Genotypic Differences in the Temperature Responses of Tropical Crops: II. SEEDLING EMERGENCE AND LEAF GROWTH OF GROUNDNUT (ARACHIS HYPOGAEA L.) AND PEARL MILLET (PENNISETUM TYPHOIDES S. & H.)

Mohamed, H. A., Clark, J. A. and Ong, C. K. 1988. Genotypicdifferences in the temperature responses of tropical crops.II. Seedling emergence and leaf growth of groundnut (Arachishypogaea L.) and pearl millet (Pennisetum typhoides S. &H.).—J. exp. Bot. 39: 1129-1135. Measurements of seedling emergence and leaf growth of five milletand seven groundnut genotypes were made at soil temperaturesranging from 7 to 27?C. The rate of seedling emergence (R_e)varied greatly between millet genotypes but R_e was remarkablysimilar in groundnut genotypes. In pearl millet there is a strongcorrelation between the rate of germination and the rate ofleaf production, hourly leaf extension and seedling emergence.The results are discussed in terms of the thermal time requirementsof various processes. Key words: Temperature, emergence, groundnut, millet     

Genotypic Differences in the Temperature Responses of Tropical Crops: III. LIGHT INTERCEPTION AND DRY MATTER PRODUCTION OF PEARL MILLET (PENNISETUM TYPHOIDES S. & H.)

Mohamed, H. A., Clark, J. A. and Ong, C. K. 1988. Genotypicdifferences in the temperature responses of tropical crops.III. Light interception and dry matter production of pearl millet(Pennisetum typhoides S. & H.).—J. exp. Bot. 39: 1137–1143. Leaf area development, light interception and dry matter productionof four contrasting pearl millet cultivars were investigatedat mean air temperatures of 19.5, 21, 26 and 31?C. Growth wasslowest as 19.5?C and fastest at 31?C. The canopies of the cultivarsvaried considerably with regard to their light transmissioncoefficients (K₁), from 0.47 for Sanio to 0.23 for Oasis andin their mean efficiency of energy conversion (e), from 1.0to 2.7 g MJ^–1. The ranking of the cultivars in these respectsis consistent with those for germination and early establishmentand early establishment reported in the preceding papers. Key words: Light, dry matter production, millet     

TDZ诱导花生幼叶的不定芽和体细胞胚发生的组织学观察

花生实生苗幼叶接种于MS TDZ 0.2mg/L NAA0.4mg/L诱导培养基上经诱导培养,继而转移到无激素培养基MS可获得不定芽和体细胞胚。组织学观察表明,花生不定芽和体细胞胚均起源于愈伤组织表层,不定芽为多细胞起源,而体细胞胚起源于单个胚性原始细胞。体细胞胚的发育经历多细胞原胚、球形胚、心形胚、鱼雷胚和子叶胚等时期发育成小植株。     

GERMINATION AND ATTACHMENT OF ZYGOTES OF HIMANTHALIA ELONGATA (L.) S. F. GRAY1

Germinating zygotes of Himanthalia elongata (L.) S. F. Gray have a prolonged stage free from rhizoids. The spherical zygote flattens when settling on a substratum and a rim-like structure develops at the periphery of the flattened base. Numerous rhizoids appear simultaneously 5–7 days after fertilization. The possible significance of the germling's shape and structure in relation to attachment is discussed.     

Time, Temperature and Germination of Pearl Millet (Pennisetum typhoides S. & H.): III. INHIBITION OF GERMINATION BY SHORT EXPOSURE TO HIGH TEMPERATURE

Seeds of pearl millet were germinated on wet filter paper attemperatures up to 50 ?C. In one experiment, the temperaturewas held at 50 ?C during imbibition and was then lowered to32 ?C or 25 ?C. Germination rate and the maximum fraction ofseeds germinating (G_m) both decreased as the time of exposureto 50 ?C increased. In contrast, exposure to 50 ?C after imbibitionfor 8 h slowed germination but did not significantly reduceG_m. When the ‘high’ temperature imposed after imbibitionwas reduced from 50 ?C to 45 ?C, there was a small reductionin the rate of germination but not in G_m. The responses haveimplications for the optimum time of sowing in the tropics whenmaximum daytime soil temperature at the depth of sowing is inthe range of 45–50 ?C. Key words: Pennisetum typhoides, Temperature, Germination     

Response to Temperature in a Stand of Pearl Millet (Pennisetum typhoides S. & H.): V. DEVELOPMENT AND FATE OF TILLERS

The development of individual tillers in stands of pearl milletwas investigated in a suite of temperature-controlled glasshousesmaintained at mean air temperatures of 19, 22, 25, 28 and 31?C. The rate of leaf appearance of individual tillers was similarto that on the main culm but later tillers produced fewer leaves.Apical dissection revealed that 2–5 leaf primordia failedto emerge from some tillers and the cessation of developmentpreceded any external signs of premature senescence by 3–4weeks. The concept of thermal time is used to determine when leaf appearanceceased on individual tillers. Tiller development stopped synchronouslyat about 430 ?Cd in all treatments, indicating that it was relatedto a common physiological or environmental condition. This periodcorresponded to the start of stem elongation and closure ofcrop canopy but because temperature has a major influence onboth it was impossible to reach a firm conclusion about themechanisms responsible for the cessation of tiller development.The yield and fate of individual tillers are also presented. Key words: Tiller development, Millet, Temperature     

Response to Temperature in a Stand of Pearl Millet (Pennisetum typhoides S. & H.): VII. FINAL NUMBER OF SPIKELETS AND GRAINS

An index which incorporates rates of plant growth and of development—athermal interception rate (TIR)/is used to analyse final spikeletand grain number in pearl millet. Growth rate was assumed proportionalto solar radiation intercepted (MJ per plant per day) and developmentalrate to the accumulation of degree days above a previously determinedbase of 10 °C. Measurements were assembled from experimentsin glasshouses with precise temperature control and from a fieldstudy in the tropics. The final number of spikelets was less sensitive to TIR thanthe final number of grains per plant. The critical period forthe determination of grain number is from floral initiationto anthesis (GS2 period). Key words: Temperature, Spikelets, Grains, Pearl millet     

Time, Temperature and Germination of Pearl Millet (Pennisetum typhoides S. & H.): I. CONSTANT TEMPERATURE

The germination of pearl millet (Pennisetum typhoides S. &H.) seeds was investigated at constant temperatures between12 ?C and 47 ?C on a thermal gradient plate. The rate of germination increased linearly with temperaturefrom a base T_b to a sharply defined optimum T_o beyond whichthe rate decreased linearly with temperature, reaching zeroat T_m. The linearity of the response both above and below T_oallowed time and temperature to be combined in a thermal timeat which a specified fraction of the seeds germinated. Withinthe population T_b and T_m were constant.     

SEEDS OF KOSTELETZKYA VIRGINICA (MALVACEAE): THEIR STRUCTURE,GERMINATION, AND SALT TOLERANCE. I. SEED STRUCTURE AND GERMINATION

Dormancy of Kosteletzkya virginica (L.) Presl. seeds is primarily due to the impermeability of the seed coat to water. The impermeable structure is assumed to be, in other Malvaceae, the palisade layer of the seed coat. The percentage of seeds capable of imbibition and germination increased with increasing time of storage at low temperatures, but the release from dormancy was not accompanied by decreased seed coat resistance to pressure. Under natural conditions, mechanical damage to the seed coat due to changes in temperature and/or abrasion may render the seeds water permeable. It is not clear what causes water permeability during storage under laboratory conditions. During seed maturation and drying, the inner epidermis of the tegmen partly separates from the rest of the seed coat and an air space, which makes the seed buoyant, is formed around the region of the chalazal cleft. The optimal temperature for germination of K. virginica seeds is between 28 and 30 C in light or darkness.     

Response to Temperature in a Stand of Pearl Millet (Pennisetum typhoides S. & H.): 4. EXTENSION OF INDIVIDUAL LEAVES

The leaf extension rate of millet plants was measured with auxanometersin temperature-controlled glasshouses. Temperature was the dominantenvironmental factor governing the rate of leaf extension. Theobserved linear relation between extension rate and meristemtemperature had a base temperature of 10 ?C and a less clearlydefined optimum of about 30–32 ?C. Leaf growth was expressed as extension per unit thermal time,mm (?C h)^–1, to examine the influence of saturation deficit,irradiance and ontogeny at different temperatures. Leaf extensionwas independent of saturation deficit below 3.0 kPA. Irradiance,ranging from 4–16 MJ m^–2 d^–1, had a greaterinfluence on the first five leaves than the subsequent onesbut there was a large effect of leaf position. The results arediscussed in relation to the growth of crop leaves in a tropicalclimate. Key words: Leaf extension, Millet, Temperature     

普通小麦与粗山羊草属间杂种的染色体构型及其后代的育性特征

利用3个推广品种(莱州953、山农辐63、陕7859)分别与原产地不同的抗白粉病的6份粗山羊草[Aegilops tauschii(Coss.)Schmal.]杂交,得到63个无胚乳的种子,将56枚幼胚接种到N6 0.5mg/L IBA 0.2 mg/L NAA的培养基上进行褓姆培养,得到37个植株。其中莱州953与粗山羊草的杂交结实率和成苗率较高,分别平均为8.58%和4.82%。粗山羊草对白粉病的抗性基因在不同的杂交组合中受到不同程度的改变或抑制。以莱州953为父本,分别与不同组合的杂种F_1回交,大多数组合均得到回交种子,回交结实率平均为1.70%;以莱州953作母本,与莱州953/Y225 F _1回交得到2粒种子,说明普通小麦与粗山羊草的杂种F_1也能产生少量有授精能力的花粉。以山农辐63为父本与山农辐63/Y219 F_1回交亦得到回交种子。通过对普通小麦与粗山羊草6个杂交组合的杂种F_1PMCMI染色体构型的分析,一般多出现14个左右单价体和一定频率的多价体,并观察到可能为A、B组染色体形成的异形二价体;粗山羊草的D组染色体和普通小麦的D组染色体联会正常,可发生自由重组,从而为将粗山羊草的有益基因导入普通小麦提供了细胞学依据。     

Response to Temperature in a Stand of Pearl Millet (Pennisetum typhoides S. & H.): III. ROOT DEVELOPMENT

This paper examines the use of thermal time (accumulated temperature)to analyse the effects of temperature on the development ofpearl millet. The plants were grown in columns of soil withinstands of millet growing in controlled environment glasshouses.A range of almost constant soil temperatures was maintainedat a number of air temperatures that were allowed to vary sinusoidallythroughout the day. The number of root axes and lateral rootswere counted on several occasions for young plants by destructivesampling of the columns. The results show that root axis and lateral development is relatedto the thermal time measured at the shoot meristem using a basetemperature of 12 ° C. The shoot meristem temperature consistentlyproved to be more closely related to root development than soiltemperature at a depth of 5.0 cm. The difficulty of relating root development to temperature ata particular depth is discussed, together with the problemsof selecting an appropriate base temperature. For the conceptof thermal time to provide a clearer understanding of temperatureeffects on root development, it will be necessary to take accountof possible differences in the thermal response of differentparts of the root system and of other environmental factors,particularly soil water status. Key words: Pennisetum typhotdes, Temperature, Thermal time, Root development     

Response to Temperature in a Stand of Pearl Millet (Pennisetum typhoides S. & H.): VIII. ROOT GROWTH

P J. Gregory. 1986. Response to temperature in a stand of pearlmillet (Pennisetum typhoides S. & H.). VIII. Root growth—J.exp. Bot. 37: 379–388. Two experiments were made in controlled glasshouscs to investigatethe growth of roots of pearl millet at different air and soiltemperatures. The experimental plants were grown in columnsof soil within stands of millet for 3 to 4 weeks and destructivelysampled at regular intervals to estimate the length of individualroot axes and of the root system. The length of individual rootaxes increased exponentially with time and at any particulartime the rate of extension was faster the higher the soil temperature.Clear ontogenctic effects on the rates of elongation were detected,with each succeeding axis elongating faster than its predecessor.Total root length was longer the higher the soil temperature(at a particular air temperature) and increased exponentiallywith time and with thermal time assessed from temperatures measuredat 2·0 cm depth. Whereas length at a particular timehad a 10-fold range, length at a particular thermal time hadonly a 3-fold range. Mean irradiance differed between the twoexperiments and as a means of exploring the importance of carbohydrateresources for root extension, relations between root length,leaf area and the amount of radiation intercepted were sought. Root length and leaf area were linearly related for all temperaturetreatments in both years as were root length and interceptedradiation. However, whilst the former relation was the samein both years, the latter was different. Root dry weight andintercepted radiation were also linearly related with the samerelation for both years so that the root length: weight ratiosdiffered between years because of factors not controlled inthese experiments. The results show the close relation between root and shoot growthand that thermal time together with the amount of radiationintercepted by the leaves might be used as the basis for quantifyingthe effects of temperature on root growth. Key words: Pearl millet, temperature, thermal time, root extension, root growth     

QUALITY OF POWDERED BLACK PEPPER (PIPER NIGRUM L.) DURING STORAGE. I. SENSORY AND PHYSICOCHEMICAL ANALYSES

Black pepper powder (60 mesh) was stored in consumer unit packs of 100g capacity in low density polyethylene (LDPE) films of 100, 300, and 500 gauge at 27°C and 65% RH. Analyses for sensory quality (odor and flavor), volatile oil, oleoresin, piperine content, and TLC were carried out at 15, 30, 45 and 80 days of storage. Significant loss of “top notes”, volatile oil, and hydrocarbons were seen after 15 days of storage itself while the “basic notes” and oxygenated compounds were retained up to 45 days. There was no loss of piperine up to the end of the study. The black pepper powder was not fit for table use after 15 days, though it could be used for other culinary purposes up to 80 days of storage.