Exploring the Potential of Gaofen-1/6 for Crop Monitoring: Generating Daily Decametric-Resolution Leaf Area Index Time Series

High spatiotemporal resolution time series of leaf area index (LAI) are essential for monitoring crop dynamics and validating coarse-resolution LAI products. The optical satellite sensors at decametric resolution have historically suffered from a long revisit cycle and cloud contamination issues that hampered the acquisition of frequent and high-quality observations. The 16-m/four-day resolution of the new-generation Gaofen-1 (GF-1) and Gaofen-6 (GF-6) satellites provide an unprecedented opportunity to address these limitations. Here, we developed an effective strategy to generate daily 16-m LAI maps combining GF-1/6 data and ground LAINet measurements. All high-quality GF-1/6 observations were utilized first to derive smoothed time series of vegetation indices (VIs). Second, a random forest regression (RF-r) model was trained to link the VIs with corresponding field LAI measurements. The trained RF-r was finally employed to generate the LAI maps. Results demonstrated the reliability of the reconstructed daily VIs (relative error (RE) < 1%) and the derived LAI time series, which greatly benefited from GF-1/6 high-frequency observations. The direct comparison with field LAI measurements by LAI-2200/LI-3000 showed the good performance of retrieved LAI maps, with bias, root mean square error (RMSE), and R2 of 0.05, 0.59, and 0.75, respectively. The LAI time series well captured the spatiotemporal variation of crop growth. Furthermore, the continuous GF-1/6 LAI maps outperformed Sentinel-2 LAI estimates both in terms of temporal frequency and accuracy. Our study indicates the potential of GF-1/6 to generate continuous decametric-resolution LAI maps for fine-scale agricultural monitoring

The Hamiltonian index of a graph and its branch-bonds

Let $G$ be an undirected and loopless finite graph that is not a path. The minimum $m$ such that the iterated line graph $L^m(G)$ is hamiltonian is called the hamiltonian index of $G,$ denoted by $h(G).$ A reduction method to determine the hamiltonian index of a graph $G$ with $h(G)\geq 2$ is given here. With it we will establish a sharp lower bound and a sharp upper bound for $h(G)$, respectively, which improves some known results of P.A. Catlin et al. [J. Graph Theory 14 (1990)] and H.-J. Lai [Discrete Mathematics 69 (1988)]. Examples show that $h(G)$ may reach all integers between the lower bound and the upper bound. \u

Old chinese and friends: new approaches to historical linguistics of the Sino-Tibetan area

List J-M, Starostin G, Yunfan L. “Old Chinese and Friends”: new approaches to historical linguistics of the Sino-Tibetan area. Journal of Language Relationship. 2019;17(1-2):1-6

Evaluation and selection of rapeseed (Brassica napus L.) mutants for higher seed yield

A field experiment was conducted to investigate some morpho-physiological characters, yield attributes and yield of three rapeseed mutants along with mother variety. Results revealed that LAI and AGR increased till 65 days after sowing (DAS) followed by a decline at later growth stages whereas RGR decreased with age of the plants. Two plant characters such as LAI and AGR contributed to the superior TDM production. Results indicated that a high yielding rapeseed genotype should possess larger LAI, higher TDM production ability, superior AGR at all growth stages, superior biochemical parameters which result in superior yield components and seed yield

CMSI Note #3: “Choose the Right Person, Choose the Right Path”: Taiwan’s Cross-Strait, National Security, and Defense Policies Under a Lai/Hsiao Administration

CMSI’s Perspectives and Key Takeaways: The incoming William Lai/Bi-khim Hsiao administration almost certainly intends to continue to execute and deepen President Tsai’s defense reforms. Lai has also stated his support for the implementation of an Indo-Pacific Strategy concept. Lai has an opportunity to leverage the national security experience of President Tsai’s outgoing advisors, who may potentially help his administration calibrate Taiwan’s responses to People’s Liberation Army (PLA) military provocations in and around the Taiwan Strait. The Lai administration likely would prove receptive to U.S. and partner overtures that contribute to Taiwan’s ability to strengthen its maritime domain awareness and security; enhance maritime law enforcement and search and rescue capabilities; conduct maritime patrols; and improve information sharing. Lai intends to maintain the cross-Strait status quo, and has stated that he is willing to conduct dialogue with the People’s Republic of China (PRC) on the basis of mutual respect and equality. Lai almost certainly will seek to continue President Tsai Ing-wen’s policy of diversifying Taiwan’s economy and expanding sustainable trade partnerships with democratic nations. He has stated that overdependence on the PRC leaves Taiwan vulnerable to economic coercion, and thus opposes pursuing further economic agreements with China under the Economic Cooperation Framework Agreement (ECFA) or a potential Cross-Strait Trade in Services Agreement (CSTSA).https://digital-commons.usnwc.edu/cmsi-notes/1002/thumbnail.jp

Estimación del índice de área foliar en un huerto de manzanos (Malus domestica) cv. Cripp’s Pink usando el sensor LAI-2000

43 P.Se realizó un estudio para evaluar el equipo LAI-2000 (LI-COR, Lincoln, Nebraska, USA) en mediciones del índice de área foliar (IAF) en manzanos cv. Cripp’s Pink. Estas mediciones fueron comparadas con datos obtenidos a través de deshoje parcial. El ensayo se llevó a cabo en la comuna de Pelarco, Región del Maule, Chile (35° 25’ 16’’ L.S 71° 23’ 58’’ L.O, 198 m.s.n.m). Para la medición con LAI-2000 se utilizaron dos protocolos de medición (vista de 90° y 180°). Para evaluar la efectividad del equipo a diferentes niveles de radiación, se registró, el área foliar durante un día completo desde las 10:00 am hasta las 20:00 pm con el objetivo de establecer el horario adecuado para la medición de IAF. Con estos datos se logró establecer que la cantidad de radiación, orientación de las hileras, y los movimientos del sol durante el día, influencias fuertemente las mediciones del sensor LAI-2000. Las mediciones realizadas con LAI-2000, presentaron una buena correlación con los datos obtenidos del deshoje. Los mejores resultados fueron obtenidos con el protocolo 180° (sin el anillo 1) con un coeficiente de determinación (R2) de 0,65 y una raíz del cuadrado medio del error (RCME) de 0,054. Los resultados anteriores, permiten establecer que LAI-2000 es un equipo dinámico y fácil de utilizar, que entrega mediciones en tiempo real. Sin embargo, LAI-2000 es altamente dependiente de las condiciones de radiación y características del dosel, por lo que su uso debe ser comparado con métodos directos para establecer los ajustes y protocolos adecuados para su uso en forma práctica./ABSTRACT: A field experiment was carried out to evaluate the LAI-2000 sensor (LI-COR, Lincoln, Nebraska, USA) for measuring leaf area index (LAI) in apple trees cv. Cripps's Pink. LAI-2000 measurements were compared with data obtained by partial defoliation of the trees. The field experiment was located in Pelarco, Region del Maule, Chile (35 ° 25 '16'' L.S 71 ° 23' 58'' L.W, 198 m.a.s.l). Two protocols (view 90 ° and 180 °) were used for LAI-2000 measurements. To evaluate the performance of the sensor at different radiation levels, LAI was recorded from 10:00 am to 20:00 pm with the objective of establishing the appropriate time for measuring LAI. With these data was possible to establish that radiation, row orientation, and sun movements during the day,has a strong influences in the LAI-2000 measurements. LAI values obtained with LAI-2000, showed a good correlation with data obtained from defoliation. The best results were obtained with the protocol 180° when the ring 1 was eliminated, with determination coefficient (R2) of 0.65 and root mean square error (RMSE) of 0.054 m2 m-2. These results show that LAI-2000 allow to obtain real-time measurements with low errors. However, LAI-200 is highly dependent of the irradiation conditions and characteristics of the canopy, so its use should be compared with direct methods to adjust and setting the suitable protocols for its practical use

Genetic Variability of some Maize Inbred Lines (Zea mays L.)in Agroecological Conditions of Kosovo

The aim of this study, conducted during the years 2005 (Y1) and 2006 (Y2), was to investigate the variability and appearance of genotype reaction in maize inbred lines. In the investigation were included 10 maize inbred lines obtained from the University of Tirana- Albania, department of Agronomy. The experiment was based on a ranomized complete block design (RCBD) with three replications in the locality of Ferizaj. The variability and genotype reaction was analysed for quantitative parameters for plants as following: Ear height (EH); plant height (PH), ear leaf area (LA) and leaf area index (LAI). The experimental average values μ for investigated parameters were: EH was 60.46 cm, PH (169.88 cm), LA (446.2 cm2) and LAI (3.23 plant m-2) respectively. The inbred lines between them for EH at the first year (Y1) and the second year (Y2) had show the variability 52.59% and 43.16%, respectively. The highest value for EH was shown by inbred L4 (76.10 cm), which differs from the value μ for +25.86%. While the lowest value was recorded at the inbred L5 (44.30 cm) that difference was a reduction of -26.72%. In the Y2 the same values were repeated but with minimal differences. The maize inbred L7 for the Y1 had a greater total plant height (196.5 cm), while for the Y2 was obtained 206.7cm. The minimal average value for PH were shown by the inbred L8 and L2, while the total variability between all inbred lines for PH were Y1 (32.61%) and Y2 (36.55%) respectively. Average values of the two years investigation for ear leaf area (LA) were obtained by inbred L7 (544.1cm2 plant-1), whereas lowest values were showed by maize inbred L10 (356.9cm2plant-1). Variability between inbred lines was 41.95 %. The highest value of LAI was obtained for inbred L7 on coefficient 3.9 plant m2 (Y1) and 4.0plant m-2(Y2) whereas the lowest LAI was realised on maize inbred L10 (2.5 plant m-2) at the Y1, while for the Y2 was obtained at maize inbred L8 (2.6 plant m-2)

Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment

Leaf area index (LAI) is an important parameter for characterizing the canopy structure ofa crop. The LAI, which is often used as a critical variable to simulate different ecosystem models, is difficult to measure directly in oil palm. In this study, optical methods for quantifYing variation in LAI under different conditions were evaluated. It was found that the accuracy of the readings depended on different factors, such as measuring technique, view cap angle, spatial variability, and height of the measuring point. The measuring technique had an effect on the LAI measurement. Results showed that the Zigzag method underestimated the LAI compared to other methods. The LAI by the Zigzag method was 11.6% less than the LAI by the "one above and four below" technique and 5.7% less than the LAI by the "one above and eight below" technique. The LAI obtained I7y the "one above eight below" technique was 6.2% less than the LAI obtained with the "one abovefour below" technique. Results from the investigation ofthe effect of view cap on LAI measurement showed that the view cap strongly influenced the LAI calculation and LAI decreased with increase in the view cap angle. PCA LAI values were also affected by spatial variability and height of the sensor. PCA LAI values increased with increase in sensor height above ground with a maximum LAI value (2.77) at 2.5-meter height above ground and mzmmum LAI value (0.932) at O-meter height from ground. Maximum values of LAI were obtained for all dIrectIOns at 0.5-meter dtstance from the trunk and minimum LA1 values were obtained near the tip of the frond. The PCA LAI values increased by about 5%- 50% with increase in distance from the frond tip to frond base