Effects of Root Zone Temperature on Root Activity of Two Potato (Solanum tuberosum L.) Clones with Different Adaptation to High Temperature

Under controlled environmental conditions, the effect of optimal (20 °C) and supraoptimal (30 °C) root-zone temperature on root activity (respiration, soluble sugar content, ethylene release, nitrogen uptake and translocation) was studied in water culture with two potato clones differing in the heat tolerance of their root systems. Root respiration was little affected by raising temperature from 20 °C to 30 °C. However, in both clones assimilate allocation to the roots was strongly depressed. In the heat sensitive clone LT-1 exposed to 30 °C root-zone temperature, concentrations of soluble sugars in the apical root zone (0–10 mm) increased with time, presumably as a result of the cessation of root growth. The rate of nitrate absorption was not significantly affected by root-zone temperature. However, the export of nitrogen (xylem exudate) was depressed in the heat tolerant clone whereas in the heat sensitive clone the export of total nitrogen and the proportion of nitrate increased. No effect of root-zone temperature on ethylene release was observed in our experiments.     

转基因纯合四倍体马铃薯多酚氧化酶活性及同工酶谱的变异

选择14个已插入反义PPO基因的纯合四倍体马铃薯“GD-9-qc”系列,进行叶片、微型薯PPO活性检测和同工酶分析,结果表明,不同品系间的叶片、微型薯PPO活性存在极显著差异,其中2个品系的叶片及8个品系的微型薯PPO活性明显低于对照;供试转基因品系间的叶片PPO同工酶谱带的颜色深浅表现差异,所示结果与PPO活性检测基本一致;     

StGATA12对马铃薯(Solanum tuberosum)生长发育的影响

GATA转录因子是广泛存在于真核植物中的一类转录因子,它是锌指蛋白家族的成员,具有锌指结构,可以识别和特异性结合DNA序列。在调控植物开花时间、叶片延伸、花的发育以及光周期和光信号转导、叶绿素合成和碳、氮代谢调节等生物学过程中发挥重要作用。研究GATA家族的基因可以为作物增产提供一定的理论基础。本研究对转StGATA12基因的株系进行了生理生化分析,结果表明:转基因株系表现出叶面积、茎直径及单株结薯量增加的性状;叶绿素含量、淀粉含量增加;激素含量发生变化。由此可知,StGATA12转录因子在马铃薯叶绿素合成及激素平衡方面起着重要的调控作用。本研究初步阐明了StGATA12转录因子在马铃薯发育过程中的生物学功能和作用机制,丰富了植物GATA12基因的功能研究,并为培育优良的马铃薯新品种提供理论参考。     

Heritability, and Intra- and Inter-Generation Associations Between Tuber Yield and its Components in Potato (Solanum tuberosum L.)

The relative importance of the components of tuber yield in selection in early generations of a potato-breeding programme was studied. In seedling generation the number of tubers were more important than average tuber weight, whereas in clonal generations the average tuber weight was more important. Correlation coefficients between number of tubers and tuber yield varied from generation to generation whereas those of average tuber weight and tuber yield were more or less constant. Unlike the number of tubers, the average tuber weight of a genotype in a generation influenced its tuber yield in subsequent generations. The average tuber weight had higher heritability than the number of tubers and tuber yield.     

Effect of Soil Temperature on the Carbohydrate Status in the Potato Plant (S. tuberosum L.)

Seed tubers of the variety Ostara were raised in growth chambers of 16°C air temperature continuously. The vessels were placed in a water bath of automatic temperature regulation so that soil temperatures of 16°C and 28°C could be maintained. Four weeks after emergence the plants were treated with ¹⁴CO₂ and 24 hours later the plants were harvested. Three more treatments and time harvests followed in two weeks intervals. C-14 activity was determined in soluble carbohydrates, in insoluble carbohydrates, and in non extractable residues respectively of the various plant parts in order to obtain information about the translocation of assimilates in the plant.
While the plants at 28°C soil temperature reduced the soluble sugar levels to 50% up to 70 days after emergence, the plants at 16° brought it down to 33% much faster. — The C-14 activity in insoluble carbohydrates amounted to only 50 % in the plants at 28°C while at 16°C it was more than 2/3 (Tables 1 and 2). — The C-14 activity in non extractable residues is much less at 28°C than at 16°C (Tables 3 and 4). — The starch weight reaches only 30% of the value obtained at lower temperature 70 days after emergence (Table 5). — At the higher temperature starch is also increasingly transferred to the tubers but to a much lesser extent and not from the stems and stolons (Table 6).
Possible causes, particularly the role of phytohormones, and consequences are discussed.     

Agronomic Performance and Nutrient Concentration of Maize (Zea mays L.) as Influenced by Nitrogen Fertilization and Plant Density

A field experiment was conducted at Samaru, Nigeria to study the influence of nitrogen fertilization and plant density on the agronomic performance and nutrient concentration of maize ( Zea mays L.). The treatments were factorial combinations of five nitrogen fertilization rates (0, 50, 100, 150 and 200 kg N/ha) and three plant density levels (25000, 50000 and 75000 plants/ha).
Nitrogen fertilization up to 150 kg N/ha enhanced grain and stover yields and increased kernel number and weight up to 100 kg N/ha. Nitrogen supply also increased maize ear length. Increased N fertilization rates increased concentrations of N, K and Mg but had no effect on P and Ca concentrations. Higher grain yield was closely associated with higher N concentration in ear leaf; with 0.1 % change in N concentration causing 177 kg/ha change in grain yield. Increased plant density increased stover yield up to 50 or 75 thousand plants/ha but depressed kernel number and weight and ear length.     

弱光对西瓜植株生长及果实发育的影响

为明确弱光下西瓜果实难以正常膨大的问题,以西瓜‘苏蜜8号’为试材,通过田间遮阴模拟弱光试验,研究弱光对西瓜植株生长、果实发育的影响。结果表明,弱光对西瓜植株生长的影响从遮光处理开始就一直存在;授粉后的3~15天为西瓜果实快速膨大期,也是弱光影响西瓜果实膨大的关键时期。弱光能显著降低植株的株高、茎粗、叶数和叶大小,并能显著抑制植株光合作用和干鲜物质的积累。弱光使西瓜果肉细胞变小,数目变少;抑制西瓜果肉的细胞核内复制,进而影响西瓜果实的正常膨大。本研究可为西瓜栽培光环境管理和抗弱光栽培技术的研究及应用提供科学依据。     

Influence of a Triazole Plant Growth Regulator on Root and Shoot Development and Nitrogen Utilisation of Oilseed Rape (Brassica napus L.)

A factorial experiment with 3 nitrogen (N) levels and 4 application rates of the triazole type plant growth regulator (PGR), BAS 111 W = l-phenoxy-3-(1H-1,2,4-triazol-1-yl)-4-hydroxy-5,5-dimethylhexane, was conducted in hydroponics to study the influence on N uptake and morphological changes of oilseed rape. The following results were obtained:
–Increased N level of the nutrient solution increased plant height and root and shoot weight. Enhanced N uptake caused a higher N concentration of root and shoot.
–Increasing PGR application rates reduced plant height and shoot biomass production; this reaction was stronger at higher doses of N.
–Root weight, root length, root diameter and root surface area were increased by N application. None of these parameters was significantly altered by the PGR. This resulted in increased root-shoot-ratios at higher PGR rates.
–As a consequence of reduced shoot production PGR application resulted in increased concentrations of N. The root reacted similarly but to a lesser degree.     

Morphogenetic Effects of Different Mineral N-compounds on Roots of Maize (Zea mays L.), Spring Barley (Hordeum vulgare L.) and Broad Bean (Vicia faba L.)

Plants of maize ( Zea mays L.), spring barley ( Hordeum vulgare L.) and broad bean ( Vicia faba L.) were raised in tubes filled with a soil-sand mixture and supplied with nutrient solution. The nutrient supply was varied with regard to concentration and typ of compound of "N". Due to the relatively high concentrations of "N", dry matter of shoots and roots was reduced in comparison to the control; root morphology was affected in terms of root length and root thickness. The N-compounds, used in the experiment, exerted quantitatively different influences on dry matter production and root morphology, NH₄NO₃ being the N-form which had the weakest detrimental effects. There was no specific response to NH⁺₄ or NO⁻₃ but a strong influence could be shown for NH₄Cl and N_aNO₃. Probably not only the concentration of "N" and the form of "N" have a specific influence, but also the cations and anions associated with the N-containing ion are effective.     

Effects of Two Planting Systems on Soil Structure and Root Growth of Maize (Zea mays L.)

In 1994 two planting systems of maize—rotary hoe-sowing (RS) and plough (2 diskings) sowing (PDS)—were compared in the field with respect to their influence on the root growth of maize and on selected physical properties. Roots were sampled at the five-leaf stage (S:5) and the milk stage of the maize seeds (S:MS).
Generally, in the PDS planting system the roots were richer compared to the RS. At the S:5 stage the correlation coefficient between the physical properties and the toot system was considerably higher, while at the S:MS stage the corresponding correlation coefficient was much lower.
In the RS planting system, at 15 cm and 30 cm distances from the sowing rows, far fewer roots were observed than in the PDS one.     

Nutrient Management Effects on Light Interception, Photosynthesis, Growth, Dry-matter Production and Yield of Indian Mustard (Brassica juncea)

A field experiment was conducted on sandy loam acidic soil to study the effect of nutrient managements on light interception, photosynthesis, growth, biomass production and yield of Indian mustard [Brassica juncea (L.) Czern & Coss.]. Plant height, number of branches per plant, number of siliqua per plant, number of seeds per siliquae, 1000‐seed weight, seed and oil yield of Indian mustard improved at 100 % recommended rates of NPK (N‐P‐K at 80‐17.2‐33.2 kg ha^?1) + 10 t ha^?1 farmyard manure (FYM) (T₃) compared with 100 % NPK rate (T₂). It was also at par with 100 % NPK + 10 kg ha^?1 borax + 20 kg ha^?1 ZnSO₄ (T₆) and 50 % NPK + 10 t ha^?1 FYM +10 kg ha^?1 borax + 20 kg ha^?1 ZnSO₄ (T₁₀). The rate of photosynthesis increased due to appropriate nutrient management treatments (T₃, T₆ or T₁₀) with concomitant increase in photosynthetically active radiation, internal CO₂ concentration and rate of transpiration and decrease in stomatal resistance. Consequent upon the higher rate of photosynthesis, dry‐matter accumulation increased. The crop receiving nutrient treatment T₃ or T₆ maintained higher light interception ratio (LIR), leaf area index (LAI), biomass production, crop growth rate (CGR) and net assimilation rate (NAR) that resulted in greater rate of photosynthesis, harvest index and seed yield. Similarly, T₁₀ was equally efficient in registering greater LIR, LAI, CGR, NAR and seed yield of mustard. The average seed yields were 1692, 1683 and 1668 kg ha^?1 in T₃, T₆ and T₁₀, respectively, and these three treatments were significantly superior to T₂ (1332 kg ha^?1), control (723 kg ha^?1) and other treatments. Significantly greater seed oil contents of 41.30, 40.60 and 41.07 % were recorded in T₃, T₆ and T₁₀, respectively. Thus, significant improvement due to appropriate combination of NPK, FYM, borax and ZnSO₄ was observed for uptake of nutrients.     

Variability in Osmotic Stress Tolerance of Starch Potato Genotypes (Solanum tuberosum L.) as Revealed by an In Vitro Screening: Role of Proline,Osmotic Adjustment and Drought Response in Pot Trials

Solanum tuberosum (potato) as a drought sensitive plant is also one of the most promising plants to meet the demands for food and starch of a growing population. Distinguishing genotypes into tolerant and susceptible is therefore of utmost interest. We subjected eighteen potato genotypes and two wild species, S. tarijense and S. chacoense, to osmotic stress applied in vitro by addition of 0.2 m sorbitol to a solid medium. Here, we report that a ratio of root:shoot dry mass (DM) together with the SSI (stress susceptibility index, equivalent to drought susceptibility index by Fischer and Maurer, Aust. J. Agron. Res., 29, 1978) of shoot DM were found to be relevant parameters to characterize genotypes in vitro for their osmotic stress tolerance. Drought stress data from pot trials in a rainout shelter (2013 and 2015) correlated poorly with the data obtained in in vitro experiments. However, the most tolerant and most sensitive genotypes in vitro were also categorized to be more tolerant or sensitive than the average to drought stress in vivo. Both, under in vitro and in vivo conditions, proline displayed an increase under osmotic stress conditions in nearly all potatoes tested, but no direct correlations were found to stress tolerance. However, a genotype classified as tolerant displayed earlier proline accumulation. Proline is thought of as one factor for plants to withstand stressful conditions, but cannot be used to distinguish potato genotypes for their stress tolerance to osmotic stress in vitro. Analysis of the osmotic potential of in vitro and in vivo stressed plants displayed a general increase compared to the control.     

低温强光对超级杂交稻及其亲本苗期光合特性的影响

研究低温强光对两优培九和母本培矮64S（PA64S）以及父本中籼9311苗期叶绿素荧光参数和光合特性的影响。结果显示低温强光处理后，与父母本相比，两优培九的光合速率、PSⅡ原初光化学效率（Fv/Fm）和光化学猝灭系数（qP）降低和光化学猝灭系数（qN）增加较少，说明在低温强光下，超级杂交稻两优培九吸收的光能能较多的转化为化学能。试验结果表明在苗期杂交稻两优培九在低温强光下具有超亲偏母本的现象。     

基质、光照和温度对羊耳菊种子萌发的影响

为了研究羊耳菊种子的萌发特性,观察了不同基质、光照和温度等条件处理对羊耳菊种子萌发的影响.种子萌发试验的基质分别为纱布、滤纸及细河沙;光照条件分别为黑暗和自然光2种;萌发温度分别为10,15,20,25℃.结果表明:1)种子萌发最佳基质为细河沙;2)种子在光照条件下具有较高的萌发率;3)最适萌发温度为25℃,萌发率达53.75％.本研究可为羊耳菊资源利用提供科学依据.     

Effects of Light, Different Growth Media, Temperature and Salt Concentrations on Germination of Cotton Seeds (Gossypium hirsutum L. cv. Nazilli 87)

Laboratory experiments were conducted to study the effects of light, different growth media, temperature, and salt concentrations on the germination ratio, mean germination period, and the beginning of germination of cotton seeds, Gossypium hirsutum L., cv. Nazilli 87. All factors considerably affected the germination rate of cotton seeds, ranging from 47% at darkness to 96% at 16 h of artificial light. The mean germination period varied from 5.6 days at 15°C and 1.3 days at 30°C under illumination and lasted longer at dark. The germination ratio was 94 % without additional salt and decreased from 63 % at salt concentration of 175 mM NaCl 1⁻¹ to only 8.7 % at 300 mM 1⁻¹. The mean germination period ranged from 5.28 days to 13.50 days at salt concentrations of 0–300 mM NaCl l⁻¹, respectively.     

Growth and Yields of Cowpea (Vigna unguiculata (L.) Walp) as Influenced by Seed Characters, Soil Moisture and Season of Planting

Cowpea ( Vigna unguiculata L. Walp) is an important food legume grown under rainfed conditions in the tropics. However, the yield of this crop varies widely in most tropical ecosystems due to crop and environmental factors. Experiments were carried out to evaluate the effects of seed characteristics, soil moisture at planting and the season of crop establishment on growth and yield parameters of cowpea as these influence the productivity of the crop. Growth and yield of cowpea plants grown from small seeds with a high conductivity of their lea-chates were significantly lower than those grown from large seeds. Root growth of seedlings was most prominent under moderate soil moisture levels. Low soil moisture retarded root growth by reducing dry weights and suppressing the development of laterals. Shoot growth was more sensitive to increasing soil moisture stress than root growth. Planting cowpea in the wet season produced the highest yields. Within a season, growth and yield were higher when the crop was planted early. Establishment of the crop later in the season produced better quality seeds measured in terms of germination after controlled deterioration.     

生长延缓剂对槟榔苗期叶绿素含量与叶绿素荧光参数的影响

为探讨生长延缓剂对槟榔苗期矮壮的光合特性。于2006年6-11月以移栽45天后海南槟榔为材料,通过喷施250mg/L与500mg/L多效唑、40mg/L和80 mg/L烯效唑及清水5个处理,研究其对槟榔苗期叶绿素含量及叶绿素荧光参数的影响。结果表明：喷施多效唑与烯效唑均能显著增加苗期槟榔叶绿素含量,且使叶绿素荧光参数Fv/Fo,Fv/Fm,qP显著增加,而降低qN、NPQ非光化学猝灭系数,并以250mg/L多效唑处理效果较明显。说明适当浓度的多效唑处理可增加PSII反应中心开放比例,推动光合电子传递,提高槟榔叶片光合性能,起到壮苗目的。     

去早果枝对转基因抗虫棉生长发育与衰老进程的调控效应

 以转基因抗虫棉品种为材料,设置了2个播期和4种去早果枝方式（去基部1个、2个、3个果枝及不去果枝的对照）处理,研究去除早期果枝对棉花生长发育及衰老进程的影响。2年结果表明,去早果枝推迟了棉花的生育进程;去掉1个早果枝处理总果枝数与对照无差异,但去掉2个、3个果枝后明显低于对照,总果节数差异不显著;去早果枝显著提高了第1播期棉花叶面积指数和干物质积累量,去1个、2个和3个果枝处理的干物质积累量在2年中平均比对照高13.5%,17.5%,19.0%,但在第2播期差异不明显;去早果枝降低了第1播期棉花脱落率和烂铃率并提高了棉花的子棉产量,脱落率在2年中平均比对照降低4.5,5.8和9.0百分点,烂铃率平均降低2.2,4.5,4.8百分点;去1个和2个果枝处理的子棉产量在2年的第1播期中比对照平均高9.6%和8.1%,但在第2播期增产不明显,甚至减产。     

Effects of Nitrogen and Plant Density on Growth, Yield and Chemical Composition of Two Winter Wheat (Triticum aestivum L.) Cultivars

A field study was conducted on the winter wheat cultivars Arminda and Okapi , using two seed rates (80 and 160 kg/ha) and three N applications (40, 80 and 120 kg/ha).
The cultivars did not differ in total dry matter production but did differ in grain yield. The difference in grain yield was mainly attributable to a higher harvest index (HI).
Increased plant density reduced HI; it resulted in more shoots per m², but in a lower grain yield. The reduction in grain yield was caused by fewer kernels per ear and a lower 1000-grain weight in both cultivars.
A higher rate of N increased total dry matter production and grain yield, except in Okapi at the high plant density. The number of kernels per ear increased, but 1000-grain weight fell.
The higher the N applications, the higher the N-content of the roots was.
Total N yield was greater in Arminda than in Okapi. The cultivars differed in the amount of nitrogen they took up after anthesis.
The content of water-soluble carbohydrates (WSC) differed between the cultivars, N treatments and growth stages. Carbohydrate formed before anthesis accounted for 23 % of Arminda's grain yield and for 10 % of Okapi's grain yield.
The content of cell-wall constituents (CWC) depended on cultivar, growth stage and the rate of the N dressing. Differences in CWC were more pronounced in Arminda than in Okapi. During leaf, stem and ear development there was a strong increase in content and amount of CWC. Concomitantly, WSC decreased. This implies that a large consumption of WSC is necessary for the formation of CWC. The competition for the WSC, necessary for CWC and shoot and ear development influences kernel initiation. Per unit of dry matter Okapi contained more CWC than Arminda. This was not in agreement with differences in straw sturdiness.     

Influence of Different Soil Moistures during the Vegetative Phase of Development of Field Bean (Vicia faba L. var. minor) on Leaf Water Status, Photosynthesis Rate and Plant Growth

The effects of exposure in the vegetative phase of growth to 10-day spells of mild (30 % of field water capacity – fwc) and severe (20 % fwc) drought on leaf water status, photosynthesis rate, plant growth and distribution of dry matter were studied in field bean. Either drought level caused similar changes of leaf water status and reduced photosynthesis rates. In older leaves these drought effects were greater. Plants exposed to mild drought quickly recovered their full photosynthetic activity and growth rate when optimum water supply was restored, but after severe drought the slower rate of these processes persisted much longer. Reduced growth caused by drought was proportionally the same in stems, leaves and roots, so that the share of dry weights of these organs in total dry matter of whole plants was similar as in control.