马铃薯氮素营养状况的SPAD仪诊断

以马铃薯品种克新1号为材料,研究了叶片SPAD值、叶片全氮含量、叶绿素含量以及块茎产量随供氮水平的变化规律及相互关系,旨在为使用叶绿素仪进行马铃薯无损伤氮素诊断和推荐施肥奠定基础。研究结果表明,从马铃薯苗期到块茎淀粉积累各个生育阶段叶片的SPAD测定值均与马铃薯叶片含氮量呈显著正相关关系。除苗期外,块茎形成期、块茎膨大期、淀粉积累期的马铃薯叶片含氮量和叶片SPAD值随土壤施氮量的变化均表现为线形加平台的模式。因此马铃薯块茎形成期后叶片的SPAD读数可揭示马铃薯的氮素营养状况。统计分析结果还表明,叶片SPAD值与块茎相对产量呈线形加平台的数量关系模式,据此确定了应用叶绿素仪SPAD-502进行马铃薯推荐施肥的SPAD临界值为块茎形成期47.3、块茎膨大期45.1、淀粉积累期40.2。     

冬油菜叶片SPAD的时空分布和氮素诊断的叶位选择

在大田试验条件下测定分析不同施氮水平冬油菜关键生育期SPAD值的时空分布特征,并对不同叶位及叶片不同部位SPAD值与叶绿素含量、叶片含氮量、植株全氮含量及籽粒产量之间的相关性进行分析,探求应用SPAD仪诊断油菜氮素营养状况的最佳测试叶位及位点。结果表明,油菜主茎顶部4片完全展开叶SPAD值存在显著空间差异,增加施氮量能显著提高各叶位叶SPAD值,同时减少叶位间的差异;六叶期、蕾薹期以顶4叶（TL4）SPAD值对氮素的敏感性最大,初花期和盛花期则最低。不同部位间,六叶期和初花期以中部SPAD值对施氮量增加的响应最敏感,盛花期则最迟钝,蕾薹期介于顶部和基部之间。综合分析认为,应用SPAD仪监测油菜氮素营养状况的最佳测试叶位和位点为主茎顶4片完全展开叶中部,该部位SPAD值与叶绿素含量、叶片含氮量和植株全氮含量之间的相关性均达到显著或极显著水平,满足氮素营养快速诊断的要求。     

数字图像技术在马铃薯氮素营养诊断中的应用

应用数码相机获取马铃薯冠层图像色彩信息,探索出马铃薯氮营养状况的一种新方法。结果表明,在块茎形成期和块茎膨大期,数码相机获取的数字图像分析得到的冠层绿光与蓝光比值(G/B)与其它描述马铃薯氮素营养状况的指标如土壤无机氮、植株全氮含量、叶柄硝酸盐浓度、叶绿素仪读数均有良好的负相关关系。     

不同加工型马铃薯品种光合特性的比较

本文通过对4个加工型马铃薯品种在块茎形成期和块茎增长期的光合作用参数、叶片的SPAD值等光合特性的测定与分析,结果表明:4个加工型马铃薯品种光合作用能力大小依次为大西洋(A tlantic)>利云6号(PB06)>利云4号(PB04)>利云8号(PB08)。     

Effect of Leaf Phosphorus and Potassium Concentration on Chlorophyll Meter Reading in Rice

Abstract

Chlorophyll meter (SPAD) is a convenient tool to estimate leaf nitrogen (N) concentration of rice plants. There is no information on the effects of leaf phosphorus (P) and potassium (K) concentration on SPAD readings and on the relationship between SPAD values and leaf N concentration in the literature. In 1996 dry season, cv IR72 was grown at the International Rice Research Institute (IRRI) and the Philippine Rice Research Institute (PhilRice) under various N, P and K fertilizer combinations. SPAD measurements were made on the topmost fully expanded leaves at mid-tillering and panicle initiation. The leaves were then detached, dried and analyzed for N, P and K. The SPAD values were highly correlated with leaf N concentration (r = 0.93 to 0.96). Fertilizer-K application did not affect SPAD values, leaf N concentration, or the relationship between the two. Phosphorus deficiency reduced leaf N concentration at mid-tillering, but increased leaf N concentration at panicle initiation when the same amount of N was applied. The SPAD values were 1 to 2 units greater for zero-P plants than P-treated plants at a given leaf N concentration at mid-tillering. At panicle initiation, the relationship between SPAD values and leaf N concentration was not significantly affected by leaf P status. These results suggest that a different regression equation between SPAD values and leaf N concentration should be used to estimate leaf N concentration of P-deficient and P-sufficient rice leaves at vegetative stage using a SPAD.     

The use of hand-held chlorophyll meters as a tool to assess the nitrogen status and to guide nitrogen fertilization of potato crop

Summary Fifteen experiments were carried out in different sites of Italy, Belgium, Scotland and The Netherlands from 1995 to 1999 to study the possible use of chlorophyll meter to assess the nitrogen status and to guide nitrogen fertilization of the potato crop. The results are gathered here and reviewed together with available information in literature. The paper deals with measuring principles of chlorophyll meter; relation between chlorophyll meter readings and analytical measurements of chlorophyll, analytical measurements of nitrogen, crop nitrogen content, tuber yield, and physiological processes in leaves; variations in chlorophyll meter readings related to nitrogen supply, potato cultivar, crop management, and sampling methods; use of chlorophyll meter readings for decision making in the management of supplemental nitrogen fertilization (assessment of chlorophyll meter critical threshold, plant response to addition of supplementary N).     

马铃薯氮素的吸收、积累和分配规律

植株体内氮素浓度的高低反映了其生长势的强弱,马铃薯生育期间各器官氮素浓度的变化始终表现为叶片>地上茎>块茎,叶片中的氮素浓度高低反映了叶片光合活性的大小。马铃薯对氮的吸收与营养生长和块茎的增长密切相关,植株对氮的需求量受其生长状况所控制。而且,氮在植物体内很容易流动,块茎形成后,大量的氮素转移到块茎中,用于块茎的建成和营养贮存。马铃薯植株在淀粉积累开始后,各器官中氮素加快了向块茎的转移,使叶片和地上茎的衰老进一步加剧。因此,在马铃薯高产栽培实践中,须注重氮、磷、钾的适量与配合施用,使之既能满足块茎的形成与生长的需要,又可防止植株生长过旺或后期发生早衰。本试验表明,在因素中量(适量)组合下,每生产500kg块茎需要纯N2 65kg。     

马铃薯生产的氮肥管理策略

氮是影响马铃薯产量和品质的重要因素,多年来中国马铃薯生产过程中氮肥管理始终缺乏科学的指导,导致许多优质马铃薯品种的产量优势和品质优势难以得到充分的发挥。通过合理施用氮肥,协调马铃薯茎叶生长与块茎生长,促进块茎的形成和膨大,减少氮肥损失,提高氮肥利用率,是马铃薯氮肥管策略的重要内容,同时也是农业可持续发展的重要保障。针对氮肥施用量和施用时期对马铃薯生长与块茎产量的影响及马铃薯氮素营养诊断措施,综述国内外马铃薯氮肥管理的研究结果,以期为中国马铃薯养分管理提供研究思路,同时也为马铃薯生产的氮肥施用策略提供参考。     

利用SPAD值诊断赣花7号氮素营养研究

为适时精确诊断赣花7号的氮素营养状况,通过设置6个氮素水平（施纯氮0、75、150、225、300、375 kg/hm2）,在不同时期（出苗后30、45、60、75和90 d）分别测定花生不同叶位（主茎倒一完全叶、倒二完全叶和倒三完全叶）的SPAD值和相应叶位叶片的含氮量,分析其施氮水平、SPAD值和叶片含氮量之间的关系,并进行方程的拟合。结果显示：施氮水平与SPAD值、叶片含氮量之间呈显著的指数相关,SPAD值和叶片含氮量之间呈显著的线性相关,并且在各叶位中,以主茎倒3叶的相关性最好,其可作为氮素诊断的理想叶位。     

Responses of rice leaf thickness,SPAD readings and chlorophyll a/b ratios to different nitrogen supply rates in paddy field

The objective of this paper was to investigate the influence of different nitrogen (N) application rates to some morphological and physiological features of leaf blades, including leaf thickness, chlorophyll content at different leaf ages and chlorophyll a/b ratios. A paddy field and a cement tank experiments were conducted simultaneously. Rice leaf thickness was measured through a specially developed displacement sensor. Meanwhile, chlorophyll content was estimated using chlorophyll meter (SPAD) and spectrophotometer after ethanol extraction of leaf samples. With the increase of N application, leaf thickness became thinner and chlorophyll a/b ratios decreased. Moreover, the sensitivity of the SPAD readings of the same leaf at different leaf ages to N rates was assessed through coefficients of variation (CV). CV of SPAD readings increased from 8.8% to 21.6% during leaf lifetime, which indicates that SPAD readings became more and more sensitive to nitrogen rates as leaf aged. Therefore, SPAD readings of the lower leaves, which were physiologically older than the upper ones, were more sensitive to nitrogen rates.     

Improvement of nitrogen management in rice paddy fields using chlorophyll meter (SPAD)

Optimum rate and timing application of nitrogen (N) fertilizer are most crucial in achieving high yield in irrigated lowland rice. In order to assess leaf N status, a semidwarf rice cultivar (Khazar) was grown with different N application treatments (0, 40, 80, and 120 kg N ha⁻¹ splited at transplanting, midtillering, and panicle initiation stages) in a sandy soil in Guilan Province, Iran, in 2003. The chlorophyll meter (SPAD 502) readings were recorded and leaf N concentrations were measured on the uppermost fully expanded leaf in rice plants at 10-day internals from 19 days after transplanting to grain maturity. Regression analysis showed that the SPAD readings predicted only 23% of changes in the leaf N concentration based on pooled data of leaf dry weight (N _dw) for all growth stages. However, adjusting the SPAD readings for specific leaf weight (SPAD/SLW) improved the estimation of N _dw, up to 88%. Specific leaf weight (SLW), SPAD readings, leaf area and weight as independent variables in a multiple regression analysis predicted 96% of the N _dw changes, while SPAD readings independently predicted about 80% of leaf N concentration changes on the basis of leaf area (N _a). It seems that chlorophyll meter provides a simple, rapid, and nondestructive method to estimate the leaf N concentration based on leaf area, and could be reliably exploited to predict the exact N fertilizer topdressing in rice.     

Relation between growth conditions and dormancy of seed potatoes. 1. Effects of nitrogen

Summary The duration of dormancy of seed potatoes varies between years and between origins. Therefore, the effects of conditions during crop growth on dormancy of progeny tubers were studied. The effect of nitrogen during tuber bulking on the duration of dormancy was investigated in three field experiments with two cultivars. In addition to an application of 125 kg N/ha at planting, top dressings of 0–150 kg N/ha were given about 2 weeks after tuber initiation. Haulm was pulled about 4 weeks later. The effect of nitrogen rate at planting was also examined in one experiment. Nitrogen top dressings shortened dormancy in all experiments by 5–8 days. An increased nitrogen rate at planting resulted in a shorter dormancy when the duration of dormancy was expressed in days after tuber initiation, but not when it was expressed in days after haulm pulling, probably because extra nitrogen also delayed tuber initiation.     

Evaluation of the SPAD Value in Faba Bean (Vicia fabaL.) Leaves in Relation to Different Fertilizer Applications

Abstract

The correlations of the reading of a portable chlorophyll meter (SPAD-502) with the chlorophyll and N contents of leaves of two faba bean (Vicia fabaL.) cultivars, Japanese (Ryousai-issun) and Egyptian (Cairo 241), were examined. The SPAD readings positively correlated (ρ<0.01) with the chlorophyll contents and the r² values were 0.99 and 1.00 for Ryousai-issun and Cairo 241, respectively. A close linear relationship (ρ0.001) was observed between SPAD reading and total leaf N content at the pod development stage of faba bean plants with r² = 0.88 and 0.99 for Ryousai-issun and Cairo 241, respectively. The SPAD reading was the highest in the 2^nd to 4^th leaves counted from the top (the youngest fully expanded leaves). The changes in leaf chlorophyll content of both cultivars from 3 weeks after transplanting to the ripening stage showed an incomplete “M” type curve. SPAD readings were significant¬ly higher in Ryousai-issun than in Cairo 241 throughout the growth season. Organic fertilizers application improved faba bean plant growth. These results suggest that the SPAD-502 chlorophyll meter can be used to measure chlorophyll and nitrogen contents of faba bean leaves for quick screening faba bean genotypes.     

马铃薯磷素的吸收、积累和分配规律

磷元素在马铃薯植株体内的流动性较大,磷营养水平与块茎膨大密切相关,块茎是磷素的最终贮存库。在块茎增长初期,叶片、地上茎和块茎中的磷素浓度均为一生中的最高值,此时是马铃薯对磷需求最多的时期,块茎形成后,则大量的磷(P2O5)向块茎转移。马铃薯对磷素(P2O5)吸收速率较低。在整个生育期内吸收速率呈单峰曲线变化,峰值出现在块茎增长期。     

马铃薯群体光合系统参数的研究

马铃薯群体LAI呈单峰曲线变化 ,峰值出现在块茎膨大中后期 ;NAR的变化趋势和LAI不同 ,即随着LAI的增加 ,NAR呈二次曲线下降 ;马铃薯群体LAD的变化在整个生育期内呈二次曲线变化。其最大叶面积持续期正处于块茎膨大和淀粉积累时期 ,是马铃薯一生中干物质积累最多的时期 ;马铃薯生产力的提高并非NAR的提高 ,而是LAD的延长。     

Growth and yield studies of potato development in a semi-arid region. 2. Effect of water stress and amounts of nitrogen top dressing on growth of several cultivars

Summary Five potato cultivars were subjected to water deficits as well as to excess water and to corresponding amounts of nitrogen top dressing (N.t.) applied in the irrigation water. The rates of growth in response to water-N. t. were highest for all cultivars whenK _p=1.06 (pan evaporation coefficient) and N.t=173 kg/ha. In the drier treatments (0.87>K _p>0.14 and 127>N.t.>12 kg/ha) and in the wetter treatment (K _p=1.27; N.t.=201 kg/ha), the growth rates decreased. The cultivars differed in their haulm size, especially atK _p=1.0, N.t.=173 kg/ha. At 70 days after planting cv. Cardinal had about half the haulm weight of cv. Désirée. Nevertheless, both cultivars exhibited similar bulking rates. On the other hand, cv. Spunta, which had high bulking rates at the earlier stage of growth, had a marked advantage in yield production in the drier treatments (K _p=0.29−0.14; N.t.=44−12 kg/ha). The maximum leaf area indices (LAI) were obtained atK _p=1.06, N.t.=173 kg/ha and were similar for all cultivars. LAI and leaf area duration (LAD) decreased with increasing water stress. In Cardinal, Désirée, Spunta and cv. Up-to-Date there was a common linear function relating to tuber weigth and to LAD; in cv. Alpha, this function had lower values of tuber weight. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 840-E, 1983 Series.     

马铃薯对氮、磷、钾的吸收及分配规律研究进展

马铃薯的生长发育受到很多因素的影响,特别是养分的供应以及马铃薯对养分的吸收、利用,对其块茎的形成、膨大及淀粉积累的影响尤为显著。氮、磷、钾在马铃薯生长发育中需要量大,必须加以补充,才能满足其正常生长需求。生产上不合理的施肥,导致马铃薯产量不高、品质较差及生产成本增高。通过分析马铃薯不同生育阶段、不同器官吸收养分的特征和分配规律,从而探索马铃薯生产中最佳的氮、磷、钾施肥组合,这对于丰富马铃薯栽培生理理论和指导生产中氮、磷、钾肥合理配施均具有重要的现实意义。     

三种氮素营养快速诊断方法在油菜上的适宜性分析

通过大田试验研究了SPAD仪法、硝酸盐反射仪法和光谱仪法在油菜氮素营养快速诊断上的适宜性。试验设施氮0、60、120、180、240、300和400kg/hm2处理,在八叶期、十叶期和蕾薹期对各处理SPAD值、冠层归一化植被指数（NDVI值）和硝酸盐含量进行检测,并测定各时期油菜生物量和收获期籽粒产量。对不同施氮量下的油菜产量进行显著性检验及方程拟合,并对三种诊断方法各测定指标与氮肥用量、籽粒产量进行相关分析。结果表明,油菜施氮量与籽粒产量具有较好的相关关系,满足氮素营养快速诊断要求。三种诊断方法中,硝酸盐反射仪法能在一定程度上反映油菜氮素营养状况,但受油菜生理特性（苗期生物量小、蕾薹期氮素奢侈性吸收等）影响,诊断结果的可信度和稳定性不高。光谱仪法比较适宜于油菜蕾薹期氮素营养诊断,但存在追肥时期过晚、操作不方便等缺点。综合分析认为,SPAD仪法诊断结果稳定,并且具有快速、简便、低耗等优点,适合于油菜氮素营养快速诊断。     

Potato Crop Nitrogen Status Assessment to Improve N Fertilization Management and Efficiency: Past–Present–Future

Improving nitrogen use efficiency is important for the potato crop, because of its relatively low ability to take up available soil mineral nitrogen (N). Splitting of N fertilizer application is a suitable approach to better match N need and supply. In-season crop N monitoring methods are therefore required to support such strategies. This paper deals with the state of the art and potential development of characteristics, use and implementation of well known and more recent methods aimed to assess in-season potato Crop Nitrogen Status (CNS). A short overview of this concept is given for the potato crop. The most important and available methods for CNS assessment are evaluated for their accuracy, precision, sensitivity, sensibility and feasibility. These are: the petiole sap nitrate concentration test; the leaf chlorophyll concentration measurement using a hand-held chlorophyll meter; the measurement of crop light reflectance through a hand-held radiometer using passive sensors. More recent methods still under investigation based on near, ground-based, air-borne or space-borne remote sensing are discussed for their scientific and practical interest in the near future. The current and potential use and implementation of these methods into decision support systems for potato N fertilization management aimed at improving the potato crop nitrogen use efficiency are analysed by: comparing relative and raw data; establishing threshold values of CNS; and combining or integrating the CNS values into models dedicated to N recommendation or to crop growth simulation.     

Chlorophyll meter to predict nitrogen sidedress requirements for short-season cotton (Gossypium hirsutum L.)

A two-location experiment was carried out at five to six nitrogen levels to study the relationship between chlorophyll-meter readings (SPAD values) and physiological or yield traits in short-season cotton. The results showed that there were highly significant (P<0.01) linear relationships between SPAD values and contents of both nitrogen and chlorophyll at each growth stage, and as well as with the daily increase in plant height during early flowering. The relationship between nitrogen concentration and SPAD was stronger when nitrogen was expressed on a leaf area (N_a) rather than on a dry weight (N_dw) basis. Significant curvilinear relationships were found between SPAD values at various stages and photosynthetic intensity, lint yield, and total boll number per hectare, respectively. Furthermore, the linear regressions between SPAD values and N fertilizer levels were highly significant (P< 0.01), and before the boll opening stage, the slopes of these regressions were similar (0.040–0.041) at the two locations. These data provided evidence that the chlorophyll meter could be used to determine sidedress N requirements of short-season cotton before boll opening stage. Critical SPAD levels for maximum lint yield were established as 32.4, 33.1, 35.0, 43.55, and 39.7 at early flowering, flowering peak, boll forming, the beginning of boll opening and boll opening stages, respectively. It was also established that 24.2–25.0 kg ha⁻¹ increase in N application should be necessary for each unit decrease in SPAD value below the critical level.