Strawberry Yield Research Articles

Strawberry Maturity Classification from UAV and Near-Ground Imaging Using Deep Learning

Strawberry is ranked third in the value of production of the crops in Florida, USA. Classifying strawberry maturity and monitoring strawberry growth status in the field is very critical for accurate strawberry yield prediction, efficient strawberry field management, and achieving the highest crop production. The traditional method of distinguishing strawberry maturity is based on either physical appearance or internal chemical substance content. However, the traditional method is time-consuming and costly. In this research, an automatic strawberry maturity classification system was developed for the rapid and accurate classification of different strawberry maturity stages. A state-of-the-art deep learning method, You Only Look Once (YOLOv3), which is good at small object detection, was trained and applied to detect strawberry flowers and strawberry fruit at different maturity stages. Two strawberry image acquisition methods, aerial imaging and near-ground imaging, were compared by using the same deep learning image processing method. As a result, three and seven strawberry maturity stages were classified for unmanned aerial vehicle (UAV) images and near-ground digital camera images, respectively. For UAV images, the highest mean average precision (mAP) of strawberry maturity classification was 0.88 for a test data set at 2 m, and the highest classification average precision (AP) was 0.93 for fully matured fruit. For near-ground digital camera images, the mAP of strawberry maturity classification was 0.89, and the highest classification AP was 0.94 for fully matured fruit as well. The result shows that YOLOv3 is an excellent approach for strawberry maturity classification on both image types.

Impact of fertigation schema on yield and chemical composition of strawberry (Fragaria×ananassa Duch.)

A frequent fertigation of garden strawberry with solute mineral fertiliser in accord with the plant growth phase allows a more efficient mineral nutrient absorption compared to a single application of larger fertiliser amount. Field studies on medium loam-granulometry sod-podzol soil in fruiting garden strawberry plantations were carried out for three years in the Moscow Region to evaluate the impact of fertigation regimes on strawberry yield and the main nutrient content in soil and plant leaves. In study setup, the control crop grew with a no-fertiliser drip irrigation, schema 1 included frequent (once in 3 days) mineral fertiliser drip application at 2-3 g/l, schema 2 — 4-6 g/l solution application twice less often (once in 6 days). Materials and methods. Yield was estimated by weight per plot area unit, plant samples analysed with conventional wet ashing. Nitrate nitrogen was determined in ionometry, exchangeable ammonium — in photocolourimetry, mobile phosphorus and potassium specimens — by the Kirsanov’s CINAO-modified method. The article presents registration data, averaged leaf chemical assays and content dynamics of major soil macronutrients over a three-year observation period. Conclusions. A significant increase in three-year total yield was observed with the mineral fertiliser fertigation schema in the Ducat strawberry cultivar; a supraoptimal phosphorus accumulation in leaves of the Rusich cultivar was facilitated by a less frequent application of concentrated fertiliser solution; a maximal nitrogen amount in Ducat leaves was observed with fractional fertigation; in a lower-yield season, concentrated mineral fertiliser fertigation contributed to the increase of mobile phosphorus and potassium specimens in soil in mid growing season. A greater correlation was observed between the soil content of mobile potassium and its uptake by strawberry plants.

Development and improvement of the CROPGRO-Strawberry model

Strawberry is a high-value horticultural crop with a global market and it has a strong regional importance in production areas such as Florida. Strawberry growers face many challenges related to weather, cultivation, and markets. Decision support tools can help optimize strawberry production but require sound models or other predictive tools as a foundation. The goal of this study was to improve a new CROPGRO-Strawberry model in the Decision Support System for Agrotechnology Transfer (DSSAT) using experimental data with observations from different seasons and multiple cultivars. Model improvements were made in three primary areas: 1) cardinal temperatures for different development processes, 2) a module for the dynamic assimilate partitioning based on photothermal age, and 3) improvement of the cultivar and ecotype coefficients. The model predicts the growth, development, and fruit production of strawberry over time using weather, soil, management and physiological parameters as inputs. Overall, the results show a good simulation of development and growth (d = 0.77 to 0.99, RRMSE = 0.26 to 0.68), but an overestimation of vegetative growth during the early season. Periodic and cumulative fruit harvests were well-simulated (d = 0.91, RRMSE 0.47), capturing the seasonal dynamics and representing differences among cultivars and harvest intervals. A strategic analysis showed the applicability of the crop model to understand and manage the impact of seasonal climate variability on total strawberry yield as well as the distribution of fruit production across different harvest months. Future work should include improvements in the simulation of vegetative growth and evaluation against new datasets representing different production environments and cultivars. The improved CROPGRO-Strawberry model will enable future work on applications to other specialty crops where modeling of continuous fruiting and multiple harvests of individual fruit instead of one end-of-season harvest is desired.

Hyperspectral imaging for early identification of strawberry leaves diseases with machine learning and spectral fingerprint features

Anthracnose and gray mold are two most devastating diseases of strawberries which can spread to healthy plants in short time and can cause large-scale yield losses worldwide. However, early identification of anthracnose and gray mold in strawberries is challenging due to that they rise fast and their course is short. Early identification of anthracnose and gray mold in strawberries is of great significance for managing strawberry production, achieving precise target spraying, avoiding the large-scale spread of disease as well as improving the yield and quality of strawberries. In this study, six machine learning-aided methods were developed based on the selected spectral fingerprint features for early identification of anthracnose and gray mold in strawberries using a hyperspectral imaging system. First, infection strawberry leaf dataset was artificially prepared by an expert, and the hyperspectral images (during the spectrum range of 400–1000 nm) of heathy, anthracnose-infected and gray-mold-infected leaves (149 of each type), and fungus-infected leaves respectively had three stages of infection (24 h:43; 48 h:47; 72 h:59). Second, the full spectra of ROI were extracted, and chemometric methods in spectral domain were used to explore the spectral fingerprint features for early identification of anthracnose and gray mold with machine learning. Third, six classification models for identification of anthracnose and gray mold in strawberries were developed, and the classification performance were evaluated and compared. For early detection of anthracnose and gray mold in strawberries, most classification models obtain relatively good accuracy (100%) and robust performance, recognizing the asymptomatic fungus infections classes before the obvious signs of disease appear notably in the strawberry. This study provides a foundational basis for the development of the rapid online inspection as well as the real-time monitoring system for field plant disease detection.

Foliar application of micronutrients enhances growth, yield and quality of strawberry (Fragaria × ananassa Duch.)

The investigation was carried out At Navsari Agricultural University, Waghai during 2018-19 to evaluate the effect of foliar application of Zn and Fe on growth, yield and quality of strawberry (Fragaria × ananassa Duch.) cv. Winter Dawn. The ZnSO4,7H2O and FeSO4,7H2O were used as a source for Zn and Fe, respectively and applied as foliar sprays individually (0.2 % and 0.4%) as well as in combination to the strawberry plants at 30, 60 and 75 days after planting of uniform runners. The plants which received no spraying were treated as control. The results indicated that foliar spraying of 0.4 % ZnSO4,7H2O + 0.2 %FeSO4,7H2O significantly increased the plant spread, number of leaves, number of crowns, leaf area, length of petiole, number of runners, number of flowers, number of fruits, fruit weight, marketable fruit percentage, marketable and total fruit yield over control plants. However, fruits with significantly the highest total soluble solid, acidity and anthocyanin content were recorded with the foliar application of 0.4 % ZnSO4,7H2O + 0.4 % FeSO4,7H2O. However, the micronutrient treatments failed to influence any significant effect on days taken to 50.0 % flowering, fruit firmness and acidity content of the strawberry fruits. All the parameters were recorded minimum in plants which received no spraying.

Effect of different growing environments on growth, yield and quality attributes of strawberry

Shading is one of the cooling methods for changing the microclimate and maximizing crop growth in hot and sunny regions. A study was conducted to determine the effect of the growing environment on the growth, yield and fruit quality parameters of strawberries. The experimental treatments include net house, poly shade house, UV poly shade house, and open field (control) conditions. The results revealed that the plants produced in the net house condition had maximum plant height (18.5 cm), total chlorophyll content (62.66), fruit number (17), and yield (289.16 g/plant) of strawberries. In contrast, plants grown under UV poly shade conditions recorded higher total soluble solid (7 °Brix), titratable acidity (0.46%), ascorbic acid (39.68 mg/100g) and lower pH (3.41). Reducing sugar (7.57 mg/g) and phenol (2.44 mg/g) levels were higher in fruits grown in poly shade. Results indicated that the most suitable growing condition for yield and yield parameters of strawberries is under the net house. In contrast, UV poly and poly house conditions are favourable for producing better quality fruit.

Season and Nitrogen Fertilization Effects on Yield and Physicochemical Attributes of Strawberry under Subtropical Climate Conditions

Strawberry (Fragaria ×ananassa Duch.) yields in winter production regions are greatly affected by early-season nitrogen (N) fertilization, especially when pre-plant N is not applied. In Florida, United States, applying N at high rates during the early season is a common fertilization practice, but little is known about its impact on fruit quality. The objective of this study was to examine season and early-season N fertilization effects on yield and physicochemical attributes of ‘Florida Radiance’ strawberry grown under subtropical climate conditions. Field experiments were conducted in west-central Florida over two growing seasons. Plants were treated with three N rates (1.12, 1.68, and 2.24 kg/ha/d) over 21 days during the early vegetative growth stage. Thereafter, all plants were treated with the same N rate of 1.12 kg/ha/d until the end of the season. Increasing the early-season N rate increased marketable yield by 15% to 18%, but it had no significant effect on any fruit quality attributes. Contrarily, marketable yield was similar in both seasons, whereas fruit quality showed remarkable seasonal variations. In the season with higher solar radiation and lower temperature, RH, and rainfall during the fruit development period, berries were redder with increased anthocyanin accumulation but had lower pH, acidity, and soluble solids. These results suggest that season has a greater effect on fruit quality than early-season N fertilization, which is complex to dissect because of the interaction between fruit quality attributes and environmental conditions. The use of high N rates during the early season appears to be an effective strategy to improve the profitability of winter strawberry production. Importantly, this fertilization technique has a minimal risk of compromising fruit quality or fertilizer N use efficiency.

Concentration Test of Liquid Bioslurry and Mushroom Baglog Waste as a Plant Medium on Growth and Results of Strawberries (Fragaria sp.)

Backlog mushrooms are organic waste used as a plant medium. Also, bio-slurry is a waste of biogas, used as an organic fertilizer, due to containing many rotting microbes. When the two ingredients are combined, it becomes a good source of organic fertilizer for plants. Furthermore, strawberry fruits (Fragaria sp.) are increasingly getting demanded, due to their vitamin content, which is very good for the health. The purpose of this study was to determine the interaction between the treatment of bio-slurry concentration and the composition of the growing media on the growth and yield of strawberries. Also, the study was conducted in the integrated laboratory of the Agrotechnology education park, Muhammadiyah University of Malang, between February to May 2019. This research used factorial experiments which were arranged randomly in groups. The first factor was the concentration of liquid bio-slurry, such as C0 (water, without bio-slurry), C1 (100 ml / l), C2 (125 ml / l), and C3 (150 ml / l), while that of the second was the volumetric comparison of the planting medium composition (soil : husk charcoal : mushroom baglog waste), namely M1 = (1: 1: 2), M2 = (1: 2: 1), and M3 = (2: 1: 1), with each treatment combination repeated 3 times. These results further showed no interaction between the concentration of bio-slurry, and the composition of planting media on the growth and yield of strawberries.

Fruit characters and yield of strawberry (Fragaria x ananassa Duch.) as influenced by different concentrations of gibberellic acid

The effect of gibberellic acid concentrations on fruit characters and yield of strawberry was studied on two varieties, namely ‘Sweet Charlie’ and ‘Winter Dawn’ during November, 2018 to March, 2019. Foliar application of three different concentration of GA3 viz. 50 ppm, 75 ppm and 100 ppm were done at 40 days and 60 days after planting. Experimental results showed that GA3 @ 75 ppm had the best effect to increase yield components and yield of both the varieties. Under GA3 @ 75 ppm, Winter Dawn exhibited higher fruit diameter (3.38cm) and fruit length (4.74cm) as compared to Sweet Charlie (3.28cm fruit diameter and 4.60cm fruit length). Though the fruit weight was slightly higher in Sweet Charlie (18.36g) as against Winter Dawn (17.90g) under the best treatment i.e. 75 ppm GA3 the yield recorded was higher in Winter Dawn (573.62g/plant and 24.04t/ha) as against Sweet Charlie (445.43g/plant and18.73t/ ha) due to higher number of fruits (32.44/plant) produced by Winter Dawn as compared to Sweet Charlie (24.94/plant). So, Winter Dawn variety produced 28.35% higher yield as compared to Sweet Charlie under GA3 @ 75 ppm treatment.

Yield and quality of strawberries when applying fertilizers

Relevance. One of the most important elements of the technology of cultivation of strawberries for increasing productivity and improving the quality of berries is the use of fertilizers that can regulate the growth, development, yield and quality of products.Methods. During 2016-2018, the impact of pre-planting application of complex mineral fertilizers on the yield and quality of strawberries in the Udmurt Republic was studied. The analysis of meteorological conditions during the growing season of the crop according to the research results is carried out.Results. The results of the use of complex fertilizers Azofoska, Perm-yagodnoye and Fusco-yagodnoye on garden strawberries when grown in the conditions of the Udmurt Republic are presented. It was found that the use of these fertilizers in comparison with the control (Azofoska) contributes to an increase in yield and has a positive effect on the quality of berries. The aftereffect of the studied fertilizers on the second and third year of fruiting of wild strawberries is noted. According to the results of research, the highest yield of berries of the garden strawberry was obtained in 2016 in the first year of fruiting when applying Chamfer-berry (1.33 kg/m2 ). The pre-planting application of the FaskoYagodnoye fertilizer provided a reliable increase in yield at all times of berry harvesting, and on average for three years by 0.13 kg/m2 with an NSR of 0.04 kg/m2 . The content of dry matter, water-soluble sugars and vitamin C in the berries corresponded to the characteristics of the Darenka variety and to a greater extent depended on the meteorological conditions of the growing season of strawberries.

Foliar application of banana pseudostem sap based liquid organic fertilizer enhances growth, yield and quality of strawberry (Fragaria × ananassa Duch.)

Foliar application of banana pseudostem sap based liquid organic fertilizer enhances growth, yield and quality of strawberry (Fragaria × ananassa Duch.)

Correlation Among Phenotypic Parameters Related to the Growth and Photosynthesis of Strawberry (Fragaria × ananassa Duch.) Grown Under Various Light Intensity Conditions.

The objective of this study was to investigate characteristics of phenotypic parameters such as physiology, yield, and fruit quality responses of strawberry (Fragaria × ananassa Duch.) to various light intensity conditions (VLICs), and to determine the correlations among these phenotypic parameters. Strawberry plants were cultivated in a smart greenhouse separated into four areas, three of which were completely shaded by curtains from 20:00 until 10:00 (3 hS), 12:00 (5 hS), and 14:00 (7 hS), respectively. The fourth area was a non-shaded control treatment (0 hS). The ambient light intensities during the experimental period for the 0, 3, 5, and 7 hS treatments were 1,285, 1,139, 770, and 364 mol⋅m–2, respectively. Strawberry plants grown under low light intensity conditions experienced decreases in photosynthetic rate, stomatal conductance, and sugar accumulation compared to the 0 hS. Petiole generation and fruit yield were also sharply decreased in proportion to the degree of decrease in light intensity. In contrast, photosynthetic pigment content was shown to increase under low light conditions. Organic acid contents (excluding acetic acid) and leaflet size did not change significantly under low light conditions compared to the 0 hS. Changes to light intensity are considered to induce changes to the phenotypic characteristics of strawberry plants to favor growth using the energy and carbon skeletons obtained through respiration and photosynthesis. In the 7 hS treatment, where light intensity was drastically reduced, NPQ, qP, and RFd values as chlorophyll a fluorescence parameters were significantly lowered, which could indicate their measurement as an important technique to check the stress response of plants grown in low light conditions.

Chloropicrin alternated with dazomet improved the soil’s physicochemical properties, changed microbial communities and increased strawberry yield

Chloropicrin (Pic) and dazomet (DZ) are effective soil fumigants that are often used to reduce soil-borne pathogens that would otherwise reduce crop yield. As Pic is scheduled to be banned, we investigated whether its consumption could be halved by alternating it with DZ. We observed that Pic alternated with DZ increased the soil NH4+-N content by 28.74–47.07 times, increased available potassium content by 40.80%−46.81% and increased electrical conductivity by 39.23%−85.81%. It generally improved the soil’s physicochemical properties. High-throughput DNA sequencing showed that Pic alternated with DZ changed the taxonomic diversity of bacteria and fungi by increasing the relative abundance of Bacillus and Firmicutes, and by decreasing Proteobacteria, Acidobacteria and Sphingomonas. Moreover, Pic alternated with DZ can inhibit key soil pathogens by more than 90% and significantly increased strawberry yield by 78.22%−116.12%. In terms of strawberry production, we recommend using DZ in the first year and Pic in the second year. Our results showed significant ecological benefit and yield benefit when Pic consumption was halved by alternating it with DZ.

Influence of different growing media on the growth and development of strawberry plants

The optimal production of strawberries requires the essential nutrients and favourable media for vegetative and reproductive growth. The present study sought to determine the effectiveness of growth parameters and fruit yield of strawberries in different media growing under a greenhouse. To analyze the significant effect for the growth and fruit yield among the growing media, four treatments such as control soil (CS), bio plus compost (T1), the combination of bio plus compost, and synthetic nutrient applied media/integrated media (T2) and synthetic nutrient applied soil media (T3) were assayed. Morphology parameters like plant height, canopy area, fresh weight, dry weight of roots were measured in each stage after eight weeks and sixteen weeks and yield attributing parameter as the number of fruits set per plant and number of fruits per plant were measured at the beginning and end of the reproductive stage eight and sixteen weeks respectively. The effects of growing media for the strawberry plant growth and productivity were analyzed using completely randomized block designs through analyzing the variance with a significance level of p < 0.05. The canopy area of the strawberry plants was calculated using the image processing technique applied in HSV colour space. Correspondingly, the vegetative stage and reproductive stage of T2 plants attained the maximum plant height of 16.93 ± 0.31 cm and 19.34 ± 0.21 cm, canopy area with 23.02 ± 1.94 cm2 and 28.78 ± 0.93 cm2, fresh weight of 18.00 ± 3.06 g, and 20.15 ± 3.49 g, dry weight of 5.15 ± 1.26 g and 6.66 ± 2.34 g and the number of fruits set per plant 18.83 ± 2.64 and number of fruits per plant 24.17 ± 2.14 followed by T1, T3, and CS respectively. A comparison of the relative growth and fruit yield at the vegetative and reproductive phases of plants T2 implied better performance. This study demonstrated that bio plus compost with synthetic nutrients act as a better source for the growth and production of strawberries under the greenhouse.

Influence of Nitrogen, Calcium and Nano-Fertilizer on Strawberry (Fragaria × ananassa Duch.) Fruit Inner and Outer Quality

The production system, especially fertilisation has an important effect on yield and quality of strawberries. In the present study, plants were fertilized with different doses of nitrogen (0–100% recommended doses), calcium chelate, as well as nano fertilizer Lithovit. Strawberry cultivar ‘Clery’ yield and quality parameters (fruit color and firmness) including nutritional indicators (total soluble solids, sugars, organic acids, phenolic and volatile compounds) were monitored. Volatiles were identified and monitored using headspace solid phase microextraction and analysed using gas chromatograph-mass spectrometry (SPME/GC-MS) and sugars, organic acids, and phenolic compounds with high performance liquid chromatography. Organic acids and phenolic compounds were detected with mass spectrometer (HPLC/MS). Both nitrogen and calcium fertilisation had altered sugars, organic acids, volatile and phenolic contents in strawberry fruits. Fertilisation with higher doses of nitrogen and calcium increased the content of unpleasant aromas aldehydes hexanal (up to 3.8-fold) and (E)-2-hexen-1- (up to 3.7-fold). The content of fruity esters was uppermost in fruits fertilised with nano-fertiliser Lithovit (up to 2.3-fold). Fertilisation with N and Ca decreased the strength of ketone and terpenoids fruity aroma. The highest content of total phenols, as well as all individual hydroxycinnamic and hydroxybenzoic acid derivatives were obtained in the nano-fertiliser Lithovit treatment. Fertilisation, especially with nitrogen, had mostly negative impact on strawberry flavour while nano-fertilization with Lithovit improved strawberry phenolic content and aroma.

Replacing winter rice in non-traditional areas by strawberry reduces arsenic bioaccumulation, and improves water productivity and profitability

Use of huge amount (1450–1650 mm) of arsenic contaminated (14.0–24.5 mg l−1) ground water to irrigate winter rice resulted in high deposition of arsenic (As) in the topsoil and in rice grains, posing a serious threat to soil and human health of the Bengal basin. Strawberry (Fragaria × ananassa Duch.) requires 250 mm irrigation and fetches 3.5 times more net return over the winter rice, and can be grown as an alternate crop in place of winter rice to save the environment. In comparison to rice As load in edible parts of strawberry reduced from 865 to 39 μg kg−1. Deficit irrigation (0.8 and 0.6 crop evapotranspiration, ETc) to strawberry further reduced total as well as different As species load in fruits. Jute and straw mulches recorded lower As in fruits over other mulches. Drip irrigation to recharge full or 80% of ETc loss and use of jute agrotextile surface mulch maximized root growth and yield in strawberry, benefit:cost ratio, and energy efficiency and productivity. Results demonstrate that strawberry cultivation in non-traditional winter rice growing areas of Bengal basin can potentially benefit millions of people by reducing As load in food chains, ensuring higher returns, and aid in reviving the local jute agrotextile industry.

Сравнительная оценка комплексных удобрений при внесении под землянику садовую

Abstract. The productivity of wild strawberries is significantly determined not only by the biological characteristics of the variety and soil and climatic conditions, but also by agrotechnical techniques and the use of organomineral fertilizers. The effectiveness of the use of mineral fertilizers on strawberries has been proven by numerous studies [5, p. 48; 6, p. 99; 14, p. 233; 15, p. 513; 16, p.101; 17, p. 513]. The purpose is a comparative assessment of the effect of various types of complex fertilizers for strawberries. The task was to study the effect of complex fertilizers on the yield of strawberry and its structure. In 2015–2018, studies were conducted on the introduction of complex fertilizers for wild strawberries, which are used during the growing season to improve their nutrition during periods of maximum consumption of nutrients. Methods. The studies were conducted according to generally accepted methods [4], [7]. The influence of “Azophoska”, “Perm-yagodnoye” and “Fasko-yagodnoye” fertilizers on the yield and elements of its structure in strawberry was studied in the conducted studies. Results. The best results for all the years of research were obtained when using the pre-planting application of the fertilizer “Fasko-yagodnoye”. In this variant, there was a significant increase in the number of berries by 1.8 pcs., their weight by 0.68 g and yield by 0.13 kg/m2. Scientific novelty. For the first time in the conditions of the Udmurt Republic, the effect of the pre-planting application of complex fertilizers “Perm-yagodnoye” and “Fasko-yagodnoye” was studied on strawberry garden. Practical significance. The obtained research results are of great practical value, since it is proved that the productivity of wild strawberries in the Udmurt Republic increases with the use of complex fertilizers.

Effect of fresh chicken manure as a non-chemical soil fumigant on soil-borne pathogens, plant growth and strawberry fruit profitability

We investigated the ability of fresh chicken manure (FCM) to control pathogens, to promote strawberry plant growth, strawberry yield and farmer income. Laboratory tests showed that FCM inhibited the growth of Fusarium oxysporum, Pestalotiopsis spp., Phytophthora infestans and Rhizoctonia solani, and root-knot nematode (Meloidogyne spp.). Although the CFU of Fusarium spp. and Phytophthora spp. in FCM was higher than in the chloropicrin (CP) treatment, it was significantly lower than in the control. Additionally, FCM and CP both promoted the growth of strawberry plants in laboratory tests. In field tests and compared with control, FCM and CP significantly reduced Fusarium spp. and Phytophthora spp. by 95.71% & 98.89% and 78.06% & 94.81%, respectively. FCM increased chlorophyll in strawberry plant leaves and promoted plant growth, compared with control and CP. Field-applied FCM also increased the content of NO3−-N, available P, K and organic matter, lowered soil pH, increased strawberry marketable yield (20.99%) and farmers' income (21.58%), compared with control. In addition, compared with control, FCM increased strawberry fruits soluble sugar and ascorbic acid content by 14.33% and 73.41%, respectively, and significantly decreased titratable acidity, which are known to contribute to improvement in fruit taste. In addition, FCM as a fumigant is readily available cheaper than chemical fumigants. Fresh chicken manure therefore has the potential to be an effective, environmentally-friendly alternative to chemical fumigants. The use of FCM reduces both environmental pollution from animal waste and the use of chemical fumigants, thereby contributing to China's goal of not increasing the use of chemical fertilizers and pesticides.

Characterizing Early-Season Nitrogen Fertilization Rate Effects on Growth, Yield, and Quality of Strawberry

In winter strawberry (Fragaria × ananassa Duch.) production, early-season nitrogen (N) fertilization greatly affects fruit earliness and yields, especially when pre-plant N is not applied. The objective of this study was to characterize the dose-responses of canopy growth, yield, and fruit quality to early-season N fertilization in ‘Florida Radiance’ and ‘Florida127’ strawberry. Field experiments were conducted in west-central Florida, United States. Treatments included four (0.56, 0.84, 1.12 and 1.40 kg ha−1 d−1) and five (0.22, 0.67, 1.12, 1.57, and 2.02 kg ha−1 d−1) early-season N rates in the first and second growing seasons, respectively. Increasing the early-season N rate increased early and total season yields by up to 62% to 65% and 56% to 58%, respectively, in the two cultivars. The total season yield had high positive correlations with leaf area and shoot DW. Model fitting analysis revealed cultivar-dependent dose-responses. Yield and berry size responses in ‘Florida Radiance’ were linear increases, whereas those in ‘Florida127’ were quadratic with peaks occurring at N rates of 1.21 or 1.57 kg ha−1 d−1. In ‘Florida Radiance’, soluble solids concentration showed a linear dose-response with a slope of –0.91 (0.91 °Brix decrease per 1 kg ha−1 d−1 N increase) during the early season. These results suggest that optimization of early-season N fertilization is an important production strategy to improve the profitability of winter strawberry production. Furthermore, fertilizer management that takes into account cultivar-dependent dose-responses can improve fertilizer use efficiency while minimizing fruit quality loss and environmental pollution risks.

Effect of phosphorous in combination with biofertilizers on growth, yield and quality of strawberry cv. Winter Dawn

Aim: This study was carried out to investigate the effect of biofertilizers in combination with phosphorus rates on growth, yield and quality of strawberry. Methodology: The experiment was conducted during the year 2017-18 and 2018-19 at hi-tech greenhouse of the Department of Horticulture, CCS Haryana Agricultural University, Hisar. The experiment was arranged in a factorial completely randomized design with four phosphorus fertilizer rates (0, 80, 100 and 120% RDP per plant) and three biofertilizers (control, VAM and PSB) at five replicates. Growth and yield parameter were estimated. Quality traits, viz., TSS, acidity, ascorbic acid, anthocyanin and juice content of fruits were also measured at maturity stages. Results: All the possible combinations of phosphorous and biofertilizers were found to have significant influence on the vegetative growth, yield and quality parameters of strawberry. The minimum number of days taken to first flowering, maximum fruit weight, size and fruit yield per plant were recorded with 100% RDP along with VAM. TSS and ascorbic acid were noted maximum with combined application of 120% RDP and biofertilizers. Interpretation: VAM and PSB inoculation in combination with 100 percent recommended dose of phosphorous showed maximum vegetative growth, yield and quality of strawberry as compared to non-biofertilizer inoculation.