中胚轴和叶片等部位,提取中胚轴长度和累积绿叶投射面积指标。水稻差异性代表品种和常见禾本科杂草的观察结果表明中胚轴伸长能力是深播后快速、整齐出苗并较早形成自养能力的关键。

[Objective] The major objectives of the experiment is to develop protocols of seedling image analysis to evaluate characteristics related to tolerance to deep sowing under dry direct sowing condition in rice. [Methods] Seeds of eighteen rice varieties with varied mesocotyl elongation and barnyard grass, crab grass were used in sand culture with 5 sowing depths of 3cm, 5cm, 7cm, 9cm, and 11cm. Seedling emergence was recorded each day. Digital images of seedling were obtained 15 days after sowing (DAS), and used to measure phenotypic parameters related to seedling growth based on image analysis. [Results] The protocol of image analysis is effective to obtain mesocotyl length and total leaf projected area simultaneously. Under 3cm sowing depth, seedlings of rice varieties without mesocotyl elongation were able to emerge on 6 DAS while seedlings with elongated mesocotyl emerged on 5 DAS. Under 5-7cm sowing depth, rice varieties without mesocotyl elongation failed to emerge while varieties with elongated mesocotyl delivered emerged seedlings on 7-10 DAS. The total leaf projected areas of 15 DAS seedlings were higher in varieties with mesocotyl elongation than varieties with short mesocotyl under same sowing depth. The differences were very noticeable under 7cm or higher sowing depths. Mesocotyl elongation was observed in both barnyard grass and crab grass seedlings that led to seedling emergence from 5cm and 3cm sowing depth, respectively. [Conclusion] Phenotyping protocol was developed to evaluated deep-sowing tolerance related parameters based on seedling image analysis. Mesocotyl length and total leaf projected area were measured after recognition of different parts like mesocotyl and leaves of the seedlings. Investigation on representative rice varieties and grass weeds indicated the key role of mesocotyl elongation on quick, uniform seedling emergence after deep sowing, and the early development of autotrophic capacity.