模拟淹水对杞柳生长和光合特性的影响

以1年生红皮柳(Salix integra cv.hongpi)和青皮柳(Salix integra cv.qingpi)为试验材料,研究了人工模拟淹水胁迫对两个杞柳品种的生长、气体交换及叶绿素荧光的影响.经过75d的淹水处理,两个品种的存活率均为100％.在试验过程中,红皮柳和青皮柳都产生了有利于吸收氧气的不定根和肥大的皮孔,但在产生的时间上红皮柳较青皮柳迟lOd左右.渍水处理促进了青皮柳的生长和光合作用,而红皮柳在渍水和轻度淹水胁迫处理下的生长、叶绿素含量(Chl)、净光合速率(PN)和气孔导度(Gs)都明显低于对照.随着淹水时间的增加,红皮柳的非光化学淬灭系数(NPQ)持续增加并高于对照,最大光化学量子效率(Fv/Fm)持续下降且明显低于对照;青皮柳的非光化学淬灭的值增加幅度较小,最大光化学量子效率一直在0.8-0.85之间波动,与对照相比都无显著差异.以上的实验结果表明在淹水胁迫下红皮柳的光合运转机构受到了一定程度的损伤,而渍水处理则促进了大青皮的生长,因此青皮柳较红皮柳而言更耐淹,更适合在河岸带和消落区生长.     

油溶性降黏剂降黏性能研究

针对胜利油田现河稠油,研究了7种油溶性降黏剂（Y-1~Y-7）及其复配体系的降黏性能,考察了降黏剂加量、原油含水率对降黏效果的影响,研究了降黏剂对蒸汽驱油效果的影响。结果表明：当油溶性降黏剂质量分数小于5%时,原油降黏率随降黏剂加量的增加而迅速增大,之后增加缓慢,加量为15%时的降黏率可达90%以上(Y-4除外)。Y-3和Y-7按质量比1:1复配后的降黏效果最好,总加量5%、10%时的原油降黏率分别为76.1%和93.14%。不含降黏剂时,随原油含水率增加原油黏度先增加后降低,原油含水50%时的黏度是不含水原油的3.9倍,形成W/O型乳状液。不同含水率下,加入降黏剂后原油黏度大幅降低;随含水率增加,原油降黏率先降低后增加,含水率10%时达到最低（Y-1除外）。稠油蒸汽驱前注入0.009~0.027 PV油溶性降黏剂,采收率增幅为2.8%~6.0%。     

旱涝交替胁迫增强水稻抗倒伏性能

茎倒伏是水稻减产的重要影响因素。本文采用小区试验,分析了旱涝交替胁迫下旱后浅蓄（T1）、旱后深蓄（T2）与目前常用的浅水勤灌（CK,对照）模式下,水稻茎秆生长指标和抗倒伏指标的差异,并结合水稻茎秆的细观特征,对水稻抗倒伏能力的影响机制进行了探讨。结果表明,与对照相比,适宜的旱涝交替胁迫处理（T1）基部节间长度降低,茎粗、茎杆截面面积增加,但差异不显著;茎杆的抗弯截面模量和累积破坏能量分别增加12.4%和9.4%,差异达到显著水平;茎杆壁厚、维管束数量、维管束面积增加,维管束细胞趋于密实,使得茎杆的抗折力增加,倒伏指数下降。但旱后淹水深度过深（T2）,水稻抗倒伏指标下降。地上部分鲜重增加是 T2处理倒伏指数增加的主要原因。上述情况表明,适宜的干旱胁迫能够拮抗淹水胁迫造成的抗倒伏能力下降,提高后期抗倒伏能力。现有节水模式下适当加大雨后蓄水深度不会增加倒伏风险。     

5个油茶物种的耐涝性

以5个油茶（Camellia spp.）物种1年生实生苗为试材,通过调查淹水处理后不同时间植株的受害情况对其耐涝性进行研究,结果表明：普通油茶（C.oleifera）和广宁红花油茶（C.semiserrata）具有较强的耐涝性,淹水处理32天才完全死亡,而香花油茶（C.osmantha）、博白大果油茶（C.gigantocarpa）和陆川油茶（C.vietnamensis）耐涝性极强,整个试验期60天后均有10％以上的植株还存活,5个物种的耐涝性由强到弱依次为香花油茶＞博白大果油茶＞陆川油茶＞广宁红花油茶＞普通油茶;5个物种内不同单株间耐涝性均有差异,其中香花油茶单株耐涝性分离最大,其次是博白大果油茶和陆川油茶.     

水库集雨区沟渠湿地耐寒植物五节芒耐淹性研究

选取浙江省长潭水库集雨区上游农田沟渠湿地中生长的耐寒牧草五节芒(Miscanthus floridulus),通过盆栽模拟试验,测定其在涝渍逆境下叶片的光合色素含量、气孔导度、胞间CO2浓度、蒸腾速率和净光合速率,并与生长于堤岸上的五节芒进行比较.结果表明:涝渍逆境虽然造成沟渠湿地生长的五节芒叶片光合色素含量减少、蒸腾速率和净光合速率降低,但与在堤岸中生长的五节芒相比,下降幅度较小.说明生长于沟渠湿地上的五节芒具有较强的涝渍逆境适应性.因此,在浙南山区水库集雨区农田沟渠湿地耐寒植物五节芒能强化沟渠湿地生态效应,降低水库水体富营养化的风险.     

Expansion of Leptochloa fusca ssp. uninervia and Leptochloa fusca ssp. fascicularis in rice fields in Valencia,eastern Spain

Due to the rapid spread of two subspecies of Leptochloa fusca through the Valencia rice‐growing region in the east of Spain, a 3‐year field study was carried out to establish the frequency, distribution and infestation level of the two subspecies in rice paddies in the area. A total of 3650 fields were visited, of which 1235 were visited in each year of the study period. Leptochloa fusca ssp. uninervia and Leptochloa fusca ssp. fascicularis were found to be widely distributed in the area, increasing from a frequency of 5.3% in 2008 to 20.1% in 2010. Leptochloa fusca ssp. uninervia was the largest contributor to the infestations, but subspecies fascicularis is now on the increase and represents a serious threat to rice crops, as it is found within the rice fields themselves. The irrigation system and the farm machinery used in the rice fields also contribute to the rapid spread of these weeds. Severe infestations have been caused by periodic water shortages, and the fact that new herbicides used to control Echinochloa spp. do not affect Leptochloa subspecies. Spatial differences in the distributions of the two subspecies are attributed to the different water management systems and also to differences in the germination and dormancy of both subspecies.     

Seed Priming Improves Agronomic Trait Performance under Flooding and Non-flooding Conditions in Rice with QTL SUB1

Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting.In contrast to irrigated condition,in rainfed lowland,direct seeding is a common practice.Early flooding controls weeds but decreases seedling establishment in direct seeded rice.Anaerobic germination is an important trait to counteract damages caused by early flooding.Management options which can help in crop establishment and improve crop growth under flooding might remove the constraints related to direct seeding.The investigation was carried out with two near isogenic lines Swarna and SwarnaSub1.Swarna-Sub1 is tolerant to submergence whereas Swarna is susceptible.Seed priming was done with water and 2% Jamun(Syzygium cumini) leaf extract,and it improved seedling establishment under flooding.Acceleration of growth occurred due to seed pretreatment,which resulted longer seedling and greater accumulation of biomass.Seed priming greatly hastened the activities of total amylase and alcohol dehydrogenase in Swarna-Sub1 than in Swarna.Swarna-Sub1 outperformed Swarna when the plants were cultivated under flooding.Weed biomass decreased significantly under flooding compared to non-flooding conditions.Seed priming had positive effects on yield and yield attributing parameters both under non-flooding and early flooding conditions.     

Responses of SUB1 rice introgression lines to submergence in the field: Yield and grain quality

Prolonged submergence is a major constraint to rice production, affecting over 15 million ha in South and Southeast Asia and causing an annual yield loss of over US$ 600 million. This is because all the modern high-yielding rice varieties are sensitive to complete submergence. A major quantitative trait locus (QTL), SUB1, associated with submergence tolerance, was mapped on chromosome 9 and recently bred into popular rainfed lowland rice varieties sensitive of complete submergence, using marker-assisted backcrossing (MABC). Here, we assessed the impact of introgressing SUB1 into three rice varieties popular in farmers’ fields of South and Southeast Asia, Swarna, Sambha Mahsuri, and IR64, under control conditions as well as following submergence in the field. Under control conditions, no differences were observed between Sub1 introgression lines and their recurrent parents in grain yield or quality aspects. Submergence substantially delayed flowering and maturity, and reduced grain yield, shoot biomass, harvest index, and yield components across cultivars. The reduction in yield was more drastic in the sensitive varieties, particularly when submerged for longer duration (17 d). The significant decline in grain yield was mainly attributed to reductions in grain filling, number of grains per panicle, and grain weight. The SUB1 QTL is effective in conferring tolerance of submergence for about 12–17 d, depending on floodwater conditions. Sub1 introgression lines showed a yield advantage of up to 3.8 t ha⁻¹ and slightly better grain quality after submergence compared with their parents. Apparently, the introgression of SUB1 into popular varieties did not have any negative impact on their performance under control conditions but considerably enhanced their yield and grain quality following short-term submergence.     

科尔沁沙丘-草甸田间持水量的综合测定与影响

以科尔沁沙丘-草甸相间地区表层土壤为对象,选用4种不同测试方法,对不同地貌与植被类型组合区土壤的田间持水量进行综合测定,并对其影响因素和影响过程进行系统分析。结果表明:1在不同地貌类型区4种试验方法得到的田间持水量变化的规律大体一致,但数值差异很大。威尔科克斯法结果比围框淹灌法和天然降水法测定结果大。2草甸地受地下水位埋深的影响很大,围框淹灌法及天然降水法测定结果不可用;沙丘区地下水位埋深大,围框淹灌法与天然降水法获得的田间持水量对实践更具指导意义,天然降水法在地下水位深埋大的沙丘区表层40 cm以内基本可以获得较准确的田间持水量,取样时间可以在降雨后12~24 h。3科尔沁沙地实施田间持水量测量时建议选用天然降水法,对漫灌型农田土壤小面积也可选择围框淹灌法,大面积测量宜选择威尔科克斯法,但应建立威尔科克斯法与天然降水法和围框淹灌法之间的转换关系,利用威尔科克斯法测量田间持水量时,沙性土壤的测量时间可选择36~40 h、草甸区壤沙土与沙壤土可选择44~48 h。     

河水漫溢干扰对土壤盐分的影响——以塔里木河下游为例

[目的]探索漫溢后出现明显的植被群落变化的原因和不同漫溢方式对表层土壤盐分的影响,为塔里木河下游植被恢复和人工植被的重建提供理论依据。[方法]利用土壤溶液电导率法测定塔里木河下游漫溢区和非漫溢区399个表层土壤样品中盐分含量,探讨不同漫溢干扰方式对土壤盐分的影响。[结果]塔里木河下游土壤的含盐量较高,但在漫溢干扰后土壤表层盐分均出现明显的下降;漫溢方式对土壤盐分的影响显著,表现为漫溢前的土壤总盐含量与多次漫溢后差异达极显著,与少次漫溢和冲刷差异显著,与长期渍水差异不显著。[结论]漫溢干扰后土壤表层盐分有所降低是植被发生明显变化的原因,其中中等频次和持续时间的漫溢干扰更有利于表层土壤盐分的淋洗和植被的恢复。