Search results for "leaf"

Estimation of leaf area index using PROSAIL based LUT inversion, MLRA-GPR and empirical models: Case study of tropical deciduous forest plantation, N…

2020

Abstract Forests play a vital role in biological cycles and environmental regulation. To understand the key processes of forest canopies (e.g., photosynthesis, respiration and transpiration), reliable and accurate information on spatial variability of Leaf Area Index (LAI), and its seasonal dynamics is essential. In the present study, we assessed the performance of biophysical parameter (LAI) retrieval methods viz. Look-Up Table (LUT)-inversion, MLRA-GPR (Machine Learning Regression Algorithm- Gaussian Processes Regression) and empirical models, for estimating the LAI of tropical deciduous plantation using ARTMO (Automated Radiative Transfer Models Operator) tool and Sentinel-2 satellite im…

Brown and green LAI mapping through spectral indices

2015

Abstract When crops senescence, leaves remain until they fall off or are harvested. Hence, leaf area index (LAI) stays high even when chlorophyll content degrades to zero. Current LAI approaches from remote sensing techniques are not optimized for estimating LAI of senescent vegetation. In this paper a two-step approach has been proposed to realize simultaneous LAI mapping over green and senescent croplands. The first step separates green from brown LAI by means of a newly proposed index, ‘Green Brown Vegetation Index (GBVI)’. This index exploits two shortwave infrared (SWIR) spectral bands centred at 2100 and 2000 nm, which fall right in the dry matter absorption regions, thereby providing…

Estimating the phenological dynamics of irrigated rice leaf area index using the combination of PROSAIL and Gaussian Process Regression

2021

The growth of rice is a sequence of three different phenological phases. This sequence of change in rice phenology implies that the condition of the plant during the vegetative phase relates directly to the health of leaves functioning during the reproductive and ripening phases. As such, accurate monitoring is important towards understanding rice growth dynamics. Leaf Area Index (LAI) is an important indicator of rice yields and the availability of this information during key phenological phases can support more informed farming decisions. Satellite remote sensing has been adopted as a proxy to field measurements of LAI and with the launch of freely available high resolution Satellite imag…

Effects of ozone on the foliar histology of the mastic plant (Pistacia lentiscus L.)

2004

[EN] An open-top chamber study was conducted to investigate the tissue and cellular-level foliar effects of ozone (O-3) on a Mediterranean evergreen species, the mastic plant (Pistacia lentiscus L.). Plants were exposed at three different O-3 levels, and leaf samples were collected periodically from the beginning of the exposure. Although no visible foliar injury was evident, alterations of the plastids and vacuoles in the mesophyll were observed. Senescence processes were accelerated with an anomalous stacking of tannin vacuoles, and a reduction in the size and number of the chloroplasts. Overall, most of the modifications induced by O-3 were consistent with previously reported observation…

Egg and larval load assessment and its influence on oviposition behaviour of the leaf beetle Galerucella nymphaeae

1993

The oviposition behaviour of the water-lily beetle Galerucella nymphaeae was examined. This species is a specialist herbivore on the floating leaves of nymphaeids Nymphaeaceae and especially on the yellow water-lily, Nuphar lutea. Females lay their eggs in clutches on the leaves, and after hatching, the larvae feed on the leaves. The quality of the leaves decreases quickly after the larvae hatch, and eventually the leaves will sink below the water surface, whereupon the eggs, 1st-instar larvae and pupae are killed by drowning. The influence of conspecific eggs, larvae and feeding tracks on the oviposition preferences of the beetles was tested. Females were allowed to choose between fresh le…

Interactions between willows and insect herbivores under enhanced ultraviolet-B radiation

2002

We studied the effects of elevated ultraviolet-B radiation on interactions between insect herbivores and their host plants by exposing two species of phytochemically different willows, Salix myrsinifolia and S. phylicifolia, to a modulated increase in ultraviolet radiation in an outdoor experiment and monitoring the colonisation of insect herbivores on these willows. We examined the effect of increased ultraviolet-B (UV-B) radiation on (1) the quality of willow leaves, (2) the distribution and abundance of insect herbivores feeding on these willows, (3) the resulting amount of damage, and (4) the performance of insect larvae feeding on the exposed plant tissue. Six clones of each of the two…

Studio Morfoanatomico di Himantoglossum robertianum ed H.hircinum (Orchideaceae) della Sicilia

2009

Morphological Characterization of Nordic Horseradish (Armoracia rusticana)

2019

AbstractMorphological diversity was studied in 101 accessions of horseradish (Armoracia rusticana) collected from old gardens in Denmark, Norway, Finland and Sweden. The characterization work was performed over three years, where a total of 19 descriptors from the UPOV guidelines TG/191/2-2001 were recorded each year. The results showed high diversity among the studied accessions, both for leaf and rhizome characters. A morphotype with long leaves and a high leaf length/leaf width quota was the most common, but also elliptic and heart-shaped leaf types were found. Some characters showed stability over the years, although there were variations in the results. Correlations between descriptors…

First Report of Tomato Leaf Curl New Delhi Virus Causing Yellow Leaf Curl of Pepper in Europe

2019

Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus (family Geminiviridae) with two circular ssDNA genome components (DNA-A and DNA-B), is transmitted in a circulative nonpropagative manner by the whitefly Bemisia tabaci (Gennadius). Although it was first reported in Asia on tomato and other solanaceous crops such as eggplant, potato, and chilli pepper in the Mediterranean basin, this virus was mainly detected on cucurbits and only sporadically on tomato and on two wild solanaceous species, Datura stramonium L. and Solanum nigrum L. (Juárez et al. 2019). In 2018, separate surveys were carried out in protected cultivations of sweet pepper (Capsicum annuum L.) in two Italian r…

COLLARD GREEN (BRASSICA OLERACEA VAR. ACEPHALA) CULTIVATION IN SICILY

2013

Collard greens (Brassica oleracea var. acephala) are a group of plants cultivated for its thick, slightly bitter, edible leaves. As other Brassicaceae, have a good nutritional value as they are a good sources of vitamin C and soluble fiber, and contain various compounds with potent anticancer properties. In order to enhance collard cultivation in Sicily, different planting dates were tested. The research was carried out during 2009-2010 in the experimental field of SAgA Department – University of Palermo. Plants of a Sicilian local cultivar, with high vigor, good emission of side shoots, large and moderately curly leaves and long and strong petiole, were planted in three different periods: …