日光温室番茄节水灌溉的灌水量指标研究终稿全套毕业论文.doc

专业名称资源环境与城乡规划管理论文题目日光温室番茄节水灌溉的灌水量指标研究题目来源科研项目（2007BAD69B06）目的意义： 水资源缺乏已成为当今人类社会共同关注的问题，我国是一个水资源相对贫乏的国家，人均占有水量相当于世界人均水平的1/4，居世界第109位，是世界上人均占有水资源最贫乏的13个国家之一；同时，我国水资源空间分布极不平衡，地处北方地区的河北省人均水资源量仅为883 m3/hm2，不足全国平均水平的1/30。水资源不足不仅造成了严重的生态环境问题，同时缺水已经成为限制河北省经济社会发展的重大问题。 从对水资源量总的消耗来看，全国总用水量5548亿m3，其中农业用水占64.6%，而蔬菜灌溉用水的消耗则占农田灌溉用水30偏高。灌溉是蔬菜生产过程中一项重要的农艺措施，但由于蔬菜节水研究与应用起步较晚，目前生产上蔬菜灌溉用水盲目，浪费严重，不仅直接造成水的浪费，还衍生了一系列生产的问题，如首先，肥随水走的原理决定了水多肥多渗漏多、土壤污染严重，面临蔬菜施肥污染土壤环境与土地可持续利用的难题；二是，由于灌水过大，引起设施内土壤和空气湿度加大，蔬菜的生长发育受到影响，诱发病害的发生，即水多病多用药多，面临蔬菜用药与产品安全的挑战；三是，由于多水多肥多病加剧了栽培管理技术繁杂程度，面临着管理繁杂与规模发展的难题。因此研究蔬菜节水，可起到一节多效的效果。研究条件：1.试验供试材料为金鹏1号番茄。2.利用比较丰富的图书资料和网络资源，查阅相关资料，以及田间试验，获取相关数据。资料齐全，数据翔实可靠 。3.本课题组在研究方面积累了较为丰富的经验，具备熟练的操作技能。可行性分析：从目前灌溉水浪费的途径来看，蔬菜灌溉浪费的主要途径是地面蒸发和根层外渗漏。据调查，目前生产上约有20的灌溉水通过根层以下渗漏损失掉。其主要原因之一是目前生产上缺乏准确的控制根层下灌溉水渗漏的灌水量指标阈值。因此本研究选择日光温室主栽蔬菜种类番茄，通过研究番茄不同生育期根系分布特征与不同灌水量与控漏灌水量关系确定番茄节水灌溉的经济灌水量阈值，就能够建立起蔬菜灌溉中既节水又满足蔬菜生长要求的灌水量阈值，达到节水灌溉的目标。可能存在的问题：1.土壤含水量的测定受土壤基础水分、灌溉方式的影响。2.人为等无法避免的因素的影响。进度安排： 2009.10.14 听取全院的实习动员大会及指导教师的具体实习内容；2009.10.15-2010.01.22 在图书馆查阅有关资料，完成论文任务书；2010.01.23-2010.03.04 完成论文设计，开题报告并进行室内实验；2010.03.05-2010.03.10 论文开题2010.03.11-2010.05.10 收集资料文献并对实验结果进行分析；2010.05.15 中期检查；2010.5.16-2010.06.10 进行对比研究，完成论文撰写；2010.06.11-2010.06.13 毕业论文答辩。专家意见：该论文通过研究番茄不同生育期根系分布特征与不同灌水量与控漏灌水量关系，确定番茄节水灌溉的经济灌水量阈值，能够建立起蔬菜灌溉中既节水又满足蔬菜生长要求的灌水量阈值，达到节水灌溉的目标，为指导农业生产提供了一定的科学依据。选题具有一定的科学性，试验方案设计合理，研究方法可行，同意立题。专家签字：2010年1 月16日学部意见: 学部主任： 2010 年1 月16 日 生命 学部 资源环境与城乡规划管理 专业 张津 学生：现把 09-10 学年，第 一、 二 学期的毕业论文安排下达给你，你本学期承担的毕业论文任务如下：1、依据本任务书中论文题目、目的意义、可行性分析的内容完成开题报告。2、按照开题报告的要求按期完成毕业论文各项工作的实施。3、完成毕业论文的撰写。4、完成毕业论文的答辩。 请按相关要求完成毕业论文任务。教师签字：2010 年 1月 16日河北农业大学现代科技学院毕业论文开题报告题 目：日光温室番茄节水灌溉的灌水量指标研究学 部： 生命学部 学生姓名： 张 津 专 业： 资源环境与城乡规划管理 班级学号： 2006614500117 指导教师姓名： 文宏达 指导教师职称： 教授 2010 年 3 月 10 日学生姓名张 津专业班级资规0601班学 号2006614500117指导教师文宏达职 称教授所在学部生命学部论文名称日光温室番茄节水灌溉的灌水量指标研究选题依据：现今灌溉措施中采取的小水灌溉，既节约了水源，又减少了肥的浪费，同时不会造成对地下水的污染和土壤的盐渍化，（原因是小水灌溉不会使肥料随水冲到作物根系不能吸收的根区以外），不仅如此小水灌溉还有利于提高西红柿的风味，减少日光温室的湿度，使那些危害蔬菜生长的喜欢高湿度环境繁殖的病原菌不能发生，病害减少。水是蔬菜生长的必需，小水灌溉的“小水”究竟是需要灌溉多少，有没有一个准确的范围，有必要进行深入的研究测定。目的意义：水资源缺乏已成为当今人类社会共同关注的问题，我国是一个水资源相对贫乏的国家，人均占有水量相当于世界人均水平的1/4，是世界上人均占有水资源最贫乏的13个国家之一；同时，我国水资源空间分布极不平衡，地处北方地区的河北省人均水资源量仅为883 m3/hm2，不足全国平均水平的1/30。水资源不足不仅造成了严重的生态环境问题，同时缺水已经成为限制河北省经济社会发展的重大问题。 从对水资源量总的消耗来看，全国总用水量5548亿m3，其中农业用水占64.6%，而蔬菜灌溉用水的消耗则占农田灌溉用水30偏高。灌溉是蔬菜生产过程中一项重要的农艺措施，但由于蔬菜节水研究与应用起步较晚，目前生产上蔬菜灌溉用水盲目，浪费严重，不仅直接造成水的浪费，还衍生了一系列生产的问题，如首先，肥随水走的原理决定了水多肥多渗漏多、土壤污染严重，面临蔬菜施肥污染土壤环境与土地可持续利用的难题；二是，由于灌水过大，引起设施内土壤和空气湿度加大，蔬菜的生长发育受到影响，诱发病害的发生，即水多病多用药多，面临蔬菜用药与产品安全的挑战；三是，由于多水多肥多病加剧了栽培管理技术繁杂程度，面临着管理繁杂与规模发展的难题。因此研究蔬菜节水，可起到一节多效的效果。研究方法、内容：研究方法：番茄根系生长发育特征研究采取了随机取样三次重复的田间调查取样法；灌水量与水渗漏关系研究中水分测定用烘干法、水分定量用仪表、土壤容重测量用环刀法、田间持水量测量用围淹法；数据处理采用田间统计方法。研究内容：（1）日光温室番茄不同生育期根系分布特征研究（2）灌水量与土壤水渗漏关系研究试验设计：根据研究思路试验需要测试番茄的根系分布特征及灌水量与灌溉水入渗特征。2.1供试材料及田间种植模式 选择采用生产上主推品种金鹏1号番茄。于2009年11月5日定植，每株留果4-5穗。种植模式采用大小行种植，每畦栽两行，大行80厘米，小行60厘米，株距33厘米。2.2 番茄根系分布动态特征测试 在番茄花果期和采收期2个典型生长发育时期试验区随机选取3个植株进行取样测试，确定其根系分布特征。2.3 灌水量与灌溉水渗漏关系研究 选择膜下沟灌番茄的盛果期进行处理。处理及采样时间在2010年3月30日-4月2日。灌水量与土壤水渗漏关系研究采取5水平单因素实验，处理因子为灌水量。灌水量设7.5mm、15mm、22.5mm、30mm、45mm的五个水平（不同灌水量处理基础水分各层次平均20.71mm，极差0.02mm；每一层次基础水分极差0.5mm）；每处理三次重复。2个栽培畦4行设为一个小区，栽培畦规格为1.2m5m，即小区面积12m2，共5*3=15个小区，不同栽培畦之间用埋深100cm塑料布隔开以防水分侧渗，灌水方式采取全覆盖膜下覆盖沟灌以防止水分的蒸发，灌溉后48小时测定水分变化，植物蒸腾耗水可忽略不计。其他田间正常管理。进度安排：2009.10.14 听取全院的实习动员大会及指导教师的具体实习内容；2009.10.15-2010.01.22 在图书馆查阅有关资料，完成论文任务书；2010.01.23-2010.03.04 完成论文设计，开题报告并进行室内实验；2010.03.05-2010.03.10 论文开题2010.03.11-2010.05.10 收集资料文献并对实验结果进行分析；2010.05.15 中期检查；2010.5.16-2010.06.10 进行对比研究，完成论文撰写；2010.06.11-2010.06.13 毕业论文答辩。指导教师意见：该学生查阅了较丰富的有关蔬菜节水的相关文献，了解试验的有关情况，熟悉试验原理及有关内容，完成了开题报告的撰写。该论文通过研究番茄不同生育期根系分布特征与不同灌水量与控漏灌水量关系，确定番茄节水灌溉的经济灌水量阈值，为指导农业生产提供了一定的科学依据。立论依据较充分，设计方案合理可行，思路较清晰，进度安排合理，预计在规定时间内能够完成论文的撰写，同意开题。指导教师：2010年 3 月 5日文献综述我国蔬菜节水灌溉方面的研究进展中国是一个水资源短缺的国家，特别是北方地区干旱缺水已经威胁到经济社会的发展，成为可持续发展的首要制约因素1。蔬菜是我国的主要园艺作物，也是一种高耗水的作物。针对蔬菜生产多年采用的传统明水沟灌和漫灌方式造成的现象水资源浪费以及湿度过大造成的病虫害日益严重的问题2，蔬菜节水灌溉研究得到了日益广泛的重视，主要研究进展体现在以下两个方面：一、针对露地的叶菜类不同水氮管理方式对蔬菜地NO3-N淋洗的分析，以及硝酸盐在整个土体中全生育期一定灌溉定额下的淋洗和积累规律的分析。1.不同灌溉与施氮措施对露地菜田土壤无机氮残留的影响. 在华北地区露地生产条件下,通过监测5季轮作蔬菜(苋菜-菠菜-花椰菜-苋菜-菠菜)的产量和土壤无机N(Nmin)的变化,比较了传统的和采用平衡方法进行推荐的水分和N素处理对土壤Nmin残留数量的影响。结果表明,除花椰菜试验外,传统N素处理与推荐的N素处理在蔬菜产量上没有显著差异,但传统的N素处理皆可导致深层土体中Nmin的大量累积。在4季蔬菜轮作后,传统灌溉措施条件下的N素处理都不同程度地造成了土体的N素淋失,所影响的土层深度已经达到了150180 cm土层,然而采用平衡方法进行推荐的水分和N素处理组合对土体深层土壤中Nmin残留数量没有造成明显的影响3。2水氮耦合对蔬菜-土壤系统中硝酸盐积累规律的影响.土壤中0100cm硝态氮积累量随着施氮量的增加而增加，随着灌水量的增加而降低。在一定的施氮量下，硝态氮的积累峰值随着灌水量的增加而下移，150mm灌水量下田区试验和模拟土柱试验0l00cm土体内硝态氮的积累峰值分别出现在030cm和5070cm; 250mm灌水量下分别出现在4060cm和6080cm; 350mm灌水量下田区试验中0100cm土体硝态氮没有出现峰值，而模拟土柱试验在80100cm则有明显的积累。另外油菜的生物量在低施氮量下，过量的灌水可使油菜有减产的趋势，水分利用效率下降;芫荽的生物量随着施氮量和灌水量的增加而增加，但是当施氮量超过一定的值后，随着施氮量的增加其增加幅度呈降低的趋势。油菜和芫荽体内粗蛋白含量在一定的氮肥用量范围内随着施氮量的增加而增加，但是当施氮量高于270 km/hm2时，施氮素可降低蛋白质的合成。油菜和芫荽体内的硝酸盐含量随着施氮量的增加和灌水量的降低而升高。氮肥用量和植株体内硝酸盐含量回归分析显示出两者间存在显著相关关系，结合对土壤中硝态氮淋溶及蔬菜产量和品质的进一步研究，确立了本地区的合理灌水量和施氮量:保护地和露地油菜的合理灌水量为250mm，施氮量分别为101.0 km/hm2 ,222.5 km/hm2，芫荽的合理灌水量为254mm，最高施氮量为171.6 km/hm2 。本研究将蔬菜一土壤系统中最重要的水分和氮素相结合，探明了蔬菜一土壤系统中硝态氮积累规律，为蔬菜生产上推荐水氮合理施用量提供了重要理论依据4。3.不同水氮管理对蔬菜地硝态氮淋洗的影响.通过3年（19992001）的田间定位试验研究了中国北方露地蔬菜种植中不同水氮管理方式对蔬菜地NO3-N淋洗的影响。结果表明，在蔬菜生长期内，通过减少灌溉水量不但能够降低蔬菜地水分渗漏量，而且明显降低蔬菜地NO3-N淋洗量。减少施氮量同样明显降低蔬菜地NO3-N淋洗量。说明在蔬菜生产中将施氮量降低到传统施氮量的20%40%，土壤含水量保持在蔬菜生长的有效土壤含水量的50%80%，能够明显降低NO3-N的淋洗风险，且蔬菜产量未受到影响5。二、现代灌溉技术与农艺技术进行有机结合，开发了适宜在蔬菜产区大面积推广的多项蔬菜节水技术，初步实现了节水、节肥、省工、省力、高产高效的目标。目前推广应用的蔬菜节水技术有以下6种6：1设施蔬菜水肥一体化技术灌溉施肥是通过灌溉系统为植物提供营养物质，在加压灌溉条件下，将施肥与灌溉结合在一起的一项农业技术，又称为水肥一体化的设施技术。其原理是按照作物的需水要求，通过低压管道系统与安装的施肥罐，将水与肥料完全溶解，以较小的流量均匀、准确的直接输送到作物根部附近的土壤中，减少了水肥的浪费。2膜下沟灌技术蔬菜起垄定植后，在两小行之间的沟上覆盖一层塑料薄膜，在膜下架设竹皮或钢丝小拱，沟中浇水，形成封闭的灌水沟。其优点是：简便易行，投入小(投入30-50元/667)；节水效果比较显著，66比传统畦灌节水30%以上；减少病虫害，节省用药费用，增产超过10%；操作简单，适宜在各类蔬菜产区示范推广应用。3膜下滴灌技术膜下滴灌技术是在地膜下面利用装在毛管上的滴头将水一滴一滴地、均匀而又缓慢地滴入作物根区附近土壤中的灌水形式。该技术投资较大，约2.25元/，适宜在日光温室种植效益较高的蔬菜上应用。优点是：(1)节水：滴灌与大水漫灌比，膜下滴灌可节水70%以上；(2)节肥：滴灌与大水漫灌相比，可节肥50%以上；(3)保护土壤滴灌水肥一体化以后，不会造成土壤盐渍化，不会造成土壤板结；(4)减少作物病害：在日光温室或大棚内使用滴灌，因为没有过多的水分蒸发，空气湿度小，可明显减少作物病害；(5)节省劳力：使用滴灌产品，打开阀门后所有滴头同时滴水，不须用人看管，省工省力；(6)增产：使用滴灌不会降低土壤温度，病害发生较轻，作物长势好，一般可提高产量30%以上。4膜下微灌技术膜下微灌技术的主要特点是微灌带上留有小孔，设有滴头，水从小孔以低压小流量流出，将灌溉水供应到作物根区土壤，实现局部灌溉。在膜下作物行间铺设微灌、微喷软管，在一定压力下微流或微喷在作物根部进行灌溉。优点：单位面积比传统畦灌节水60%以上，增产幅度达20%以上；一次性投资少，约0.75元/，能准确地控制灌水量，对水压和水质要求较低；在灌溉的同时，能实现肥水一体化。5喷灌技术喷灌是利用专门设备将有压水送到灌溉农田，并喷射到空中散成细小的水滴，象天然降雨一样进行灌溉。喷灌的优点：对地形的适应性强、机械化程度高、灌溉均匀、灌溉水利利用系数较高，尤其是适合于透水性强的土壤，并可调节空气湿度和温度。但基础建设投资较高，而且受风的影响大。6地膜覆盖和高垄栽培技术地膜覆盖栽培又称护根栽培或促根栽培，是将极薄的塑料薄膜(俗称地膜)紧密地贴于畦面或垄面上的一种栽培方式。优点是：地膜覆盖能够提高作物产量、促进早熟、提高品质、增加效益、防水抗涝、防止土壤板结、提高肥效、改善近地面光照条件、抑制盐碱效应、抑制杂草生长、增强抗逆性等功效。高垄栽培有利于蔬菜生长期间排、灌技术的发挥；同时通过起垄作业，可使活土层增厚、土壤通透性好、使蔬菜根系生长健壮、吸收能力增强、有利于获得高产。高垄栽培能够有效的防止一些病害的流行，增强蔬菜的抗逆能力。我国关于蔬菜节水灌溉的研究仍然主要集中在对灌水始点及灌水方式方面,对于其它节水灌溉指标的研究开展较少或没有进行,例如灌溉上限、灌溉次数等指标的研究尚属空白。节水灌溉所选择的蔬菜作物以番茄、黄瓜、茄子、辣椒等为主,而普遍栽培的蔬菜达60余种,关于大部分蔬菜作物节水灌溉指标的研究几乎没有进行。由于缺乏科学的理论指标,生产实际中仍然以“看天、看地、看庄稼”为灌溉管理手段。目前，我国蔬菜种植业已经作为一个农业中的领先行业由传统农业过渡到现代农业,迅速开展蔬菜等节水灌溉指标的研究显的更为紧迫和必要7。参考文献1赵英，郭旭新.节水灌溉新技术在温室生产中的应用与发展J.农业工程技术(温室园艺) . 2007.(11) 2曾文艳.蔬菜节水灌溉技术J.热带农业工程.2009.(06):44-453 汤丽玲等.不同灌溉与施氮措施对露地菜田土壤无机氮残留的影响J. 植物营养与肥料学报2002,8(3):282-287. 4 马雪娇.水氮耦合对蔬菜-土壤系统中硝酸盐积累规律的影响D.保定:河北农业大学,20035 于红梅等.不同水氮管理对蔬菜地硝态氮淋洗的影响J.中国农业科学,2005,38(9):1849-1855.6 曾文艳.蔬菜节水灌溉技术J.热带农业工程.2009.(06):44-457李建明，邹志荣，王晓燕.蔬菜节水灌溉指标的研究现状及存在问题J.干旱地区农业研究,2000,18(2):118-123IRRIGATION REQUIREMENTS OF GREENHOUSE VEGETABLES IN CRETEK. CHARTZBULAMIS and N. DROSOS NAGWEF, Subtropical Plants and Olive Tree Instit.,73100 Chania, Crete, Greece Horticultural Research Station, 72200 Ierapetra, Crete, GreeceAbstract: Studies, over a number of years, were carried out in Crete ,Greece to determine the water consumptive uses of drip-irrigated vegetables (tomato, cucumber , eggplant and pepper) grown in unheated greenhouses. The amount of water applied and the irrigation frequency were controlled by tensiometers , so that soil water potential at a depth of 25 cm was maintained at values higher than -20 KPa . Maximum yields for an eight-month growing season (October to May) were obtained with seasonal water application of 260 mm for tomato,296 for pepper and 325 mm for eggplant .Cucumber was the most water-consuming crop, requiring 290mm of water application for 3.5 months growing season. The number of fruits per plant was mainly reduced with less water application. The crop maximum evapotranspiration (ETm) in October (at planting) was 0.2 of class A pan evaporation(Epan), located outside the greenhouse. This value remained almost constant until February, since crop growth and production are low due to low temperatures, and then increased gradually up to 1. 1xEpan, depending on the crop.INTRODUCTIONVegetable crops grown in greenhouses for out of season production are spreading in Greece, like in many areas of the world, since they ensure a relatively higher income to the farmers. On the island of Crete, where climatic conditions are favourable and heating is not usually required, about 46% of the total cultivated area in Greece is found. The main crops are cucumber (45%) and tomato (44%), while far behind are eggplants (5%) and pepper (3.8%). Water scarcity in many of the growing areas in the island, besides the increasing competition for municipal use, makes it necessary to optimise its use by the farmers. The supply of the required water to the plant is of prime importance for its growth and economic production, especially into greenhouse, where irrigation is the unique source of water for the plant. Drip irrigation -which ensures efficient water use, improved fertiliser application, salinity control and labour saving-, is mainly used by our farmers but irrigation intervals and water volumes are usually set according to empirical criteria. Although a lot of papers deals with water requirements of greenhouse grown vegetables, the results are not applicable to our region, since they are referred to different climatic conditions (Sonneveld,1981;Frenz and Lechl, 198 1; Catzeflis,1 Sm), different growing season (Chiaranda and Zebri,1984, 1986; Hamar and Warms, 1986) or to heated greenhouse (Hiades,1988,1992).The objectives of these studies, carried out over 10 years, were to determine the water requirements of the main vegetable crops (tomato, cucumber, eggplant and pepper), and to relate them with class A pan evaporation and solar radiation. MATERIALS AND METHODS The experiments were carried on in unheated greenhouses for two cropping seasons for each crop, at the experimental farm of Subtropical Plants & Olive Tree Institute of Chania , north-west of Crete, (for tomato and cucumber) and at Horticultural Research Station of Ierapetra, south-east of Crete (for eggplant and pepper). The following hybrids, widely used by our farmers, were used:Dombito for tomato, Pepinex for cucumber, Delica for eggplant and Sonar for pepper. Information on plant population, planting dates and harvesting periods .are given in Table1. The top 40 cm soil layer of the greenhouse was amended, containing 60-68% sand 16-22% silt and 12-16% clay. Irrigation water was of good quality with electrical conductivity (ECw) of 0.3-0.6 dS.m. Cultivation cares (fertilisation, soil fumigation, and pruning, pest and disease control) were exactly the same for all treatments. Plants were drip irrigated. For tomato and cucumber, the amount of water per irrigation and the frequency of water application were controlled by tensiometers installed at the depth of l5 and 30 cm. Irrigation was started when the soil water potential reached -20 KPa (treatment A), -40 KPa (treatment B) and -70 KPa (treatment C) at the depth of 15 cm, and was stopped when applied water reached at the depth of 30 cm. For eggplant and pepper the amounts of water tested were based on maximum evapotranspiration data obtained by the use of a tensiometer. It was assumed that maximum evapotranspiration (ETm) between two successive irrigations was calculated by the formula ETm= Iw -Dw, where Iw was the amount of irrigation water needed to keep the soil at field capacity (soil water potential higher than -20 KPa); and Dw was the amount of water drained at the soil depth of 45 cm. So , an electro-tensiometer was installed at the depth of 25 cm in order to pilot irrigation. Irrigation was started when soil water potential (SWP) reached at -20 KPa and stopped soon as applied water was reaching at the depth of 25 cm. Drainage at the depth of 45 cm, after a large amount of soil-water content measurements, was considered as negligible. Thus, maximum evapotranspiration was equal with the amount of irrigation water applied to keep SWP higher than -20 KPa, since drainage was zero at the soil depth of 45 cm. Four amounts of water were tested: 100% of ETm (treatment A), 85% of ETm (treatment B), 65% of ETm (treatment C) and 40% of ETm (treatment D). The frequency of irrigation ,determined also by electro- tensiometer , was the same for all treatments, but the corresponded water for B, C and D treatments was applied to plants the next day. Irrigation treatments began after plant establishment (fifteen days after transplanting). The experimental layout was complete randomised block design with four or six replications. Evaporation from a Class A pan evaporimeter and the actual sunshine duration from a Campbel- Stokes sunshine recorder, located outside the greenhouse, 100 m far away, were recorded daily. The potential evapo-transpiration of the crop (ETP) was estimated using the formula: where C1 is the penetration percentage in solar radiation for PE (0.8), Ra is the extra terrestrial radiation in mm, n is the mean actual sunshine duration in hr/day, N is the maximum possible sunshine duration in hy/day and a, b are constants (0.30 and 0.45 respectively). The mature fruits were harvested once or twice a week, and their number and weight were recorded. RESULTS AND DISCUSSIONCrop yield response to different amounts of water applied is given in Fig. 1. For tomato, the highest yield(6.3 kg /plant) was achieved with a seasonal water application of 260 mm,while any further increase in water application did not increase yield. With less amount of applied water, fruit yield was reduced significantly, because fruits were smaller (Table 3). The same pattern was followed by cucumber, although water requirements were much higher than tomato, for a 3.5 months cropping season. The highest yields were obtained with 290m of water (Chartzoulakis and Michelakis, 1990), while application of 220 mm reduced yield significantly because of the formation of fewer fruits (Table 2). Eliades (1988)also reported less fruit formation with less water application for the cucumber, CV Maram , grown in a heated greenhouse. For eggplant the highest yield(6.5 Kg/plant) was obtained with the treatments A and B, corresponding to seasonal water application of 380 and 325 mm respectively .Seasonal water application of 250 and 150 mm reduced the yield significantly in both growing seasons (Chartzoulakis and Drosos,1995). Although the fruit yield of A and B treatments was almost the same. The water use efficiency for harvested yield (kg of produced fruits per unit of applied water) of treatment B was higher (31.1 instead of 27.2 kg.mm-1); such a difference is significant for water sort area such as Crete. Eliades (1992) reported that the eggplant could grow successfully in a heated greenhouse for a 7-month period with as low as 285 mm of water. For sweet pepper, the highest yield(4.4 Kg/plant) was obtained with300 mm of water, while less water application reduced the yield significantly. The effect of irrigation water applied on the number of marketable fruits harvested per plant is shown in Table 2. For cucumber, eggplant and pepper, less water application reduced significantly the number of fruits harvested per plant, while for tomato no reduction was observed. The water requirements of tomato, eggplant and pepper, when the soil water potential was kept higher than -20 ma, ranged between O. and 4.5 mm per day (Figure 2). Two periods can be distinguished from Figure 2 for the crop demand for irrigation water; a period characterized with low water requirements (October to February) because rates of plant growth and production are low due to low air temperatures (10 C)inside the greenhouse. The second period from March to May is characterised by a fast increase of water requirements, due to the increase in the evaporative demand of the atmosphere and the faster rates of plant growth and production achieved under the optimum climatic conditions prevailing at that period. For cucumber, daily water requirements increased from March (at planting) up to June, while at fall cropping season,water requirements reached at a maximum (4.3 mm/day) at September, and then start to decline. Although the results are merely indicative ,they emphasise that season-al evapotranspiration depends on the length of the cropping season as well as on growing period during the year. More general and useful indications for practical use are drawn from ETm/Epan ratios during the cropping cycle of each species under consideration. The crop ETm in October for tomatoes was 0.3 of class A pan, located outside the greenhouse, reaching a maximum of 0.45 during November, then declined until February, and then started to increase again (Figure 3). The increase in ETm/Epan noticed at the initial stages of growth of tomato has been also reported by Graaf and Ende (1981). Fo