DPC~+化学封顶对不同施氮量下棉花叶片光合生理特性的影响

在北疆气候条件下,为明确棉花对不同施氮量下增效缩节胺[DPC+,25%甲哌鎓(1,1-dimethylpiperidinium chloride, DPC)水剂]化学封顶效应的响应,以新陆早53号为试验材料,在150(N1)、300(N2)和450(N3) kg hm~(–2)施氮水平下,以人工打顶(P0)为对照,研究DPC+剂量[450(P1)、750(P2)和1050(P3) mL hm~(–2)]对棉花叶绿素含量(Chl)、叶面积(LA)、气体交换参数、叶绿素荧光参数及干物质累积与分配的影响。结果表明,同一DPC+剂量下,随施氮量增加, Chl、LA、气体交换参数、叶绿素荧光参数和生殖器官干物质(RODM)均呈现先上升后下降的趋势;同一施氮量下,上述参数因DPC+剂量不同呈不同变化趋势,其中N1水平下以P1处理、N2水平下以P2处理、N3水平下以P3处理表现出较高的RODM、Chl、净光合速率(Pn)、实际光化学效率(ФPSII)、电子传递速率(ETR),较低的非光化学淬灭(NPQ)。DPC+与施氮量互作表现为,与其他处理相比, Chl、Pn、蒸腾速率(Tr)、气孔导度(Gs)、ФPSII、ETR、RODM在N2P2处理下分别提高了15.52%、29.39%、27.97%、36.77%、23.28%、23.55%、8.41%～22.24%, NPQ降低了34.54%。相关分析表明,干物质累积和Chl、LA、Pn、Gs、ФPSII均呈显著正相关,与NPQ呈极显著负相关。因此,在喷施DPC+(750 mL hm~(–2))条件下,适量追施氮肥(300kghm~(–2))能改善棉花光合性能,在增加干物质累积的基础上,促进了光合产物向生殖器官分配。     

RZWQM2模型模拟牛场肥水施用夏玉米土壤硝态氮迁移特征

为研究华北平原种养结合中养殖肥水的合理施用,减少典型农田水肥施用后土壤氮淋溶对地下水的影响。该研究以河北省徐水区夏玉米为研究对象,应用RZWQM2模型验证牛场肥水施用玉米农田的可行性,对2014—2016年玉米种植前后数据进行模型参数率定与验证。验证结果表明,土壤体积含水率的均方根误差和平均相对误差值分别在0.000 6～0.070 7 cm~3/cm~3和0.21%～21.44%之间变化,土壤硝态氮均方根误差和平均相对误差值分别在0.000 8～2.617 3 mg/kg和0.03%～18.58%之间变化,其中牛场肥水施用土壤中硝态氮主要在0～120 cm土层发生变化,说明RZWQM2模型可以用来模拟华北平原牛场肥水施用对土壤水分、硝态氮含量及玉米产量的动态变化。利用率定和验证后的模型进行了夏玉米农田硝态氮淋溶的验证与预测,表明硝态氮淋溶浓度随肥水氮量的增加而增加。RZWQM2模型可以应用于牛场肥水施用农田的模拟,为预测和评估土壤适宜的肥水施用提供更合适的方法。     

1-MCP对猕猴桃后熟质地品质的临界浓度研究

为探究1-甲基环丙烯(1-MCP)对猕猴桃后熟质地品质作用效果的差异,寻找适宜的1-MCP临界使用浓度,研究通过应用质地多面分析(TPA)测试法,以"贵长"猕猴桃为试材,比较不同处理果肉质地品质差异和好果率,分析各质地参数之间相关性,并且用主成分分析法进行综合评价。结果表明:0.75μL/L和0.50μL/L 1-MCP处理均能够更好地保持猕猴桃货架期的好果率;果实的咀嚼性、弹性、硬度、回复性和凝聚性相互之间都有较好的相关性,但黏着性与其他指标相关性较差,所以用咀嚼性、弹性、硬度、回复性和凝聚性作为评价猕猴桃果实质购性能的主要参数。与对照比较,6种浓度1-MCP处理中,0.75μL/L 1-MCP的处理对维持猕猴桃后熟质地品质效果最好,其次是0.50μL/L1-MCP处理,两组处理均能够延缓果实硬度并且使果实正常后熟。而高浓度(1.50μL/L和1.25μL/L)的1-MCP对猕猴桃果实后熟质地的保持效果较差,出现"僵尸果"现象。另外综合主成分分析显示,货架末期(9 d)时,不同处理猕猴桃质地品质从高到低的排列顺序为:0.75μL/L0.50μL/L1.00μL/L0.25μL/L1.25μL/L1.50μL/L0μL/L。因此,从经济和后熟质地品质考虑,采后用0.50～0.75μL/L1-MCP来处理猕猴桃对保持果实质地品质的效果最好。     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.     

Zinc biofortification of maize (Zea mays L.): Status and challenges

Zn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.     

施氮量和采收时期对油蔬两用型油菜菜薹维生素合成的影响

为明确施氮量和采收时期对油蔬两用型油菜薹维生素含量的影响,以富硒1号为材料,采用裂区试验设计,设置3个施氮量(120、180和240 kg·hm^-2)和4个采收时期(以株高20、30、40和50 cm表示),分析了油菜薹维生素C、维生素E、维生素B₁和维生素B₆含量的变化;比较了半乳糖内酯脱氢酶(GalLDH)、抗坏血酸氧化酶(AAO)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDHAR)活性,并分析了维生素家族基因在菜薹中的表达量。结果表明,随着施氮量的增加,油菜薹还原型维生素C(AsA)含量降低;氧化型维生素C(DHA)含量在株高20 cm采收时增加,但在30 cm及以上株高采收时则降低;维生素E和维生素B₆含量先增加后降低;维生素B₁含量增加;维生素C合成关键酶GalLDH活性先略增加后降低;AAO和DHAR活性增加,APX和MDHAR活性则整体表现为先增加后降低。且施氮量增加后,维生素家族各基因在株高30和40 cm采收的菜薹中主要表现为正向调控,而在株高20和50 cm采收的菜薹中主要表现为负向调控。就采收时期而言,菜薹中的维生素含量在株高30~40 cm时高于其他时期;在同一施氮量下,随着菜薹采收株高的增加,维生素家族基因的表达量主要呈上调模式。综合分析可知,GalLDH活性的降低以及AAO/DHAR和APX/MDHAR代谢平衡是增施氮肥导致菜薹维生素C含量降低的重要原因。本研究结果为油蔬两用型油菜薹优质栽培技术提供了理论依据。     

施氮量对油后直播棉花产量、品质及生物量的影响

为研究施氮量对油后直播棉花生物量累积特征及其与产量、品质的关系,于2016-2017年在湖南常德设置了施氮量分别为0、90、180、270、360 kg·hm^-2氮肥水平试验。结果表明,在施氮量为0~360 kg·hm^-2范围内,施氮量越大棉株营养器官生物量累积越多,而棉株生殖器官生物量则在施氮量为270 kg·hm^-2时累积最多;皮棉产量、成铃数和单铃重均在施氮量为270 kg·hm^-2时达到最大;0~270 kg·hm^-2范围内,衣分随施氮量增加而增加。在施氮量为270 kg·hm^-2条件下,纤维长度和断裂比强度最高;适宜施氮量有利于纤维长度、断裂比强度的提高和马克隆值的优化,对伸长率和整齐度基本无影响。综上所述,适宜施氮量可提高棉花的产量、品质,洞庭湖棉区适宜的施氮量为180~250 kg·hm^-2。本研究结果为环洞庭湖棉区的氮肥合理运筹提供了技术参考。     

基于15N示踪技术的干旱区滴灌葡萄氮素利用分析

为研究水氮调控对干旱区滴灌葡萄氮素吸收利用的影响,以新疆鲜食葡萄弗雷为试验材料,利用¹⁵N 示踪技术,设置2种灌水处理(灌水量为4 950、5 400 m³·hm^-2,分别记作W1、W2),3种施氮处理(施氮量为177、235、292 kg·hm^-2,分别记作F1、F2、F3)进行大田试验。结果表明,各处理土壤全氮含量和¹⁵N丰度差异极显著(P<0.01),并且在0~20 cm土层出现富集现象。各器官征调氮素能力随水氮投入加大极显著增强(P<0.01)。根系、茎秆、叶片器官的生物量随着吸氮量的增加极显著提高(P<0.01),而较高施氮量(F3)不利于果实器官生物量的积累。果树吸收的肥料氮量随水氮投入的加大逐渐增加,受水氮调控影响极显著(P<0.01),果树吸收的土壤氮量大于肥料氮量。W2F1的¹⁵N标记氮肥利用率和¹⁵N标记氮肥偏生产力最高,分别为38.36%和114.20 kg·kg^-1,W2F2的产量最高,为20 253 kg·hm^-2,但与W2F1差异不显著。表明水氮投入过多会引起茎秆和叶片器官徒长且不利于提高¹⁵N标记氮肥利用率。综上所述,灌水量5 400 m³·hm^-2、施氮量177 kg·hm^-2(W2F1)是兼顾经济效益与生态效应的可行水氮运筹模式。本研究结果为干旱区滴灌葡萄高产高效种植提供了参考。     

Specific ion effect of H+ on variably charged soil colloid aggregation

Specific ion effects (Hofmeister effects) have recently attracted the attention of soil scientists, and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil. However, this explanation cannot be applied to H⁺. The aim of this work was to characterize the specific ion effect of H⁺ on variably charged soil (yellow soil) colloid aggregation. The total average aggregation (TAA) rate, critical coagulation concentration (CCC), activation energy, and zeta potential were used to characterize and compare the specific ion effects of H⁺, K⁺, and Na⁺. Results showed that strong specific ion effects of H⁺, K⁺, and Na⁺ existed in variably charged soil colloid aggregation. The TAA rate, CCC, and activation energy were sensitive to H⁺, and the addition of a small amount of H⁺ changed the TAA rate, CCC, and activation energy markedly. The zeta potential results indicated that the specific ion effects of H⁺, K⁺, and Na⁺ on soil colloid aggregation were caused by the specific ion effects of H⁺, K⁺, and Na⁺ on the soil electric field strength. In addition, the origin of the specific ion effect for H⁺ was its chemical adsorption onto surfaces, while those for alkali cations were non-classic polarization. This study indicated that H⁺, which occurs naturally in variably charged soils, will dominate variably charged soil colloid aggregation.     

Integrated rice management simultaneously improves rice yield and nitrogen use efficiency in various paddy fields

The hilly area of Southwest China is a typical rice production area which is limited by seasonal droughts and low temperature in the early rice growth period. A field experiment was conducted on three typical paddy fields (low-lying paddy field, medium-elevation paddy field, and upland paddy field) in this region. Nitrogen (N) treatment (180 kg N ha^-1 year^-1) was compared to a control treatment (0 kg N ha^-1 year^-1) to evaluate the effects of integrated rice management (IRM) on rice growth, grain yield, and N utilization. Integrated rice management integrated raised beds containing plastic mulch, furrow irrigation, and triangular transplanting. In comparison to traditional rice management (TRM), IRM promoted rice tiller development, with 7-13 more tillers per cluster at the maximum tillering stage and 1-6 more tillers per cluster at the end of tillering stage. Integrated rice management significantly increased the rice aboveground biomass by 34.4%-109.0% in different growth periods and the aboveground N uptake by 25.3%-159.0%. Number of productive tillers significantly increased by 33.0%, resulting in a 33.0% increase in grain yield and 8.0% improvement of N use efficiency (NUE). Grain yields were significantly increased in all three paddy fields assessed, with IRM being the most important factor for grain yield and productive tiller development. Effects of paddy field type and N level on N uptake by aboveground plants were reflected in the rice reproductive growth period, with the effects of IRM more striking due to the dry climate conditions. In conclusion, IRM simultaneously improved rice yield and NUE, presenting a valuable rice management technique in the paddy fields assessed.