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1、Unit 7 Rice ecosystems in Asia,Unlike many other crops，rice is grown in diverse land and water management systems. Therefore，tillage practices for land preparation in rice vary considerably starting with the cultivation practicesThe cultivation practices for rice differ with the rice ecosystems and
2、are broadly categorized as follows：,Words to remember,1、tillage tld n. 耕作，耕种 tillage practices：耕作方式 2、land preparation 农学 整地 3、cultivation kltven n. 培养；耕作；耕种 cultivation practices：栽培方式 4、rice ecosystem：水稻生态系统,Irrigated rice ecosystems are those areas that have bunded, puddle fields with assured irri
3、gation for one or more crops per yearThis ecosystem，which is concentrated mostly in the humid and subhumid subtropics, accounts for about 80 million ha (55%) of the harvested rice area and contributes 76% of global rice production, with average yields varying from 3 to 9 t ha-1.,Irrigated rice ecosy
4、stems,Words to remember,5、irrigate rget vt. 灌溉；冲洗 6、irrigation renn. 灌溉 7、bund bnd n. 堤岸；码头 8、puddle pd()l n. 水坑，水道； 9、humid hjumd adj. 潮湿的；湿润的； 10、subhumid sbhju:mid adj.半湿润气候的 11、subtropics ,sbtrpks n. 地理 亚热带,There are three rice environments in this ecosystem, namely, i. Irrigated with favourable
5、 temperature, ii. Irrigated with unfavourable temperature-tropical zone and iii.Irrigated with unfavourable temperature-temperate zone,Words to remember,12、favourable temperature:适宜温度 13、unfavourable temperature：不适宜温度 14、tropical trpkladj. 热带的 15、zone zonn. 地带 16、temperate temp()rt adj. 温和的；适度的 trop
6、ical zone：热带 temperate zone：温带,Improved rice cultivars that have been developed for irrigated rice lands are of short duration and are responsive to nitrogen fertilizer, and incorporate resistance to several biological stresses and some tolerance to adverse soils. It is characterized by high croppin
7、g intensity and intensive use of agrochemicals,Words to remember,17、duration durenn.生育期，持续的时间 18、nitrogen fertilizer：氮肥 19、biological stress：生物逆境 20、cropping intensity：种植密度 21、agrochemical ,rokmkln. 农用化学品,Production constraints in low (1ess than 3t ha-1) and medium yield (3-5t ha-1) areas are delaye
8、d plantings, shortage of labour, use of low to medium potential varieties, low input rates, poor input management, poor weed management, inadequate water supply, unavailability of irrigation at one or more critical stage, salinity/alkalinity problem; associated poor drain-age and environmental stres
9、ses.,Words to remember,22、constraint knstrent n.约束；限制 23、salinity：slntin. 盐度；盐分；盐性 24、alkalinity ,lklntin. 碱度；碱性 25、drainage drendn. 排水；排水系统,Problems associated with high production (more than 5t ha-1) areas are yield instability due to pests, multiple cropping systems-delaying transplanting and env
10、ironmental degradation.,Words to remember,26、instability ,nstbltin. 不稳定，基础薄弱 27、multiple cropping systems： 多熟制种植 28、transplanting：移栽 mechanical transplanting 机械化移栽,Rain fed lowland rice grows in budded fields that are flooded for at least part of the cropping season to water depths that do not excee
11、d 50 cm for more than ten consecutive daysRain fed lowlands are characterized by lack of water control, with floods and drought being potential problems. About 40 million ha (25%) of the global rice area is rain fed, contributing 18% of the total production.,Rainfed lowland rice ecosystems,Words to
12、remember,29、Rain fed lowland rice 雨养湿地水稻 30、consecutive knsekjtv adj. 连贯的；连续不断的,Rainfall is often erratic, so that conditions are diverse and unpredictable. Typically，traditional photoperiod-sensitive cultivars, which do not respond to fertilizer，are grown. No water harvesting/conservation facilitie
13、s are available on the farm and there is no irrigation water availableFive major environments have been identified within the rainfed lowland ecosystem. These are,Words to remember,31、erratic rtkadj. 不稳定的 32、photoperiod ftprd n.光周期 photoperiod-sensitive cultivars 光周期敏感的品种 33、water harvesting：雨水收集,i.
14、 Rainfed shallow favourable environments：No drought or waterlogging ii. Rainfed shallow drought prone environments：These areas have frequent and severe water-deficit problems and are drought proneThe rainy season may be short (90-100 days) as in central and eastern India or long with erratic distrib
15、ution as in Bangladesh and Thailand,iii. Rainfed shallow drought and submergence prone environment: Areas subjected to both drought and waterlogging. iv. Rainfed shallow submergence prone environments: Frequent short-term flooding that may damage or destroy the crop. v. Rainfed medium deep rice envi
16、ronment: Water 25-30 cm deep may stand for a substantial period of growing season.,Words to remember,34、waterloggingw:t,lgi n涝；水浸 35、prone pronadj.有倾向的，易于的 36、submergencesbmdns n. 下潜，淹没,Of the 148 m. ha total rice area, this ecosystem covers about 18 million hectares of which 64 per cent is located in Asia, 25 per cent in Latin Amer
