Second Growth Stage Research Articles

Exploring Lignin Biosynthesis Genes in Rice: Evolution, Function, and Expression.

Lignin is nature's second most abundant vascular plant biopolymer, playing significant roles in mechanical support, water transport, and stress responses. This study identified 90 lignin biosynthesis genes in rice based on phylogeny and motif constitution, and they belong to PAL, C4H, 4CL, HCT, C3H, CCoAOMT, CCR, F5H, COMT, and CAD families. Duplication events contributed largely to the expansion of these gene families, such as PAL, CCoAOMT, CCR, and CAD families, mainly attributed to tandem and segmental duplication. Microarray data of 33 tissue samples covering the entire life cycle of rice suggested fairly high PAL, HCT, C3H, CCoAOMT, CCR, COMT, and CAD gene expressions and rather variable C4H, 4CL, and F5H expressions. Some members of lignin-related genes (OsCCRL11, OsHCT1/2/5, OsCCoAOMT1/3/5, OsCOMT, OsC3H, OsCAD2, and OsPAL1/6) were expressed in all tissues examined. The expression patterns of lignin-related genes can be divided into two major groups with eight subgroups, each showing a distinct co-expression in tissues representing typically primary and secondary cell wall constitutions. Some lignin-related genes were strongly co-expressed in tissues typical of secondary cell walls. Combined HPLC analysis showed increased lignin monomer (H, G, and S) contents from young to old growth stages in five genotypes. Based on 90 genes' microarray data, 27 genes were selected for qRT-PCR gene expression analysis. Four genes (OsPAL9, OsCAD8C, OsCCR8, and OsCOMTL4) were significantly negatively correlated with lignin monomers. Furthermore, eleven genes were co-expressed in certain genotypes during secondary growth stages. Among them, six genes (OsC3H, OsCAD2, OsCCR2, OsCOMT, OsPAL2, and OsPAL8) were overlapped with microarray gene expressions, highlighting their importance in lignin biosynthesis.

Phenological growth stages of Amaranthus palmeri according to the extended BBCH scale

AbstractAmaranthus palmeri S. Watson is a problematic weed that has been encountered almost all over the world because of its stronger adaptability, which causes huge economic losses and local plant diversity decline. As an invasive plant, A. palmeri has been found throughout China. We thus make a code system to describe the phenological growth process of A. palmeri according to the extended BBCH scale to better understand the phenological growth of this weed in China. The growth process of A. palmeri was divided into vegetative growth phases and reproductive growth phases. The vegetative growth phases are composed of seed germination (0), leaf development (1), formation of side shoots (2) and main stem elongation (3). Likewise, the reproductive growth phases include inflorescence emergence (5), blooming (6), fruit development (7), seed maturity (8) and senescence (9). Based on the extended BBCH scale, the first digit stands for the primary growth stages, and the third digit represents the secondary growth stages. In particular, the second digit defines the growth progress: the number 0, means the vegetative growth phases, and the number 1 stands for the reproductive growth phases. Owing to the fact that its seed can germinate multiple times within a year, a general illustration of the phenological development stages of A. palmeri germinating in different months was provided here to describe the growth dynamic characteristic at different times. These data are of great significance to develop effective strategies for weed control and management of A. palmeri.

Coding and description of phenological stages of blue honeysuckle (Lonicera caerulea L.) according to the BBCH scale

Blue honeysuckle (Lonicera caerulea L.) is an emerging fruit crop from the temperate to circumpolar climate regions with outstanding agronomic traits, substantial nutritional value, and versatile processing applications. However, the limited understanding of its phenology poses substantial challenges to its cultivation, breeding, and research. In this study, we characterized the progressive phenological growth stages of blue honeysuckle according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale by investigating three major cultivars (L. caerulea) and a wild accession (L. caerulea var. edulis) in Harbin, China (hot-summer humid continental climate) during 2022–2023. The annual growth of blue honeysuckle was characterized by eight primary stages, including bud development (0), leaf development (1), shoot development (3), inflorescence emergence (5), flowering (6), fruit development (7), fruit ripening (8), and senescence and dormancy (9). Additionally, 35 secondary growth stages were documented, among which eight stages are related to fruit development and ripening. The annual growth period of blue honeysuckle spans 6.5–7 months, starting from late March and ending in early October. The flowering season lasts for 2–3 weeks, ranging from late April to mid-May. The fruit development and ripening last for 7–9 weeks, beginning in early May and ending in early July. This study provides valuable insights for the cultivation and research of blue honeysuckle.

Reproductive morphophysiology of an iteroparous batch spawner fish: from early follicle development to ovulation.

Batch spawner fishes develop successive clutches of oocytes which allows them to participate in many reproductive cycles during their adult life (iteroparous) and spawn in multiple events within each breeding cycle. Here, ovarian follicular development was morpho-functionally analyzed in females of the iteroparous batch spawner fish Gymnocorymbus ternetzi. To obtain better insights into the reproductive morpho-physiology in batch spawners, the objective of this research was to analyze the dynamics of the follicular development, with its hormonal regulation between two active reproduction events. We found that over 16 days, follicles progressed asynchronously to chromatin nucleolus, Primary and Secondary growth stages of oogenesis with progressive secretion of 17β-estradiol (E2). During the end of secondary growth, the increase in 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-p) was measured relative to the maturation process of the ovarian follicles (e.g., nuclear migration and its rupture during the resumption of meiosis). Interestingly, an additional increase in E2 was observed after fish reproduction, probably related to the recruitment of new batch follicles for secondary growth. We also measured the high values of multiple condition factor post-reproduction measurements, reflecting more energy invested during the pre-reproductive process. We also quantified high concentrations of 17,20β-p, probably related to the recruitment of a new batch of oogonia to meiosis, presumably secreted by post-ovulatory follicles, after fish reproduction. We finally found that fish without exposure to reproductive stimulus developed a regression phase at day 24, characterized by massive follicle atresia, that allow them to recycle energy and constitutive materials of the follicles invested during oogenesis for another reproductive cycle.

Forest cover and environment type shape functional diversity of insectivorous birds within the Brazilian Atlantic Forest

SummaryTropical insectivorous birds comprise a diverse group that has a distinct response to habitat degradation. However, knowledge on birds’ ecological functions and their large-scale functional responses to human impacts across various habitats is scarce. We sampled 22 1-km-radius buffer landscapes within the Cantareira-Mantiqueira region (south-east Brazil), including native forests, pastures and marshes, to assess how landscape and habitat characteristics might affect insectivorous birds within the Brazilian Atlantic Forest. We studied whether bird species and functional diversity might respond to habitat turnover and nestedness and to native forest cover using generalized linear mixed models. We found negative effects of increased native forest cover on functional diversity indices. Bird communities in pastures show more nestedness, whereas marsh areas exhibit higher turnover. Forest areas receive a balanced contribution from both nestedness and turnover. These results are attributable to the predominantly secondary growth and early successional stages of the native forest fragments in the region, emphasizing the connection between landscape characteristics, habitat types and bird functional diversity in the Brazilian Atlantic Forest.

Phenological growth stages of Xanthoceras sorbifolium Bunge: Codification and description according to the BBCH scale

Xanthoceras sorbifolium Bunge is a kind of unique oil tree species found in northern China that has high ecological, ornamental, and economic value. Its seed oil is not only a high-quality edible oil well supplied with unsaturated fatty acids but also a superior raw material for biodiesel production. In the present study, the different phenological growth stages of X. sorbifolium were characterized according to the Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) scale. Eight principal growth stages were described for the bud, leaf and shoot development; inflorescence emergence and flowering; fruit development and maturity, together with senescence and beginning of dormancy. Meanwhile forty-two secondary growth stages were described in detail. Illustrative pictures with a codification were provided to better define and describe these phenological growth stages. Phenological records from two growing seasons were used to create a schematic representation of the principal growth stages. This study provides a beneficial reference for general orchard management, scientific research, and cultivation of new cultivars.

BUDDHIST EDUCATION SYSTEM IN ANCIENT INDIA: AN INTRODUCTION

Education in ancient India touched a high level of development both in the sphere of organised and unorganized sectors and provided water and manure to Indian knowledge traditions. Now ancient education system and culture is not only history but also became a reality through the adoption of its several features in National Education Policy 2020. The present essay will introduce the Buddhist education system and associated institutional culture in detail with its important features. It should be noted with emphasis that the structure of ancient Indian education primarily materialized from religions like Brāhmaṇism, Jainism and Buddhism. Especially in the process of consolidation and expansion religions like Brāhmaṇism and Buddhism played vital roles in creating, preserving and transmitting Indian knowledge through its gurukulas and mahāvihāras. The chapter will focus on Buddhist monasteries, which represent the beginning of the second stage of growth i.e. organised instruction in ancient India. Ancient Indian monasteries like Nālandā, Vikramaśīlā, Valabhī and Odantapurī were both a centre of Buddhism and the world-famous institution of learning. The organised and unorganised stages went on parallel and interacted with each other. Altogether the pre-modern Indian education became the world’s pinnacle with creation, preservation and transmission of the latest knowledge in both secular and religious subjects.

Phenological growth stages of a new kiwifruit cultivar (Actinidia deliciosa ‘Jinfu’)

The BBCH scale is employed to describe the phenological growth stages of Actinidia deliciosa ‘Jinfu’ kiwifruit. This study provides comprehensive descriptions of the key growth stages encompassing bud, leaf, and shoot development, inflorescence emergence, flowering, fruit development, fruit ripening, senescence, and 41 additional secondary growth stages. Furthermore, the investigation encompasses changes in fruit taste, volatile compounds, antioxidant activities, and ethylene production across five different firmness stages during the eating window, with the aim of determining the optimum time for consumption. Principal component analysis of the collected data indicated that fruit firmness ranging from 12 N to 8 N represented the optimal eating window for ‘Jinfu’ kiwifruit. Additionally, this study explored the practical applications of the BBCH scale in orchard management and the production of high-quality fruit. Overall, the insights derived from this research provide valuable and substantial information that can effectively support the introduction and promotion of the new ‘Jinfu’ cultivar.

Transcriptome and miRNAs Profiles Reveal Regulatory Network and Key Regulators of Secondary Xylem Formation in "84K" Poplar.

Secondary xylem produced by stem secondary growth is the main source of tree biomass and possesses great economic and ecological value in papermaking, construction, biofuels, and the global carbon cycle. The secondary xylem formation is a complex developmental process, and the underlying regulatory networks and potential mechanisms are still under exploration. In this study, using hybrid poplar (Populus alba × Populus glandulosa clone 84K) as a model system, we first ascertained three representative stages of stem secondary growth and then investigated the regulatory network of secondary xylem formation by joint analysis of transcriptome and miRNAs. Notably, 7507 differentially expressed genes (DEGs) and 55 differentially expressed miRNAs (DEMs) were identified from stage 1 without initiating secondary growth to stage 2 with just initiating secondary growth, which was much more than those identified from stage 2 to stage 3 with obvious secondary growth. DEGs encoding transcription factors and lignin biosynthetic enzymes and those associated with plant hormones were found to participate in the secondary xylem formation. MiRNA-target analysis revealed that a total of 85 DEMs were predicted to have 2948 putative targets. Among them, PagmiR396d-PagGRFs, PagmiR395c-PagGA2ox1/PagLHW/PagSULTR2/PagPolyubiquitin 1, PagmiR482d-PagLAC4, PagmiR167e-PagbHLH62, and PagmiR167f/g/h-PagbHLH110 modules were involved in the regulating cambial activity and its differentiation into secondary xylem, cell expansion, secondary cell wall deposition, and programmed cell death. Our results give new insights into the regulatory network and mechanism of secondary xylem formation.

Phenological growth stages of biquinho pepper according to the BBCH scale

Biquinho pepper has been gaining prominence on the national scene because of its sweet taste and low pungency. Therefore, this study aimed to describe the phenological growth stages of biquinho pepper according to the BBCH scale. Based on this general scale, biquinho pepper showed 9 of the 10 principal stages (germination, leaf development, formation of side shoots, shoot development, development of the harvestable vegetative parts of the plant, flowering, fruit development, coloring or ripening of fruits and senescence). In addition, 25 secondary growth stages have also been described. The study will act as a tool for adoption of better crop management practices (nutrient management, irrigation scheduling, monitoring of management of pests and timely harvest of fruits).

Phenological growth stages of Astragalus membranaceus var. mongholicus according to the Biologische Bundesanstalt Bundessortenamt and Chemical Industry (BBCH) scale

AbstractAstragalus membranaceus var. mongholicus (Astragalus) is a perennial medicinal plant belonging to Leguminosae. Its main agronomic and industrial interest is the accumulation of astragaloside IV and calycosin‐7‐O‐β‐D‐glucoside in roots, two components that play crucial pharmacological roles in the finished pharmaceutical products. Phenological research is a prerequisite for improving the yield quality of cultivated medicinal plants. However, there are no standardized phenological studies on Astragalus. To expand phenotyping knowledge on this medicinal plant, researchers and breeders need a universal scale to describe the development of this plant. This study aims to define the phenological growth stages of Astragalus, based on the existing Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale to provide a standard scale for Astragalus, and grown under temperate conditions of production and climate, proposes a disease and pest control reference. This study was conducted in Inner Mongolia, North China. The existing BBCH scale with a three‐digit code was used to define Astragalus's phenological growth codes, supplemented with pictures. Phenological observations were performed twice monthly, based on the developmental stages. The chronology and duration of each stage were also observed and described according to the accumulation of degree days during the growing season. Based on the data obtained, the influence of the average temperature and GDD on the phenophases was evaluated. The phenological description is divided into two principal growth stages: five for vegetative growth (perennating bud, leaf development, formation of branches, main stem elongation and root development), four for reproductive growth (reproductive organ development, flowering, fruit development and fruit maturation), and one for senescence according to the BBCH scale. Seventy secondary growth stages were described within the 10 principal growth stages. Under each secondary growth stage, six mesostages are also taken into account, which contains the distinct patterns of the phenological characteristics in Astragalus varieties and the process of transplanting seedlings. A practical management program for disease and pest control was also proposed by using the BBCH code and the phenological data proposed in this work. Our study presents the first BBCH scale established for Astragalus cultivated in temperate conditions and a chronology of phenological stages based on the accumulation of thermal time, through growing degree day calculation. This work provides a general tool that can be widely used by researchers, breeders, and manufacturers of medicinal materials leading to better agricultural production and scientific communication.

Study on fatigue crack propagation behavior of 2050 Al[sbnd]Li alloy during non-isothermal aging

The fatigue crack propagation behavior of 2050AlLi alloy at different stages during non-isothermal aging (NIA) was tested. It was found that when the aging temperature was reduced to 150 °C, the alloy exhibited higher fatigue crack growth resistance and lower fatigue crack growth rate and the fatigue crack growth path was mainly transgranular propagation in different stages of NIA. In addition, in the first stage of fatigue crack growth, the size and quantity of precipitates in the grain are the main factors affecting the crack growth. Because the tiny T1 phase can be sheared by dislocation without damage accumulation, it can effectively prevent crack propagation. In the second stage of fatigue crack growth, the strength difference between grain boundary and intragranular will directly affect the fatigue crack growth resistance of the alloy. The smaller the strength difference is, the more uniform the deformation of crack tip in the process of crack growth, and it is not easy to produce stress concentration and damage accumulation at the grain boundary. In this case, the alloy exhibits the better the fatigue crack growth resistance and the slower the crack growth rate.

From Layer-by-Layer Growth to Nanoridge Formation: Selective Area Epitaxy of GaAs by MOVPE.

Selective area epitaxy at the nanoscale enables fabrication of high-quality nanostructures in regular arrays with predefined geometry. Here, we investigate the growth mechanisms of GaAs nanoridges on GaAs (100) substrates in selective area trenches by metal-organic vapor-phase epitaxy (MOVPE). It is found that pre-growth annealing results in the formation of valley-like structures of GaAs with atomic terraces inside the trenches. MOVPE growth of GaAs nanoridges consists of three distinct stages. Filling the trench in the first stage exhibits a step-flow growth behavior. Once the structure grows above the mask surface, it enters the second stage of growth by forming {101} side facets as the (100) flat top facet progressively shrinks. In the third stage, the fully formed nanoridge begins to overgrow onto the mask with a significantly reduced growth rate. We develop a kinetic model that accurately describes the width-dependent evolution of the nanoridge morphology through all three stages. MOVPE growth of fully formed nanoridges takes only about 1 min, which is 60 times faster than in our set of molecular beam epitaxy (MBE) experiments reported recently, and with a more regular, triangular cross-sectional geometry defined solely by the {101} facets. In contrast to MBE, no material loss due to Ga adatom diffusion onto the mask surface is observed in MOVPE until the third stage of growth. These results are useful for the fabrication of GaAs nanoridges of different dimensions on the same substrate for various applications and can be extended to other material systems.

Fuzzy clustering for the within-season estimation of cotton phenology.

Crop phenology is crucial information for crop yield estimation and agricultural management. Traditionally, phenology has been observed from the ground; however Earth observation, weather and soil data have been used to capture the physiological growth of crops. In this work, we propose a new approach for the within-season phenology estimation for cotton at the field level. For this, we exploit a variety of Earth observation vegetation indices (derived from Sentinel-2) and numerical simulations of atmospheric and soil parameters. Our method is unsupervised to address the ever-present problem of sparse and scarce ground truth data that makes most supervised alternatives impractical in real-world scenarios. We applied fuzzy c-means clustering to identify the principal phenological stages of cotton and then used the cluster membership weights to further predict the transitional phases between adjacent stages. In order to evaluate our models, we collected 1,285 crop growth ground observations in Orchomenos, Greece. We introduced a new collection protocol, assigning up to two phenology labels that represent the primary and secondary growth stage in the field and thus indicate when stages are transitioning. Our model was tested against a baseline model that allowed to isolate the random agreement and evaluate its true competence. The results showed that our model considerably outperforms the baseline one, which is promising considering the unsupervised nature of the approach. The limitations and the relevant future work are thoroughly discussed. The ground observations are formatted in an ready-to-use dataset and will be available at https://github.com/Agri-Hub/cotton-phenology-dataset upon publication.

Estadios fenológicos de crecimiento de árboles de guanábana (Annona muricata L.) utilizando la escala BBCH extendida

The soursop is a species of tropical fruit well accepted by consumers due to its creamy white pulp and excellent flavor. Currently, Mexico is the largest producer and consumer; however, the agronomic practices in use were established without a systematic knowledge of A. muricata L. phenology. The objective of this work then, was to conduct such a study in two of the main producing regions of Mexico: Tepic and Compostela (both in the state of Nayarit). For this, a total of 20 ungrafted trees were selected and their growth stages described using the extended BBCH-scale (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie). Overall, eight main phenological stages were identified over the course of a year. These were: the development of buds (stage 0), leaves (stage 1),and shoots (stage 3), the emergence of flowers (stage 5), flowering (stage 6), fruit development and maturity (stages 7-8), and senescence of branches (stage 9). In addition, 37 secondary growth stages were also described and quantified. The highest number of vegetative shoots occurred from March-July, 2017 and the biggest increase in floral structures from July–September, 2017. Fruit setting to physiological maturity took an average of 114 days in both Tepic and Compostela, with the most intense defoliation occurring in October, 2017 in the former (Tepic) and in December, 2016 in the latter (Compostela). Hopefully, improved agronomic practices will be established using this information, as well as suitable protocols for future physiological studies.

The dynamics of cylinder-wake/boundary-layer interaction revealed by turbulent transports

The flow past a cylinder near a plane wall for small gap ratios (G/D=0.1, 0.3, and 0.9) and fixed ReD = 1000 is numerically studied. The fundamental flow features are characterized by the instantaneous and mean fields. Then, the dynamics of cylinder-wake/boundary-layer interaction are revealed by the turbulent momentum transport and kinetic energy production. The turbulent fluctuations caused by the secondary vortex (SV) (at G/D=0.3, 0.9) and the novel tertiary vortex (TV) (at G/D=0.9) can be observed in the distributions of Reynolds stresses. For G/D=0.1 and G/D=0.3, the wake/boundary-layer interaction is dominated by ejection and sweep events, which are related to the generation of the hairpin vortex. These two bursting events lead to the momentum transport between the high- and low-speed sides. For G/D=0.9, the ejection event is not found in the interaction region because the head of the hairpin vortex is entrained into the wake. The upper roller (RU) helps to transport high-momentum fluid toward the wall in this case, although it does not take part in the interaction directly. The shedding of RU, the lower roller (RL), SV (at G/D=0.3 and 0.9), and KH (Kelvin–Helmholtz) vortex (at G/D=0.1) and the generation of the hairpin vortex are crucial to turbulent kinetic energy (TKE) production. The RU, KH vortex, and SV transfer ⟨u′u′⟩ out to ⟨v′v′⟩ and ⟨w′w′⟩ resulting redistribution of the TKE. While RL, surviving for a shorter time, transfers ⟨v′v′⟩ out to ⟨u′u′⟩ and ⟨w′w′⟩, helping explain why it disappears quickly, TV only transfers out ⟨v′v′⟩ out to ⟨u′u′⟩, and its TKE comes from other terms rather than the production term. The redistribution of TKE due to the generation of the hairpin vortex can result in the slower growth rate of the secondary disturbance growth stage, promoting the wall boundary layer transition.

The Interconnected Relationship between Auxin Concentration Gradient Changes in Chinese Fir Radial Stems and Dynamic Cambial Activity

Auxin has been shown to exhibit a striking concentration gradient distribution in radial sections of angiosperm and gymnosperm species, in which peak auxin levels are concentrated in dividing cambial cells, while the absolute auxin concentration sharply declines toward developing secondary phloem and xylem regions. The coincidence of auxin concentration gradient across shoot tissues and xylem cell developmental gradient has prompted that auxin could act as “a plant morphogen” to provide a positional signal for cambial cell development. However, the specific location of vascular cambium and the lack of mutants altering auxin distribution in shoots of woody species made further verification experiments difficult to explore. To address this issue, different concentrations of exogenous IAA were applied to decapitated Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) trunks in this study to induce the change in the auxin concentration gradient in radial stems, and its effects on cambial activities were examined on the physiological, cellular and molecular levels. Our findings manifested that exogenous IAA treatments resulted in vast changes in endogenous hormone concentrations (including IAA, ZR, GA3 and ABA), cambial cell developmental behaviors and transcriptional activities of genes related to polar auxin transport (PAT), auxin signaling, the biosynthesis and signal transduction of other plant hormones and the genetic control of cambial activity. Based on above findings, we postulated a model of auxin concentration gradient involved in the control of cambial activity and secondary growth in tree trunks. In this model, the contrasting expression of AUX1/LAX and PIN family carriers in distinct Chinese fir wood-forming tissues dynamically modulates PAT into the cambial zone adjacent to the secondary phloem side and secondary xylem tissues, resulting in a sharp and wide auxin spatial gradient distribution across shoots in different stages of secondary growth, respectively. This change in auxin concentration gradient distribution in radial sections in turn acts on cambial developmental behaviors by modulating the expression of auxin signaling genes and key transcription factors and the production of other plant hormones in distinct woody tissues. Findings in this study provide important insights for understanding the biological significance of auxin concentration gradient existing in the radial stems of woody species.

Phenological growth stages of shea tree (Vitellaria paradoxa subsp. paradoxa) according to the BBCH scale

AbstractThe shea tree is among the socio‐economically and environmentally most important plants in the Sudano‐Sahelian region of Africa. Shea butter is internationally valued for use in pharmaceutical, cosmetic and confectionary industries. Scaling and describing phenological growth stages is of great importance in crops management. However, such phenological scale is still lacking for shea tree. To fill this gap, we documented the different growth stages of shea tree by referencing to the Biologische Bundesantalt, Bundessortenamt und Chemische Industrie (BBCH) scale. Eight of the ten principal growth stages (0–9) and 43 secondary growth stages (0–9) were described in shea tree. Among the eight principal stages, four were related to reproductive phenophases: inflorescence emergence stage (5), flowering stage (6), fruit development stage (7), and fruit maturity stage (8). The remaining four principal stages concerned vegetative phenophases and contained: bud development stage (0), leaf development stage (1), shoot development stage (3), and senescence stage (9). Observations of shea tree phenophases depicted asynchronous growth patterns with overlapping secondary growth stages of different principal stages within an individual tree canopy at the same time. The proposed phenological growth scale specific to shea tree but compatible with other crops is a valuable contribution for the implementation of crops management protocols and the standardisation of research between different laboratories.

Phenological description and thermal time requirement of tamarind (Tamarindus indica) in tropical conditions

AbstractTamarind is one of the highly valued fruit trees of the tropical world. Considering the potential of the crop, a precise standardised description of its growth stages and thermal time requirement were studied to ensure efficient agronomic practices. Phenological growth stages of tamarind are defined according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale using a three‐digit numerical system. The phenology of tamarind is characterised by eight principal growth stages: bud growth, leaf growth, shoot growth, inflorescence growth, flower development, fruit growth, fruit maturation and dormancy. Principal growth stages of tamarind are defined and described through 39 secondary growth stages. For each phenological stage, duration and thermal time were also ascertained. It is evident that thermal time for fruit growth and maturation of tamarind is substantially high, whereas inflorescence and leaf require less thermal time to complete their growth. The study could be of great help to tamarind growers and scientists for implementation of efficient agronomic management protocols as well as for assessing the response of critical phenological growth stages to temperature.

Sensitivity to water deficit of the second stage of fruit growth in late mandarin trees

In citrus fruits, phases I and II of fruit growth are sensitive to water deficit, and for this reason, deficit irrigation (DI) has been usually restricted to the final ripening phase. However, the optimal timing and intensity of stress during sensitive phases have not been clearly defined. The main objective was to determine the sensitivity of the second stage of fruit growth to water deficit in adult mandarin trees, and to explore the suitability of different soil and plant water status indicators, including the leaf-scale spectrum, according to the water stress level. Four irrigation treatments were tested: a control (CTL) irrigated at ~ 80% of ETc during the entire crop cycle, and three irrigation suppression treatments, in which no water was applied during the end of phase I and the beginning of phase II (DI1), the second half of phase II (DI2), and phase III of fruit growth (DI3), respectively. Phase II of fruit growth can be considered as a non-critical phenological period until the fruit reaches approximately 60% of its final size, with the application of a water deficit using an irrigation threshold of midday stem water potential of − 1.8 MPa, and a cumulative water stress integral close to 28 MPa day. The novel visible infrared ratio index (VIRI) showed a high sensitivity for trees subjected to moderate and severe water stress and can be complementarily used to estimate on a larger temporal and spatial scale the plant water status. Wavelengths in the short-wave infrared (SWIR) region allowed differentiation between non-stressed, moderately, and severely water-stressed trees, and can be considered as an initial basis for determining the water status of mandarin trees at various stress intensities by remote sensing.