Response of red pepper to deficit irrigation and nitrogen fertigation

The main objective of this investigation was to evaluate the response of red pepper grown in a subhumid climate to different irrigation and nitrogen levels. Open-field trials were conducted in the Marmara Region, Turkey. Plants were subjected to three water levels [full irrigation (FI) = 100% crop evapotranspiration (ETc) and two deficit irrigations (DIs)= 66 and 33% ETc restoration] and four levels of N (0, 80, 160, and 240 kg N ha^?1) during the 2012, 2013, and 2014 growing seasons. A split-plot experimental design was used. The highest values of biomass and marketable yield (MY) were observed under FI. DI significantly increased the fruit soluble solids content. The biomass yield, MY, and fruit weight significantly improved with increasing nitrogen levels. The 240 kg N ha^?1 treatment under FI provided the maximum net income. Increasing N supply under DI conditions enhanced the water-use efficiency based on both biomass yield and MY. These results indicate that with respect to the yield, the net income, and the water productivity of red pepper, the FI with a nitrogen supply of 160–240 kg ha^?1 is recommended for drip irrigated and N-fertigated red pepper under subhumid climate conditions.     

Response of bell pepper grown inside plastic houses to nitrogen fertigation

Abstract

Two field experiments were conducted for two consecutive seasons inside plastic houses to evaluate bell pepper (Capsicum annuum) response to nitrogen fertigation. Nitrogen fertilizers were applied through irrigation water at rates of zero, 150, 250, and 350 N kg ha^‐1. The crops were irrigated in weekly bases with the amount of water equivalent to 80% of the E Pan reading. All treatments were replicated four times in a randomized complete block design. Five plants were sampled from each experimental unit at 30, 60, 90, 120, 150, and 180 days after planting. Growth rate, nutrient uptake and yield were determined. The results indicate that the yield and marketable number of fruits in both seasons increased with the addition of nitrogen. The highest yield was obtained with the addition of 150 kg N ha^‐1. The maximum growth rate and the maximum rate of accumulation of dry matter in the fruits occurred during the period of 90 to 150 days after planting. This may indicate that the peak of the pepper N requirement and utilization would be during the same period of the maximum growth rate. Increasing the rates of nitrogen applied increased the uptake of nitrogen by the plants and at the same time stimulated the uptake of potassium and phosphorus through the synergistic effect of nitrogen on both nutrients.     

Genotypic variation for nitrogen uptake and assimilation using hydroponic culture technique in wheat

Hydroponic culture technique is an alternative way of studying nitrogen metabolism. In this study, the response of six wheat genotypes (PBW 621, PBW 636, GLU 1356, BW 8989, GLU 700, and PBW 343) with respect to nitrogen-metabolizing enzymes in relation to accumulation of soluble proteins and amino acids at two concentrations of nitrogen (2 and 6 mM) was studied. Activities of nitrate reductase (NR) and glutamine synthetase as well as soluble proteins, amino acids, and nitrogen content increased in all six genotypes with increasing concentration of nitrogen in roots as well as shoots. Shoots maintained higher activities of NR and glutamine synthetase; apparently contents of soluble protein, amino acid, and nitrogen were also higher. The upregulation of NR and glutamine synthetase activities with increased concentration of nitrogen possibly contributes to higher nitrogen assimilation efficiency of three genotypes (PBW 621, PBW 636, and GLU 1356) compared to other genotypes.     

主动遥感光谱仪Greenseeker与SPAD对玉米氮素营养诊断的研究

以手持式主动遥感光谱仪Greenseeker和叶绿素仪SPAD对玉米不同氮素水平下各个生育期的NDVI值及叶片SPAD值进行测试,研究不同氮素对玉米群体和个体营养状况的变化以及田间条件下简便、快速、非接触性的作物氮素营养状况诊断方法。结果表明,在一定的范围内随着氮肥用量的增加NDVI值也增加,氮肥施用量为N 300kg/hm2时NDVI值达到最高,NDVI 与氮肥施用量符合线性加平台的关系;玉米不同生育期间NDVI 值变化明显,苗期NDVI值比较低,大喇叭口期NDVI 值达到最高,以后逐渐下降并在抽雄期后趋于稳定。SPAD值与NDVI 值的变化趋势相一致,SPAD值与叶绿素含量成正相关关系,大喇叭口期完全展叶的SPAD 与产量存在正相关关系。手持式主动遥感光谱仪Greenseeker和叶绿素仪SPAD结合能够对玉米的氮素营养状况作营养诊断。     

滴灌施氮肥对盆栽玉米生长的影响

本研究通过滴灌施氮肥与常规的基施氮肥进行比较试验,以了解两种不同的施肥方式下施用不同品种氮肥对氮肥利用率的影响。试验设10个处理,所选用的氮肥品种有:尿素、硝酸铵、硝酸钙、硫酸铵。试验结果表明,同基施氮肥+滴灌处理相比,滴灌施氮肥处理能显著提高氮肥的利用率,其增幅达8.75%～21.50%,有利于玉米对氮肥的吸收及生物量的积累;在同一灌溉施肥条件下施用不同品种的氮肥时,各处理间的氮肥利用率表现出一定的差异性,其中硝酸钙处理的氮肥利用率显著低于另外3种氮肥处理。     

Effects of nitrogen fertigation frequency on yield and nitrogen retention in drip-irrigated cotton

Fertigation techniques have been widely used in drip-irrigated cotton. The timing of nitrogen (N) fertilizer injections then becomes a management question producers need guidance on. This study investigated the effect of nitrogen (N) fertigation frequency on drip-irrigated cotton. Experiments were conducted in the Southeastern Anatolia Region of Turkey in 2011 and 2012. A split-plot experimental design was applied. The main plots contained two different lateral spaces: A, one drip-line (lateral) per row; and B, one lateral for every two rows. Sub-plots were designed with different frequencies of fertigation as follows: a, the application of fixed amount of N at each irrigation cycle (5 days); b, the application of fixed amount of N every two irrigation cycles (10 days); and c, the application of one-fifth of the total N between the first irrigation and first flowering, two-fifths between the first flowering and formation of the first boll, and one-fifth between the formation of the first boll and last irrigation cycle. One-fifth of the total N was applied to the soil at sowing in all treatment regimens. The maximum cotton yield (4120 kg ha^?1) and highest total N content (2.57–2.94%) in the leaves were obtained with one lateral for every two rows and the application of fixed amount of N every two irrigation cycles (10 days). One-fifth of the total N might be applied to the soil at sowing, and the remaining N should be applied in equal doses (an average of 7 fertigations) every two irrigation cycles (10 days) by fertigation. However, further research fertigation methods for cotton, including the amount of N that needs to be applied and the use of different injection systems, is required.     

小白菜的中红外光谱特征及其在氮营养诊断中的应用

采用不同中红外光谱（漫反射光谱、 衰减全反射光谱和光声光谱）对不同氮处理的小白菜进行表征。结果表明,小白菜不同的红外光谱具有明显不同的光谱特征,主要表现于峰形、 峰位以及相对峰强度;中红外漫反射光谱的主要吸收峰分别为2800~3800 cm-1、 2200~2500 cm-1、 1500~1700 cm-1和1000~1500 cm-1,衰减全反射光谱由于水的强烈干扰可用的吸收峰主要在1200~1500 cm-1,而中红外光声光谱的主要吸收峰分别为2800~3800 cm-1、 1500~1700 cm-1、 1200~1500 cm-1和1000~1200 cm-1。漫反射光谱、 衰减全反射光谱和光声光谱的主成分分析表明,不同氮处理主成分分布特征明显不同,且第一主成分（PCA1）均与施氮量显著相关,相关系数（r）分别为0.9103、 0.8527和0.9366。这三种光谱利用主成分分布均可实现小白菜氮营养快速诊断,且光声光谱由于其独特的原位逐层扫描功能而表现出更好的诊断效果,在植物营养诊断中表现出较强的应用潜力。     

基于包络线消除法的油菜氮素营养高光谱评价

该文将广泛应用于岩矿高光谱分析中的包络线消除法借用至鲜叶片的光谱分析及作物氮素营养状况评价。利用油菜主要生育期的不同氮处理下鲜叶片反射光谱及全氮含量数据,对鲜叶片可见光波段反射光谱进行包络线消除处理,以及吸收特征与叶片全氮含量的统计分析。结果表明:在可见光区域,叶片反射率随着施氮量的增加而减小,包络线消除处理扩大了原始反射光谱中由氮素胁迫引起的吸收特征微小变化。在油菜的苗期、现蕾期至开花始期三个生育期中,550～750 nm波段的红光吸收峰总面积、吸收峰左面积和吸收峰右面积均随着施氮量的增加而增大,面积归一化最大吸收深度均随着施氮量的增加而减小。相关分析表明,苗期叶片全氮含量与吸收特征参量相关性最为密切。进一步基于各光谱吸收特征参数建立了油菜氮素营养的评价模型,这些评价模型除现蕾期外,其他均达到了1%的极显著性水平。研究表明,利用包络线消除法为定性和定量评价油菜氮素营养是可行的,苗期是利用光谱吸收特征来定量评价油菜氮素营养的最佳生育期。     

氨基酸态氮和硝态氮混合营养下番茄生长及其生态化学计量学特征

在水培条件下,设计了7种试验处理其N源分别为NO3--N、NO3--N+谷氨酸态氮、NO3--N+苯丙氨酸态氮、NO3--N+谷氨酸态氮+苯丙氨酸态氮、谷氨酸态氮、苯丙氨酸态氮、谷氨酸态氮+苯丙氨酸态氮,这些处理中除了N素形态不同外,其N、P、K的含量均相同。研究不同处理对番茄生长的影响,并在此基础上利用生态化学计量学的方法研究了氨基酸态氮和NO3--N混合营养下番茄生长及其与生态化学计量学特征之间相关关系。研究结果表明,番茄植株光合速率与其地上部C/P之间存在显著正相关关系;番茄地上部硝酸盐含量、亚硝酸盐含量、游离氨基酸含量、硝酸还原酶活性和谷氨酰胺合成酶活性与其地上部N/P、C/N、C/P和P/K之间均不存在显著相关关系;和N源为NO3--N的处理相比,氨基酸态氮和NO3--N混合营养促进番茄(地上部和根系)生长,两种氨基酸态氮和NO3--N混合的营养效应好于单一氨基酸态氮和NO3--N混合的营养效应。     

滴灌施肥条件下不同种类氮肥在土壤中迁移转化特性的研究

采用室内土柱模拟方法研究了滴灌条件下不同种类氮肥(硝态氮、铵态氮和尿素态氮)在土壤中的迁移、淋溶和转化特征。结果表明,3种氮肥在2种质地土壤中的淋失量均是硝态氮肥>尿素>铵态氮肥,淋失的氮素主要为肥料氮。砂壤土上氮素的淋失量明显高于粘壤土。滴灌施用铵态氮肥,显著增加了土壤中NH4+-N含量,随着硝化作用的进行,NH4+-N的量在培养的第5d左右达高峰,尔后含量逐渐降低。与滴灌施用硝态氮肥相比,施用铵态氮肥和尿素后在培养期间土壤矿质态氮(NO3--N+NH4+-N)的含量有降低的趋势，降低的原因可能与N+NH4+-N在土壤中的固定、挥发等有关。     

负压水肥一体化灌溉对黄瓜产量和水、氮利用效率的影响

【目的】本试验采用自行设计的新型负压水肥一体化灌溉系统,进行了系统供水负压对土壤硝态氮分布和黄瓜水氮利用效率影响的研究,以期为实际应用和管理提供理论依据和技术参考。【方法】在遮雨网室内进行了供水和施氮双因素盆栽试验。以常规灌溉为对照(CK),设4个供水水平:0(W1)、–5(W2)、–10(W3)和–15 k Pa(W4),2个施氮水平(N1,N 0.3 g/kg土;N0,不施氮),共10个处理。分析检测了黄瓜生育期内0—25土壤水分变化动态、土壤硝态氮的空间分布特征,计算了黄瓜的水、氮利用效率。【结果】随着黄瓜耗水量的增加,系统供水量也增大,系统累计供水量与黄瓜累计耗水量之间存在极显著线性关系y=0.96x+3.4(R2=0.99,P0.01)。不同供水负压对同一时期土壤含水量变化有极显著影响(P0.01),当供水负压设定在0、–5、–10和–15 k Pa时,土壤平均质量含水量分别为28.7%、22.7%、20.0%和15.6%,而在同一系统供水负压下黄瓜整个生育期土壤含水量保持相对稳定,其变化属于弱变异(变异系数CV≤0.1)。负压灌溉水肥一体化能显著提高0—25 cm土壤氮素分布的均匀性,土壤硝态氮沿垂直方向的平均变差系数分别比常规灌溉降低了58.6%~71.2%。同一系统供水负压下,施氮处理(N1)黄瓜植株干物质量、产量和水分利用效率比不施氮处理(N0)分别提高了4.6%~256.1%、12.6%~196.6%和7.76%~86.27%。当供水负压为–5 k Pa时,黄瓜植株平均干重和产量均为最高,分别为153 g/pot和1406 g/pot,黄瓜平均水分利用效率和氮肥表观利用率分别比常规灌溉提高了136.8%和52.32%。【结论】适宜的供水负压下,负压灌溉系统通过土壤水分平衡供应机制,实现了作物对水分的连续自动获取,黄瓜整个生长期间,灌溉系统可以保持平稳均匀与适时适量供水,因而,负压灌溉水肥一体化显著提高了黄瓜的水、氮利用效率。本试验条件下,系统供水负压为–5 k Pa更有利于黄瓜的产量和氮素利用率的提高。     

Animal-based organic nutrition induces comparable fruit quality to that of inorganic fertigation in soilless-grown grape tomato

The aim of the present study was to determine the effect of animal-based organic nutrition and environmental parameters on tomato fruit quality, as well as to establish relations among colour and morphological values performed by the Tomato Analyzer (TA) software application. Organic tomato fruits produced by three organic nutrient solutions, which consisted of different mixtures of several OMRI certified nitrogen fertilizers and one inorganic nutrient solution (Steiner’s solution) as the control, were evaluated for their polyphenol and carotenoid content. We used Tomato Analyzer (TA) to evaluate fruit size and shape. Moreover, we implemented a digital image analysis tool, Color Test (CT), as part of the TA software application to collect and analyse fruit colour parameters. The application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. The high air temperature (>30°C) and sub-optimal light intensity negatively affected the carotene content of tomato fruits, as well as their morphological and colour attributes. Plants fed with organic solutions containing ASA + ASB + NK2SO4 showed comparable morphology and fruit colour attributes to those of the control plants that received Steiner’s nutrient solution. The results indicated that the application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. Plants fed with the Steiner’s nutrient solution exhibited the highest carotenoid content in tomato fruits. Organically produced tomatoes through animal-based fertilizer application displayed similar fruit morphology and colour attributes compared to conventionally produced tomatoes.     

基于临界氮浓度的水稻氮素营养诊断研究

【目的】 依据水稻品种的氮素营养特征计算其氮营养指数 (NNI) 和氮素亏缺 (N_and) 值,可实现作物氮素状况的精确定量调控。本研究比较了杂交稻和常规稻在不同氮水平下的NNI和N_and值,为该诊断方法的精准使用提供依据。 【方法】 本研究选用超级杂交稻 (Y两优一号、超优千号) 和常规稻 (粤农丝苗、金农丝苗) 为对象进行田间试验。设施氮水平0、40、80、120、160、200、240 kg/hm2(分别以N0、N40、N80、N120、N160、N200、N240表示),分析测定了水稻移栽后15、30、45、60、75天和成熟期地上部干物质量及其氮浓度,构建临界氮浓度变化曲线,利用该曲线计算了不同品种在不同时期的临界氮浓度、氮营养指数和氮亏缺值。 【结果】 杂交稻地上部干物重在N0、N40、N80、N120、N160处理间差异显著,N200、N240处理间差异不显著,但显著高于其他处理;常规稻地上部干物质重在N0、N40、N80、N120处理间差异显著,N160、N200、N240处理间差异不显著,但显著高于N0、N40、N80、N120处理。水稻植株氮浓度均随着施氮水平的提高而增加,但随生育期的延长和地上部干物重的增加,水稻植株氮浓度均呈下降趋势。根据地上部干物质重与其氮浓度变化关系构建水稻临界氮浓度 (Nc) 变化曲线,杂交稻为N_c=3.36DM–0.31(R2=0.91),常规稻为N_c=2.96DM–0.25(R2=0.86)。基于临界氮浓度曲线,计算不同水稻品种的NNI和N_and,其中杂交稻和常规稻NNI变化范围分别为0.73～1.05和0.78～1.11,N_and变化范围分别为–9.8～117.8 kg/hm2和–25.4～90.3 kg/hm2。 【结论】 常规稻品种临界氮浓度高于相同生育期的杂交稻品种,但杂交稻的干物质量生产能力大于常规稻。在本试验条件下,依据N_and计算结果,杂交稻临界氮浓度下的氮素积累量大于常规稻,其中杂交稻和常规稻适宜施氮量分别为200 kg/hm2左右和160～200 kg/hm2。      

水培燕麦根系形态和氮吸收流量对硝态氮供应浓度的响应

【目的】苗期根系的形态结构与作物的养分吸收和抗倒伏性密切相关,对燕麦如何合理施肥以达到最大的增产效果,需要对不同燕麦品种的氮吸收利用效率做出评价。【方法】本研究以3个不同燕麦栽培品种(坝莜9号、 坝莜3号和200215)为材料,分析了低、 中、 高NO-3-N浓度下(NO-3浓度为1、3、6 mmol/L)根系生长以及NO-3吸收流量的变化。将燕麦种子萌发至一片真叶展开时,每个品种挑选长势一致的10株幼苗放入含不同NO-3浓度的Hoaglands培养液中培养,培养3周后选取长势基本一致的幼苗,采用非损伤微测技术测定根系NO-3流量并利用根系图像分析系统WinRhizo分析根系形态指标。【结果】NO-3-N浓度对不同燕麦品种节根数影响不显著,对侧根密度、 总根长、 根系平均直径和不同直径范围内根系长度分布均有显著影响; NO-3-N浓度的变化对坝莜3号根系吸氮量有显著影响,对坝莜9号和200215根系吸氮量的影响不显著; 根系NO-3吸收流量的动态变化与侧根数量变化有一致性; NO-3平均吸收流量与总根长、 平均直径及根系平均直径≤0.16 mm的细根在根系中所占比例的变化一致。【结论】不同NO-3-N供应浓度主要影响燕麦苗期侧根(直径≤0.16 mm的细根)的形成和生长,对根系NO-3吸收流量的影响因品种而异; 根系NO-3吸收流量的变化主要受总根长、 根系平均直径及细根在根系中所占比例的影响。     

玉米氮营养指数的高光谱计算模型

快速、准确、动态地诊断大面积玉米氮营养状态对于评价玉米长势、预测产量和指导农业生产均具有重要的意义。该研究利用北京昌平、长春市西北市郊的四间房村2个试验区的玉米冠层高光谱数据演变得到的多种光谱参数,采用逐步回归分析方法,建立了玉米氮营养指数与高光谱参数的定量关系,提出了玉米氮营养指数的敏感光谱参数及预测方程。研究结果显示,红边/绿边比值参数、红边/近红外比值参数、红边敏感点参数与玉米氮营养指数高度相关,是诊断玉米氮营养指数的敏感光谱参数。通径分析得到红边/绿边比值参数、红边/近红外比值参数与玉米氮营养指数的通径系数分别为-0.14942和-0.35218,表明玉米氮营养指数对红边/绿边比值参数、红边/近红外比值参数有间接影响,红边敏感点参数与玉米氮营养指数的通径系数为1.41549,表明红边敏感点参数对玉米的氮营养指数高度敏感。基于敏感光谱参数的玉米氮营养指数多元回归预测模型的相关系数R为0.95507,观测值与拟合值的拟合误差小于0.1,均方根误差为0.06016,F值达到了167.727,显著水平P为0.0045。由此可以得出利用敏感光谱参数定量分析玉米氮营养指数是可行的。     

基于叶片光谱透过特性的植物氮素测定

该文通过不同施氮水平下营养液栽培的水稻和黄瓜叶片在300～1100 nm的分光光谱透过率,与其叶绿素含量和含氮量的相关性分析,确定了560、650和720 nm作为特征波长,940 nm作为参比波长可用于植物营养的快速无损诊断。以上述波长的光谱透过率构建的21组光谱特征参数中,(T940-T560)/(T940+T560)、log(T940/T560)和log(T940/T650)与水稻和黄瓜叶片的叶绿素含量和含氮量的相关性较好,且经回归估测检验的相对误差均小于8%。因此,上述光谱特征参数可作为植物氮素营养指标用于植物叶片的叶绿素含量和含氮量的快速无损估测,从而为植物营养无损诊断提供技术支持。     

滴灌施氮对烤烟氮素吸收利用及土壤无机氮分布的影响

为明确适合烤烟生长并降低土壤氮素损失的滴灌施氮策略,为烤烟生产提供理论指导。以烤烟品种K326为材料,在盆栽条件下,研究了滴灌施氮对烤烟氮素积累、分配和利用及土壤无机氮含量与分布的影响。结果表明:移栽后28 d滴灌追氮一次,增加追氮比例,叶片的氮素含量、氮素积累量和分配比例增加,根和茎的氮素积累量和分配比例降低,烟株表观氮素利用率提高;土壤无机氮含量升高,土壤无机氮的表观盈余量降低。移栽时施氮50%,移栽后28和42 d滴灌追氮两次的氮素利用率显著高于追氮一次处理;而追氮比例为70%和90%时,氮素利用率低于追氮一次处理。移栽后滴灌追氮两次提高了距滴注点垂直距离5～20 cm和水平距离15～20 cm土层的土壤无机氮含量,降低了距滴注点垂直距离20～25 cm土层的土壤无机氮含量。从烟株氮素利用,土壤无机氮分布及盈余量等方面考虑,移栽时施氮50%,移栽后28 d滴灌追氮35%,42 d滴灌追氮15%可作为生产中参考的滴灌施肥制度。     

基于高光谱的冬小麦氮素营养指数估测

为了准确定量诊断氮素状况,为施肥和产量、品质的估测提供参考,该文通过设置不同氮素水平和品种类型的冬小麦田间试验,分析孕穗至灌浆初期不同光谱参数在小麦氮素营养状况监测上的差异,筛选叶片氮素含量和冠层氮素密度反演效果较好的参数,建立其与氮营养指数(NNI,nitrogen nutrition index)的经验模型。研究表明,线性内插法红边位置(REPLI)、修正红边单比指数(mSR705)、比值指数(RI-1dB)、简单比值色素指数(SRPI)、红边指数(VOG)等光谱参数与氮素营养指标具有良好的相关性(r0.85),且不受生育期影响,可用来反演评价冠层氮素营养状况;研究对筛选的光谱参数与各氮素指标进行回归建模,并用独立试验数据对所建模型进行验证,结果显示,REPLI在氮营养指数估测方面表现较好(r=0.93),估测模型精度较高(决定系数R2=0.86,均方根误差RMSE=0.08)。NNI在氮素营养状况诊断方面有一定的优势,通过高光谱反演氮营养指数进行氮素营养状态的定性定量诊断有一定的可行性。     

基于氮素营养指数的冬小麦籽粒蛋白质含量遥感反演

基于遥感实现小麦籽粒蛋白质含量提早估测对农业生产具有重要意义。为提高预测小麦籽粒蛋白质含量的准确度,该研究引入能更好反映作物氮素营养状况的农学参数－氮素营养指数,作为衔接遥感信息与产终籽粒蛋白质含量的桥梁。在田间试验的基础上,探讨氮素营养指数与其他农学参数在诊断籽粒蛋白质含量上的优劣,并基于“遥感参数－氮素营养指数－籽粒蛋白质含量”间关系,利用主成分回归算法构建估测籽粒蛋白质含量的遥感反演模型。结果表明,相比于其他参数,冬小麦旗叶期氮素营养指数能更好的反映产终籽粒蛋白质含量;以氮素营养指数为中间变量,所建遥感反演模型能准确预测小麦籽粒蛋白质含量,模型的预测决定系数为0.48,预测标准误差为0.38%,相对误差为2.32%。     

Drip fertigation with nitrogen and potassium and postharvest susceptibility to bacterial soft rot of bell peppers

In 1991 and 1992, drip irrigation was used to apply various rates and timings of nitrogen (N) and potassium (K) to black polyethylene plastic‐mulched bell pepper (Capsicum annuum L.) to determine the effect on fruit quality and susceptibility to postharvest bacterial soft rot (Ervinia carotovora subsp. carotovora). Neither rate nor application timing affected total yield in either year. In 1991, the high fertilizer rate (266–309 kg/ha of N and K, respectively) increased class 1 yield in the first harvest and reduced total discards. In 1992, a year with a colder than average spring, the low fertilizer rate (70–81 kg/ha of NK) increased class 1 yield in the first harvest. Mid‐ or late‐season fertigation produced more second harvest yield and less discards than the first harvest in 1991, but not in 1992. Fruits of plants fertilized with high N and K rates had greater N and dry matter concentration. No differences in color or wall thickness at harvest were detected among treatments. Stored fruits turned red slower with the late season low fertilizer rate. There were no differences in rate of weight loss during storage at 10°C. No differences in progression of bacterial soft rot were detected among treatments in 1991, but the higher fertigation rates or late timing application increased resistance in 1992.