Number Of Crowns Research Articles

EVALUATION OF NEW STRAWBERRY CULTIVARS FOR IRAN

To study evaluate new strawberry cultivars, two field trials were conducted on 14 cultivars of strawberry (‘Ventana’, ‘Diamante’, ‘Karcynberg’, ‘Classica’, ‘Camarosa’, ‘Fresno’, ‘Gaviota’, ‘Pajaro’, ‘Paros’, ‘Missionary’, ‘Marak’, ‘Selva’, ‘Queen Elisa’ and ‘Kurdistan’) in a randomized complete block design with three replicates in two different regions in the 2007-2011 period. Morpho-physiological and phenological traits such as: total leaves, number of crowns, number of runners, total number of fruits, total yield, number of inflorescences/plant, petiole length, leaf area, chlorophyll content, initial runnering date, number of inflorescences/crown, inflorescence length, blooming date, flowering period, first fruits ripening, fruiting period, , fruit volume, fruit weight, total soluble solids (TSS), titratable acidity (TA) and anthocyanins were evaluated. Compound variance analysis of data showed a significant difference (P≤0.01) between cultivars for all evaluated traits. Different years did not show significant difference (P≤0.05) in total leaves/plant, petiole length, initial runnering date, number of crowns, blooming date, TA and anthocyanins content, but showed significant differences in other evaluated traits. The highest yield was obtained from ‘Queen Elisa’ (953.7 g/plant) and the lowest from ‘Gaviota’ (100.9 g/plant). Significant and positive correlations (P≤0.01) between yield and total leaves/plant, petiole length, number of crowns/plant, number of inflorescences/plant, total fruits, fruit size and fruit weight were observed.

INTERRELATIONSHIPS OF TRAITS AND PATH ANALYSIS OF YIELD IN STRAWBERRY (FRAGARIA × ANANASSA DUCH.)

A field trial was carried out on 20 cultivars of strawberry (‘Queen Elisa’, ‘Pajaro’, ‘Paros’, ‘Camarosa’, ‘Gaviota’, ‘Mrak’, ‘Selva’, ‘Classica’, ‘Missionary’, ‘Fresno’, ‘Kurdistan’, ‘Blakemore’, ‘Macdonance’, ‘Aliso’, ‘Catskill’, ‘Yalova’, ‘Chandler’, ‘Sequoia’, ‘Tennessee beauty’ and ‘Tioga’) in a RCBD with 3 replicates at the agricultural research center of Kurdistan, Iran during 2008-2010. Morphophysiological and phenological parameters consisting of total leaves of plant, petiol length, leaf area, chlorophyll content, crop production habit, number of crowns per plant, number of inflorescences per plant, number of flowers per inflorescence, inflorescence length, number of frosted flowers, blooming date, flowering period, date of first ripen fruit, fruiting period, runnering start date, number of runners per plant, number of total fruits per plant, fruit size, fruit weight, total yield per plant, TSS, titratable acidity (TA) and anthocyanin pigments content were measured. In order to determine relationships among traits, some multivariate statistical analyses were calculated. According to the combined analysis of variance for two years cultivation of strawberry cultivars, there were high and significant differences (p≤0.01) among cultivars related to all measured parameters. Positive significant correlations were among yield with total leaves, number of crowns, number of inflorescences, number of total flowers, number of total fruits and fruiting period. Based upon the path analysis of yield components, total fruit number has the highest direct effect on yield. Fruit number in conjunction with fruit weight, runnering start date, fruiting start date and fruiting period were the most important factors contributing to yield among morphological traits and were the main yield components (adjusted R-square = 0.918).

Pengaruh Pemberian Variasi Dosis Pupuk Kandang Terhadap Pertumbuhan Tanaman Mahkota Dewa (Phaleria macrocarpa (Scheff.) Boerl.)

Research on the effect of dose variations of manure on God’s Crown (Phaleria macrocarpa (Scheff.) Boerl.) growth was implemented in Ambarketawang, Gamping, Sleman, Yogyakarta. This study aimed to determine the effect of administration of dose variations of manure on God’s Crown growth. This research method using a complete randomized design (CRD) with one treatment factors which is administrating manure into polybags containing 2 kg of soil with dose variations of 0 g, 50 g, 100 g, 150 g, 200 g, and 250 g. The parameters measured in this study are height, leaf number, and fresh weight of Crown’s God plant. The results were analyzed by analysis of variance (ANOVA), if the data is meaningful (significant difference) then followed by LSD test level of 5%. The results obtained are the effects of administration of manure dose variation produce different Crown’s God (Phaleria macrocarpa (Scheff.) Boerl.) growth, and the best dose for Crown’s God (Phaleria macrocarpa (Scheff.) Boerl .) growth is 250 grams. Keywords: crown’s god (Phaleria macrocarpa (Scheff.) Boerl.), dose of manure

Improving Remote Species Identification through Efficient Training Data Collection

Plant species identification and mapping based on remotely-sensed spectral signatures is a challenging task with the potential to contribute enormously to ecological studies. Success in this task rests upon the appropriate collection and use of costly field-based training data, and researchers are in need of ways to improve collection efficiency based on quantitative evidence. Using imaging spectrometer data collected by the Carnegie Airborne Observatory for hundreds of field-identified tree crowns in Kruger National Park, South Africa, we developed woody plant species classification models and evaluated how classification accuracy increases with increasing numbers of training crowns. First, we show that classification accuracy must be estimated while respecting the crown as the basic unit of data; otherwise, accuracy will be overestimated and the amount of training data needed to perform successful classification will be underestimated. We found that classification accuracy and the number of training crowns needed to perform successful classification varied depending on the number and spectral separability of species in the model. We also used a modified Michaelis-Menten function to describe the empirical relationship between training crowns and model accuracy, and show how this function may be useful for predicting accuracy. This framework can assist researchers in designing field campaigns to maximize the efficiency of field data collection, and thus the amount of biodiversity information gained from remote species identification models.

Growth and Yield as Affected by Controlled Crowns of the New Ever-bearing Strawberry ‘Goha’ in Highlands

본 실험은 고랭지에서 신품종 사계성 딸기 '고하' 품종의 생육 및 수량에 영향을 미치는 관부수를 구명하고자 실시하였다. 정식은 4월 29일에 재식거리를 <TEX>$55{\times}30cm$</TEX>로 실시하였으며, 시험구 처리는 관부수를 1, 3, 5개로 하고 대조구로 방임을 두었다. 생육초기에 관부수가 적을수록 잎은 커졌고, 화방경은 굵어졌다. 최종수확 시 초장은 크라운수가 많을수록 길어졌다. 생체중은 관부수 방임구가 118g으로 관부수 1개구의 40.8g보다 77.2g이 더 무거웠다. 발생된 화방수는 관부수 5개구와 방임구가 20.1개로 관부수 1개구의 6.8개에 비해 13.3개가 더 많았다. 그러나 관부수에 따른 과실품질의 유의적인 차이는 보이지 않았다. 관부수가 많을수록 평균과중은 가벼웠으며, 상품과율은 감소하였다. 상품수량은 관부수 방임구가 <TEX>$17,372kg{\cdot}ha^{-1}$</TEX>로 가장 많았으며, 관부수 1개구에 비해 68% 증수되었다. 따라서 고랭지 사계성 딸기 '고하'의 여름재배 시 안정생산을 위해서는 관부는 방임하며, 화방굵기가 3mm 이하인 화방은 제거하는 것이 가장 적당하였다. This study was conducted to investigate the effects of crown numbers on growth and yield of ever-bearing strawberry (Fragaria <TEX>${\times}$</TEX> ananassa Duch.) 'Goha' cultivar. Strawberry seedlings were planted with <TEX>$55{\times}30cm$</TEX> distance on April 29, and the randomized block experimental was designed by putting the crown numbers by 1, 3, 5 and crown-unremoved as the control. At the early growth stage, as the numbers of crown decreased, the size of leaf became larger and inflorescence diameter became thicker. Plant height became higher as the number of crown increased at the final harvesting time. Fresh weight of crown-unremoved plants was 118 g, showing 77.2 g higher than that of plants with one crown. Numbers of the developed inflorescence of plants with five crowns and crown-unremoved was 20.1, whereas 6.8 of plants with one crown, resulted in 13.3 more crowns. However, crown number did not significantly affect the fruit quality. As the crown number increased, the average fruit weight was lighter and the marketable fruit rate was shown to decrease significantly. The marketable yield of crown-unremoved plants was <TEX>$17,372kg{\cdot}ha^{-1}$</TEX>, showing 68% higher than plants with one crown. Therefore, crown management without thinning crowns was recommended and inflorescence thickness less than 3 mm should be removed for successful production of ever-bearing strawberry 'Goha' cultivar during summer season.

Forest species colonizing cerrado open areas: distance and area effects on the nucleation process

Nucleation is a natural process in which trees scattered in the landscape promote changes in the surrounding environment, which increases the probability of seedling and sapling colonization in a nucleus area. This study aimed to describe forest species community under the crown of Bowdichia virgilioides (Fabaceae) in cerrado sensu stricto, testing two hypotheses: (a) distance: more distant nuclei will have fewer numbers of colonizing species and individuals; (b) crown area: nuclei with larger crown will have more individuals and species. We selected six B. virgilioides nuclei at Estacao Ecologica do Panga (EEP) in which we traced two transects (D1 and D2) and calculated crown area by ellipse formula. In the under-crown area, we identified all individuals (regardless of size) of tree forest species and also measured their height and diameter at stem base. We performed a Pearson correlation between crown area and the number of individuals and species, and between distance from nucleus to closest forest edge and density. In the six nuclei, we found 517 individuals of 24 species, distributed in 14 families, with a total density of 2.48 individuals per square meter. Correlation between crown area and the number of individuals was statistically significant (r = 0.80; n = 6; p = 0.05). There was no correlation statistically significant between crown area and number of species (r = 0.29; n = 6; p > 0.05). There was a negative correlation between density of individuals and the distance from nucleus to forest edge (r = −0.79; n = 6; p = 0.05). This study shows that some forest species were capable to colonize the area under the crown of B. vigilioides in cerrado, facilitated by this nucletor specie. This colonization process was influenced by the environmental changes promoted by B virgilioides, nuclei crown size, distance of nuclei from propagule source, and the capability of some forest species to survive in an environment different from forest.

Variability in the number of stems in Lotus tenuis seedlings growing at high density

Successful establishment of Lotus tenuis, an important legume to improve grasslands in the Pampa Deprimida, might be limited by low seedling vigor. The number of crown stems is an important component of vigor. The objective of this work was to determine the variability in the number of crown stems on seedlings of 11 Lotus tenuis natural populations sown at high density under semi-controlled conditions. Seeds of all populations were collected in the Province of Buenos Aires, Argentina. They were sown in plastic pots and cultivated in a greenhouse. Eight weeks after seeding, seedlings of each population were grouped according to their number of stems per crown. Variability in the crown stem number was studied within and among populations. Number of seedlings with different stem crown numbers within each population, dry weight (PS) of the group of individuals and mean for each group, the predominant groups of crown stem numbers from the total number of seedlings within each population, and those that presented a greater grouped dry weight and average per individual of each group were also determined. Simple linear regression of the crown stem numbers versus dry weight was conducted. ANOVA and Tukey´s tests were used (p≤0.01). The relationships between crown stem numbers and number of seedlings within each population tended to bimodal in 10 out of 11 populations. The crown stem number presented differences among (p≤0.01) and within (variation coefficient=44 to 56%) populations. Classes of 1 to 3 stems per crown were dominant (p≤0.01). Groups of 3 or 5 stems per crown showed greater dry weight (p≤0.01) when they were grouped or taken as a mean per individual, respectively. The regression was significant (p≤0.01) for mean dry weight per individual. Using of high density allowed the expression of variability within and among populations in the number of stems per crown. This variability can be attributed to genetic causes, considering the semi-controlled conditions under which the experiment was conducted. This implies the possibility of improving such parameter and the seedling vigor indirectly.

Mechanical Performance of Cup-spherical-shaped and Straight Form Braided Esophageal Stent

This article introduces the application background and research overview of esophageal stent. The finite element models of two different forms of braided esophageal stent, such as cup-spherical-shaped and straight shaped, are created. Based on the configuration of material model selection and boundary condition, the stress and axial elongation of the stent with different wire numbers, different wire diameters and different leads are compared. The analysis results show that the maximum stress increases with the increase of the wire diameter and head, but decreases with the increase of the lead in straight stent while the maximal stress has a positive relationship with the wire diameter in cup-spherical-shaped stent. In the case the other parameters are the same, it is shown that the cup-spherical-shaped stent has the minimal stress when the crown number is 24. Meanwhile, the analysis results show that the lead has a great impact on the axial elongation of braided stent. In the case all parameters are the same, the axial elongation of cup-spherical-shaped stent is less than that of straight stent, which conclusively proves that the performance of cup-spherical-shaped stent is superior to that of the straight stent. DOI: http://dx.doi.org/10.11591/telkomnika.v11i11.3512 Full Text: PDF

Seed Safening from Herbicidal Injury in Switchgrass Establishment

ABSTRACTWeed control during the establishment year of switchgrass (Panicum virgatum L.) is critical for a successful stand. Laboratory and field studies were conducted for 2 yr to evaluate the effectiveness of seed safeners for protecting switchgrass seed from the preemergent herbicide metolachlor. Initial evaluations of six seed safeners determined that fluxofenim was the only successful protectant tested for switchgrass seedling germination. Safener rates 0, 25, 50, and 100% of the recommended rate (40 mg a.i. 100 g per seed), method of application (coating vs. controlled hydration), ecotype (lowland vs. upland), dry matter yield, and number of crowns per row were analyzed in replicated field trials conducted in Starkville, MS, Ames, IA, Blacksburg, VA, and Brookings, SD, in a randomized complete block design. Two establishment years were planted in single‐row (6.1 m) plots spaced 50.8 cm apart. Subsequent biomass yield was harvested at the end of each growing season. Exceptional stands were achieved with all rates of safener in both years due to the reduction or elimination of annual grassy weeds and no crop injury was experienced at any test location. The controlled hydration (combination of 25, 50, or 100% fluxofenim) method resulted in significantly greater yields and crown counts than the coating technique at most locations for both years.

Seasonal population fluctuations of the diamondback moth, Plutella xylostella (L.) (Lep.: Plutellidae) on different cauliflower cultivars

The diamondback moth, Plutella xylostella (L.) (Lep.: Plutellidae) is one of the most important pests of cruciferous plants throughout the world. In recent years, it has been identified as a serious pest of the cauliflower fields in Tehran province. Resistance of P. xylostella to all main groups of insecticides has been recorded and it is ranked in the 20 most resistant pest species reported until now. According to many researchers, to solve the problem of pest resistance to chemical pesticides, an integrated pest management programme should be used. Despite this condition, it seems that the use of resistant cauliflower cultivars is an appropriate policy for integrated control of the pest in the field. In order to identify the most resistant cultivar in the field, eight cauliflower cultivars in a completely randomised design with five replicates were planted at the Shahed University research field (south of Tehran). Density of eggs, larvae and pupae of P. xylostella were measured every 10 days in these cultivars. The results showed that there is no significant difference between numbers of eggs per plant on different cultivars. But number of larvae and pupae per plant were significantly different among different cultivars. Smilla and Snow mystique cultivars had the highest number of larvae and pupae. On the other hand, Buris and Snow crown cultivars had the lowest number of pupae and Snow crown and SG cultivars had the lowest number of larvae per plant. According to the results, the Buris and Snow crown cultivars had the lowest infestation and had a kind of resistance to pest.

Estimating Vegetation Beta Diversity from Airborne Imaging Spectroscopy and Unsupervised Clustering

Airborne remote sensing has an important role to play in mapping and monitoring biodiversity over large spatial scales. Techniques for applying this technology to biodiversity mapping have focused on remote species identification of individual crowns; however, this requires collection of a large number of crowns to train a classifier, which may limit the usefulness of this approach in many study regions. Based on the premise that the spectral variation among sites is related to their ecological dissimilarity, we asked whether it is possible to estimate the beta diversity, or turnover in species composition, among sites without the use of training data. We evaluated alternative methods using simulated communities constructed from the spectra of field-identified tree and shrub crowns from an African savanna. A method based on the k-means clustering of crown spectra produced beta diversity estimates (measured as Bray-Curtis dissimilarity) among sites with an average pairwise correlation of ~0.5 with the true beta diversity, compared to an average correlation of ~0.8 obtained by a supervised species classification approach. When applied to savanna landscapes, the unsupervised clustering method produced beta diversity estimates similar to those obtained from supervised classification. The unsupervised method proposed here can be used to estimate the spatial structure of species turnover in a landscape when training data (e.g., tree crowns) are unavailable, providing top-down information for science, conservation and ecosystem management applications.

Fracture strength of minimally prepared all-ceramic CEREC crowns after simulating 5 years of service

ObjectivesTo examine the strength and mode of fracture of traditionally and minimally prepared all-ceramic resin bonded CAD/CAM crowns after fatigue loading. MethodsThirty human maxillary molars were used and divided in three groups namely; traditional crown preparation group (I), minimal crown preparation group (II) and occlusal veneer preparation group (III). A leucite reinforced glass ceramic (IPS Empress CAD) was used for fabricating the crowns. The CEREC InEOS system (v3.10) was used for scanning, designing and milling. Five years of clinical service were simulated and the fracture strength of the crowns was measured. One-way ANOVA and Kruskal–Wallis test were used for data analysis (α=0.05). ResultsThe mean fracture strength and SD in Group I was 1070N (±181) and in Group II 1110N (±222). One-way ANOVA analysis showed no statistically significant difference between the two groups (p>0.05). In Group III all restorations developed cracks during TCML and were not subjected to fracture loading. Three of the traditionally designed crowns (Group I) and 4 of the minimally designed crowns (Group II) developed surface cracks during TCML. SignificanceMinimal all-ceramic resin-bonded crowns can potentially form a viable restorative option as they demonstrated comparable strength to traditional all-ceramic crowns. However, this should be interpreted with caution as a number of crowns showed cracks after 5 years of simulated service. All the occlusal veneers developed cracks during simulation and further investigation is needed for this to be considered a viable option.

EFFECTS OF FERTIGATION TIMING ON GROWTH AND DEVELOPMENT IN STRAWBERRY 'KORONA'

EFFECTS OF FERTIGATION TIMING ON GROWTH AND DEVELOPMENT IN STRAWBERRY 'KORONA'

Genetic variation in progenies of 23 relic trees of Metasequoia glyptostroboides in their original habitat

Seeds of 23 relic Metasequoia glyptostroboides trees were randomly collected from their original, natural populations found in Lichuan City, Hubei Province, China. The seed characteristics and growth of their three-year-old progenies were investigated. Results show that the average intra-family coefficient of variation (CV) in height growth of the 23 three-year-old families was 14.53%, slightly higher than that of the inter-family CV (14.02%). Correspondingly, these two parameters for root-collar diameter growth were 15.44% and 13.15%. The 23 relic mother trees were significantly differed in their general combining abilities (GCA) and relative effect values of GCA (RGCA) of height growth and root-collar diameter growth over the three years. Both height and root-collar diameter growth had high family heritability in this seedling stage. After eliminating two inferior families, i.e., 15 and 46, 2.21% of genetic gain in height growth was obtained and 1.50% in root-collar diameter growth. It was also significantly different in crown size and number of branches among the 23 three-year-old seedling families. From a cluster analysis we concluded that eight families, i.e., 23, 28, 29, 30, 31, 33, 35 and 44 displayed superior GCA and RGCA in both height and root-collar diameter growth. Therefore, these relic mother trees displayed their potential as parents in seed orchards. With the exception of family 23, the other seven superior families were all collected at Guihua Village, Zhonglu Town, Lichuan City, which has been identified as an optimum district of M. glyptostroboides for seed collection.

Multitemporal change detection of urban trees using localized region-based active contours in VHR images

This study introduces active contours for multitemporal monitoring of urban trees using fine resolution imagery. In our implementation active contours locally identify tree crown image regions using a localized data energy term and competition of energy forces between adjacent contours. The simultaneous evolution of n contours represents an equivalent number of tree crowns which are initialized based on a fast and efficient image fitting procedure. We incorporate prior information into the multitemporal analysis, as optimized contours are propagated through a sequence of images. We demonstrate the applicability of the method to monitor individual trees and tree groups in two residential areas in the Netherlands using multispectral aerial images acquired over a period of five years. The method allowed the identification of abrupt and gradual tree crown changes in both areas and performed superior to an alternative region growing segmentation approach. We conclude that the method extracts meaningful image objects that facilitate tree crown monitoring and is effective to update tree crown spatial-databases in urban areas.

A retrospective analysis of 102 zirconia single crowns with knife-edge margins

Clinical reports of feldspathic porcelain veneered-zirconia crowns placed on teeth with knife-edge marginal finish lines have recently been presented but with data available for only a limited number of crowns in the anterior maxilla. This retrospective study evaluated the clinical success and survival of feldspathic porcelain veneered-zirconia crowns fabricated with knife-edge margins in a private practice. One hundred and two teeth (51 anterior, 51 posterior) were prepared with knife-edge margins and restored with feldspathic porcelain veneered-zirconia crowns. The modified California Dental Association (CDA) criteria were used to clinically evaluate subjects recalled between May and December 2010. Data were analyzed with descriptive statistics. The mean follow-up time was 20.9 months (SD, 13.6; range, 10-72). One tooth had to be extracted because of an endodontic problem not related with the restoration, 2 crowns had minor chipping of the veneering porcelain, while no crowns exhibited fracture of the zirconia core. In this retrospective evaluation, feldspathic porcelain veneered-zirconia crowns with knife-edge margins provided clinical performance similar to that reported with other margin designs.

Effects of some growing media on the growth of strawberry cvs. 'Camarosa' and 'Fern'

This study evaluated the development of above and under ground parts of strawberry plants cvs. 'Fern' and 'Camarosa ' in a glasshouse using perlite, forest soil, finpeat, peat, finpeat+perlite (1:1) and peat+perlite (1:1) as substrates. The effects of different growing media on development of above and under ground parts of plant were statistically significant. The highest number of primary roots per plant, length of the most developed roots and number of crowns per runner were obtained from perlite, finpeat+perlite and peat medium, respectively, in both cultivars. The runner length, number of runners per plant, leaf area, fresh root weight and dry root weight varied between cultivars according to growth medium. In general peat, finpeat or finpeat+perlite gave the best results in terms of above and under ground parts of plants in both cultivars. Some important properties such as water retention capacity, cation exchangeable capacity, pH, porosity etc. of growing media using in this study were also determined.

PROPAGATION CAPACITY AND PLANT QUALITY OF MEXICAN AND FOREIGN STRAWBERRY VARIETIES

This work was carried out in order to compare propagation capacity and quality of Mexican strawberry varieties (CP-Jacona and CP-Zamorana) and foreign commercial varieties (Festival and Albion). The four varieties were established in two nurseries located in Mi-choacán, Mexico at different altitudes: Tanaquillo (1,700 m) and Zirahuén (2,228 m). Eight mother plants and eight daughter plants were sampled as replications. Number of crowns, number of runners and daughter plants per mother plant were the variables studied. Root starch content and fresh and dry plant weight were recorded of the daughter plants. The statistical analysis was performed using the stu-dent’s t-test with 5 % significance level. The Mexican variety ‘Festival’ produced more runners, crowns and daughter plants in the nursery of Zirahuén, compared to other varieties; however, the starch content was higher in the Mexican varieties. In the nursery of Tanaquillo, both the ‘Festival’ and ‘CP-Jacona’ varieties showed higher number of daughter plants; however, the starch content in the ‘Festival’ variety was higher than in the ‘CP-Jacona’ variety. In the nursery of Zirahuén, the starch content of daughter plants was higher than in the nursery of Tanaquillo, but the number of daughter plants produced was notably higher at the nursery of Tanaquillo. At the nursery of Zirahuén, the ‘CP-Jacona’ variety had a lower capacity of runners and daughter plants production but these plants showed greater starch content but dry weight of daughter plants was similar to the USA varieties. At the nursery of Tanaquillo, the Mexican varieties were better in the production of daughter plants than the ‘Albion’ variety

Influence of soil hydrothermal environment, irrigation regime, and different mulches on the growth and fruit quality of strawberry (Fragaria × ananassa L.) plants in a sub-temperate climate

SummaryThe present study was undertaken over two consecutive years under sub-temperate climatic conditions in the mid-hill region of Himachal Pradesh (30°52'N, 77°11'E; 1,175 m asl) on loamy sand Inceptisols. The aim was to investigate the effects of irrigation and mulch material on the growth, flowering, fruiting behaviour, relative leaf water content (RLWC), yield, and quality of strawberry (Fragaria × ananassa L. ‘Chandler’). The drip irrigation treatments included irrigation with 100, 80, or 60% (coded 1.0, 0.8, and 0.6 V) of the total water requirement. Both mulches increased the minimum soil temperature to a depth of 5 cm. The drip and surface irrigation treatments raised the minimum soil temperature by 3.0º – 5.4ºC, and lowered the maximum temperature by 2.2º – 5.8ºC compared to the rainfed control. Hay mulch was more effective in raising the minimum temperature and lowering the maximum soil temperature than black polyethylene mulch. Moisture conservation increased by 2.8 – 12.8% under the black polyethylene mulch compared to the no-mulch treatment. Drip and surface irrigation methods, as well as mulching, were found to be effective for enhancing the growth, irrigation water use efficiency (IWUE), fruit yield, and quality of strawberry plants. However, the number of crowns per plant, the percentage berry set, the RLWC, root length density (RLD), and fruit yield were highest under treatment M3I3 [i.e., black polyethylene mulch plus drip irrigation (1.0 V)] by 565.5%, 94.5%, 32.8%, 394.5%, and 549.6%,respectively, compared to the no mulch plus rainfed control. The maximum IWUE values for plant biomass [1.39 metric tonnes (MT) ha–1 m–1] and fruit yield (2.79 MT ha–1 m–1) were recorded under treatment M3I5 [i.e., black polyethylene mulch plus drip irrigation (0.6 V)]; whereas, the lowest values (0.39 and 0.68 MT ha–1 m–1, respectively) were observed using treatment M1I2 (i.e., without mulch, plus surface irrigation). Fruit size, weight, sugar content, and anthocyanin content increased significantly under treatment M2I3 [i.e., hay mulch, plus drip irrigation (1.0 V)] compared with all other treatments. Total soluble solids (TSS) contents and total acidity (TA) were highest under treatment M1I1 (i.e., no mulch, plus rainfed). A linear regression model could describe the variations in quality parameters of strawberry plants grown under sub-temperate climatic conditions. Root density was found to be the best indicator with which estimate fruit quality.

A forest structure model that determines crown layers and partitions growth and mortality rates for landscape‐scale applications of tropical forests

Summary1. We present a model to quantify tropical forest structure and explain variance in dynamic rates (growth and mortality) that is computationally simple and can be applied to landscape‐scale forest inventory and, potentially, remote sensing‐derived data.2. The model is a modification of the perfect plasticity approximation (PPA) based on tree allometry, tree locations and sizes. The model quantifies crown area index (CAI) (number of crowns per unit ground area) and assigns trees to crown layers, which determines the expected number of crowns above each tree and thus its light environment.3. The structural model, parameterized and tested for the Barro Colorado Island, Panama 50‐ha forest dynamics plot using data from forest inventories and stereo aerial photographs, reproduces most canopy and understorey structural and dynamic properties. The PPA model worked as well or better than a computationally intensive, spatially explicit model. A single allometry for all trees worked equally well as functional group or species allometries. Models of growth and mortality were always improved by adding crown layers as defined by the PPA model.4. The mean CAI of the 50‐ha plot was 3.1 with low variance. The observed variance was lower than when tree locations were randomized, which drastically lowered the variance in tree density per plot, indicating that there are regulating forces towards a small range of crown area indices.5. Synthesis. A number of simplifying characteristics in structure were uncovered with the PPA structural model applied to a tropical forest: species allometries were not needed despite the high species diversity in the forest; the model worked on a range of plot sizes; and the variance in CAI was surprisingly low, suggesting regulatory mechanisms. The PPA structural model can be used to develop a fully dynamic simulation model for tropical forests. The ability of the simulation model to predict temporal changes in landscape patterns of biomass, dynamic rates, and species and/or functional group composition will provide validation for the partitioning of dynamic rates by crown layers in the PPA structural model.