Varietal identification plays a pivotal role in viticulture for several purposes. Nowadays, such identification is accomplished using ampelography and molecular markers, techniques requiring specific expertise and equipment. Deep learning, on the other hand, appears to be a viable and cost-effective alternative, as several recent studies claim that computer vision models can identify different vine varieties with high accuracy. Such works, however, limit their scope to a handful of selected varieties and do not provide accurate figures for external data validation. In the current study, five well-known computer vision models were applied to leaf images to verify whether the results presented in the literature can be replicated over a larger data set consisting of 27 varieties with 26 382 images. It was built over 2 years of dedicated field sampling at three geographically distinct sites, and a validation data set was collected from the Internet. Cross-validation results on the purpose-built data set confirm literature results. However, the same models, when validated against the independent data set, appear unable to generalize over the training data and retain the performances measured during cross validation. These results indicate that further enhancement have been done in filling such a gap and developing a more reliable model to discriminate among grape varieties, underlining that, to achieve this purpose, the image resolution appears to be a crucial factor in the development of such models.

Greenfall leaves caused by hailstorms may represent a resource pulse of nutrients. We determined the contribution of greenfall versus senescent leaves to total litterfall production, carbon, nitrogen and phosphorus input to the system, and leaf decomposition rate. Litterfall was collected monthly for three years in two cloud forests (F1, F2) and a restoration planting area (R) in Veracruz, Mexico. Two fortuitous hailstorms occurred in the second year. Leaf decomposition rate was determined in all three sites but did not differ across them. Total annual litterfall, excluding greenfall, was 10.0, 10.1, and 7.7 Mg ha−1 y−1 for F1, F2, and R, respectively. Senescent leaves represented 65% of the litterfall, while greenfall leaves increased the annual leaf biomass component of the litterfall by 12%. Concentrations of carbon, nitrogen, and phosphorus were 2.3, 5.7, and 18.1% higher, respectively, in greenfall than in senescent leaves. Greenfall increased the annual input of C, N, and P by 12, 13, and 14%, respectively. Despite their short duration (approximately 70 minutes), the hailstorm events generated a substantial contribution of greenfall leaves and a source of extra C, N, and P, since these leaves decompose and are incorporated into the cloud forest system.

Helicoverpa zea (Boddie) is a damaging pest of many crops including soybean, Glycine max (L.), especially in the southern United States. Previous studies have concluded that oviposition and development of H. zea larvae mirror the phenology of soybean, with oviposition occurring during full bloom, younger larvae developing on blooms and leaves, intermediate aged larvae developing on varying tissue types, and older larvae developing on flowers and pods. In a field trial, we investigated the presence of natural infestations of H. zea larvae by instar in determinate and indeterminate soybean varieties. In complementary experiments, we artificially infested H. zea and allowed them to oviposit on plants within replicated cages (one with a determinate variety and two with an indeterminate variety). Plants were sampled weekly during the time larvae were present. In the natural infestation experiment, most larvae were found on blooms during R3 and were early to middle instars; by R4, most larvae were found on leaves and were middle to late instars. In contrast, in the cage study, most larvae were found on leaves regardless of soybean growth stage or larval stage. Determinate and indeterminate growth habit did not impact larval preference for different soybean tissue types. Our studies suggest H. zea larvae prefer specific tissue types, but also provide evidence that experimental design can influence the results. Finally, our finding of larval preference for leaves contrasts with findings from previous studies.

A random binary search tree grown from the uniformly random permutation of [n] is studied. We analyze the exact and asymptotic counts of vertices by rank, the distance from the set of leaves. The asymptotic fraction ck of vertices of a fixed rank k ≥ 0 is shown to decay exponentially with k. We prove that the ranks of the uniformly random, fixed size sample of vertices are asymptotically independent, each having the distribution {ck}. Notoriously hard to compute, the exact fractions ck have been determined for k ≤ 3 only. We present a shortcut enabling us to compute c4 and c5 as well; both are ratios of enormous integers, the denominator of c5 being 274 digits long. Prompted by the data, we prove that, in sharp contrast, the largest prime divisor of the denominator of ck is at most 2k+1 + 1. We conjecture that, in fact, the prime divisors of every denominator for k > 1 form a single interval, from 2 to the largest prime not exceeding 2k+1 + 1.

The importance of leaf surface wax compounds from the rice-field weed Ludwigia octovalvis (Jacq.) Raven (Onagraceae) was determined in the flea beetle Altica cyanea (Weber) (Coleoptera: Chrysomelidae). Extraction, thin layer chromatography and GC-MS and GC-FID analyses of surface waxes of young, mature and senescent leaves revealed 20, 19 and 19 n-alkanes between n-C15 and n-C35, respectively; whereas 14, 14 and 12 free fatty acids between C12:0 and C22:0 fatty acids were identified in young, mature and senescent leaves, respectively. Tricosane was predominant n-alkane in young and mature leaves, whilst eicosane predominated in senescent leaves. Heneicosanoic acid, palmitic acid and docosanoic acid were the most abundant free fatty acids in young, mature and senescent leaves, respectively. A. cyanea females showed attraction to 0.25 mature leaf equivalent surface waxes compared with young or senescent leaves in a short glass Y-tube olfactometer bioassay. The insects were attracted to a synthetic blend of 0.90, 1.86, 1.83, 1.95, 0.50 and 0.18 µg ml−1 petroleum ether of hexadecane, octadecane, eicosane, tricosane, palmitic acid and alpha-linolenic acid, respectively, comparable with the proportions as present in 0.25 mature leaf equivalent surface waxes. A. cyanea also laid eggs on a filter paper moistened with 0.25 mature leaf equivalent surface waxes or a synthetic blend of 0.90, 1.86, 1.83, 1.95, 0.50 and 0.18 µg ml−1 petroleum ether of hexadecane, octadecane, eicosane, tricosane, palmitic acid and alpha-linolenic acid, respectively. This finding could provide a basis for monitoring of the potential biocontrol agent in the field.

Although the advent of microwave technologies has both improved and accelerated tissue processing for microscopy, there still remain many limitations in conventional chemical fixation, dehydration, embedding, and sectioning, particularly with regard to plant materials. The Proteaceae, a family of plants widely distributed in the Southern Hemisphere and well adapted to harsh climates and nutrient-poor soils, is a perfect example; the complexity of Proteaceae leaves means that almost no ultrastructural data are available as these are notoriously difficult to both infiltrate and section. Here, a step-by-step protocol is described that allows for the successful preparation of Banksia prionotes (Australian Proteaceae) leaves for both light and transmission electron microscopy. The method, which applies a novel combination of vibratome sectioning, microwave processing and vacuum steps, and the utilization of an ultra low viscosity resin, results in highly reproducible, well-preserved, sectionable material from which very high-quality light and electron micrographs can be obtained. With this, cellular ultrastructure from the level of a leaf through to organelle substructure can be studied. This approach will be widely applicable, both within and outside of the plant sciences, and can be readily adapted to meet specific sample requirements and imaging needs.

Introduction. In recent decades, there has been increased interest in developing natural non-caloric sweeteners, providing sensory properties similar to sucrose. One of the most promising alternatives is the steviol glycosides, high-sweetness compounds extracted from the leaves of Stevia rebaudiana Bertoni. Characteristics and properties. In this review article, the characteristics of this plant are described. According to the relevant literature data, this review provides insight into the major steviol glycosides as well as their main characteristics and properties. Toxicity and legislation. We describe the current situation on the toxicity and the legal framework of the above sweeteners. Extraction techniques. This review describes the techniques developed for extraction and purification, including conventional extraction with water/solvent, ion exchange, enzymatic extraction, supercritical fluid and with a focus on membrane filtration, for its proven advantages in the purification of aqueous extract obtained by leaching of the leaves. Applications. This review also presents various evidence relating to the implementation of steviol glycosides in the food industry, with an emphasis on their use in the formulation of fruit juices. Conclusions. Finally, the future prospects of these natural sweeteners are presented. They highlight the need for research in this area, and the great appeal and commercial potential of such compounds, which should be focused on continuous assessment in relation to issues such as the intensity, persistence of sweetness and the absence of other residual flavors, in order to ensure their acceptance, preference and choice by the general public.

In heterotrophic streams the retention and export of coarse particulate organic matter and associated elements are fundamental biogeochemical processes that influence water quality, food webs and the structural complexity of forested headwater streams. Nevertheless, few studies have documented the quantity and quality of exported organic matter over multiple years and under a range of conditions that includes both droughts and hurricanes. This study quantifies the export of coarse particulate organic matter (CPOM, > 12.7 mm), over 18 y in two headwater streams in north-east Puerto Rico. Daily exports ranged from 0 to over 170 g ha−1 d−1 and averaged 7.39 g ha−1 d−1, with similar amounts coming from leaves (3.5 g ha−1 d−1) and wood (3.2 g ha−1 d−1). Export of coarse particulate organic carbon was 3.0 g ha−1 d−1 which constitutes only 1.32% of carbon exports. Most litter falling into the streams was processed in place as only 2.3% of the leaf litter falling directly into these perennial channels was exported as CPOM. On average, 6 wk y−1 had no exports while events transporting more than 10 g ha−1 d−1 occurred every 2.8 mo. Instead of a single annual pulse as observed in deciduous systems, there were annual peaks in CPOM exports during May and September and less export during the drier period from December to February. Ratios of C:N in the exported material were highest in the driest month and lowest during rainy months, while leaf fluxes for nitrogen, phosphorus and calcium were highest in rainy months and lowest during February. Although median daily exports and exports during low- and base-flow periods were similar before and after Hugo, after 16 y exports during moderate- and high-flow periods were still less than those in the 2 y prior to the hurricane. Our observations indicate a system with high rates of internal processing that quickly returns to median daily conditions following hurricanes but requires several decades for storm-flow exports to return to pre-disturbance conditions and indicates that the long-term pattern of CPOM export is associated with the level of maturity of watershed vegetation.

Introduction Le baobab (Adansonia digitata L.) est un arbre caractéristique du paysage agricole dans les zones semi-arides d’Afrique. Il est utilisé quotidiennement par la population locale africaine. La diversité des services et des produits du baobab suggère d’effectuer une évaluation de sa variabilité morphologique afin d’avoir une meilleure connaissance de son potentiel. Notre article a cherché à identifier des descripteurs morphologiques discriminants chez le baobab en relation avec la diversité agro-écologique du Mali. Matériel et méthodes Notre évaluation a concerné huit provenances de baobab reparties sur l’ensemble de son aire de distribution géographique au Mali. Elle a porté sur les caractères foliaires, fruitiers et sur ceux liés aux graines. Le coefficient de variation a été utilisé pour évaluer la variabilité. Les données ont été analysées par analyse de variance et analyse multi-variée. Résultats Une importante variabilité a été observée selon les provenances et les descripteurs utilisés. Les descripteurs morphologiques discriminants pour les baobabs que nous avons échantillonnés ont été la longueur et la largeur des fruits, la longueur du pédoncule des fruits, la longueur, la largeur et le nombre de lobes des feuilles.

Introduction. Leaf area is often related to plant growth, development, physiology and yield. Many non-destructive models have been proposed for leaf area estimation of several plant genotypes, demonstrating that leaf length, leaf width and leaf area are closely correlated. Thus, the objective of our study was to develop a reliable model for leaf area estimation from linear measurements of leaf dimensions for citrus genotypes. Materials and methods. Leaves of citrus genotypes were harvested, and their dimensions (length, width and area) were measured. Values of leaf area were regressed against length, width, the square of length, the square of width and the product (length × width). The most accurate equations, either linear or second-order polynomial, were regressed again with a new data set; then the most reliable equation was defined. Results and discussion. The first analysis showed that the variables length, width and the square of length gave better results in second-order polynomial equations, while the linear equations were more suitable and accurate when the width and the product (length × width) were used. When these equations were regressed with the new data set, the coefficient of determination (R2) and the agreement index ‘d’ were higher for the one that used the variable product (length × width), while the Mean Absolute Percentage Error was lower. Conclusion. The product of the simple leaf dimensions (length × width) can provide a reliable and simple non-destructive model for leaf area estimation across citrus genotypes.

Large deviation principles and related results are given for a class of Markov chains associated to the ‘leaves' in random recursive trees and preferential attachment random graphs, as well as the ‘cherries’ in Yule trees. In particular, the method of proof, combining analytic and Dupuis–Ellis-type path arguments, allows for an explicit computation of the large deviation pressure.

The soil of remnant primary rainforest on granite in Singapore is very acidic (pH mostly 3.5–4.2 at 0–10 cm) and has unusually low total concentrations of nitrogen and phosphorus, but the mean concentrations of N and P in the living leaves and freshly fallen leaves of the more shade-tolerant species are within the ranges found for other lowland forests on infertile oxisols and ultisols. The concentration of Ca in freshly fallen leaves is very low. The soil under secondary forest (bselukar) on sandstone dominated by Adinandra dumosa (Theaceae) was degraded during use for agriculture. It has the same pH range but even lower values of total N and P. The mean concentrations of N, P, K, Ca and Mg in the living leaves are slightly higher than in leaves of the more shade-tolerant trees of primary forest, but lower than in the leaves of the species which require canopy gaps for establishment or early onward growth. The few species sampled in both primary forest and belukar show no consistent trend in foliar concentrations. The degraded soil has selected species with inherently lower foliar concentrations.

Mites use the leaf domatia of many woody plant species in Australasia and North America. Different types of leaf domatia, including pits, pockets and tuft domatia, are present among plant species in disturbed forests, plantations and gardens of Bangladesh in South Asia. These structures are frequently occupied by mites. Pooling across all species, domatia were often (66%) occupied by mites and used by them for shelter, egg-laying and development. On average, 70% of all mites on leaves were found in domatia, and over three-quarters of these were potentially beneficial (i.e. of predaceous or microbivorous taxa) to the plant. Further, when species were pooled across sites, leaves of domatia-bearing plants had significantly more predaceous mites than those of plants without domatia. These results are consistent with the patterns of mite-domatia association reported in Australasia, North America and North Asia and with predictions of mutualism between plants and mites.

Introduction. Hibiscus sabdariffa L. est une plante herbacée, vivace, localisée dans les zones tropicales et subtropicales des deux hémisphères. L’espèce est exploitée pour sa fibre et principalement pour ses calices qui sont de trois types : vert, rouge et rouge foncé. Composition. Les calices de type rouge sont les plus utilisés et se caractérisent par leur concentration élevée en anthocyanes qui peut atteindre 1,5 g·kg–1. La delphinidine 3-sambubioside et la cyanidine 3-sambubioside sont les anthocyanes majoritaires avec, respectivement, (71 et 29) % des anthocyanes totaux. Les acides organiques, minéraux et acides aminés sont présents dans les calices, feuilles et graines d’H. sabdariffa à des teneurs variables suivant la variété et la zone géographique. Utilisations. Les utilisations des différentes parties de l’H. sabdariffa sont nombreuses et variées aussi bien dans l’alimentation que dans la médecine traditionnelle. Les calices, du fait de leur concentration élevée en acides, vitamine C et surtout en anthocyanes, constituent la partie de la plante la plus valorisée. Ils sont surtout utilisés pour la production de boissons désaltérantes et tonifiantes sans alcool. Les graines d’H. sabdariffa de par leur richesse en protéine (26 %), lipides (20 %) et sucres totaux (40 %) sont très utilisées dans l’alimentation dans de nombreux pays africains. Les feuilles constituent une bonne source de nutriments et sont utilisées en Afrique pour la préparation de sauces.

Dioecious plant populations have generally been considered to maintain sex ratios of 1:1 (Allen & Antos 1993, Carroll & Mulcahy 1993, Charnov 1982). The sex ratio does, however, change if the plants are growing in a stressful environment, often being male-biased under these conditions (Ortiz et al. 1998, 2002). This pattern has been explained by differences in how the sexes resolve their respective energy requirements (Obeso et al. 1998). Females generally assign more resources to reproduction in comparison to growth and maintenance than do males, and they are smaller and longer-lived (Allen & Antos 1993, Nicotra 1999, Obeso et al. 1998, Willson 1983). Thus their higher reproductive costs take a toll on females, modifying the population sex ratio in favour of males (Allen & Antos 1993, Lovett-Doust & Lovett-Doust 1988). However, in order to determine the reproductive cost it is necessary to consider the compensatory mechanisms (Obeso 2002). These reduce the reproductive cost and include plastic response in terms of plant architecture and plant physiology. For example, nutrient resorption is a process that may help decrease dependence on nutrient intake, thereby constituting an important nutrient economy mechanism that can also reduce the reproductive cost if a significant proportion of the nutrients had been reassigned to reproduction (Killingbeck 1986, Obeso 2002).

Introduction. Under the sub-tropical climate of India, ‘Sweet Charlie’ strawberry is being grown on a large scale. However, under such climatic conditions, it is not possible to transplant runners before mid-October, because the environmental temperature is very high, and planting after mid-October is also not good because then winter sets in and affects growth, development, flowering and fruiting of strawberry. Under such circumstances, covering of strawberry beds with row covers and mulching with plastic mulch can be useful for early and high production by way of modifying the leaf physiology and producing marketable berries in high number. Materials and methods. Row covers of transparent polyethylene (100-µm thickness) were erected over beds after one month of transplanting of the runners. Mulching (black polyethylene, white polyethylene and paddy straw) was also applied after one month of transplanting of the runners; it was removed only after fruiting was over. Observations on different leaf physiological parameters were made. Results. Row covers and mulching individually or in combination significantly influenced plant physiology, growth, berry yield attributes and albinism incidence. Plants showed better growth and physiological attributes under row covers than without row covers. Plants had the best growth and physiological attributes under black polyethylene mulch. Berry weight and yield were the highest in plants under row covers and black polyethylene mulch. Although the [row covers × mulching] interaction showed the highest incidence of albinism, berry yield per plant (excluding albino fruit) was significantly the highest with that combination. Conclusion. Erection of row covers and mulching in winter is highly useful for better growth and production of strawberry under a sub-tropical climate.