大田条件下增强UV-B辐射对元阳梯田2个地方水稻品种叶片形态解剖结构的影响

研究了大田原位种植条件下,人工模拟UV-B辐射增强(0、2.5、5.0、7.5kJ·m-2)对元阳梯田2个地方水稻品种——月亮谷、白脚老粳分蘖期、拔节期和孕穗期的叶片形态解剖结构的影响。结果表明:(1)UV-B辐射增强导致2个供试水稻叶片的叶长、叶宽和单叶面积逐渐减小;叶片厚度显著或极显著增加;叶片上表皮厚度不同程度的增加和下表皮厚度显著或极显著减小;叶片上、下表皮角质层厚度显著或极显著增加;(2)对叶片解剖结构观察进一步发现,UV-B辐射增强导致水稻叶肉细胞排列疏松,细胞间隙增大;(3)2个供试水稻相比,只有5.0与7.5kJ·m-2UV-B辐射处理的白脚老粳叶片下表皮角质层厚度显著大于月亮谷,其他处理均没有显著性差异;(4)各辐射处理间的抑制率相比,2个供试水稻5.0和7.5kJ·m-2UV-B辐射处理的叶长、叶片上表皮厚度和下表皮角质层厚度以及白脚老粳7.5kJ·m-2UV-B辐射处理的单叶面积和叶片上表皮角质层厚度显著或极显著大于2.5kJ·m-2UV-B辐射处理,其他处理均无显著性差异。表明UV-B辐射增强对元阳梯田地方水稻品种叶片的形态、解剖结构有显著影响。     

水稻直立穗突变体抗倒伏性的遗传力分析

为研究直立穗突变体R1338和R334在抗倒伏特性方面的遗传力与配合力,选用弯曲穗型不育系川农1A、ABG15s和2个含有DEP1直立穗基因的直立穗不育系E69A、E102A,与蜀恢498及其直立穗突变体R1338、R334进行不完全双列杂交,比较F1基部各节的抗倒伏特性。发现F1基部各节抗折力与倒伏指数呈极显著负相关性,抗折力与茎节的直径和茎壁厚度呈极显著正相关;通过回归分析发现影响水稻基部节抗倒伏能力的主要影响因子为茎节的抗折力和弯曲力矩,抗折力越大、弯曲力矩越小其倒伏指数也就越低;2个直立穗突变体基部节倒伏指数的一般配合力效应值均低于野生型,其中R1338的倒伏指数的一般配合力效应值更低一些。因此利用直立穗亲本配组可以显著改良杂交后代的抗倒伏能力。     

UV-B辐射增强对元阳哈尼梯田稻田CH4排放规律的影响

在大田条件下,原位种植传统水稻品种白脚老粳,采用静态箱-气相色谱法研究了UV-B(ultraviolet-B)辐射增强(7.5 kJ m-2d-1)对元阳哈尼梯田海拔1600 m处稻田CH4排放量的影响,同时观测UV-B辐射增强对水稻生长的影响。结果表明:(1)UV-B辐射增强显著降低了水稻植株分蘖末期、拔节孕穗期、抽穗扬花期、成熟期地上部和地下部生物量(P0.05)。(2)UV-B辐射改变了稻田CH4的季节和日排放(成熟期)规律:对照组在拔节孕穗期出现1个排放峰,处理组在拔节孕穗期和成熟期出现2个排放峰;与对照相比,UV-B辐射增强改变了水稻成熟期CH4日排放第2个峰值出现的时间。(3)处理组CH4的季节排放通量与箱内温度的季节变化有显著的正相关性(R=0.789,P0.05)。(4)UV-B辐射增强在分蘖末期、拔节孕穗期、成熟期都极显著提高了CH4的累计排放量(P0.01),分别提高了47.2%,293.8%和74.4%。总之,UV-B辐射增强促进了元阳哈尼梯田传统水稻田CH4的排放。     

硅钾肥配施对水稻茎秆理化性状及抗倒伏能力的影响

该研究以易倒伏品种‘B优827’为试验材料,通过分析硅钾肥配合施用对水稻茎秆的弯曲力矩、抗折力以及倒伏指数的影响,探索通过肥料调控提高水稻抗倒伏能力的方法与技术措施。结果显示:(1)硅钾肥配施能显著增加水稻基部节间茎秆直径和壁厚,缩短节间长度,并在低硅中钾处理(T2,硅肥300kg/hm2、钾肥400kg/hm2)下基部各节间长度缩短幅度最大(12.44%~20.80%),直径和壁厚增加幅度分别为2.82%~5.76%、22.95%~28.57%。(2)硅钾肥配施处理后,水稻基部各节间纤维素、木质素及灰分含量显著变化,并以低硅中钾处理(T2)差异较显著,且基部节间木质素含量分别比对照显著提高14.55%、8.67%、7.73%。(3)硅钾肥配施处理能显著增加水稻基部节间抗折力,降低倒伏指数,同时仍以低硅中钾处理(T2)的抗折力最大、倒伏指数最小,对提高‘B优827’植株抗倒伏能力效果最好。研究表明,合理的硅钾肥配比(硅肥300kg/hm2、钾肥400kg/hm2)能显著增加易倒伏水稻品种‘B优827’的茎秆壁厚和直径,缩短基部节间长度,提高抗折力,同时还能增加其基部节间木质化程度,最终增强植株抗倒伏能力;硅钾肥配合施用可通过改善茎秆物理化学特性有效增强易倒伏水稻植株的抗倒伏能力。     

种植密度与喷施多效唑对冬小麦抗倒伏能力和产量的影响

于2008-2010年2个生长季在山东农业大学试验农场,以烟农21和藁城8901为材料,研究了不同种植密度下喷施多效唑对冬小麦基部茎秆形态特征、抗折力和抗倒指数及产量的影响.结果表明：藁城8901的抗倒伏能力高于烟农21,但籽粒产量低.与低密度（基本苗为180×10⁴株·hm^-2）条件相比,同一品种高密度（基本苗为240×10⁴株·hm^-2）使茎秆抗折力和抗倒指数下降,尤以烟农21表现更为明显.喷施多效唑可明显降低株高和基部节间长度,显著提高茎秆抗折力和抗倒伏指数,增强其抗倒伏能力,提高单位面积穗数和产量.相关分析表明,茎秆抗倒伏指数与基部第2节间长度、基部(1+2)节间长度占节间总长的比例和表观倒伏率均呈显著负相关.因此,采用合理的种植密度并结合喷施多效唑,能够提高小麦的抗倒伏能力和产量,可作为半湿润地区小麦高产栽培的重要技术措施.     

不同养分和水分管理模式对水稻抗倒伏能力的影响

大田试验下,通过对水稻茎秆基部物理性状、形态特征和硅、钾含量的测定和比较,系统研究了不同养分和水分管理模式对水稻茎秆抗倒伏能力的影响．结果表明,有机无机肥配施,特别是秸秆与化肥配施(CS)养分模式可明显提高水稻植侏茎秆粗度、茎壁厚度和茎重,从而有效提高了基部茎秆的抗折力(RS)和明显降低了水稻的倒伏指数(LI),秸秆与化肥配施(CS)养分模式对水稻抗倒伏能力的效果在干湿交替(AWD)和控水模式(DRA)下表现更为明显。有机无机肥配施,特别是秸秆与化肥配施(CS)的养分模式在干湿交替(AWD)和控水模式(DRA)下更有助于提高水稻茎秆的硅、钾含量、相关分析表明,水稻基部茎秆茎壁厚度、茎重和抗折力与茎秆硅、钾含量存在显著(P<0．05)或极显著正相关(P<0．01)。     

秸秆还田对水稻固碳特性及产量形成的影响

以中浙优1号为材料、秸秆不还田为对照,在大田试验条件下研究了不同秸秆还田量（4000、6000、8000 kg·hm^-2）对水稻群体干物质积累、运转、植株固碳及产量形成的影响. 结果表明： 与对照相比,秸秆还田处理的水稻群体干物质积累总量平均增加63.03 g·m^-2,以6000 kg·hm^-2处理的干物质积累量最高,比对照增加154.40 g·m^-2;在水稻各生育阶段中,秸秆还田处理对分蘖盛期—齐穗期干物质积累的影响最为明显,干物质积累量比对照平均增加71.25 g·m^-2;与对照相比,秸秆还田处理的茎叶干物质输出率和表观转变率分别平均增加4.2%和3.7%,均以6000 kg·hm^-2处理最高,分别为12.8%和11.1%.秸秆还田处理的群体植株固碳量比对照平均增加55.38 g·m^-2,以6000 kg·hm^-2处理的增幅最大,为17.8%;从固碳量在各器官中的分配来看,秸秆还田有利于生育前期茎叶固碳量的积累和生育后期固碳量向穗部的分配.秸秆还田处理的水稻产量比对照平均增加794.59 kg·hm^-2,增幅9.5%,其中6000和4000 kg·hm^-2处理的产量均显著提高,而8000 kg·hm^-2处理的产量增加不显著;从产量构成因素来看,秸秆还田处理单位面积有效穗数的增加是增产的主要原因,平均增加8.4穗·m^-2.     

短期增强UV-B辐射对青榨槭幼苗生理特性的影响

在中国科学院茂县生态站选择2年生青榨槭幼苗进行室外盆栽实验,以人工增强0.27 W·m^-2(7.7kJ·m^-2·d^-1)的UV-B辐射剂量,研究模拟当地平流层臭氧削减1%时近地面太阳UV-B的增强对木本植物幼苗生理生态适应性的影响.处理0 d后,移除UV-B处理装置,就地测定气体交换参数和叶绿素荧光参数,并取样测定叶绿素及UV吸收物质含量.结果表明,增强UV-B辐射显著降低了青榨槭幼苗叶片最大净光合速率P_max(对照为6.214,处理为4.42),显著增加叶片暗呼吸速率Rd(对照为0.413,处理为1.29)和光补偿点LCP(对照为21.629,处理为9.861),但对表观量子速率a(对照为0.021,处理为0.032)影响不明显;它降低青榨槭幼苗每日净光合速率和水分利用效率,以及原初光化学效率(F_v/F_m)和实际光化学量子产量(ΦPS∏).此外,增强UV-B辐射使叶片叶绿素a、b含量降低(对照为16.23,.39,处理为13.17,4.93),但对叶绿素b含量影响未达显著水平.增强UV-B处理降低了青榨槭幼苗UV吸收物质含量(对照为0.87,处理为0.79).光合指标、叶绿素荧光指标和叶绿素含量的变化有较好的一致性,表明增强UV-B对青榨槭幼苗的光合作用可能有一定的抑制作用.     

UV-B增强下施硅对水稻生长及CH4排放的影响

通过盆栽试验,研究了UV-B增强下不同施硅量和硅肥种类对水稻生长及甲烷(CH₄)排放的影响.UV-B辐射设2个水平,即对照(自然光,A)和增强20%(E);硅肥设4个水平,即Si₀(不施硅,0 kg SiO₂·hm^-2)、Si₁(硅酸钠,100 kg SiO₂·hm^-2)、Si₂(硅酸钠,200 kg SiO₂·hm^-2)和Si₃(钢渣硅肥,200 kg SiO₂·hm^-2).结果表明: 施硅能缓解UV-B增强对水稻生长的抑制作用,使分蘖数、叶绿素含量、地上部和地下部生物量增加.施硅对水稻生长的促进作用随施硅量(硅酸钠)的增加而增加,钢渣硅肥的促进作用大于硅酸钠.UV-B增强可提高稻田CH₄的排放通量和累积排放量,施硅显著降低CH₄的排放通量和累积排放量,且CH₄排放随施硅量的增加而减少.在施硅量相同的情况下,钢渣硅肥的减排效果优于硅酸钠.表明在水稻生产中,施用钢渣硅肥不仅能实现废弃物利用,而且可有效降低UV-B增强下CH₄的排放量.     

UV-B增强下施硅对水稻生长及CH4排放的影响

通过盆栽试验,研究了UV-B增强下不同施硅量和硅肥种类对水稻生长及甲烷(CH₄)排放的影响.UV-B辐射设2个水平,即对照(自然光,A)和增强20%(E);硅肥设4个水平,即Si₀(不施硅,0 kg SiO₂·hm^-2)、Si₁(硅酸钠,100 kg SiO₂·hm^-2)、Si₂(硅酸钠,200 kg SiO₂·hm^-2)和Si₃(钢渣硅肥,200 kg SiO₂·hm^-2).结果表明: 施硅能缓解UV-B增强对水稻生长的抑制作用,使分蘖数、叶绿素含量、地上部和地下部生物量增加.施硅对水稻生长的促进作用随施硅量(硅酸钠)的增加而增加,钢渣硅肥的促进作用大于硅酸钠.UV-B增强可提高稻田CH₄的排放通量和累积排放量,施硅显著降低CH₄的排放通量和累积排放量,且CH₄排放随施硅量的增加而减少.在施硅量相同的情况下,钢渣硅肥的减排效果优于硅酸钠.表明在水稻生产中,施用钢渣硅肥不仅能实现废弃物利用,而且可有效降低UV-B增强下CH₄的排放量.     

UV-B增强下施硅对水稻抽穗期生理特性日变化的影响

通过盆栽试验,研究了UV-B增强下施硅对水稻抽穗期光合和蒸腾生理相关参数日变化的影响.光辐射设对照(自然光,A)和UV-B辐射增强(比自然光增加20%,E)2个水平;硅肥设4个水平,即Si₀(不施硅,0 kg SiO₂·hm^-2)、Si₁(硅酸钠,100 kg SiO₂·hm^-2)、Si₂(硅酸钠,200 kg SiO₂·hm^-2)和Si₃(钢渣硅肥,200 kg SiO₂·hm^-2).结果表明: 不施硅条件下(Si₀),UV-B增强处理的净光合速率(P_n)、胞间二氧化碳浓度(C_i)、蒸腾速率(T_r)、气孔导度(g_s)和水分利用效率(WUE)的日均值比对照(A)分别下降了11.3%、5.5%、10.4%、20.3%和6.3%,施硅条件下(Si₁、Si₂和Si₃)上述参数则分别下降了3.8%～5.5%、0.7%～4.8%、4.0%～8.7%、
7.4%～20.2%和0.7%～5.9%,说明UV-B增强降低了水稻P_n、C_i、T_r、g_s和WUE,而施硅能缓解UV-B增强引起的抑制效应.UV-B增强下施硅处理(Si₁、Si₂和Si₃)的P_n、C_i、g_s和WUE的日均值比不施硅对照(E+Si₀)分别提高了16.9%～28.0%、3.5%～14.3%、16.8%～38.7%、29.0%～51.2%,T_r降低了1.9%～10.8%,说明施硅通过显著提高水稻P_n、C_i、g_s和WUE,降低T_r,以缓解UV-B增强引起的抑制效应.不同施硅处理对UV-B增强的缓解效应存在明显差异,表现为Si₃ >S/a#₂>Si₁>Si₀.表明在水稻生产中,施用钢渣硅肥不仅能实现废弃物再利用,而且可有效缓解UV-B增强对水稻光合和蒸腾生理的抑制作用.     

不同小麦品种茎秆特性及其与抗倒性的关系

以黄淮麦区优良品种矮抗58、周麦18、豫麦49、百农418为研究对象,采用田间试验与实验室分析相结合的方法,对不同小麦品种在不同生育时期的抗倒伏性状进行研究.结果表明: 茎秆机械强度在开花期至花后20 d处于较高水平,在花后30 d明显下降;倒伏指数在开花期最小,花后30 d最大,其余两个时期处于中间水平.相关分析表明,开花期机械强度与重心高度呈显著负相关,与纤维素、木质素含量呈显著正相关,倒伏指数与节长、株高、重心高度呈显著正相关,与纤维素、木质素含量呈显著负相关;花后10 d和花后20 d机械强度与节长、株高、重心高度呈显著负相关,与茎粗、纤维素、半纤维素、木质素含量呈显著正相关,倒伏指数这段时期正好与之相反;花后30 d机械强度与株高、重心高度呈显著负相关,倒伏指数与株高、重心高度呈显著正相关,与木质素含量呈显著负相关.因此,明确各个生育时期与抗倒性相关的茎秆特性,可为黄淮麦区高产抗倒性品种的选育提供依据.     

The responses of spatial situation,surface structure characteristics of leaves and sensitivity of two local rice cultivars to enhanced UV-B radiation under terraced agricultural ecosystem

Under the situ terraced field experiments, effects of artificial UV-B radiation enhancement (0, 2.5, 5.0, 7.5 kJ m^?2) on spatial situation and surface structure of leaves and responses index of two local cultivars rice (Oryza sativa L.)—Yuelianggu and Baijiaolaojin in Yuanyang County, China in shooting stage were studied. The results showed that: (1) due to the enhanced UV-B radiation, leaf apex–base distance, leaf pedestal height, leaf rolling degree and wax content in leaves increased, while leaf apex–stem distance, distance between leaves and leaf angle decreased. The response index of growth was positive when UV-B levels were 2.5 and 5.0 kJ m^?2, which showed some adaptation. (2) The enhanced UV-B radiation resulted in smaller stomata with higher density and more papilla for both rice cultivars. (3) The enhanced UV-B radiation also leaded to larger silica cells and significantly increases the amount of papilla, spike and epidermal hair for both rice cultivars. (4) Yuelianggu cultivar showed an excellent adaptation on the aspect of spatial situation with UV-B radiation of 2.5 and 5.0 kJ m^?2, while Baijiaolaojin exhibited better adaptation respecting the surface structure of leaves when UV-B was 2.5 kJ m^?2. By changing spatial situation of leaves, structure and density of stomata, and non-stomatal structures (wax layer, silica cell, cork cell, papilla, spike and epidermal hair), two self-retention rice cultivars could adapt to the increased UV-B radiation. On the aspect of the response index, Baijiaolaojin showed better adaptation than Yuelianggu did when the UV-B was 2.5 kJ m^?2.     

Loss of Gn1a/OsCKX2 confers heavy-panicle rice with excellent lodging resistance

Significant achievements have been made in breeding programs for the heavy-panicle-type (HPT) rice (Oryza sativa) in Southwest China. The HPT varieties now exhibit excellent lodging resistance, allowing them to overcome the greater pressures caused by heavy panicles. However, the genetic mechanism of this lodging resistance remains elusive. Here, we isolated a major quantitative trait locus, Panicle Neck Diameter 1 (PND1), and identified the causal gene as GRAIN NUMBER 1A/CYTOKININ OXIDASE 2 (Gn1A/OsCKX2). The null gn1a allele from rice line R498 (gn1a^R498) improved lodging resistance through increasing the culm diameter and promoting crown root development. Loss-of-function of Gn1a/OsCKX2 led to cytokinin accumulation in the crown root tip and accelerated the development of adventitious roots. Gene pyramiding between the null gn1a^R498 allele with two gain-of-function alleles, STRONG CULM 2 (SCM2) and SCM3, further improved lodging resistance. Moreover, Gn1a/OsCKX2 had minimal influence on overall rice quality. Our research thus highlights the distinct genetic components of lodging resistance of HPT varieties and provides a strategy for tailor-made crop improvement of both yield and lodging resistance in rice.     

水稻基部伸长节间性状与茎秆机械强度的相关分析和QTL定位

分析水稻品种‘沈农265’和‘丽江新团黑谷’杂交的F2群体基部第二节间茎秆机械强度与该节间形态和茎秆解剖结构的相关性,并对基部第二节间机械强度和相关性状进行QTL定位的结果表明：机械强度与茎粗、茎壁面积、茎壁厚度、大小维管束数目、大小维管束面积、大小维管束韧皮部面积、大小维管束木质部面积呈显著或极显著的正相关,与节间长度呈极显著的负相关,而与茎秆扁平率的相关不显著。采用复合区间作图,从研究的14个目标性状中检测到18个QTL。控制基部第二节间的抗折力的QTL检测到4个,位于第4、7、9和10号染色体上,可解释遗传变异的12%～23%。在第4和第7染色体上的相同区间上还同时检测到了控制茎壁性状和维管束性状QTL,贡献率在12%～21%之间。说明这两个位点是控制基部第二节间机械强度的重要区域,也是茎壁性状、维管束性状与机械强度高度正相关的遗传学基础。     

Isolation,expression, and evolution analysis of the type 2C protein phosphatase gene <Emphasis Type="Italic">BcABI1</Emphasis> involved in abiotic and biotic stress in <Emphasis Type="Italic">Brassica campestris</Emphasis> ssp. <Emphasis Type="Italic">chinensis</Emphasis>

Dense plant cultivation is an efficient approach to utilize the maximum inputs for increasing maize production. However, dense plant populations may prone to lodging as it results in increased plant height and reduced culm diameter; therefore, we hypothesized that weaker stems may be responsible for maize lodging. In this study, we examined the regulatory effects of paclobutrazol under two commonly used application methods (seed-soaking and seed-dressing). Seed-soaking with paclobutrazol at the rate of 0 (CK1), 200 (S1), 300 (S2), and 400 (S3) mg L^?1, while seed-dressing at the rate of 0 (CK2), 1.5 (D1), 2.5 (D2), and 3.5 (D3) g kg^?1 were used. Results showed that paclobutrazol improved the culm physical strength by increasing the rind penetration strength, stalk breaking strength, culm diameter, wall thickness, and dry weight per unit length of basal third internode, compared to control plants. Moreover, paclobutrazol reduced the internode length, plant height, ear height, center of gravity height and lodging rate in both growing seasons. In addition, more lignin was accumulated in the basal internode and the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate: CoA ligase (4CL) increased with paclobutrazol, and their maximum values were observed in the S2 and D3 treatments, resulting in strong lodging resistance. Lignin content was positively and significantly correlated with the rind penetration strength, breaking strength of internode, and activities of PAL, 4CL, POD, and CAD, while significantly and negatively correlated with lodging percentage. The present findings suggested that 300 mg L^?1 and 3.5 g kg^?1 of paclobutrazol may efficiently be utilized to minimize the risk of lodging, not only by manipulating plant height but also by enhancing culm physical strength and lignin accumulation in basal internodes.     

Effects of ultraviolet-B radiation on cotton (Gossypium hirsutum L.) morphology and anatomy

Cotton (Gossypium hirsutum L.) crop, cultivated between 40 degrees N and 40 degrees S, is currently experiencing 2-11 kJ m-2 d-1 of UV-B radiation. This is predicted to increase in the near future. An experiment was conducted to study the effect of enhanced UV-B radiation on vegetative and reproductive morphology and leaf anatomy of cotton in sunlit, controlled environment chambers. From emergence to harvest, cotton plants were exposed to 0, 8 or 16 kJ m-2 d-1 of UV-B in a square wave approach for 8 h from 0800 to 1600 h. Changes in plant height, internode and branch length, mainstem node number, leaf area, length and area of petals and bracts, and anther number per flower were recorded. Epidermal cell and stomatal density, stomatal index, leaf thickness, and epidermal, palisade and mesophyll tissue thickness were also measured. Initial chlorotic symptoms on leaves turned into necrotic patches on continued exposure to enhanced UV-B. Exposure to high UV-B reduced both vegetative and reproductive parameters and resulted in a smaller canopy indicating sensitivity of cotton to UV-B radiation. Enhanced UV-B radiation increased epicuticular wax content on adaxial leaf surfaces, and stomatal index on both adaxial and abaxial leaf surfaces. Leaf thickness was reduced following exposure to UV-B owing to a decrease in thickness of both the palisade and mesophyll tissue, while the epidermal thickness remained unchanged. The vegetative parameters studied were affected only by high levels of UV-B (16 kJ m-2 d-1), whereas the reproductive parameters were reduced at both ambient (8 kJ m-2 d-1) and high UV-B levels. The study shows that cotton plants are sensitive to UV-B at both the whole plant and anatomical level.