Mixed Compound of DCPTA and CCC Increases Maize Yield by Improving Plant Morphology and Up-Regulating Photosynthetic Capacity and Antioxidants

DCPTA (2-diethylaminoethyl-3, 4-dichlorophenylether) and CCC (2-chloroethyltrimethyl- ammonium chloride) have a great effect on maize growth, but applying DCPTA individually can promote the increase of plant height, resulting in the rise of lodging percent. Plant height and lodging percent decrease in CCC-treated plants, but the accumulation of biomass reduce, resulting in yield decrease. Based on the former experiments, the performance of a mixture which contained 40 mg DCPTA and 20 mg CCC as active ingredients per liter of solution, called PCH was tested with applying 40mg/L DCPTA and 20mg/L CCC individually. Grain yield, yield components, internode characters, leaf area per plant, plant height and lodging percent as well as chlorophyll content, chlorophyll fluorescence, enzymatic antioxidants, membranous peroxide and organic osmolyte were analyzed in two years (2011 and 2012), using maize hybrid, Zhengdan 958 (ZD 958) at density of 6.75 plants m^-2. CCC, DCPTA and PCH were sprayed on the whole plant leaves at 7 expanded leaves stage and water was used as control. Compared to control, PCH significantly increased grain yield (by 9.53% and 6.68%) from 2011 to 2012. CCC significantly decreased kernel number per ear (by 6.78% and 5.69%) and thousand kernel weight (TKW) (by 8.57% and 6.55%) from 2011 to 2012. Kernel number per ear and TKW increased in DCPTA-treated and PCH-treated plants, but showed no significant difference between them. In CCC-treated and PCH-treated plants, internode length and plant height decreased, internode diameter increased, resulting in the significant decline of lodging percent. With DCPTA application, internode diameter increased, but internode length and plant height increased at the same time, resulting in the augment of lodging percent. Bending strength and puncture strength were increased by applying different plant growth regulators (PGRs). In PCH-treated plants, bending strength and puncture strength were greater than other treatments. Compared to control, the bending strength of 3rd internode was increased by 14.47% in PCH-treated plants in 2011, increased by 18.40% in 2012, and the difference was significant. Puncture strength of 1st, 3rd and 5th internode was increased by 37.25%, 29.17% and 26.09% in 2011 and 34.04%, 25% and 23.68% in 2012, compared to control. Leaf area and dry weight per plant reduced significantly in CCC-treated plants, increased in DCPTA-treated and PCH-treated plants from 2011 to 2012. Chlorophyll content and chlorophyll fluorescence improved with CCC and DCPTA application. Due to the additive effect of DCPTA and CCC, PCH showed the significant effect on chlorophyll content and chlorophyll fluorescence. Compared to control, total enzyme activity (SOD, POD, CAT, APX and GR) and soluble protein content increased, malonaldehyde (MDA) and hydrogen peroxide (H₂O₂) content reduced in PCH-treated plants. The transportation of soluble sugar from leaf to kernel improved significantly at the late silking stage. The research provided the way for the further use of DCPTA and CCC into the production practice.     

Experiments with CCC on wheat: effects of spacing, nitrogen and irrigation

In experiments with spring and winter wheat at Rothamsted and Woburn during 4 years CCC increased yield at close spacing (4 in) (10 cm) more than at usual spacing (8 in) (20 cm), but there was no interaction between spacing and yield. Some experiments tested up to 2·4 cwt/acre (300 kg/ha) N to see whether yields continued to increase with more than usual amounts of N, when CCC prevented lodging. There was no evidence of this. When a short dry spell occurred at ear emergence, yield of spring wheat was increased by 6 cwt/acre (750 kg/ha) by CCC and 10 cwt (1250 kg) by irrigation. CCC probably improves yield in these conditions because the larger root system it causes enables more ear-bearing shoots to survive. CCC increases yield in two ways, either by increasing ears or grain per ear. In an unlodged crop CCC usually makes the grains smaller, but by preventing lodging it can also increase size. Usually CCC decreases the leaf area per shoot. The flag leaf may be smaller, unchanged or larger than those of untreated plants. There was no obvious connexion between flag-leaf area and grain yield; when CCC decreased flag-leaf area duration by 25 %, grain yield was unchanged. The results suggest that using CCC gives a more than even chance of a profitable yield increase.     

不同配比施肥对马尾松幼苗生长特征的影响

为获得马尾松幼苗最佳施肥配方,该文以1年生马尾松幼苗为试验材料,采用L₁₆（4³）正交设计,并通过测定幼苗苗高、地径、生物量、叶绿素含量、叶片N、P、K含量,探讨不同N、P、K配比施肥对马尾松幼苗生长特征影响。结果表明：（1）不同配比施肥处理间马尾松幼苗苗高、地径、生物量、质量指数、叶绿素和养分含量存在显著差异,其中,处理12生物量、质量指数、叶绿素a和总叶绿素含量、隶属值最高。（2）施N对幼苗生长及生理指标均有极显著影响;施K对苗高、地径、地上生物量、总生物量有显著影响,对叶绿素和针叶养分有极显著影响;施P对叶绿素a、叶绿素b、针叶N和P含量有极显著影响,对苗高、地下生物量、总叶绿素含量有显著影响。（3）施N对苗高、地径、地上生物量、总生物量、质量指数、叶绿素a含量、总叶绿素含量和针叶N含量的影响最大,K次之,P最小。各因素对地下生物量和针叶P含量的影响均表现为N>P>K。（4）N3水平利于幼苗苗高地径的生长及生物量的积累,N4水平利于叶绿素a和总叶绿素含量及针叶N、P含量的积累,P4水平利于生物量、叶绿素含量和养分P含量的积累...     

Effects of watering regime and nitrogen application rate on the photosynthetic parameters,physiological characteristics,and agronomic traits of rice

Water and nitrogen (N) are two of the most important abiotic factors limiting rice yield. However, a little information is available on why a moderate water and N interaction significantly increase rice biomass, from the point of view of photosynthetic physiology. A pot experiment with three water regimes [continued flood (CF), alternate wetting and moderate drying (WMD), and alternate wetting and severe drying (WSD)] and four N application levels (no nitrogen, N0; 90 kg hm^?2, N1; 180 kg hm^?2, N2; 270 kg hm^?2, N3) was carried out to investigate this problem. Results demonstrated that WSD significantly inhibited rice height, leaf area, chlorophyll content, photosynthesis, and yield at the four different N levels, as compared to that with CF and WMD. However, WMD substantially alleviated these reductions, and their values were not significantly different from those of CF. Contents of leaf soluble protein and total chlorophyll in WMD were increased compared to the WSD, and this mitigating effect was beneficial to the increase of rice photosynthesis and yield development. Photosynthesis in rice leaf was significantly affected by water status but not N level. Analysis of variance demonstrated a significant effect of water on spikelet number, which indicates that the reduction of spikelet number under water stress may be the major reason for its low yield. Therefore, we concluded that WMD could be considered as an effective water management regime to obtain high yield in rice production, and its strengthened drought tolerance was closely associated with the higher dry matter and in the physiological characteristics including an increase in spikelet number, chlorophyll and soluble protein contents, and photosynthetic rate.     

Physiological response of dwarf wheat to chlorocholinechloride under soil moisture stress

Spraying of CCC (500 ppm) on wheat cv. Kalyan Sona-227 averted the adverse effect of soil moisture stress at the anthesis phase, by maintaining a higher level of chlorophyll, nucleic acids and protein content and acidity of the tissues. Treated plants after recovery from moisture stress yield even more than the untreated plants.     

不同光质补光对火龙果茎生理特性及开花结果的影响

为探究不同光质补光对火龙果茎生理特性的影响,该文采用红光、白光、蓝光3种不同光质对火龙果进行夜间补光,测定火龙果茎中可溶性糖、可溶性蛋白、叶绿素、线粒体蛋白、线粒体膜电位及细胞分裂素(CTK)、吲哚乙酸(IAA)、赤霉素(GA)3种内源激素的含量,并统计茎长、开花数、果实产量相关指标.结果表明:3种光质补光均可提高火龙...     

喜钙和嫌钙植物对外源Ca2+的生长生理响应

以喜钙植物伞花木和嫌钙植物大白杜鹃为实验材料,以Hoagland营养液并设置其Ca2+浓度分别为0、5、10、25、50mmol/L培养试验,比较不同浓度外源Ca2+对其生长、叶绿素含量、渗透调节和矿质元素积累的影响,探索喜钙植物生长的适应特征,为喀斯特地区喜钙植物嗜钙机制研究提供基础资料。结果显示:(1)随着外源Ca2+浓度的增加,伞花木植株高度、茎粗以及叶干重、叶长、叶宽和叶形指数均得到不同程度提高,叶绿素和可溶性蛋白质含量增加,脯氨酸和可溶性糖含量无显著变化;而嫌钙植物大白杜鹃的生长却受到抑制,叶绿素和蛋白质含量降低,脯氨酸和可溶性糖含量增加;当Ca2+浓度为50mmol/L时,伞花木叶绿素和蛋白质含量分别为2.99mg/g和17.10mg/g,大白杜鹃叶绿素和蛋白质含量分别为1.39mg/g和14.30mg/g。(2)在实验设置的钙范围内,Ca2+可促进伞花木对P、N吸收并稳定体内Ca、K动态;而低浓度的Ca2+(<10mmol/L)促进大白杜鹃对Ca累积,抑制N、P吸收。     

Cultivar Differences in Growth and Chloroplast Ultrastructure in Rice as Affected by Nitrogen

Plant growth, leaf protein and chlorophyll content, and chloroplastultrastructure as affected by nitrogen (N) were examined infour rice (Oryza sativa L.) cultivars grown in culture solutionunder controlled conditions. Increasing N concentration generallyincreased height and shoot dry weight of all cultivars. Cultivardifferences were significant at normal N level (40 ppm). Amongcultivars, IR8 was most responsive to increasing N, having thesignificantly highest shoot dry weight and protein content.Total chlorophyll and protein contents varied with cultivarand N, but chlorophyll a/b ratio remained constant. At the ultrastructurallevel, chloroplasts had generally well-developed grana and stromalamellae at 40 ppm.N. Chloroplasts at high N had from one tofour times as many grana as the N-deficient chloroplasts. Nitrogendeficiency reduced the size of the chloroplast, grana-stromalamellae and resulted in fewer poorly stacked grana. Increasingthe N level (120 ppm) above the normal level did not significantlyaffect chloroplast size of any cultivar, except for IR8 whichhad the largest chloroplast. A reduction in the number of starchgrains was observed in IR8, but more were present in ER36 underN-deficient conditions. The size of starch grains was not affectedby N and did not differ among cultivars. Plastoglobuli appearedto be larger under N-deficient conditions. Nitrogen had no effecton the number of plastoglobuli but cultivar differences existed.The highly N-responsive IR8 (based on dry weight) had the largestchloroplast which increased with N level. The increase in chloroplastsize accounted for the increase in both chlorophyll and proteincontents and, consequently, dry weight. Key words: Oryza sativa L., chloroplast, chlorophyll, protein     

Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators

In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO₂ assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of ¹⁴C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.     

高温胁迫下三唑酮对黄瓜幼苗某些生理性质的影响

研究了三唑酮浸种对黄瓜幼苗抗热性的影响。结果表明,高温胁迫下黄瓜幼苗子叶叶绿素a、b及可溶性蛋白质含量下降,Chla／b比值、游离脯氩酸和可溶性糖含量增加。20mg／L三唑酮浸种抑制了黄瓜幼苗子叶的叶绿素a、b和可溶性蛋白质含量的下降及可溶性糖含量的增加,但脯氨酸含量降低,Chla／b比值上升。恢复温度后子叶的叶绿素a、b及可溶性蛋白、脯氨酸和可溶性糖含量与胁迫后相比均有不同程度的下降,但三唑酮处理下降的幅度低于对照。综上结果,三唑酮增强了黄瓜幼苗的耐热性。     

添加生化抑制剂和腐植酸的稳定性增效尿素在黄土中的施用效果

采用田间盆栽试验,研究生化抑制剂与生物刺激素腐植酸结合制成的高效稳定性增效尿素肥料在黄土中的氮素转化特征、增产效果和氮素肥料表观利用率,以探明其施用效果,为开发适宜黄土施用的新型增效尿素肥料提供理论依据。本研究以不施氮肥(CK)和施尿素氮肥(N)为对照,在尿素中分别添加腐植酸(F)、N-丁基硫代磷酰三胺(NBPT)、3,4-二甲基吡唑磷酸盐(DMPP)和2-氯-6-三甲基吡啶(CP),以及腐植酸与3种生化抑制剂分别组合(NBPT+F、DMPP+F、CP+F)。结果表明: 与N处理相比,F、NBPT+F、DMPP+F和CP+F处理均能显著提高玉米的产量、叶片叶绿素含量、叶面积指数和植株吸氮量,对土壤铵态氮和硝态氮含量也有显著影响。与单独施用生化抑制剂相比,添加腐植酸可提高玉米叶片叶绿素含量。与CP相比,CP+F玉米的植株吸氮量、叶绿素含量、氮肥吸收利用率均显著提高;与NBPT相比,NBPT+F硝化抑制率提高10.7%,但玉米产量、叶面积指数、植株吸氮量和氮肥利用率等均有所降低;与DMPP相比,DMPP+F显著降低了玉米产量、叶面积指数、植株吸氮量、氮肥利用率和硝化抑制率等。综合玉米产量、植株吸氮量、氮肥吸收利用率以及土壤铵态氮、硝态氮含量等指标,在黄土地区施用尿素肥料时,建议添加腐植酸和CP以提升尿素性能,从而提高产量和肥料利用率。     

The inhibition by high concentrations of (2-chloroethyl)-trimethylammonium chloride (CCC) of chlorophyll and protein synthesis in excised barley leaf sections

Summary CCC at concentrations of 10^-3 M and higher inhibits chlorophyll synthesis and ³H-leucine incorporation into a protein fraction by barley leaf sections. Neither of these effects is reversed by exogenous GA₃. No effect of CCC was observed on oxygen uptake by the leaf sections. The results indicate that high concentrations of CCC may act through an inhibition of protein synthesis, rather than through a direct effect on endogenous gibberellin production.     

氮、磷、钾肥不同用量对花生生理特性及产量品质的影响

在田间条件下研究了氮、磷、钾肥不同用量对花生叶片生理特性及产量品质的影响.结果表明:与不施肥处理相比,花生分别单独施用氮、磷、钾肥可提高叶片叶绿素、可溶性蛋白质含量和光合速率,增加SOD、POD和CAT活性,降低MDA积累量,以施N300～450kg.hm-2、施P5O2150～225kg.hm-2、施K2O300～450kg.hm-2的效果最显著;对叶片光合性能的改善,氮肥的作用主要在前期,磷在中后期,钾肥前后期比较一致.施肥可显著提高花生荚果产量,随施氮量的增加花生产量显著提高,施磷、钾肥以中等施肥量(P5O2150kg.hm-2、K2O300kg.hm-2)花生产量最高,钾肥的增产作用大于氮、磷肥.少量施用磷、钾肥(P2O575kg.hm-2、K2O150kg.hm-2)可显著增加花生籽仁蛋白质和脂肪含量,少量施用氮肥(N150kg.hm-2)可显著增加蛋白质含量,大量施用氮肥(N450kg.hm-2)才可显著增加脂肪含量;磷肥对提高籽仁蛋白质和脂肪含量效果明显,氮肥对增加蛋白质含量作用较大,钾肥主要提高了可溶性糖含量.施用氮、磷、钾肥可增加花生籽仁的赖氨酸、蛋氨酸和油酸、亚油酸含量,提高油酸/亚油酸比值,从而改善花生营养品质,延长花生制品的货价寿命.     

Chemical Changes in Lolium temulentum L. after Treatment with (2-Chloroethyl) Trimethylammonium Chloride (CCC)

Two experiments with an inbred line of the summer annual Loliumtemulentum L. are described. The plants were grown under 18-hourdays in 8.5 cm pots containing pure vermiculite. The first experimentwas concerned with the effect of (z-chloroethyl) trimethylammoniumchloride (CCC) upon soluble carbohydrate content, and the secondwith the combined effects of CCC and nitrogen upon soluble carbohydrate,free amino-N, and chlorophyll content. Concentrations of CCCfrom 0.01–0.5 M inhibited growth and induced large increasesin the free sugar content of the plant. With 0.05 M CCC andabove, large amounts of fructosan were formed. Adequate nitrogensupply lowered the free sugar level and large amounts of free amino-N appeared. Crude protein content (per cent dry weight)was increased by CCC at low nitrogen levels but was less affectedwhen N was adequate. Chlorophyll production was stimulated inthe presence of CCC. The metabolic implications of the CCC-inducedchemical changes are discussed and a possible scheme for CCCaction is suggested.     

控失尿素对稻田氨挥发、氮素转运及利用效率的影响

通过田间试验,以普通尿素分次施用处理(CU)为对照,研究了控失尿素分次施用(LCUS)和一次施用(LCUB)对水稻田土壤氨挥发特征、水稻氮素营养状况、稻谷产量及氮肥利用效率的影响. 结果表明: 普通尿素分次施用、控失尿素分次施用和控失尿素一次施用条件下,生育期氨挥发总量占总施氮量的比例分别为15.8%、13.4%和19.7%. 与普通尿素分次施用处理相比,控失尿素分次施用处理可降低土壤氨挥发损失量4.4 kg N·hm^-2,降幅达18.0%,而控失尿素一次施用处理稻田土壤氨挥发总量却增加了7.2 kg N·hm^-2,增幅达24.7%. 与普通尿素分次施用处理相比,控失尿素分次施用处理的水稻叶片叶绿素、籽粒和茎叶氮含量与氮素积累量、稻谷产量均有不同程度提高,氮肥利用率显著提高了7.6%,但氮素转运量、转运率和对穗氮贡献率均显著降低,而控失尿素一次施用处理的水稻叶片叶绿素、籽粒和茎叶氮含量与氮素积累量以及氮肥利用率均显著降低,氮素转运量、转运率、对穗氮贡献率以及稻谷产量无显著差异. 综上所述,控失尿素分次施用处理可以在保证稻谷稳产的同时,有效降低稻田土壤氨挥发损失,改善植株氮素营养状况,显著提高氮肥利用效率.     

Improved salt tolerance of melon (Cucumis melo L.) by the addition of proline and potassium nitrate

A pot experiment was carried out under glasshouse conditions with melon (Cucumis melo) cv. “Tempo F1” in a mixture of peat, perlite and sand (1:1:1) to investigate the effects of external proline and potassium nitrate applications to salinity-treated (150 mM) plants with respect to fruit yield, plant growth, some physiological parameters and ion uptake. Treatments were—(i) control (C): plants receiving nutrient solution, (ii) salinity treatment, as for control plus 150 mM NaCl. Salinity treatment was combined with or without either 5 mM supplementary KNO₃ or 10 mM proline. The salt treatment (150 mM NaCl) led to significant decreases in plant growth, fruit yield, relative water content (RWC), stomatal density, uptake of Ca²⁺, K⁺ and N, and chlorophyll a and b contents, accompanied by significant increases in Na⁺ uptake, proline concentration and membrane permeability. Supplementary KNO₃ and proline treatments significantly ameliorated the adverse effects of salinity on plant growth, fruit yield and the physiological parameters examined. This could be attributed to the effects of all the external supplements in maintaining membrane permeability, and increasing concentrations of Ca²⁺, N and K⁺ in the leaves of plants subjected to salt stress.     

Effect of two plant growth retardants on steviol glycosides content and antioxidant capacity in Stevia (Stevia rebaudiana Bertoni)

Two greenhouse experiments were conducted to study the effect of two plant growth retardants, Chlorocholine chloride (CCC) and Paclobutrazol (PBZ), on growth, Steviol glycosides (SVglys) content and antioxidant capacity in Stevia (Stevia rebaudiana Bertoni). Five concentrations of CCC (0, 250, 500, 750 and 1,000 ppm) and PBZ (0, 6, 12, 18 and 24 ppm) with three replications were applied to Stevia plants as treatments based on completely randomized design. CCC was sprayed on Stevia shoots, but PBZ was applied as a drench. The obtained results showed that CCC reduced plant height but improved leaf and stem dry weight, especially with 750 ppm concentration. Total SVgly content and consequently SVglys yield were significantly reduced by CCC application, and 1,000 ppm of CCC concentration was more effective than other treatments. PBZ had no effect on Stevia height while it significantly enhanced stem and dry weight at 12 ppm. Moreover, PBZ remarkably increased total SVglys contents, SVglys yield, and Rebaudioside A/Stevioside ratio. Total antioxidant capacity significantly varied with CCC and PBZ and the highest activity was obtained with 1,000 and 12 ppm of CCC and PBZ, respectively. The results of these experiments indicated that, although CCC and PBZ are plant growth retardants and act as anti-gibberellins, only CCC reduced plant height and SVglys production in Stevia. On the contrary, PBZ at 12 ppm concentration, improved Stevia growth, SVglys production, and antioxidant capacity.     

Photosynthesis and Chlorophyll Fluorescence Characteristics in Relationship to Changes in Pigment and Element Composition of Leaves of Platanus occidentalis L. during Autumnal Leaf Senescence

The loss of chlorophyll and total leaf nitrogen during autumnal senescence of leaves from the deciduous tree Platanus occidentalis L. was accompanied by a marked decline in the photosynthetic capacity of O₂ evolution on a leaf area basis. When expressed on a chlorophyll basis, however, the capacity for light-and CO₂-saturated O₂ evolution did not decline, but rather increased as leaf chlorophyll content decreased. The photon yield of O₂ evolution in white light (400-700 nanometers) declined markedly with decreases in leaf chlorophyll content below 150 milligrams of chlorophyll per square meter on both an incident and an absorbed basis, due largely to the absorption of light by nonphotosynthetic pigments which were not degraded as rapidly as the chlorophylls. Photon yields measured in, and corrected for the absorptance of, red light (630-700 nanometers) exhibited little change with the loss of chlorophyll. Furthermore, PSII photochemical efficiency, as determined from chlorophyll fluorescence, remained high, and the chlorophyll a/b ratio exhibited no decline except in leaves with extremely low chlorophyll contents. These data indicate that the efficiency for photochemical energy conversion of the remaining functional components was maintained at a high level during the natural course of autumnal senescence, and are consistent with previous studies which have characterized leaf senescence as being a controlled process. The loss of chlorophyll during senescence was also accompanied by a decline in fluorescence emanating from PSI, whereas there was little change in PSII fluorescence (measured at 77 Kelvin), presumably due to decreased reabsorption of PSII fluorescence by chlorophyll. Nitrogen was the only element examined to exhibit a decline with senescence on a dry weight basis. However, on a leaf area basis, all elements (C, Ca, K, Mg, N, P, S) declined in senescent leaves, although the contents of sulfur and calcium, which are not easily retranslocated, decreased to the smallest extent.     

Effects of Chlorocholine Chloride on Phytohormones and Photosynthetic Characteristics in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.)

Effects of chlorocholine chloride (CCC) on phytohormones and photosynthetic characteristics of Zhongshu 3, a potato (Solanum tuberosum L.) variety widely cultivated in south China, were studied by foliar CCC application on 24 and 28 days after emergence, that is, at the tuber initiation stage. It was found that on 42 days after emergence, that is, at the tuber bulking stage, spraying CCC increased indolacetic-3-acid (IAA) and zeatin (Z) contents but decreased abscisic acid (ABA) content in leaves. The content ratios of IAA/Z, IAA/ABA, Z/ABA, and (IAA + Z)/ABA in leaves treated with CCC were higher than those of the control. CCC plays a prominent regulating role in the photosynthesis of Zhongshu 3. The net photosynthetic rate (P _n), stomatal conductance (G _s), intercellular CO₂ concentration (C _i), and transpiration rate (T _r) of treated leaves were superior to those of controls at the tuber bulking stage. CCC markedly increased tuber yield and quality. The contents of sucrose and starch in tubers treated with CCC increased at the end of the vegetation period, whereas the contents of reducing sugars and solanine decreased. CCC at 2.0 g L⁻¹ was found to be the most effective concentration. Collectively, the results of this research identify phytohomonal metabolism and photosynthetic physiology of potato leaves as processes affected early after application of CCC resulting in significantly improved increases in tuber yield and quality.     

Effects of low nitrogen supply on relationships between photosynthesis and nitrogen status at different leaf position in wheat seedlings

Hydroponic experiments were conducted to investigate the effects of low nitrogen (N) nutrition on photosynthesis and its relationships with N status in wheat (Triticum aestivum L.). Two wheat cultivars, Zaoyangmai and Yangmai158, differing in low N nutrition tolerances, were used. The results show that under low N nutrition the area of the first top leaf was significantly reduced, while there was no significant difference in the top second and third leaf areas compared with the control for either cultivar. The net photosynthetic rate and chlorophyll content were significantly reduced in the top three leaves of Zaoyangmai, while no significant difference in these factors was observed in the top first and second leaves of Yangmai158 compared with control under N-limited conditions. The effective quantum yield of photosystem II (PSII) photochemistry and the maximal quantum yield of PSII photochemistry were only slightly altered in both cultivars, indicating that PSII was not damaged by low N nutrition. In addition, the non-photochemical quenching coefficient increased significantly in the top three leaves of Zaoyangmai, and only in the top third leaf of Yangmai158 under N-limited conditions. Furthermore, the ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and soluble protein contents decreased significantly in the top second and third leaves of Zaoyangmai, while no significant difference was observed in the top first and second leaves of Yangmai158 between low N nutrition and control. We concluded that in Yangmai158, N status changed less, and it maintained almost normal photosynthesis in young leaves, thus Yangmai158 could be more tolerance to low N nutrition.