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1.
Maria Antonia Machado Barbosa Kacilda Naomi Kuki Pedro Santos Peno Bengala Emilly dos Santos Pereira Angélica Fátima de Barros Sebastián Giraldo Montoya Leonardo Duarte Pimentel 《Journal of Agronomy and Crop Science》2020,206(2):263-276
Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season. 相似文献
2.
Yu Xin Chi Shakeel Ahmad Ke Jun Yang Jian Fu Li Yang Xun Bo Zhou Hong De Zhu 《Journal of Agronomy and Crop Science》2023,209(1):161-175
Water scarcity is known to be a strong limiting factor affecting maize grown and yield in cold semi-arid regions. Numerous studies have shown that rehydration improves maize growth. Our study aimed to explore the effects of rehydration treatments on maize growth and yield under water and nitrogen stress during different growth stages. We selected the drought-tolerant maize variety Nendan 19 (ND19) and subjected it to water stress during the V6 (sixth-leaf), R2 (filling) and R6 (maturity) growth stages and a rehydration treatment after each stress stage. Our results indicated that N1 (N100 kg N ha−1) and N3 (N300 kg N ha−1) treatments significantly increased the leaf moisture status relative to water content (RWC), bound water content (BWC), free water content (FWC) and water potential (WP)) at different growth stages. Similar trends were observed in the accumulation of plant leaf and root hormones (zeatin+zeatin riboside, indole-3-acetic acid, abscisic acid and gibberellic acid), photosynthetic pigments and chlorophyll fluorescence. However, under the same water stress conditions, they decreased as the N rate increased and reached a minimum value in the S3 (water stress for N3) treatments. In addition, with growth stage advancement and extension of the rehydration time, both showed a gradual upward trend. The results showed that to save water resources in the cold semi-arid region, rehydration treatments (R2S1 and R2S3) significantly increased the photosynthetic pigments and chlorophyll fluorescence parameters, leaf moisture status, biomass, 100-grain weight, hormone content, ear characteristics and grain yield of maize. 相似文献
3.
U. R. Sangakkara W. Richner F. Steinebrunner P. Stamp 《Journal of Agronomy and Crop Science》2003,189(6):361-366
A field study evaluated the residual effect of a cropping system in two minor (dry) seasons on the productivity pattern and nitrogen utilization of a maize crop grown in the subsequent major (wet) seasons. The cropping systems established in the minor seasons, where evaporation exceeds rainfall, were either monocultures of maize (Zea mays L), or maize intercropped with either common bean (Phaseolus vulgaris L) or sunhemp (Crotolaria juncea L). In addition, monocultures of two green manures, namely sunhemp (Crotolaria juncea) or Tithonia (Tithonia diversifolia), were established. The residues of maize and beans and the green manures were incorporated at the end of the minor season; at the onset of rains in the major season, maize crops were established on the same plots. Germination of maize was not affected by the previous cropping system. In contrast, crop growth and yields of maize and nitrogen utilization were affected by the previous cropping system. Optimum growth and highest yields were procured in maize that was grown after a green manure crop. Similarly, although the yields were high, the planting of a green manure crop reduced nitrogen utilization by maize in the major season, thereby indicating its potential contribution to sustainability, due to its lower mining of soil nitrogen. On the basis of the results of this two‐year study, the impact of cropping systems in minor seasons on the productivity of maize, a very important highland cereal in the tropics, grown under rain‐fed conditions in a major season, is presented. 相似文献
4.
The spatially and temporally continuous leaf area index (LAI) mapping is very crucial for many agricultural applications, such as crop yield estimation and growth status monitoring. Data assimilation technology provides an innovational way to improve spatio-temporally continuous crop LAI estimation through integration of remotely sensed observations and crop growth models. In this study, a very fast simulated annealing (VFSA)-based variational assimilation scheme was proposed to integrate the crop growth model (CERES-Maize), MODIS reflectance product (MOD09A1) and a two-layer canopy reflectance model (ACRM) to estimate time-series crop LAI at regional scale. Simultaneously, a new sensitivity analysis method (called “histogram comparison”) was developed to identify sensitive parameters of CERES-Maize and ACRM models. The proposed scheme was applied for continuous crop LAI estimation during the maize growing season in the dominating spring maize planting area of Jilin province, China. Results showed that R2 values between LAI estimations from the proposed assimilation scheme (referred to as assimilated LAI) and fine resolution LAI reference maps were 0.24 and 0.63, with RMSE values of 0.21 and 0.54 for Julian day 176, 2010, and Julian day 196, 2010, respectively. The assimilated results were closer to LAI reference maps than the MODIS LAI product and ACRM-based inversion results (referred to as ACRM LAI). Moreover, by introducing the prior information of LAI dynamics depicted by a crop growth model, the assimilated LAI showed better temporal consistency than the MODIS LAI product, LAI profiles simulated by CERES-Maize model (referred to as CERES-Maize LAI), and ACRM LAI. It was found that the accuracies of LAI estimations could be enhanced by assimilating satellite observations into a crop simulation model in the VFSA framework at a regional scale. 相似文献
5.
2009-2011年在山东临沂冬小麦-夏玉米生产田,探讨了麦季施氮水平和施氮时期对两季作物干物质积累与分配、籽粒产量、氮肥农学利用率和氮肥偏生产力的影响。施氮量设4个处理,分别是0 (N0)、168.75 (N1)、225 (N2)和281.25 kg hm-2 (N3);氮肥追施时期设2个处理,分别为拔节期(S1)和拔节期+开花期(S2)。在S1条件下,冬小麦和夏玉米的籽粒干物质积累量及夏玉米和周年生物产量均表现为N3>N2>N1,冬小麦和夏玉米的籽粒产量N2和N3处理间无显著差异;氮肥农学利用率和氮肥偏生产力在麦季随施氮量增加显著降低,而在玉米季则逐渐升高,但玉米季氮肥偏生产力N3与N2处理间无显著差异。S2条件下麦季施氮量由N2处理增加25% (N3),冬小麦和夏玉米籽粒干物质积累量、生物产量和籽粒产量无显著变化,氮肥农学利用率和氮肥偏生产力在麦季显著降低、在玉米季无显著变化。与S1相比,S2有利于提高N1和N2条件下冬小麦籽粒与营养器官的干物质积累量、生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力,但对N3条件下的这些指标无显著影响;而在玉米季,3个施氮量水平下夏玉米的各项指标均显著升高。综合周年生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力结果,麦季总施氮量225 kg hm-2及拔节期+开花期追氮是本试验条件和种植模式下的最佳麦季氮肥运筹模式。 相似文献
6.
氮肥后移对超高产夏玉米产量及氮素吸收和利用的影响 总被引：47，自引：1，他引：46
采用田间试验研究了氮肥后移对超高产夏玉米产量、氮素吸收积累和氮肥效率的影响,旨在了解超高产夏玉米(≥ 12 000 kg hm-2)的氮素吸收和转运特性,为实现夏玉米超高产合理施肥提供依据。结果表明,夏玉米施氮显著增产,增产幅度为9.62%~15.95%,氮肥后移比习惯施氮增产2.27%~5.33%。超高产夏玉米吐丝后氮素吸收积累量占总积累量的40.30%~47.78%,保证后期氮素养分充足供应对于夏玉米达到超高产水平至关重要;氮肥后移可促进超高产夏玉米后期的氮素吸收积累,降低夏玉米茎和叶片氮素的转运率,显著增强灌浆期夏玉米穗位叶硝酸还原酶活性,提高灌浆期叶片游离氨基酸含量,增加蛋白质产量;氮肥后移比习惯施氮的氮肥利用率提高1.88%~9.70%、农学效率提高0.96~2.21 kg kg-1,以“30%苗肥+30%大喇叭口肥+40%吐丝肥”方式施用氮肥的产量和氮肥利用效率最佳。 相似文献
7.
长期定位施肥对夏玉米氮代谢的影响 总被引：5，自引：1，他引：4
基于 30年的长期定位试验, 研究了长期定位施肥对夏玉米氮代谢的影响。随施肥量增加,氮代谢旺盛,吐丝后穗位叶NR活性高,其中M2N2处理NR活性平均比对照提高了4.0%,其次是M2N1、N2PK、M1N2,分别比对照提高了3.7%、3.4%、3.1%。穗位叶的游离氨基酸和蛋白质含量也表现为与NR活性类似的趋势。M2N2处理游离氨基酸和蛋白质含量与对照比较差异显著。分别比对照提高了19.6%和22.2%。其次M2N1、N2PK、M1N2处理。游离氨基酸含量分别比对照提高了17.9%、16.7%、和15.4%。蛋白质含量分别比对照提高了18.5%、18.4%和17.9%。有机肥氮肥配施处理,穗位叶NR活性在籽粒形成期间维持高活性时间长,穗位叶中的可溶性蛋白含量高。氮磷钾肥配施处理穗位叶NR活性、可溶性蛋白含量显著高于氮磷、氮钾处理。 相似文献
8.
不同氮肥模式对冠层结构及部分生理和农艺性状的影响 总被引：10，自引：0，他引：10
以郑单958为试验材料,设基肥低氮、基肥高氮、第1次氮肥在拔节期施入和不施氮4个处理,研究了施氮模式对冠层结构及部分生理和农艺性状的影响。结果显示,施氮处理各指标均优于不施氮处理。适当减少基肥氮量,具有以下优势,(1)在保证苗期氮肥供给的同时,每公顷节肥90 kg;(2)改善了冠层结构,增加了群体底层的透光率,使穗上叶和整株的茎叶夹角更紧凑,与基肥高氮处理相比分别减少4.33°和4.67°,同时降低了株高和穗位高,缩短了基部节间长度,有效防止茎秆倒伏;(3)与前期高氮处理相比,基肥低氮在灌浆初期叶片的叶绿素相对值和全氮含量均处于较高水平;(4)基肥低氮处理提高了单位面积的株数,并减少了秃尖长度,同时千粒重和穗粒数有所增加,最终获得较高产量。第1次氮肥在拔节期施入,前期控氮时间过长,营养元素失衡,苗期发育不良,不利于产量形成。 相似文献
9.
1961—2010年宁夏灌区主要作物需水量时空分布特征 总被引：2，自引：0，他引：2
明确气候变化背景下作物需水量的时空分布特征是水资源高效利用和作物合理布局的重要依据。基于宁夏引黄灌区13个气象台站的气象数据及作物生育期数据,利用FAO推荐的彭曼公式和订正的作物系数,计算了1961—2010年宁夏灌区主要作物（春小麦、玉米、水稻、冬小麦）全生育期及不同发育阶段有效降水量及需水量,分析了其时空分布特征,并计算了各作物不同发育阶段灌溉需水量及需水强度。结果表明：1961—2010年宁夏灌区秋粮作物（水稻、玉米）全生育期有效降水量是夏粮作物（春/冬小麦）的2倍,1961—2010年宁夏灌区水稻、玉米生育期有效降水量为降低趋势,春小麦、冬小麦为增加趋势。高值区分布在石炭井、灵武和中宁,北部的石嘴山各站为低值区。宁夏灌区作物需水量从大到小依次为水稻、玉米、冬小麦、春小麦,灌溉需水量在不同发育期的分布和需水量的分布相似,北部的石嘴山各站及中宁为高值区。1961—2010年宁夏灌区4种作物全生育期及不同发育阶段需水量也呈显著增加趋势。所有作物需水强度均在拔节（返青）后开始明显增加,春小麦、冬小麦需水强度开花—乳熟阶段最大,玉米需水强度拔节—开花阶段、开花—乳熟阶段最大,水稻拔节后需水强度一直较大,乳熟—成熟阶段达最大。 相似文献
10.
D. M. Hegde 《Journal of Agronomy and Crop Science》1986,157(4):227-234
Studies were carried out at the Indian Institute of Horticultural Research, Bangalore during winter seasons of 1982—83 and 1983—84 to analyse the growth rhythm of onion in relation to irrigation and N fertilization. It was observed that irrigation at 0.45 to 0.65 bar soil water potential recorded higher dry matter accumulation and distribution, leaf area index (LAI), leaf area duration (LAD), leaf area ratio (LAR) and crop growth rate (CGR) during most of the stages, while net assimilation rate (NAR) and relative growth rate (RGR) were not markedly affected. Highest harvest index was noticed with irrigation at 0.65 bar.
Nitrogen fertilization significantly increased dry matter accumulation and distribution into different parts, LAI, LAD, LAR, CGR and harvest index. Although NAR and RGR showed an increasing trend with N fertilization, the effect was not significant during most of the stages. There was no significant interaction between soil water potential and N fertilization on any of the growth parameters. 相似文献
Nitrogen fertilization significantly increased dry matter accumulation and distribution into different parts, LAI, LAD, LAR, CGR and harvest index. Although NAR and RGR showed an increasing trend with N fertilization, the effect was not significant during most of the stages. There was no significant interaction between soil water potential and N fertilization on any of the growth parameters. 相似文献
11.
硫对不同氮水平下小麦旗叶氮硫同化关键酶活性及产量的影响 总被引：6，自引：0，他引：6
在大田条件下,以豫麦34为试材,研究了2个施氮水平（330和240 kg .hm-2）下施用纯硫0、60、100 kg.hm-2对小麦旗叶氮、硫同化关键酶活性及其产量的影响。结果表明,两种氮素水平下施硫对小麦旗叶中硝酸还原酶（NR）、谷胺酰氨合成酶（GS）、谷氨酸-丙酮酸转氨酶（GPT）活性均有影响。高氮水平下随施硫量的增加NR活性降低,GS活性提高,GPT活性在灌浆中期也表现出与GS活性相同的趋势,中氮水平下表现为随施硫量的增加NR活性提高,GS活性S60处理显著高于其他处理,GPT活性不同施硫处理间差异不明显。表明高氮条件下施硫抑制了NR活性,但提高了GS、GPT活性,中氮条件下施硫提高了NR和GS活性。两种氮素水平下乙酰丝氨酸水解酶（OASS）活性均随施硫量的增加而降低,尤其高氮和低硫条件下OASS活性升高。两种施氮水平下干物质积累量均随施硫量的增加而提高。氮和氮硫互作对籽粒产量的影响达到显著水平,硫对籽粒产量的影响达到极显著水平,两种氮素水平下均随施硫量的增加而提高,N330水平显著低于N240水平,N330水平下S100和S60 与对照相比达显著水平,N240水平下,施硫处理籽粒产量均显著高于对照。两种氮素水平下施硫处理千粒重均较对照显著提高,但穗数和穗粒数差异不显著,无论何种施氮水平下,千粒重提高是产量增加的主要原因。 相似文献
12.
不同缓释肥水平对超高产夏玉米产量及群体质量的影响 总被引：6，自引：2，他引：4
以玉米品种苏玉29、苏玉30为材料,设置7个缓释肥水平（N 0、270、315、360、405、450、495 kg/hm2）进行大田试验,研究不同生育阶段的叶面积指数、干物质积累及其对产量形成的作用。结果表明：（1）随着施氮量增加,籽粒产量呈单峰变化趋势,在N 450 kg/hm2水平下达最大值,两品种（苏玉29、苏玉30）分别为16193、14040 kg/hm2,且两品种均在N 405 kg/hm2水平下达边际产量。（2）高产处理下玉米群体干物质积累速率及叶面积指数在灌浆中前期大,干物质积累量多,中后期下降缓慢。对干物质积累的Richards方程解析表明,与对照相比,高产条件下干物质积累速率最大时的日期推迟了10天,且越晚产量越高;生长活跃期平均延长了9天,最大干物质积累速率平均提高了43.5%。因此,通过缓释肥运筹,降低花后叶面积指数及干物质积累下降速率,推迟干物质积累速率最大时的日期,延长生长活跃期,最终提高籽粒产量。 相似文献
13.
不同模式下春玉米物质生产与群体光合性能研究 总被引：1，自引：0，他引：1
为构建高产春玉米良好的群体结构,提高春玉米光能利用率,充分发挥春玉米的增产潜力,在大田试验条件下,从玉米品种、密度和肥料管理方面研究了3种模式（农户模式、优化模式、高产模式）对春玉米物质生产与群体光合生理指标的影响。结果表明：优化模式和高产模式较农户模式分别增产10.79%、27.62%,秃尖长度显著减少。3种模式的叶面积指数(LAI),群体光合势(LAD),干物质累积(DMA)以及生长率(CGR)规律依次为高产模式>优化模式>传统模式。由此证明,优化品种、合理增密以及加强养分资源管理是春玉米获得高产的关键措施。 相似文献
14.
P. Ramesh 《Journal of Agronomy and Crop Science》2000,185(2):83-89
A field experiment was conducted at Coimbatore (11° N, 77° E), India during the 1996 and 1997 crop seasons, using four commercial sugarcane varieties (Co 8021, Co 419, Co 8208 and Co 6304), to study the effect of three levels of drought (severe, moderate and control) during the formative phase (60–150 days after planting) on growth determinants and their relationship with dry matter accumulation. The reduction in dry matter content was 60.8, 52.4 and 25.9 % in severe drought and 46.3, 36.3 and 15.1 % in moderate drought at the ends of the formative, grand growth and maturity phases, respectively. High net assimilation rate, optimum leaf area index, high crop growth rate and an early shift in dry matter allocation to the stem were found to be desirable for higher biomass production, especially under water‐limited drought conditions. Measurement of growth parameters such as net assimilation rate, relative growth rate, leaf area index and leaf area duration under drought and crop growth rate and stalk elongation rate under normal irrigated conditions, particularly during the formative phase, might help to predict total dry matter at harvest. Leaf area ratio was not found to correlate with total dry matter at harvest in either drought or normal irrigated conditions. 相似文献
15.
施氮量与地膜覆盖对长江中游春玉米产量性能及氮肥利用效率的影响 总被引：17，自引：0，他引：17
以宜单629为试验材料,于2012-2013年在湖北武穴通过大田试验,研究施氮量和地膜覆盖对长江中游春玉米产量及其性能参数的调节效应以及氮肥利用效率的影响。结果表明,增施氮肥促进春玉米生长发育,抽雄期和吐丝期提前8~12 d,延长籽粒灌浆期2~6 d,全生育期减少2~7 d;地膜覆盖促进种子萌发和玉米植株发育,种子出苗提前7~8 d,抽雄期和吐丝期提前6~11 d,生理成熟期提前3~6 d。增施氮肥和地膜覆盖优化长江中游春玉米产量性能参数,增施氮肥使平均叶面积指数(MLAI)提高81.18%~112.38%,平均净同化率(MNAR)提高19.20%~25.82%,穗粒数(GN)和千粒重(GW)增加72.61%~95.30%和13.09%~21.26%;同等施氮条件下,地膜覆盖提高MLAI (11.12%~17.12%)、MNAR (0.80%~10.66%)、HI (0.44%~6.50%)、GN (7.02%~16.07%)和GW (5.64%~7.93%);由于产量性能参数间的超补偿作用,增施氮肥和地膜覆盖使春玉米籽粒产量提高6.80%~24.66%和7.16%~22.19%。施氮量增加显著降低春玉米氮肥利用效率,氮肥偏生产力(PFPN)和氮肥农学利用效率(ANUE)分别降低31.34%~51.20%和30.39%~42.12%;地膜覆盖促进春玉米的氮素吸收能力,显著提高春玉米氮肥利用效率,PFPN和ANUE分别提高18.30%~31.67%和25.83%~56.80%。统筹考虑长江中游春玉米产量性能优化补偿增产机制和氮肥利用效率特征,可选用优化施氮量202.5 ~270.0 kg hm-2和覆膜增温降渍,其产量可达8995~9220 kg hm-2。 相似文献
16.
D. M. Hegde 《Journal of Agronomy and Crop Science》1988,160(5):296-302
Analysis of growth and yield of watermelon in relation to irrigation and N fertilization carried out at the Indian Institute of Horticultural Research, Bangalore, during 1983–84 and 1984–85 indicated that frequent irrigations when the soil matric potential at 15 cm depth reached -25 kPa resulted in maximum dry matter accumulation and distribution, leaf area index (LAI), leaf area duration (LAD), net assimilation rate (NAR) and crop growth rate (CGR) leading to higher fruit yield as compared to irrigations at -50 and -75 kPa. Imposing a stress of -75 kPa either during pre-flowering or flowering or fruit development phase adversely affected various growth parameters resulting in reduced yield as compared to that irrigated uniformly at -25 kPa. Increasing levels of N fertilization increased the dry matter accumulation and distribution through higher LAI, LAD and CGR and contributed larger proportion of the dry matter to fruits resulting in higher fruit yield. 相似文献
17.
以陆地棉早熟品种中棉所58和中熟品种邯郸109为材料,研究子叶衰老过程中氮素的再利用率（NRE）及氮代谢相关指标的变化。结果表明：子叶衰老过程中,单位面积总N含量（NPA）逐渐降低,中棉所58 NRE为69.26%,邯郸109为54.45%;叶绿素、可溶性蛋白质含量和硝酸还原酶（NR）活性先上升后降低,NR最先降低,中棉所58和邯郸109分别在9 d、14 d开始下降;中棉所58各指标比邯郸109早下降4～8 d。谷氨酸脱氢酶（GDH）活性先下降后上升,表明GDH可能是氮素再利用的关键酶。 相似文献
18.
冬小麦-夏玉米“双晚”种植模式的产量形成及资源效率研究 总被引：14，自引：2，他引：12
为了进一步明确黄淮平原冬小麦晚播、夏玉米晚收的“双晚”增产及资源高效的效应,选用2个中熟冬小麦品种和2个中晚熟夏玉米品种,于2006—2008年先后在河南温县和焦作进行大田试验,研究作物群体物质生产、产量形成参数定量指标及光温资源的分配利用。结果表明,冬小麦晚播产量降低不明显,夏玉米晚收产量显著提高747~2 700 kg hm-2,“双晚”周年产量21 891~22 507 kg hm-2,比对照提高442~2 575 kg hm-2。冬小麦晚播平均叶面积指数、每平方米穗数和穗粒数降低,但平均净同化率、收获指数和粒重提高达5%显著水平;夏玉米晚收平均叶面积指数、收获指数、生育期天数和粒重均显著提高。“双晚”栽培优化了周年资源分配,提高生育期与光、温资源变化的吻合度,其生产效率分别提高2.22%~10.86%和0.47%~11.56%。小麦和玉米品种的遗传类型是影响“双晚”栽培技术的关键。因此,选用小麦晚播早熟高产和玉米长生育期晚熟品种,通过有效调节资源配置,将小麦冗余的光温资源分配给C4高光效作物玉米,是提高周年高产高效的重要途径。 相似文献
19.
长期施用有效微生物肥对冬小麦-夏玉米生长和产量的影响 总被引：5，自引：0，他引：5
在多年连续定位试验研究的基础上,研究了不同施肥方式对冬小麦、夏玉米生长和产量的影响。结果表明:EM微生物堆肥能明显增加冬小麦和夏玉米的产量。EM微生物堆肥处理的年均总产比等量传统堆肥增产8.3%~8.9%,其中冬小麦增产8.3%,夏玉米增产8.2%~9.4%。EM微生物堆肥能在一定程度降低土壤容重,增加土壤含水量,改善作物的生长环境。EM微生物堆肥处理的冬小麦、夏玉米总光合势比等量传统堆肥分别高5%~36%,5.2%~14.3%,比化肥处理分别高19%~72%,19.6%~46.4%,随EM微生物堆肥施用量的增加差异更明显。EM微生物堆肥比较高的光合势加快了干物质的积累速度,从而提高了冬小麦、夏玉米的群体生长速率。 相似文献
20.
Sustainable N management of intensive vegetable crops requires accurate and timely on-farm assessment of crop N status. Proximal fluorescence-based sensors are promising tools for monitoring crop N status, by providing non-destructive optical measurements of N-sensitive indicator compounds such as chlorophyll and flavonols. The ability of the Multiplex® fluorescence sensor to determine crop N status was evaluated in two indeterminate cucumber crops grown in contrasting seasons (autumn and spring). Three fluorescence indices, leaf chlorophyll (SFR) and flavonols (FLAV) contents, and their ratio (Nitrogen Balance Index, NBI) were evaluated, and their consistency between the two crops compared. Actual crop N status was assessed by the Nitrogen Nutrition Index (NNI), calculated as the ratio between the actual and the critical crop N contents (i.e., the minimum N content for maximum growth). There were strong relationships between each of SFR, FLAV and NBI with crop NNI, for most weekly measurements made throughout the two crops. For the three indices, coefficients of determination (R2) were mostly 0.65–0.91 in the autumn crop, and 0.71–0.99 in the spring crop. SFR values were generally comparable between the two crops, which enabled the derivation of common relationships with NNI for individual phenological phases that applied to both cropping seasons. FLAV and NBI values were not comparable between the two crops; FLAV values were appreciably higher throughout the spring crop, which was attributed to the higher solar radiation. Consequently, phenological relationships of FLAV and NBI with NNI were established for each individual cropping season. Our findings suggested that SFR was the most consistent index between cropping seasons, and that NBI was the most sensitive index within each season. Regardless of the index and crops, all fluorescence indices were weakly related to crop NNI during the short vegetative phase while stronger relationships were found in the reproductive and harvest phases. This study also showed that the three fluorescence indices were sensitive to and able to distinguish deficient from optimal crop N status, but that they were insensitive to discriminate optimal from slightly excessive N status. Overall, this study demonstrated that fluorescence indices of chlorophyll content (SFR), flavonols content (FLAV) and nitrogen sufficiency (NBI) can be used as reliable indicators of crop N status in cucumber crops; however, there was variability in FLAV and NBI values between cropping seasons and a lack of sensitivity in the range of optimal to slightly excessive crop N status. 相似文献