Seedling Quality Index Research Articles

Best Combination of Liquid Organic Fertilizer with NPK Fertilizer for Cocoa Seedling Growth (Theobroma cacao L.)

One strategy for achieving sustainable agriculture is the reduction of inorganic fertilizers. Inorganic fertilizers are reduced by substituting them with organic fertilizers. This study aimed to identify the optimal combination of LOF with NPK fertilizers to promote the growth of cocoa seedlings in polybags. The study used completely randomize design. The treatment design, namely the combination of LOF with NPK fertilizers, consisted of five distinct combinations: control, 100% LOF, 100% NPK, 75% LOF +25% NPK, 50% LOF + 50% NPK, and 25% LOF + 75% NPK. The parameters observed were plant height, stem diameter, number of leaves, total leaf area, plant dry weight, shoot dry weight, root dry weight, soil physical properties, soil water content, soil analysis, and seedling quality index. The results showed that treatment 25% LOF + 75% NPK increased the percentage of plant height by 73.47%, stem diameter by 42.13%, number of leaves by 67.36%, total leaf area by 75.30%, plant dry weight by 45.70%, shoot dry weight by 24.81%, root dry weight by 95.54%, and seedling quality index by 90.65%. LOF can reduce the use of NPK fertilizer by 25% in cocoa seedling

The Influence of Logging-Related Soil Disturbance on Pioneer Tree Regeneration in Mixed Temperate Forests.

The recovery of soil properties and the proper growth of natural tree regeneration are key elements for maintaining forest productivity after selective logging operations. This study was conducted on the soil properties and natural growth of two pioneer seedling species of alder and maple which were on skid trails in the mixed beech forests of northern Iran. To examine the long-term effects, we randomly selected six skid trails, with two replicates established for each of three time periods since last use (10, 20, and 30 years ago). Random plots 4 m × 10 m in size, three plots on each skid trail and six plots on areas without soil compaction (control), were selected. Measurements included the physical and chemical properties of the soil and the growth, and the architectural and qualitative characteristics of the seedlings. The results showed that all the soil properties of the 10- and 20-year-old skid trails were significantly different from the control area (except for the soil moisture in the 20-year-old skid trail). The 30-year-old skid trail showed values of other soil properties which were not significantly different from the control area, except for the amounts of organic matter and soil nitrogen, which was less than the control. The skid trails had a negative effect on all of the growth, qualitative, and architectural indices of seedlings. The characteristics of seedlings were related to soil characteristics and had the highest correlation with the soil penetration resistance (R-value from -0.41 to -0.63 for stem growth, p < 0.05; -0.57 to -0.90 for root growth, p < 0.01; and -0.76 to -0.86 for biomass, p < 0.01). The correlation coefficient between soil penetration resistance and the Dickson quality index of alder and maple seedlings was, respectively, -0.74 and -0.72, p < 0.01. The negative effect of soil compaction on root growth (-27.69% for alder seedlings and -28.08% for maple seedlings) was greater than on stem growth (-24.11% for alder seedlings and -16.27% for maple seedlings). The amount of growth, qualitative, and architectural indices of alder seedlings were higher than that of maple seedlings. Although alder is a better choice as compared to maple seedling in the initial year, the results of our study show that it is recommended to plant both alder and maple on skid trails after logging operations.

Suhu dan Masa Simpan Benih Memengaruhi Viabilitas Benih Mahoni (Swietenia macrophylla King.)

Swietenia macrophylla or big-leaf mahogany is an exotic species from Central and South America. This tree has various benefits, so it’s used as an industrial plantation forest and afforestation in Indonesia. However, seed storage of mahogany is a major problem in cultivation, because it can reduce seed viability. The storability of seeds is influenced by seed and environmental conditions. Therefore, this study aimed to examine the effect of temperature and storage time on the viability of S. macrophylla seeds and to calculate the Seedling Quality Index (SQI). The experiment was carried out using a factorial Randomized Block Design (RBD) with 2 factors. The first factor was consisted of four levels of temperature treatment, namely room temperature (24), 4, 0, and -20°C. The second factor was the storage period treatment which consisted of 4 levels, namely 1 up to 4 weeks, with 1-week intervals. The results showed that the interaction between temperature and storage time affected mahogany leaves, primary and secondary roots, root/shoot ratio, and total wet weight of S. macrophylla seedlings. Mahogany seeds that were stored at room temperature for 1 week resulted in the highest seed viability, with SQI of 0.03-0.04.

Dissimilarities of Shallot (Allium ascalonicum L.) Seedlings Growth and Quality through Priming with Moringa Leaf Extract

Seed priming is one method for increasing the growth and quality of seedlings. This study aims to evaluate moringa leaf extract as a priming agent and its effect on the seedling growth and quality of shallot from true seed. This study used a randomized block design with five replications. Priming treatment consisted of unprimed, hydropriming, and three levels of Moringa leaf extract concentration, including 12.5%, 25%, and 37.5%. A one-way analysis of variance was used to perform statistical analysis, with a p-value of 0.05 considered significant. In addition, the mean comparison was performed by Tukey multiple comparison test. According to the research, seed priming with moringa leaf extract at 37.5% resulted in the best effects on the parameter seedling emergence index (1.20), plant height (31.12 cm), number of leaves (4.80), pseudo stem diameter (3.22 mm), total root length (329.70 mm), number of root tips (94.60), root volume (4.64 mm3), fresh weight seedling (2.77 g), dry weight seedling (0.19 g) and seedling quality index (0.0126), while compared to other treatments.

Effect of organic manure and biofertilizers on early growth and vigour of Swietenia macrophylla King. (Mahogany)

The present investigation was aimed at adopting organic production, promoting forest nurseries for sustainable tree plantation, and exploring Swietenia macrophylla King for timber purposes in present times for local conditions. The experiment was designed to assess the growth and vigour of big-leaf mahogany seedlings amongst various organic manures (FYM, Vermicompost, Neem cake, and Poultry manure) in different combinations with red soil and drenching of various biofertilizers (Azotobacter, Azosprillum, Acetobacter, PSB, Pseudomonas, VAM) in early stages of the nursery in comparison to control (Red soil). Among different organic manure treatments, red soil + poultry manure (2:1) exhibited fair qualitative as well as quantitative responses in growth parameters whereas, the maximum seedling quality index was found in Vermicompost treatment. In another aspect of the study, the results showed the highest growth and vigour were recorded in seedlings drenched with VAM @ 10 ml plant-1.

Seed Characteristics and Seedling Quality of Selected Teak Clones in Eastern India

Teak (Tectona grandis L.f.) is one of the important timbers of the world and is honoured as the ‘King’ of Indian timbers. It is grown in large scale by people in farm forestry and agroforestry programme and also by various agencies. To understand the characteristics of seeds and the quality of seedlings raised from seeds of selected teak clones, an investigation was carried out. Fruits were collected from 25 clones of teak grown at Silviculture Research Station, Koshala, Angul, Odisha (India) and tested at College of Forestry, Odisha University of Agriculture &amp; Technology, Bhubaneswar (India). Experiments were carried out under Completely Randomized Design with 3 replications. Significant variation in fruit characteristics such as fruit length, fruit width, 100 fruit weight, number of seeds per fruit, fruit viability and germination percent was observed. Fruit length varied from 1.08 to 1.57cm and ORANP-4 produced longest fruit while MHALA-7 had minimum value. Fruit width differed from 1.20 to 2.58cm and the highest width was recorded in ORAN-1 (1.58 cm) and lowest in MHALA- 7. Weight of 100 fruits ranged from 34.28 to 56.64g and ORAN-1 recorded maximum fruit weight which was at par with MHALP-9 (54.23 g) while ORPUB -13 registered the minimum value which statistically similar to MHALA-7. Number of seeds per fruit varied from 3.10 to 4.00. Fruit viability varied from 47.56 to 70.38% and ORAN-4 excelled in viability and remained statistically at par with ORPUB-23, MHALA-9 and ORANR-6. Germination percent of fruit varied from 30.5 to 49.50% and ORANP-4 recorded maximum germination percent, but it was statistically similar to MHALA-9 and ORANR-6. The growth and quality of seedlings raised from the open pollinated seeds of clones also exhibited significant difference. MHALA-9 excelled over others with regard to collar diameter, height, number of leaves, shoot weight, root weight and quality of seedling in 15 month of assessment in nursery. It recorded seedling quality index of 16.41 at the age of 15 month.

Serratia marcescens LYGN1 Reforms the Rhizosphere Microbial Community and Promotes Cucumber and Pepper Growth in Plug Seedling Cultivation.

The vegetable plug seedling plays an important role in improving vegetable production. The process of plug seedling contributes to high-quality vegetable seedlings. The substrate composition and chemical fertilizer are widely studied to promote seedling growth. However, little is known about the effect of beneficial bacteria in the rhizosphere microbial community and vegetables' growth during plug seedling. The use of beneficial microbes to promote vegetable seedling growth is of great potential. In this study, we showed that the Serratia marcescens strain LYGN1 enhanced the growth of cucumber and pepper seedlings in plug seedling cultivation. The treatment with LYGN1 significantly increased the biomass and the growth-related index of cucumber and pepper, improving the seedling quality index. Specifically, LYGN1 also improved the cucumber and pepper root system architecture and increased the root diameter. We applied high-throughput sequencing to analyze the microbial community of the seedlings' rhizosphere, which showed LYGN1 to significantly change the composition and structure of the cucumber and pepper rhizosphere microbial communities. The correlation analysis showed that the Abditibacteriota and Bdellovibrionota had positive effects on seedling growth. The findings of this study provide evidence for the effects of Serratia marcescens LYGN1 on the cucumber and pepper rhizosphere microbial communities, which also promoted seedling quality in plug seedling cultivation.

The growth of mahogany seedlings (Swietenia macrophylla King.) in various planting media and shade intensity

Swietenia macrophylla has potential in the economic, health and environmental sectors; so, this tree is one of the species used for forest rehabilitation. The growth of S. macrophylla is influenced by environmental factors, including the quality of the growing medium and shade intensity. This study aimed to obtain the right planting medium and shade for the growth of S. macrophylla seedlings. This research was conducted using a split-plot design with randomized groups. The main plot was shade using paranet which consists of 2 levels, while the subplot was the planting medium which consists of 5 levels. The results showed that the interaction of mineral soil medium treatment and without shade resulted in the highest seedlings height and total fresh weight in mahogany seedlings. The quality index of mahogany seedlings (SQI) is influenced by no-shade treatment

The Application of Nitrogen, Phosphorus, and Potassium Regulate the Growth and Morphological Development of Torreya grandis (Taxaceae) Saplings

Torreya grandis Fort. ex Lindl. cv. “Merrillii” is an important woody oil crop, and the development of plantations relies on the cultivation of high-quality saplings. For this study, 6-year-old grafted T. grandis saplings, which will soon be planted on the mountain, were selected to investigate the regulatory effects of nitrogen (N), phosphorus (P), and potassium (K) on their growth and morphology. To determine the optimal dosage and ratio of N–P–K fertilizer for sapling cultivation, we employed a three-factor four-level L16 (43) orthogonal experiment design. The experiment included a total of 17 treatments—a control group where no fertilizer was applied and 16 treatments with varying levels of NPK supply. We conducted a one-season experiment under a prescribed fertilizer regime and measured root collar diameters and sapling heights, the root, shoot, leaf biomass, total biomass, and the nutritional status of plant organs (root, shoot, leaf). From these measurements, we calculated the root–shoot ratio (RS) and seedling quality index (QI). The application of N–P–K fertilizer exhibited significant benefits for T. grandis sapling cultivation, promoted their growth and biomass accumulation and altered the nutrient allocation patterns in organs. Ultimately, we determined the ideal N–P–K ratio for T. grandis growth to be 1:0.46:0.75, with a fertilizer application of 1.38 g·sapling−1 of N, 0.64 g·sapling−1 of P (P2O5), and 1.04 g·sapling−1 of K (K2O).

The Influence of Various Legume Composts and Microbes on Nutrient Absorption and Growth of Ebony Seedlings

The research aims to find out how much influence legume leaf compost and microbes on improving nutrient absorption andgrowth of ebony seedlings. The research was conducted from August 2, 2022 to February 2, 2023 for 6 months at the BPDAS Palu-Poso Permanent Nursery. The compost used is compost derived from legume leaves consisting of gamal, lamtoro, and turi trees and the microbes used are Plant Growth Promoting Rhizobacteria (PGPR) and Plantarum Plant Growth Stimulant (PPGS) which are microbes that are widely traded in agricultural specialty online stores, The samples of this study amounted to 108 ebony seedlings with 12 treatments andeach treatment contained 9 seedlings/samples. This study used analysis of variance of complete randomized design (CRD) to determine the significant and non-significant effects of each treatment by looking at several variables from height, diameter, number of leaves, sturdiness, nutrient uptake, seedling quality index in each seedling/sample. The results showed that seedlings treated with tailings soil + lamtoro leaf compost + PGPR microbes (K3M2) had the best average growth in each variable. While the lowest growth of seedlings with control soil treatment (K0M0).

Effects of Shading on the Growth and Photosynthetic Fluorescence Characteristics of Castanopsis hystrix Seedlings of Top Community-Building Species in Southern Subtropical China

Castanopsis hystrix is a major community-building species in the top communities of southern subtropical China, with a high natural regeneration capacity. However, excessive logging and the introduction of exotic tree species have substantially reduced the area of natural forest patches of Castanopsis hystrix, and seedling regeneration is essential for the long-term continuation of Castanopsis hystrix populations. To explore the effects of light intensity on the seedling emergence and early growth of Castanopsis hystrix, shading experiments were conducted under four shading treatments (0%, 40%, 60%, and 80%). The growth, biomass accumulation, and distribution, the quality index of seedlings, the morphology and structure of the root systems of seedlings, and the leaf chlorophyll content and chlorophyll fluorescence properties of seedlings under different shading treatments were analyzed. The results displayed the following: (1) Shade intensity impacts growth of Castanopsis hystrix seedlings and biomass allocation, with optimal results observed at 60% shade, leading to the promotion of organic matter production in leaves and the limitation of stem growth. (2) Using a multi-indicator composite index, it was determined that seedling quality for Castanopsis hystrix peaks at 60% shade intensity. (3) Shade significantly impacts the morphology and structure of Castanopsis hystrix’s root system, with most root characteristics peaking at 60% shade, indicating a substantial increase in root development compared to no-shade conditions. (4) The D-values indicated the most suitable shade intensity for seedling growth to be 60%, suggesting that Castanopsis hystrix seedlings are sensitive to light and excessive light can be detrimental to their growth. (5) The 60% shade treatment showed the maximum values of chlorophyll fluorescence characteristics and photochemical activity, with variations in energy conversion efficiency and dissipation reflected in parameters like photochemical burst coefficient (qP), photochemical burst coefficient (qN), the actual photometric yield of PSII under light acclimation (YII), and the maximum photosynthetic electron transport rate in photoinhibition (ETR), thereby supporting seedling growth and maintaining the normal function of photosynthetic organs. In conclusion, 60% shade treatment can effectively improve the growth and photosynthetic characteristics of Castanopsis hystrix seedlings and promote the accumulation of nutrient elements, ultimately promoting their growth.

The effect of various doses of biofertilizers on the growth response of medang (Dehaasia firma Blume) seedling

The increasing demand of wood whilst log production from natural forest decreasing is answered by a forest planting program in unproductive lands. The Medang (Dehaasia firma Blume) tree of Lauraceae family is one of the recommended species for plantation forests due to its its wide distribution areas in Indonesia and its wood’s multi-functionality. To increase its growth, application of biofertilizer could supply organic matter and improve the soil’s physical, chemical, and biological properties. The aim of this study was to determine the effect of biofertilizer doses on the growth of medang. The research was conducted in the Silvicultural nursery of the Forest Research and Development Center in Bogor. A Completely Randomize Design (CRD) comprising one factor with three replications was employed as the research method. The dosage of bionature as a treatment factor consists of control (without fertilizer), bionature-25, bionature-50, and bionature-100. The measured growth parameters were height, diameter, shoot ratio, and seedling quality index. The results showed that the dose of bionature-50 generated the best growth of medang seedlings for height and diameter; bionature-25 generated the best growth for root shoot ratio while bionature-100 generated the best growth for total dry weight and Seedling Quality Index.

PRODUCTION OF AÇAÍ SEEDLINGS UNDER DIFFERENT SHADE LEVELS AND CONTROLLED RELEASE FERTILIZER

This study aimed to evaluate the production and quality of açaí seedlings regarding the presence and absence of controlled-release fertilization under different shading levels. The study was conducted at the experimental field of Embrapa - Acre, using a completely randomized design in a 4 x 4 factorial arrangement. The factors included four evaluation periods (60, 120, 180, and 240 days after transplanting) and four shading environments (20%, 30%, 50%, and 75%), along with the presence or absence of controlled-release fertilization. The following variables were analyzed: plant height, stem diameter, number of leaves, dry mass of leaves, stem, root, and total dry mass, as well as the seedling quality index and foliar levels of macro and micronutrients. The growth and development of açaí seedlings are influenced by the evaluation periods, shade environments, and the use of fertilization. Fertilization with controlled-release fertilizer and environments with30% and 50% shading improved the quality of açaí palm seedlings.

Effects of Drip Irrigation-Fertilization on Growth, Flowering, Photosynthesis and Nutrient Absorption of Containerized Seedlings of Hibiscus syriacus L. (Haeoreum).

The amount of irrigation and fertilization should be considered first for the production and standardization of high-quality H. syriacus L. seedlings using container seedlings. This study was conducted to investigate the optimal conditions suitable for container cultivation of hibiscus by analyzing growth and physiological responses according to the control of irrigation and fertilization. Therefore, in this study, H. syriacus L. for. Haeoreum (3-year-old hardwood cutting propagation), a fast-growing, was transplanted into a 40 L container. The irrigation amount per container was adjusted (0.2, 0.3 and 0.4 ton/yr/tree), and the amount of fertilizer applied (0, 69.0, 138.0 and 207.0 g/yr/tree). The growth rate according to the irrigation-fertilization treatment was higher in the 0.3 ton-138.0 g/yr/tree irrigation-fertilization treatment (p < 0.001). Total biomass yield and seedling quality index (SQI) were highest in the 0.3 ton-138.0 g/yr/tree irrigation-fertilization treatment (p < 0.001). The higher the fertilization concentration, the faster the flowering and the longer the flowering. The photosynthetic capacity of H. syriacus L. was reduced in bare root seedling cultivation and container-non-fertilized treatment. The chlorophyll fluorescence response was also affected by bare root cultivation and containerized seedling cultivation fertilization. Nutrient vector diagnosis showed "nutritional suitability" in the 0.3 ton-138.0 g/yr/tree treatment. Overall, containerized seedling cultivation was superior in growth, photosynthetic performance, photochemical efficiency, and nutrient storage capacity compared to bare root cultivation. These results be expected to contribute not only to the industrial production of excellent container seedlings of H. syriacus L. but also to the production of other woody plants.

Pengaruh Inokulasi Bakteri Endofit dan Ekoenzim Terhadap Pertumbuhan Bibit Kayu Kuku (Pericopsis mooniana Thw.)

Improving the physical quality of kayu kuku seedlings can be done by applying endophytic bacteria and ec-enzymes. The aims of this study were to examine (1) the effect of inoculation of endophytic bacteria on the germination of kuku wood seeds, and (2) the effect of inoculation and application of eco-enzymes on the growth of kuku wood seedlings. The endophytic bacteria were isolated from the shoot of Shorea balangeran plant with the codes SBP 1, SBP 2, and SBP 19. Bacterial application was conducted on seeds and seedlings, while eco-enzyme application was only conducted on kayu kuku seedlings. The results of the research at the seed level showed that inoculation of the endophytic bacteria SBP 19 could accelerate the germination rate of kayu kuku seeds. At the seedling level, inoculation of endophytic bacteria SBP 1, SBP 2, SBP 19 and application of eco-enzymes had no significant effect on height, diameter, number of new leaves, total fresh weight and total dry weight of kayu kuku seedlings. The shoot root ratio of kayu kuku seedlings ranged from 2.66-5.04 and the seedlings quality index ranged from 0.41-0.93, indicating that the seedlings were ready to be transplanted into the field. In general, inoculation of endophytic bacteria had a significant effect on kayu kuku seed germination, but had not been able to increase the growth of kayu kuku seedlings during the 14 weeks of observation.&#x0D; Keywords: Pericopsis mooniana Thw., seed dormancy, seed germination, seedling quality index, shoot root ratio

Prediction Model of Pumpkin Rootstock Seedlings Based on Temperature and Light Responses

Temperature and light are the key factors that affect the quality of pumpkin rootstock seedlings’ growth process. Responses to temperature and light are an important basis for optimizing the greenhouse environment. In order to determine the quantitative effects of temperature and light on the growth and development of pumpkin (Cucurbita moschata cv. RTWM6018) rootstock seedlings, relationships between temperature, light, and pumpkin rootstock seedlings growth were established using regression analysis. The results indicated that the daily average temperature had a significant negative correlation with the development time of pumpkin rootstock seedlings, and the shoot dry weight of pumpkin rootstock seedlings increased within a certain range of the daily light integral (DLI). We established a prediction model of pumpkin rootstock seedling quality indicators (hypocotyl length, stem diameter, shoot dry weight, root dry weight, root shoot ratio, and seedling quality index) based on thermal effectiveness and photosynthetic photon flux density (TEP). The coefficient of determinations (R2) of the hypocotyl length and seedling quality index prediction models of pumpkin rootstock seedlings, based on accumulated TEP, were 0.707 and 0.834, respectively. The hypocotyl length and seedling quality index prediction models of pumpkin rootstock seedlings, based on accumulated TEP, were y1 = 0.001 x2 − 0.180 x + 13.057 and y2 = 0.008 x0.722, respectively, which could be used for predicting the growth of pumpkin rootstock seedlings grown under different temperature and light conditions.

Влияние объёма и состава субстрата на качество рассады при выращивании петунии гибридной в условиях Ростовской области

Experiments on growing petunia seedlings in protected ground conditions were carried out in 2020-2022 on the basis of the greenhouse complex of the Don State Agrarian University in the Oktyabrsky district of the Rostov region. The object of research was a hybrid of petunia Grandi-flora Limbo JP. The repetition of the experience is fourfold. The scheme of the experiment in-cluded variants with containers of 450, 350 and 230 cm3. Peat, sand, fertilizer based on Karelian shungite "Shungiterra" and organic mineral fertilizer Agrovit-Core were used to prepare the sub-strate for growing seedlings. The highest indicators of the quality index in the experiment were obtained using a substrate consisting of ¾ peat, ¼ sand and fertilizer "ShungiTerra" based on Ka-relian shungite of the Turastamozr deposit (substrate mixed with Shungiterra 1: 10). When using containers with a substrate volume of 450 cm3, the seedling quality index increased by 0.40 com-pared to the control variant, with a volume of 350 cm3 – by 0.17 and 230 cm3 – by 0.13. Keywords: VOLUME, FERTILIZER, SUBSTRATE, QUALITY INDEX, HYBRID PETUNIA

Technical feasibility of the use of sludge from the water treatment plant in lettuce production

The sludge generated in water treatment plants (WTP sludge), despite having physicochemical characteristics with agricultural potential, is a solid waste discarded in landfills. This research aimed to: 1) evaluate the technical feasibility of WTP sludge in substitution of commercial substrates in the production of lettuce seedlings; 2) to evaluate the yield commercial, in the municipality of Arapiraca, semiarid region of the state of Alagoas - Brazil. The research was carried out in two stages: 1) seedling production in greenhouse in 4 x 4 x 5 factorial arrangement, with four sludge doses (0, 20, 40 and 60%), four commercial substrates (Pindstrup®, Vida Verde®, Bioplant 434® and Bioplant 401®) and five cultivars (Veneranda, Camila, Elba, ‘Vitória Verdinha’ and Diva); 2) seedlings produced at field level were used in 3 x 3 x 5 factorial arrangement, in which Pindstrup treatments and 60% sludge dose were excluded, as they did not promote seedling emergence. In the 1st experiment, it was observed linear reduction of seedling quality index with the addition of sludge. In the 2nd experiment, the average yield was 5.4 Mg ha-1, in which 20% sludge dose promoted the highest values, being recommended for lettuce production in the semiarid region of Alagoas.

Morphophysiology and quality of custard apple seedlings irrigated with saline water and foliar nitrogen

The establishment of quality seedlings when irrigated with water with a high saline index has become a challenge for fruit growers in arid and semi-arid regions, requiring the adoption of techniques that will mitigate such effects. In this scenario, this study aimed to evaluate the effects of irrigation with saline water and foliar nitrogen fertilization on the formation of custard apple seedlings. The experiment was conducted in a randomized block design and arranged in a 5 × 5 factorial corresponding to five electrical conductivity levels of irrigation water—ECiw (0.5, 1.15, 2.75, 4.35, and 5.0 dS m−1) and five nitrogen levels applied on the leaves (0, 0.33, 1.15, 1.97, and 2.3 g L−1), with four replicates and two plants per plot, totaling nine combinations generated by Box’s central composite design. Irrigation with the electrical conductivity level of 1.33 dS m−1 caused acceptable losses of up to 10% in the net photosynthesis rate, phytomass accumulation, and quality of custard apple seedlings. Nitrogen fertilization at the level of 1.45 g L−1 mitigated the effects of salt stress on the morphophysiology and quality of custard apple seedlings. The N level of 1.59 g L−1 associated with the ECiw of 0.5 dS m−1 increased the gas exchange, phytomass accumulation, and Dickson Quality Index of custard apple seedlings 90 days after emergence. The application N level from 0.95 ml L−1 maintains the acceptable quality of custard apple seedlings under irrigation conditions with water of 5.0 dS m−1.

Stand structure adjustment influences the biomass allocation in naturally generated Pinus massoniana seedlings through environmental factors.

The natural regeneration of seedlings is a key factor for forest succession. Nevertheless, studies explaining the mechanism of growth and biomass allocation in regenerated seedlings after disturbance are lacking. Therefore, we measured the growth, biomass accumulation, and biomass allocation in current-age seedlings of Pinus massoniana after selective logging (logging of competitive trees, LCT; logging of inferior trees, LIT; and unlogged control, CK), and established structural equation models (SEMs) among the spatial structure characteristic indexes of the stand, environmental factors, and biomass allocation in different organs. As compared to the CK, the mingling index (M), uniform angle index (W), opening degree (O), soil organic carbon (SOC), available nitrogen (SAN), available phosphorus (SAP), available potassium (SAK), and bulk density (SBD) significantly increased (p < 0.05), while the competition index (CI) and neighborhood comparison (U) significantly decreased after logging (p < 0.05). After the LCT, seedling branch biomass improved, with an increase in the ground-diameter, crown-root ratio, and seedling quality index. More biomass was allocated to foliage and roots by an increase in the height and height-diameter ratio under the LIT. In the CK, increasing stem biomass helped the seedlings absorb and utilize more light. The Pearson correlation coefficient showed that biomass allocation to organs was independent, and seedlings adopted the strategies of heterogeneous adaptation and growth, thereby resulting in the separation of the allocation patterns among the organs. As per the redundancy analysis (RDA), CI was the main factor in biomass allocation. Environmental factors had direct effects on biomass allocation to organs, while the stand spatial structure characteristic indexes had indirect effects on biomass allocation based on SEMs. In summary, the LCT had significant, albeit indirect, effects on SOC, SAN, and SBD by reducing the CI for the regeneration and growth of seedlings in the stand, which was of great significance to the sustainable development of the forest stand of P. massoniana.