RELIABILITY OF PETIOLE SAP TEST FOR N NUTRITIONAL STATUS ASSESSING IN PROCESSING TOMATO

A field experiment was carried out in Central Italy to assess the reliability of petiole sap for determining nitrogen (N) status on processing tomato. The crop was fertilized with different N rates and fertigation-irrigation frequencies. Reduced-N and nitrate-N concentrations were determined by lab analyses at 30, 42, 57, 71, and 84 days after transplanting. At each sampling date, the assessment of N nutritional status as resulted by sap test was compared with the actual plant N status as determined by nitrogen nutrition index (NNI). Results from sap test were in agreement with NNI indications for about 2/3 of crop cycle that represents the crucial time for N fertilizer management in tomato. The correlation coefficient of the two methods was, on average 0.854 and it was statistical significant in the whole sampling period. The nitrate concentration in the petiole sap provided a good agreement with laboratory analysis across the full range on N-nitrate (NO₃) concentrations examined.     

施肥对农田氮磷污染物径流输出的影响研究

施肥不当是造成农田地表径流 N、P 污染的主要原因。本文采用实地调查与模拟实验相结合的方法,研究了不同肥料品种、不同施肥强度、不同施肥时间与方式对土壤地表径流 N、P 流失的影响。结果表明,农田径流 N、P 的流失量与肥料投入水平有一定的正相关性,施肥后土壤地表径流中总 P 浓度比未施肥前成倍增加。不同肥料品种以硝酸铵最易增加径流中 N 的含量;通过经济与环境协调分析,相对于其他处理而言,一定量的尿素与普钙配合施用可减少 N、P 流失,同时获得较高的白菜产量;就施肥方式而言,深施或穴施比表施可显著降低径流中 N、P 的流失量。     

FERTILIZER RATE EFFECTS ON FORAGE YIELD STABILITY AND NUTRIENT UPTAKE OF MIDLAND BERMUDAGRASS

Our objectives were to document effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates on forage yields and uptake of N, P, and K by Midland bermudagrass [Cynodon dactylon (L.) Pers.] on a Minco fine, sandy loam in southern Oklahoma. After six years of this long-term experiment, forage yield responses to fertilization were mixed and depended on year. Stability analysis indicated forage yields responded positively to N fertilization during favorable weather conditions but negatively during poor weather conditions. Application of 112 kg N ha^?1 provided the best yield stability and mean annual forage yield among treatments, 11.5 Mg ha^?1, across years. In years with near-average weather conditions, uptake of N, P, and K increased linearly with N application rate. Limited water holding capacity of the soil and high soil P and K may have contributed to the limited yield responses to fertilization in this semi-arid environment.     

EFFECT OF LATE-SEASON FERTILIZATION ON NUTRIENT RESERVES AND CARBOHYDRATE ACCUMULATION IN BAREROOT LARIX OLGENSIS SEEDLINGS

It is not clear about the interactive effects of nitrogen, phosphorus, and potassium additions on carbohydrate accumulation in tree seedlings in the late-season of fall. In late September of 2009, 0 or 60 kg nitrogen ha^?1 urea (46-0-0) was applied with 30 and 60 kg phosphorus ha^?1 potassium hydrogen phosphate (0-41-45) to transplanted bareroot Changbai larch (Larix olgensis Henry) seedlings. One month after first fertilization, seedlings receiving nitrogen addition had higher nitrogen and phosphorus, but lower potassium, concentrations in combined stems and roots. The higher rate phosphorus and potassium treatment increased nitrogen concentration in coarse roots (diameter > 5 mm) without nitrogen addition and improved potassium reserves. Fertilization did not affect seedling growth and whole-plant carbohydrate accumulation. In conclusion, we recommend a fertilizer regime of 60 kg N ha^?1 urea and 60 kg phosphorus ha^?1 potassium hydrogen phosphate applied in fall to improve nutrient reserves and increase root carbohydrate accumulation in Changbai larch seedlings.     

植物根系分泌物对污染胁迫响应的研究进展

根系分泌作用是植物实现对外交流的重要形式,研究根系分泌物对环境胁迫的响应是明确植物环境适应性机制的重要途径。本文综述了植物根系分泌物对重金属污染和有机物污染的响应特点,分析了根系分泌物应对重金属和有机物污染胁迫的机制,对污染胁迫下根系分泌作用的研究和应用进行了展望,并讨论了需要进一步研究的问题。     

羽脉山黄麻嫩枝扦插繁殖技术研究

羽脉山黄麻速生 ,耐干旱 ,耐瘠薄 ,适应性强 ,是长江两岸冲刷严重和受到人为开山修路等活动严重破坏地段的理想造林树种 ,大力发展羽脉山黄麻具有重要的生态、经济和社会意义。本试验通过对比和统计分析方法研究了ABT生根剂、扦插基质、枝条的剪切部位等因子对羽脉山黄麻生根的影响。试验结果表明 :扦插时取枝条中上部作为插穗 ,用浓度为 50 0mg L的ABT溶液速蘸插穗基部 ,以珍珠岩为基质扦插生根效果最好。同时对生根质量与移栽成活率的关系进行了回归分析 ,该分析结果为提高羽脉山黄麻扦插生根苗的移栽成活率提供了依据     

微生物肥对水稻产量及氮肥利用的影响

以杂交稻中浙优1号和甬优9号为材料,研究微生物肥对水稻产量及氮肥利用的影响。结果表明,在相同施氮水平下,施用微生物肥后2个水稻品种分别增产41%和87%,其中主要增加了水稻有效穗,提高结实率和籽粒粒重;但分蘖成穗率有所下降;微生物肥能提高水稻叶片的光合速率,穗分化期和齐穗期的叶片光合速率均高于对照,也有利于增加齐穗期的物质生产量。研究表明微生物肥能提高氮素的农学利用率,实现减肥增产,且随着施氮量下降,氮素利用率呈升高趋势。     

施磷量对不同磷效率小麦氮、磷、钾积累与分配的影响

在土培盆栽条件下,以磷高效小麦(CD1158-7、省A3宜03-4)和磷低效小麦(渝02321)为材料,研究了不施磷、施磷(P)10、20和30mg/kg对小麦不同生育时期生物量、籽粒产量及氮、磷、钾的积累与分配的影响。结果表明:(1)随施磷量的减少,不同磷效率品种小麦籽粒产量和生物量均减少;同一施磷处理,磷高效品种籽粒产量和生物产量高于磷低效基因型。不施磷、施磷10mg/kg,高效品种CD1158-7、省A3宜03-4的籽粒产量为低效品种渝02321 的1.84 倍和1.74倍、1.64倍和1.27倍。(2)低磷处理,磷高效品种小麦植株能够积累较多的氮素;扬花期之前,磷高效品种氮素积累量占小麦全生育期积累量的比例高于低效品种。拔节期、孕穗期氮素分配比例为叶>茎>根,扬花期为叶>茎>穗>根,而成熟期为籽粒、颖壳>茎>叶>根。拔节期和孕穗期磷高效品种根的氮素分配比例高于低效品种,而扬花期和成熟期磷高效品种穗(籽粒)氮素分配比例较高。(3)小麦植株磷素积累量主要集中在拔节期以后的生育时期,占全生育期的82.32%~94.23%。低磷处理,高效品种在拔节期和孕穗期磷素积累量高于低效品种,孕穗期尤为突出。扬花期之前,不施磷处理下,磷高效品种根的磷素分配比例较高。(4)不同施磷处理下,拔节期、孕穗期及扬花期,磷高效品种小麦的钾积累量高于低效品种。不同器官钾素分配比例拔节期和孕穗期均为叶>茎>根,扬花期为茎>叶>穗>根,成熟期为茎>叶>籽粒、颖壳>根。磷高效品种在颖壳和籽粒的钾素分配比例高于低效品种。     

硅氮磷颗粒肥对水稻吸收NP的影响

利用~(15)N、~(32)P示踪研究硅氮磷颗粒肥对水稻吸收利用NP影响结果表明,硅氮磷颗粒肥对促进水稻生长发育、增蘖、增穗有明显作用。插秧时施用,稻谷平均增产18.4％。水稻植株体内积累总N量比不施硅氮磷颗粒肥的高11.45％,全磷高12.1％。水稻植株对肥料N、P利用率分别提高7.7％和3.4％。     

磷素水平对大豆氮素积累及产量的影响

利用砂培方法和15N示踪技术研究了磷素水平对大豆氮素积累、根瘤固氮和产量的影响。结果表明:大豆植株氮素积累、根瘤固氮和产量均随磷素营养水平的提高而呈单峰曲线变化,营养液磷素浓度31mg/L左右时达到峰值,当营养液磷素浓度达11mg/L时,再提高磷素浓度对大豆根瘤固氮率无明显促进作用;而对于大豆植株氮素积累、根瘤固氮量和产量,只有当营养液磷素浓度达到21mg/L时,再提高磷素浓度才无明显促进所用,表明满足根瘤固氮的磷素营养水平较产量形成的水平要求低。     

EFFECT OF SWINE MANURE EXTRACT ON LEAF NITROGEN CONCENTRATION,CHLOROPHYLL CONTENT,TOTAL POTASSIUM IN PLANT PARTS AND STARCH CONTENT IN FRESH TUBER YIELD OF CASSAVA

The effects of swine manure extract (SME) as foliar fertilizer (FSME), soil fertilizer (SSME), and both soil and foliar fertilizer (FNSSME) on leaf nitrogen (N) concentration, chlorophyll content, total potassium (K) in plant parts and starch content in the fresh roots, compared to a conventional, chemical fertilizer (CF) were studied in cassava cultivar ‘Hauybong 60’. The results showed that plants on FNSSME had the highest chlorophyll contents and SPAD values at four months after planting (MAP). Cassava plants treated with SSME and FNSSME had highest starch content and was significantly higher than in plants treated with CF and a FSME. There was a strong, positive relationship between the leaf nitrogen concentration and chlorophyll content in cassava at 6 MAP. The results of the study indicated that an application of FNSSME to cassava plants could provide a higher chlorophyll content and higher tuber quality of the plants than those applied with chemical fertilizer.     

膨润土和磷肥对石灰性土壤无机磷形态转化及有效性的影响

对山西石灰性土壤无机磷的形态、加入外源磷后无机磷形态的转化及施加膨润土后对提高磷素的有效性进行了初步探讨 ,结果表明 :山西石灰性土壤中磷素以无机磷为主 ,而无机磷中以Ca P为主 ,Ca10 P和Ca8 P占无机磷总量的 85 % ,Ca2 P仅占 4 42 %。土壤加入外源磷后 ,Ca2 P有所增加 ,其次是Ca8 P、Ca10 P、Fe P ,Al P和O P增加很少。施加膨润土后使加入外源磷的土壤无机磷都有所增加 ,其中Ca2 P增加最明显 ,Ca8 P、Al P、Fe P增加较多 ,而Ca10 P和O P增加最少 ,说明施用膨润土是实现土壤无机磷释放的主要途径     

硝酸钾和硫酸钾对番茄幼苗生长、根系形态及钾素吸收和生理利用效率的影响

采用水培试验,研究不同钾肥种类(KNO3、K2SO4)、不同钾素水平(0、2.0、4.0和8.0mmol/L)对"天福冠露"和"毛粉802"2个番茄品种幼苗生长、根系特征及对钾素吸收、生理利用效率的影响。结果表明,随钾素水平提高,番茄鲜重、干重以及根长、根体积、根直径等根系特征显著提高。在钾素水平为4.0、8.0mmol/L时,硝酸钾处理的番茄株高、根长显著高于硫酸钾。钾素水平为8.0mmol/L时,硫酸钾根直径显著高于硝酸钾处理的;"天福冠露"施用硝酸钾的根尖数显著高于施用硫酸钾;"毛粉802"施用硫酸钾,植株的根直径、钾含量和钾素积累量显著高于硝酸钾处理。番茄水培适宜的钾素浓度为8.0mmol/L,硝酸钾有利于番茄生长发育,硫酸钾有利于番茄对钾素的吸收。在相同钾素水平条件下,2个番茄品种鲜重、干重均无显著差异。     

EFFECT OF PHOSPHORUS APPLICATION ON HIERARCHICAL LATERAL ROOT MORPHOLOGY AND PHOSPHORUS ACQUISITION IN SOYBEAN

Root growth systems are hierarchical and sensitive to nutrient availability in soil. Lateral roots are an important component of plant root morphology. Phosphorus (P) availability regulates root branching in plants such as Arabidopsis thaliana, barley (Hordeum vulgare), and rice (Oryza sativa L.). However, little information is available for soybean (Glycine max L.). A pot experiment was conducted to determine the morphological characteristics of lateral roots of different orders and P acquirement of soybean seedlings under three levels of applied P of 0, 50 and 100 mg P kg^?1 soil. Root length, an important parameter of root characteristics, differed in four orders. Lateral roots in the second and third order contributed 39.4 and 34.2% of total root length, respectively. Moreover, since most of lateral roots were fine roots (roots having a diameter 0.5 mm), fine roots had a frequency distribution of 58.5 to 61.4% in the second and third orders. Phosphorus application significantly increased dry weight, total length and number of lateral roots in the four orders with the ranking of fourth > third > second > first (P ≤ 0.05), but did not affect the average length of a lateral root. Phosphorus application reduced the frequency distribution of fine lateral roots in the first and second orders, while increased in the third and fourth orders (P ≤ 0.05). Compared with the medium P application (50 mg P kg^?1 soil), the high P application (100 mg P kg^?1 soil) inhibited lateral root growth with decreases in root dry weight, root length and root number at all orders. Phosphorus concentration and content increased with the increase in P application. The correlation between characteristics of lateral root and P status in the plants varied among root orders. The length of lateral roots from first to third order had a positive correlation with P concentration in root and shoot, and had a good relationship with P content. Lateral root numbers at the second, third and fourth orders were significantly correlated with P content while no correlation was found with the average length of a lateral root. It is proposed that the main effect of P application appears to be on the lateral root initiation rather than on lateral root elongation, and P favors the lateral root formation of the higher orders. The total length and number of lateral root at the second and third orders play a more important role in P content than those at other lateral root orders.     

根系交互作用对等高绿篱—大豆间作系统N素吸收转移的影响

通过15N标记叶片和15N标记土壤的地下部分隔箱栽试验,探讨了根系交互作用对大豆/绿篱间作体系氮素吸收和转移的影响。结果表明,紫穗槐-大豆系统无隔处理大豆和紫穗槐生长被抑制,其生物量和吸氮量均低于网隔和板隔2种分隔方式;而香根草-大豆间作下,大豆与香根草的生物量和吸氮量都表现为根系无隔时最高。大豆植株体内15N丰度,香根草-大豆间作下,尼龙网分隔处理高于无隔处理,香根草则表现为无隔处理较高;紫穗槐-大豆间作下,紫穗槐和大豆体内15N丰度都表现为根系无隔处理较低。大豆和绿篱共生期内,2种绿篱都从大豆体内竞争了氮素,发生了大豆向绿篱的氮素转移。表明香根草与紫穗槐对肥料氮的竞争能力均强于大豆;紫穗槐和大豆间作表现为种间抑制作用,不利于大豆和紫穗槐生长;香根草和大豆间作表现为互补作用,营养竞争和促进同在,促进了大豆和香根草生长。     

局部根系水分胁迫下氮形态对玉米幼苗光合特性的影响

本文通过测定玉米幼苗光合特性的变化来研究局部根系水分胁迫下氮形态对植物生长的影响及其机理。试验采用分根装置,聚乙二醇(PEG6000)只向一侧根室加入以模拟局部根系水分胁迫。设置3种形态氮(铵态氮;硝态氮;含铵态氮、硝态氮各为50%的混合氮),两侧根室均匀供应。水分胁迫后第4、5、7天测定玉米幼苗光合与叶绿素荧光参数、生物量等的变化。结果发现在局部根系水分胁迫时,相对于另外2种氮形态,在胁迫初期铵态氮供应的植株光合速率(Pn)、实际光化学量子产量(Yield)、电子传递速率(ETR)、光化学淬灭系数(qP)较高,玉米幼苗生长较快;而在水分胁迫第7天,铵态氮供应的植株光合速率、Yield、ETR、qP较低,叶绿素含量下降,植株生长滞缓,而硝态氮以及混合氮处理的植株生长相对加快。     

冷诱导基因转录因子CBF1的组成型表达对植物的抗寒性及生长发育的影响

通过农杆菌介导法将玉米泛素启动子(Pubi)调控的CBF1基因以及CaMV35启动子调控的GUS基因一起转化烟草,研究了冷诱导基因的转录因子CBF1(CRT/DRE binding factor 1)对植物抗寒性及生长发育的影响。结果表明:CBF1的组成型表达增强了冷敏感植物的抗寒性;在表型上使植株矮壮,叶片着生密集,叶色深绿,叶厚度增加;促进侧枝生长,延长营养生长期,推迟花期;对植株的结实性无明显影响。植株抗寒能力以及表型变化程度与CBF1的表达强度相关。因此,利用CBF1基因进行植物遗传改良时应根据物种的应用特点采用合适的表达调控策略。     

碳酸盐及甲硫氨酸对抗盐碱水稻根系发育的影响

以12个黑龙江省主要栽培的具有不同抗盐碱性水稻品种和7个碳酸盐抗性突变体品系的种子为材料,分别用0.02%甲硫氨酸或0.2%碳酸钠进行处理,并以0.5%琼脂培养基为对照培养,10d后调查种子根的长度、侧根数量等。结果表明,7个突变体材料经甲硫氨酸和碳酸钠处理后,侧根数和种子根长均比对照有明显的减少;而原品种没有显示出差异。突变体材料吸收碳酸盐量明显减少,抗性得到了提高。12个栽培品种材料经甲硫氨酸处理后,侧根数较对照有明显的减少;大多数种子的根长较对照无明显变化,少数种子根长较对照发生正向式负向变化。经碳酸钠处理后,侧根数和种子根长均明显变少和变短。因此经甲硫氨酸和碳酸钠处理10d后的侧根数和根长的负向极显著变化可成为衡量水稻抗盐碱的一项新指标。     

NITROGEN,PHOSPHORUS, AND POTASSIUM NUTRIENT EFFECTS ON GRAIN FILLING AND YIELD OF HIGH-YIELDING SUMMER CORN

A three-site-year field experiment was conducted to determine nitrogen (N), phosphorus (P), and potassium (K) fertilizer effects on grain filling dynamics and yield formation of high-yielding summer corn (Zea mays L.) in a wheat (Triticum aestivum L.)-corn double crop cropping system. Application of combined NPK fertilizers resulted in the greatest grain yield, largest grain number and grain weight when compared with the treatments receiving N, NP, or NK. Grain filling rate and duration, grain volume, and grain yield increased with NPK rates; however, doubling the rate of 180 kg N ha^?1, 40 kg P ha^?1, and 75 kg K ha^?1 fertilizer only led to minimal increases in grain filling rate (0.8%), grain filling duration (1.6%), grain volume (1.3%) and grain yield (0.4%). Our results suggested that for the high-yielding summer corn, a combined NPK fertilization is required to enhance grain filling and yield, and that under well-fertilized circumstances, limited increases in both grain filling and sink capacity might be the main factor restricting further yield improvement.     

保护性耕作对小麦-土壤系统综合效应研究

采用长期定位试验与短期田间试验相结合的方法,通过室内化验分析和数理统计,研究了河南省不同土壤类型区保护性耕作对土壤理化性质、土壤微生物生物量碳氮及小麦(Triticum aestivum L.)籽粒产量和产量构成因素的影响。结果表明,与传统耕作相比,保护性耕作显著提高土壤有机质、碱解氮、有效磷及交换性钾含量,分别提高24.8%、14.3%、7.8%和24.8%;而对小麦增产效果并不显著。4种不同保护性耕作方式下,免耕、浅耕相比旋耕、深耕,提高小麦穗数15.0%～32.2%,提高穗粒数2.6%～12.6%,但4种处理间小麦千粒重及籽粒产量效果无显著差异;免耕、浅耕较旋耕、深耕可以一定程度上提高苗期和灌浆期土壤含水率、以及土壤碱解氮和有效磷,并显著提高小麦不同生育时期的土壤微生物生物量碳氮。免耕与浅耕是较为适宜河南省小麦生产及土壤可持续利用的保护性耕作方式。