施肥量与氮肥基追比对西农979产量和品质的效应

为给小麦品种西农979的优质高产栽培提供理论依据,在高、中两种施肥量(高肥:每公顷施纯氮270kg、P2O5 225 kg、K2O 120 kg;中肥:每公顷施纯氮180 kg、P2O5 120 kg、K2O 120 kg)和氮肥7:3、6:4、5:3 :2、10:0四种基追比例(一次追氮在拔节期进行,两次追氮分别在拔节期与孕穗期进行)条件下,研究了施肥量和氮肥基追比例对西农979产量和品质的影响.结果表明,高肥处理产量比中肥处理产量提高9.66%;无论在中肥或高肥条件下,籽粒产量均随氮肥追施比例的增加而提高.施肥量和氮肥基追比例对千粒重的影响较小,对穗粒数的影响居中,对群体穗数的调控作用较大.氮肥基追并施可显著提高成穗率.随施肥量的提高和氮肥追施比例的加大,群体穗数逐渐增加,籽粒蛋白质含量和湿面筋含量也有逐渐提高的趋势,但蛋白质含量增幅小,湿面筋含量增幅大.高施肥量下,氮肥基追比例5:3:2,西农979的籽粒产量、蛋白质含量和湿面筋含量最高,分别达到8 573.5 kg·hm-2、14.97%和32.12%.     

施氮量对新疆滴灌冬小麦根系生长及产量的影响

为探明滴灌冬小麦高产需氮肥规律,利用大田试验研究了N_0(0 kg·hm~(-2))、N_1(90kg·h~(-2))、N_2(180kg·h~(-2))、N_3(270kg·h~(-2))、N_4(360kg·h~(-2))施氮量对新冬18号0~60cm土层根系生长的影响及其与产量和氮肥利用率的关系。结果表明,随着施氮量的增加,拔节至成熟期间0~60cm土层根系干重、根长和根系活力均增加,N_3处理孕穗期小麦0~60cm土层根干重、根长分别较N_0处理增加11.93%、29.0%,增幅基本表现为0~20cm20~40cm40~60cm土层;N_3处理较N_0处理小麦产量增加30.35%,氮肥农学利用效率为6.90kg·kg-1。拔节期前后施适量氮肥可促进0~60cm土层根系生长和活力增强,是氮肥增产的重要原因。本试验条件下最适宜施氮量为180~270kg·h~(-2),可获得产量7 591.49~8 004.85kg·h~(-2),氮肥农学利用效率为6.90~8.06。     

基于临界氮浓度稀释曲线的小麦氮肥需求量估测研究

为探究基于临界氮浓度稀释曲线估测小麦氮素需求量的可行性,基于不同生态区开展的不同品种及氮肥水平的小麦试验,结合小麦临界氮浓度曲线(N_c=4.16W~(-0.41)),构建了拔节期、孕穗期、抽穗期和开花期四个关键生育时期下,小麦氮营养指数(NNI)、氮素需求量(NR)及相对产量(RY)三者间的关系模型,并进行了验证。结果表明,在江苏地区,当总施氮量在120～180kg·hm~(-2)时,小麦的氮素需求量最接近于0,氮营养指数最接近于1,为最优的氮素施用量。氮营养指数与氮素需求量(NNI-NR)在小麦生长的各关键阶段存在极强的线性关系(R~2=0.93～0.97);相对产量与氮营养指数(RY-NNI)在各生育时期呈现线性加平台关系,在开花期表现最好,R~2=0.86;相对产量与氮素需求量(RY-NR)的拟合关系在抽穗期表现最好,R~2值为0.72。NNI-NR验证结果与建模结果一致,即在各时期均表现良好,其中拔节期相关关系最强;但RY-NNI和RY-NR验证结果显示两模型分别在开花期和抽穗期预测效果表现最佳。综上,所构建的NNI-NR、RY-NNI和RY-NR三种模型均具有良好的拟合优度和稳定性,运用基于临界氮浓度曲线的小麦氮营养指数和确立的相对产量水平,可以较好地估测当季的小麦氮素需求量,并进行小麦田间氮素精确管理。     

小麦籽粒谷蛋白大聚合体粒度分布特征及对氮素的响应

为了给小麦品质改良提供依据,以强筋小麦品种藁城8901和弱筋小麦品种山农1391为材料,设置不同氮素水平,研究了籽粒谷蛋白大聚合体(GMP)颗粒粒径分布特征及对氮素水平的响应.结果表明,小麦籽粒GMP颗粒粒径范围为0.375～200 μm.GMP颗粒体积分布总体上呈双峰曲线变化,＜12 μm的GMP颗粒体积百分比为11.2％～45％,＞12 μm的GMP颗粒体积百分比为55.0％～88.8％.与弱筋小麦山农1391相比,强筋小麦藁城8901有较高比例的＞12 μm颗粒.GMP颗粒数目分布表现为单峰分布,＜4 μm和＜12 μm的颗粒数目百分比分别为97.5％～98.0％和99.9％,表明小麦GMP颗粒中绝大多数为＜4 μm的小颗粒.在施氮0～240 kg·hm-2范围内,随着施氮量的增加,＜12 μm颗粒体积百分比显著降低,12～90 μm、＞90 μm颗粒体积百分比增加,说明适量施氮能够显著提高GMP大、中颗粒比例.过量氮素不利于小麦籽粒谷蛋白大聚合体的形成.     

施氮对优质小麦颖果腹部和背部胚乳细胞物质充实的影响

为直观揭示施氮对小麦籽粒灌浆的生理效应,以徐麦30（强筋小麦) 和扬麦13（弱筋小麦）为材料,采用树脂包埋样品进行半薄切片和Image Pro Plus图像分析软件从形态学角度研究了孕穗期施氮对小麦颖果腹部和背部胚乳细胞物质充实的影响。结果表明,施氮后颖果腹部和背部胚乳细胞蛋白体数目增加,花后11、15和19 d最显著,同时蛋白体的聚集方式发生改变,对照组（不施氮）胚乳细胞内以小蛋白体为主,呈散状分布,而施氮组胚乳细胞含有许多大蛋白体或蛋白聚积体,分布较为集中。徐麦30蛋白体发育对氮素的响应程度高于扬麦13。施氮后腹部胚乳细胞淀粉粒排列更为紧密,细胞充实率增加,且扬麦13的响应程度大于徐麦30。施氮也增加了徐麦30背部胚乳细胞充实率,而对扬麦13的影响表现相反。     

四川棉区施氮水平对棉花产量及效益的影响

在四川棉区研究不同氮肥施用水平时棉花产量及经济效益的影响.试验站果表明:在一定水平下.随着氮肥施用量的增加棉花株高、单株果节数和产量相应提高;当纯氮施用达到450kg/hm2时.其产量、经济效益达到最高,而当施用术达到600k/hm2时,其经济效益还低于零氮水平.在一定氮肥施用水平的基础上,配合施用一定数量有机肥料,其经济效益最高.     

基于光谱参数估算滴灌小麦干物质氮肥偏生产力和农学效率

为了解应用遥感技术估测滴灌小麦氮肥利用效率的可行性,以新春17号、新春6号和新春22号为材料,通过大田试验,分析了不同施氮处理下小麦干物质氮肥偏生产力(RDN)和干物质氮肥农学效率(DMA En)与光谱参数的相关关系,并建立小麦RDN和DMAEn的光谱参数估算模型.结果表明,在分蘖、抽穗和开花期RDN与绿度植被指数和比值植被指数呈极显著正相关,在拔节和抽穗期DMAEn与土壤调整比值植被指数和归一化差值植被指数呈显著正相关.光谱参数估算模型的均方根误差为7.64～33.31,说明利用光谱参数可以有效地估算小麦氮肥利用效率.     

Comparative Studies on the Stability of Various Forms of vitamin C

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Seasonal Changes of Mineral Nutrients in Fruit and Leaves of ‘Newhall’ and ‘Skagg's Bonanza’ Navel Oranges

In southern Jiangxi province of China, ‘Newhall’(Citrus sinensis Osbeck) navel orange presented a conspicuous symptom of boron (B) deficiency in mature leaves, whereas B deficiency symptoms were not manifested on ‘Skagg's Bonanza’(C. sinensis Osbeck) navel orange. In this study, changes in concentrations of B, calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) were comparatively investigated in the structural parts of the fruit (rind and pulp) and leaves (old leaves from last season and spring-flush leaves from current year) of ‘Newhall’ and ‘Skagg's Bonanza’ navel orange during the growing season. Two peaks of B concentrations were observed in the rind of the two cultivars during fruitlet growth and fruit enlargement, respectively. Boron concentrations were relatively high in the rind during fruitlet growth, and then decreased in both rind and pulp, whereas, during middle and late fruit enlargement significant increases were found for B in both rind and pulp of the two cultivars. Boron concentrations in old leaves of ‘Newhall’ decreased progressively and remained relatively low, whereas that of ‘Skagg's Bonanza’ was relatively high and changed slightly as the season progresses. Both Ca and K concentrations were above the critical threshold values, while their dynamics were reverse to that of B in fruit and leaves during certain times. Old leaf Mg concentrations of samples at 140 days after full bloom from the two cultivars and spring-flush leaves from ‘Newhall’ were below the threshold limit for sufficiency. In addition, Mg in old leaves was much lower from ‘Newhall’ than from ‘Skagg's Bonanza’. Spring-flush leaf concentrations of Mn and Zn and Mn concentrations in old leaves from ‘Newhall’ were relatively lacking during middle and late season, which accelerated the occurrence of B deficiency symptoms on mature leaves of ‘Newhall.’     

Studies on post‐reddening changes in amino acid content leaves of hirsutum cotton and its control with chemicals

The aspartic acid,tyrosine and serine contents of leaves were found reduced in prematurely reddened leaves of hirsutum cotton (Gossypium hirsutum) as compared to healthy green leaves. Amino acids other than those listed above were higher in the affected red leaves. Amino acids threonine and proline increased 63.7 and 2.3 fold over green leaves respectively. Chemical sprays not only maintained the levels of various amino acids at par with green leaf but tended to increase the concentration above the levels obtained in normally found green leaf. However, threonine level was dropped in treated leaves as compared to partly affected red leaf and chemical sprays significantly reduced the leaf reddening when it was sprayed before flowering. It can be suggested that the leaf reddening can possibly be arrested by monitoring threonine content in leaves of hirsutum cotton ov. L‐147.