H. Jalink

Phenomics for photosynthesis, growth and reflectance in Arabidopsis thaliana reveals circadian and long-term fluctuations in heritability

BackgroundRecent advances in genome sequencing technologies have shifted the research bottleneck in plant sciences from genotyping to phenotyping. This shift has driven the development of phenomics, high-throughput non-invasive phenotyping technologies.ResultsWe describe an automated high-throughput phenotyping platform, the Phenovator, capable of screening 1440 Arabidopsis plants multiple times per day for photosynthesis, growth and spectral reflectance at eight wavelengths. Using this unprecedented phenotyping capacity, we have been able to detect significant genetic differences between Arabidopsis accessions for all traits measured, across both temporal and environmental scales. The high frequency of measurement allowed us to observe that heritability was not only trait specific, but for some traits was also time specific.ConclusionsSuch continuous real-time non-destructive phenotyping will allow detailed genetic and physiological investigations of the kinetics of plant homeostasis and development. The success and ultimate outcome of a breeding program will depend greatly on the genetic variance which is sampled. Our observation of temporal fluctuations in trait heritability shows that the moment of measurement can have lasting consequences. Ultimately such phenomic level technologies will provide more dynamic insights into plant physiology, and the necessary data for the omics revolution to reach its full potential.

Chlorophyll fluorescence of the testa of Brassica oleracea seeds as an indicator of seed maturity and seed quality

Chlorophyll fluorescence of the testa of seeds is proposed as a non-invasive method for the determination of maturity and quality of seeds. In this study cabbage seeds (Brassica oleracea) were sorted individually based on the chlorophyll fluorescence signals into four subsamples labeled with respect to their chlorophyll fluorescence signal (low, medium, high and very high). The results show that the magnitude of the chlorophyll fluorescence signal was inversely related to the quality of the seeds, expressed as germination %, normal seedling %, germination rate (T50) and uniformity of germination (T75-T25). The seed lot could be improved from 90 to 97% normal seedlings by sorting out 13% of the seeds with very high chlorophyll fluorescence signals. Advantages of the chlorophyll fluorescence method for sorting seeds are the high sensitivity, the method being fully non-destructive, the high speed at which the fluorescence is generated and measured and the specificity for only chlorophyll. Other pigments or substances which can influence seed colour but do not fluoresce at the specific wavelengths of excitation and emission of chlorophyll, will not contribute to the fluorescence signal. These characteristics make chlorophyll fluorescence highly suitable as a new sorting technique.

Resonant Stark spectrophone as an enhanced trace level ammonia concentration detector: design and performance at CO 2 laser frequencies

A design of a Stark photoacoustic cell capable of detecting ammonia in ambient air at trace levels is discussed.

High-sensitivity, interference-free, Stark-tuned CO2 laser photoacoustic sensing of urban ammonia

Low‐concentration (few ppbv), interference‐free, on‐line photoacoustic detection of ambient ammonia (NH3) is reported by Stark tuning the Q(J=5, K=5, M=5) NH3 absorption line into resonance with the CO2 laser. Measurements were made over a range of total pressure between 600 and 50 mbar.

A Laboratory Goniometer System for Measuring Reflectance and Emittance Anisotropy

In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers.

INFRARED TRANSIENT THERMOGRAPHY FOR NON-CONTACT, NONDESTRUCTIVE INSPECTION OF WHOLE AND DISSECTED APPLES AND OF CHERRY TOMATOES AT DIFFERENT MATURITY STAGES

Introduction Fruits and vegetables used in various processed products, as well as in fresh market sales, are expected to comply with the certain quality standards. However. quality is everything but a single parameter state and, therefore, a variety of subjective and objective measurements are usually performed. In particular, the firmness and maturity are considered important attributes to the quality of fruits and vegetable crops. Presently. these parameters are usually determined either destructively (by a pressure tester) or by means of ultrasound; a development of alternative methods has been strongly encouraged in the recent years.

Cucumber (Cucumis sativus L.) seed performance as influenced by ovary and ovule position

The performance of cucumber (Cucumis sativus L.) seeds in relation to ovary and ovule position was monitored during seed production. Seeds from three (first, seventh and tenth nodes) fruit positions and three (stylar, intermediate and peduncular) ovule positions were harvested serially during development and characterized with physiological and cellular markers. Seed moisture contents declined to 30%approx. 35 d after pollination (DAP) and remained constant thereafter. At 42 DAP the maximum dry weight was acquired in seeds except those from peduncular segments, whose dry weight accumulation lagged behind. The onset of germinability and desiccation tolerance occurred before the attainment of maximum dry weight, whereas seed performance, as shown by laboratory germination and greenhouse emergence, was largely improved after the completion of seed development. Cell cycle activities (DNA per nucleus and -tubulin content) ceased by 28 DAP, whereas the degradation of seed chlorophyll continued during the entire maturation period. Seeds from the top fruit and from the peduncular fruit segments were delayed in reaching maximum quality compared with seeds from other positions, and this was correlated with a slower decline of chlorophyll fluorescence

Seed research for improved technologies

The production of high-quality seed is the basis for a durable a profitable agriculture. After production, seed is processed, conditioned, stored, shipped and germinated. For quality assurance, seed quality has to be controlled at all steps of the production chain. Seed functioning is accompanied by programmed transitions from cell proliferation to quiescence upon maturation and from quiescence to reinitiation of cellular metabolism upon imbibition. Despite the obvious importance of these control mechanisms, very little information is available at the molecular level concerning those elements that regulate seed germination. In the present study, the induction of cell cycle activity and the regulation of s-tubulin expression is related to the water content and other physical properties of the seed.

Use of chlrophyll fluorescence sorting to improve soybean seed quality

A ocorrencia de sementes esverdeadas de soja [Glycine max (L.) Merrill] e um problema estreitamente relacionado a condicoes climaticas desfavoraveis, principalmente seca, que ocorrem nos estadios finais de maturacao. Esse problema causa serias perdas de qualidade da semente de soja no Brasil. Em sementes esverdeadas, a clorofila nao e degradada adequadamente durante a fase final da maturacao das sementes, afetando a sua qualidade. Com a tecnica de fluorescencia de clorofila, e possivel remover sementes esverdeadas e melhorar a qualidade do lote de sementes de diversas especies em que a ocorrencia dessa caracteristica tambem e um problema. Assim, a pesquisa teve o objetivo de estudar a utilizacao da tecnica de fluorescencia de clorofila na separacao de sementes esverdeadas em amostras de sementes de soja e avaliar a sua relacao com a qualidade. Cinco amostras de sementes de soja, cultivar TMG 113 RR, com 0%, 5%, 10%, 15% e 20% de sementes esverdeadas, foram utilizadas na pesquisa. As sementes de cada amostra foram separadas em duas fracoes baseadas nos sinais de fluorescencia de clorofila e comparadas com a testemunha (amostra original, sem separacao). O processo de separacao proporcionou grande diferenca entre as fracoes de baixa e de alta fluorescencia de clorofila, permitindo concluir que: as sementes esverdeadas de soja apresentam alta fluorescencia de clorofila e isto afeta a sua qualidade; e possivel melhorar a qualidade do lote com a remocao de sementes esverdeadas, utilizando a tecnica de separacao por fluorescencia de clorofila.

DUAL-BEAM THERMAL LENS MEASUREMENT OF CONDENSED-PHASE SAMPLE AT CO2 LASER WAVELENGTHS : DETECTION OF OCTADECANOIC ACID IN CARBON TETRACHLORIDE

Detection of monobasic, straight-chain saturated fatty acid (octadecanoic C18:0) in CCl4, based on the thermal lens effect after excitation by CO2 laser radiation at 934.9 cm−1, is described for the first time. The achieved limit of detection (LOD = 0.3%) is comparable to that of the transmission infrared technique. Possibilities for further improvements in sensitivity and detection limit are also discussed.