Astringency of douglas-fir foliage in relation to phenology and xylem pressure potential

Astringency (tannin content) of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] foliage was examined in relation to phenology and water status. Foliage was sampled from control trees, trees on south-facing slopes, and trenched trees prior to budbreak and at periods of two, six, and 12 weeks after budbreak. Astringency of prebudbreak foliage from untrenched trees was comparable to that of mature foliage. Foliage expansion was accompanied by dilution of the tannin content. Percent relative astringency of control trees was significantly and positively related to the absolute value of predawn xylem pressure potential, while this relationship was negative for trees in the south-facing group. Coefficients of determination for the relationship between astringency and predawn xylem pressure potential were high (0.67 and 0.79 for the control and south-facing groups, respectively). Astringency of foliage from trees in the south-facing group also was affected significantly by daytime xylem pressure potential. Astringency of foliage from trees in the control and south-facing groups was not significantly related to tissue age, while that from trenched trees was significantly related only to age. Results demonstrate that water status is a better predictor of foliage astringency than is tissue age in unperturbed trees of this species and that, depending on the magnitude and/or timing of water deficits, opposite relationships between astringency and xylem pressure potential can be observed.     

Weight loss from ripening berries of Shiraz grapevines (Vitis vinifera L. cv. Shiraz)

Environmental and phenological correlatives associated with the onset of weight loss during ripening in Vitis vinifera cv. Shiraz berries were examined. An irrigation experiment concerned with transient water deficit effects on berry growth over four consecutive seasons provided source data. Timing of maximum berry weight was more closely correlated with the number of days after flowering than with temperature summation. Prior to maximum berry weight, Brix was more closely correlated with days after flowering than with temperature summation, while the number of days from flowering to 10 and 15Brix was remarkably uniform despite contrasting seasons. Driving variables for weight loss during advanced ripening remain a matter of conjecture, but loss of berry water under highly evaporative conditions of late summer is a likely contributor.     

基于MODIS时间序列数据的作物季相信息提取

基于MODIS NDVI时间序列数据对浙北平原单季稻区进行作物季相一致性分析。对NDVI时间序列数据进行离散傅立叶变换去除噪声,再利用土地利用现状图提取耕地区的NDVI影像图,根据时间序列曲线的最大值研究作物的季相。结果表明:水稻生长期对NDVI时间序列曲线的响应和季相一致性均较小麦和油菜好;8 d合成的数据较16 d合成的数据可以更详细地反映作物季相信息。研究证实了MODIS NDVI时间序列曲线对区域作物季相分析的意义。     

Growth, yield and seed composition of native Australian legumes with potential as grain crops

BACKGROUND: Many Australian native legumes grow in arid and nutrient‐poor environments. Yet few Australian herbaceous legumes have been investigated for domestication potential. This study compared growth and reproductive traits, grain yield and seed composition of 17 native Australian legumes with three commercial grain legumes. RESULTS: Seed yields of seven native legumes were > 40% of Cicer arietnum, with highest seed yields and harvest indices in Glycine sp. (14.4 g per plant, 0.54 g g^?1) and Lotus cruentus (10.2 g per plant, 0.65 g g^?1). Five native species flowered earlier than field pea (Pisum sativa) (109 days), though many were slower to flower and set seed. Largest seeds were found in Glycine canescens (17 mg), with seed of other native species 14 times smaller than commercial cultivars. Seed composition of many native legumes was similar to commercial cultivars (200–330 g protein kg^?1 dry weight (DW), 130–430 g dietary fibre kg^?1 DW). Two Cullen species had high fat content (>110 g kg^?1 DW) and Trigonella sauvissima had the highest crude protein content (370 g kg^?1 DW). CONCLUSION: The seed composition and reproductive traits of some wild native Australian legumes suggest they could offer potential as grain crops for soils and environments where the current grain legumes are uneconomic. Further evaluation of genetic diversity, especially for seed size, overall productivity, and reproductive development is needed. Copyright © 2011 Society of Chemical Industry     

Characterisation of selected hazelnut cultivars: phenology, growing and yielding capacity, market quality and nutraceutical value

BACKGROUND: Sixteen hazelnut cultivars growing in the continental climate of Slovenia were analysed over 15 years for their phenology, growth habit, yield potential, susceptibility to hazelnut weevil and the pomological traits and phenolic content of their nuts in order to obtain a complex value of these cultivars for growers, the confectionary industry and consumers. RESULTS: Blooming occurred over an interval of 10–23 days for female (pistillate) flowers and 11–22 days for male (staminate) flowers. Nocchione, Romai, Pauetet, ID and Daria were the most productive cultivars, with a nine‐year cumulative yield ranging from 31.8 to 44.7 kg per plant. Pauetet, F. Coutard, Nocchione and Segorbe were less susceptible to unfavourable weather conditions during blooming and fertilisation, in terms of maintaining acceptable yields with limited blank production. Under integrated pest management, less than 2% of the nuts of Romai, Daria, TGDL and Nocchione were affected by hazelnut weevil, compared with an average of 5.5% for the other cultivars. Daria, Pauetet and T. Giffoni performed best with regard to kernel percentage and blanching ratio. The results suggest that raw kernels are a good source of the natural antioxidants gallic acid and epicatechin. CONCLUSION: The results of this study provide direction when choosing hazelnut cultivars for planting, consuming or processing. They can be applied not only in Slovenia and nearby countries but also in other parts of central and northern European countries with similar climates and growing conditions. Copyright © 2011 Society of Chemical Industry     

Green leaf phenology at Landsat resolution: Scaling from the field to the satellite

Despite the large number of in situ, plot-level phenological measurements and satellite-derived phenological studies, there has been little success to date in merging these records temporally or spatially. In this research, we bridge this scale gap through higher resolution satellite records (Landsat) and quantify the accuracy of satellite-derived metrics with direct field measurements. We compiled fifty-seven Landsat scenes from southern New England (P12 R51) from 1984 to 2002. Green vegetation areal abundance for each scene was derived from spectral mixture analysis and a single set of endmembers. The leaf area signal was fit with a logistic-growth simulating sigmoid curve to derive phenological markers (half-maximum leaf-onset and offset). Spring leaf-onset dates in homogenous stands of deciduous forests displayed significant and persistent local variability. The local variability was validated with multiple springtime ground observations (r² = 0.91). The highest degree of verified small-scale variation occurred where contiguous forests displayed leaf-onset gradients of 10-14 days over short distances (< 500 m). These dramatic gradients occur in of low-relief (< 40 m) upland regions. The patterns suggest that microclimates resulting from springtime cold-air drainage may be influential in governing the start of leaf growth; every 4.16 m loss in elevation delayed spring leaf onset by 1 day. These microclimates may be of crucial importance in interpreting in situ records and interpolating phenology from satellite data. Regional patterns from the Landsat analyses suggest topographic, coastal, and land-use controls on phenology. Our results indicate that deciduous forests in the Providence, RI metropolitan area leaf out 5-7 days earlier than comparable rural areas. The platform-independent curve-fit methodology may be extended across platforms and field data. The methodologically consistent approach, in tandem with Landsat data, allows an effective scaling from plot to satellite phenological observations.     

Monitoring vegetation phenology using MODIS

Accurate measurements of regional to global scale vegetation dynamics (phenology) are required to improve models and understanding of inter-annual variability in terrestrial ecosystem carbon exchange and climate-biosphere interactions. Since the mid-1980s, satellite data have been used to study these processes. In this paper, a new methodology to monitor global vegetation phenology from time series of satellite data is presented. The method uses series of piecewise logistic functions, which are fit to remotely sensed vegetation index (VI) data, to represent intra-annual vegetation dynamics. Using this approach, transition dates for vegetation activity within annual time series of VI data can be determined from satellite data. The method allows vegetation dynamics to be monitored at large scales in a fashion that it is ecologically meaningful and does not require pre-smoothing of data or the use of user-defined thresholds. Preliminary results based on an annual time series of Moderate Resolution Imaging Spectroradiometer (MODIS) data for the northeastern United States demonstrate that the method is able to monitor vegetation phenology with good success.     

Response of sorghum to fertilizer phosphorus and its residual value in a Vertisol

The response of crops to added P in Vertisols is generally less predictable than in other soil types under similar agroclimatic conditions. Very few studies have considered the residual effects of P while studying responses to fresh P applications. Field experiments were conducted for three years to study the response of sorghum to fertilizer P applied at 0, 10, 20 and 40 kg P ha^–1, and its residual value in a Vertisol, very low in extractable P (0.4 mg P kg^–1 soil), at the ICRISAT Center, Patancheru (near Hyderbad), India. In order to compare the response to fresh and residual P directly in each season, a split-plot design was adopted. One crop of sorghum (cv CSH6) was grown each year during the rainy season (June-September).The phenology of the sorghum crop and its harvest index were greatly affected by P application. The days to 50% flowering and physiological maturity were significantly reduced by P application as well as by the residues of fertilizer P applied in the previous season. In the first year of the experiment, sorghum grain yield increased from 0.14 t (no P added) to 3.48 t ha^–1 with P added at the rate of 40 kg P ha^–1. Phosphorus applied in the previous year was 58% as effective as fresh P but P applied two years earlier was only 18% as effective as fresh P.     

Validating satellite phenology through intensive ground observation and landscape scaling in a mixed seasonal forest

Phenology is a key component of monitoring terrestrial ecosystem variations in response to global climate change. Satellite-measured land surface phenology (LSP) has been widely used to assess large scale phenological patterns and processes. However, the accuracy of LSP is rarely validated with spatially compatible field data due to the significant spatiotemporal scale mismatch. In this study, we employ intensive field observations specifically designed to address this deficiency. High density/frequency spring phenological observations were collected in a mixed seasonal forest during 2008 and 2009. A landscape up-scaling approach was used to derive landscape phenology (LP) indices from plot-level observations in order to validate Moderate-resolution Imaging Spectroradiometer (MODIS) based LSP. Results show that the MODIS Enhanced Vegetation Index (EVI) derived start of spring season (SOS) measure was able to predict LP full bud burst date with absolute errors less than two days. In addition, LSP derived SOS captured inter-annual variations and spatial differences that agreed with ground observations. Comparison of complete time series of LP and LSP revealed that fundamental differences exist between the two observation means, e.g., LP development had increased influence on LSP during the course of spring onset. Therefore, inferring continuous LP processes directly from LSP measures could be problematic. However, using LSP derived from techniques such as logistic curve modeling for extracting seasonal markers appears more promising. This study contributes to a more explicit understanding of the linkages between remotely sensed phenology and traditionally observed (ground-based) phenology.