High Plant Density Research Articles

Dynamic plant spacing in tomato results in high yields while mitigating the reduction in fruit quality associated with high planting densities.

High planting densities achieve high light interception and harvestable yield per area but at the expense of product quality. This study aimed to maintain high light interception without negative impacts on fruit quality. Dwarf tomato was grown at four densities in a climate-controlled room-at two constant densities (high and low) and two dynamic spacing treatments (maintaining 90% and 75% ground coverage by decreasing planting density in 3-4 steps)-resulting in ~100, 19, 54, and 41 plants/m2 averaged over 100 days of cultivation, respectively. Constant high density resulted in the highest light use efficiency (LUE; 7.7 g fruit fresh weight per mol photons incident on the canopy) and the highest harvestable fruit yield (11.1 kg/m2) but the lowest fruit size and quality. Constant low density resulted in the lowest LUE and yield (2.3 g/mol and 3.2 kg/m2, respectively), but higher fruit size and quality than high density. Compared to low density, maintaining 90% ground coverage increased yield (9.1 kg/m2) and LUE (6.4 g/mol). Maintaining 75% ground coverage resulted in a 7.2 kg/m2 yield and 5.1 g/mol LUE. Both dynamic spacing treatments attained the same or slightly reduced fruit quality compared to low density. Total plant weight per m2 increased with planting density and saturated at a constant high density. Assimilate shortage at the plant level and flower abortion lowered harvestable fruit yield per plant, sweetness, and acidity under constant high density. Harvestable fruit yield per plant was the highest under dynamic spacing and low density. Under constant high density, morphological responses to lower light availability per plant-i.e., higher specific leaf area, internode elongation, and increased slenderness-coincided with the improved whole-plant LUE (g plant dry weight per mol photons). We conclude that a constant high planting density results in the highest harvestable fruit yield per area, but with reduced fruit quality. Dynamic spacing during cultivation produces the same fruit quality as constant low density, but with more than double the harvestable yield per area.

PROXIMATE ANALYSIS AND MINERAL PROFILE OF TARO (Colocasia esculenta) IN EMBU, KENYA

<p><strong>Background.</strong> Taro (<em>Colocasia esculenta</em>) is one of the underutilized crops in Kenya, grown under a wide range of environmental and edaphic conditions. This crop has exceptional dietary value and numerous culinary applications due to its edible leaves and corms. However, the mineral nutrient composition of taro in Kenya is still not well known due to a lack of scientific information concerning production. <strong>Objective. </strong>To determine the proximate composition and mineral profile of taro under different watering regimes and planting densities in Embu, Kenya. <strong>Methodology.</strong> A study was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) – Embu Research Centre, during the long rains (LR) 2021, and short rains (SR) 2021/2022. A factorial experiment with a split-plot layout arranged in a completely randomized block design was adopted. The watering regimes (100 %, 60 %, and 30 % based on the field capacity (FC)) were the main factor while the sub-factor was the planting density, with three replications. The planting densities used were 0.5 m × 0.5 m (40,000 plants ha<sup>-1</sup>), 1 m × 0.5 m (20,000 plants ha<sup>-1</sup>), and 1 m × 1 m (10,000 plants ha<sup>-1</sup>), representative of high, medium, and low planting densities respectively. Proximate analysis and mineral content were determined. <strong>Results.</strong> Significant differences (<em>P < 0.05</em>) in seasons were noted for protein, fibre, potassium, calcium, sodium, and zinc in the taro corms. The high carbohydrate content observed in this study (35 – 39 %) indicates that taro tubers are a good source of nutritional energy. Potassium (> 5000 mg kg <sup>-1</sup>) and magnesium (> 1000 mg kg <sup>-1</sup>) were the most prevalent mineral elements in taro corms and leaves, with copper (< 25 mg kg <sup>-1</sup>) being the least prevalent. <strong>Implications.</strong> Consumption of nutrient-rich foods such as taro helps the body to utilize the necessary nutrients to combat malnutrition and promote food security in rural communities. <strong>Conclusion.</strong> Taro leaves can be recommended as leafy vegetables as they are good sources of potassium, magnesium, calcium, manganese, iron, copper, and zinc; and the corms have low fat and protein content, high calorific energy, and high carbohydrate content. Taro represents one of the main sources of energy in many parts of the tropics and its production can be recommended in sub-humid areas in Kenya.<strong></strong></p>

The effects of viewing forests with different planting densities on physiological and psychological responses: A between-subject experiment

Beyond their traditional role in timber production, plantation forests are increasingly recognized for their therapeutic potential. Forest management practices allow for modifications to meet diverse demands, making it crucial to understand the association between stand density and human responses. This knowledge is essential for forest therapy practitioners and landscape designers aiming to maximize the therapeutic effects of these landscapes. This article delves into the effects of viewing forest plantations on health responses, exploring whether different planting densities influence human physiological and psychological reactions. To investigate this, we conducted a between-subject, pretest-posttest field experiment in three plantation forests with varying stand densities (high, medium, and low), using a parking area as a control. Our findings revealed that viewing plantation forests led to both physiological and psychological relaxation effects. Notably, medium-density plantation forests with a 3-meter spacing between trees, demonstrated a more significant relaxation effect on reducing heart rate compared to high and low-density plantations with spacing of 1 m and 5 m, respectively. High-density plantation forests were more effective in reducing total mood disturbance and specific negative mood states, including fatigue-inertia, depression-dejection, and tension-anxiety. Interestingly, regardless of stand density, restorative components were similar among the four experimental settings (high, medium, low, and control). These findings have practical implications for designing restorative environments and leveraging the therapeutic potential of plantation forests.

Photosynthetic capacity and assimilate transport of the lower canopy influence maize yield under high planting density.

Photosynthesis is a major trait of interest for the development of high-yield crop plants. However, little is known about the effects of high-density planting on photosynthetic responses at the whole-canopy level. Using the high-yielding maize (Zea mays L.) cultivars "LY66," "MC670," and "JK968," we conducted a 2-yr field experiment to assess ear development in addition to leaf characteristics and photosynthetic parameters in each canopy layer at 4 planting densities. Increased planting density promoted high grain yield and population-scale biomass accumulation despite reduced per-plant productivity. MC670 had the strongest adaptability to high-density planting conditions. A physiological analysis showed that increased planting density primarily led to decreases in the single-leaf area above the ear for LY66 and MC670 and below the ear for JK968. Furthermore, high planting density decreased chlorophyll content and the photosynthetic rate due to decreased canopy transmission, leading to severe decreases in single-plant biomass accumulation in the lower canopy. Moreover, increased planting density improved presilking biomass transfer, especially in the lower canopy. The yield showed significant positive relationships with photosynthesis and biomass in the lower canopy, demonstrating the important contributions of these leaves to grain yield under dense planting conditions. Increased planting density led to retarded ear development as a consequence of reduced glucose and fructose contents in the ears, indicating reductions in sugar transport that were associated with limited sink organ development, reduced kernel number, and yield loss. Overall, these findings highlighted the photosynthetic capacities of the lower canopy as promising targets for improving maize yield under dense planting conditions.

The effect of various drugs on the survival of sterlet fry in bacterial contamination of water

Currently, aquaculture is a reliable source of increasing the volume of fish food products and serves as a guarantor of food security. The sterlet Acipenser ruthenus L. is one of the main objects of freshwater aquaculture. Feeding with artificial feed, high planting densities and other negative factors of industrial fish farming inevitably lead to increased stress loads. This affects the physiological state of fish. Disturbances in the functioning of the immune system leads to outbreaks of infectious diseases and epizootic disadvantage of pond fish farms. In modern aquaculture, various antibiotics, probiotics and plant preparations are used to treat and prevent bacterial diseases. In this paper, the effect of different feed additives on the survival rate of sterlet fry to infectious agents was investigated. For this purpose, 150 individuals each were seeded into separate pools with high content of myxobacteria and aeromonads in the water microflora. Studies were conducted in 5 separate pools: control group with feed and 4 experimental pools with different feed additives. The duration of the experiment was 75 days. During the experiment, the number of surviving fries was recorded, and at the end, survival rate was calculated as a percentage of the total number of fish initially planted in each pool. Differences in the effect of different feed additives on the survival rate of fry were found. The highest escapement was recorded in the control group and the least in the group with Antibac-100. In the other experimental groups, the percentage of surviving fry was higher than in the control.

Variability analysis and PCA studies for fruiting behaviour in high density guava

The investigations on PCA and variability analysis were conducted to understand the relationship among productivity traits of guava trees under high-density planting. This study established the link between agronomic and yield-related traits for the direct and indirect effects of independent variables on the crop’s managerial capacity. Three districts of Himachal Pradesh, viz., Sirmaur, Kangra and Bilaspur, were specifically chosen. The multistage probability proportional to the size sampling design was used. Primary data were gathered on the vegetative development indices, blooming, generative, and fruiting factors. Trees in the high-density system were placed 2 × 1.5 m apart. Based on yield performance, a sample size of 160 trees was determined to be the ideal number, with 110 plants being 3-year-old and 50 being 8-year-old. Vegetative growth, flowering, generative and fruit quality characteristics are significantly and positively linked with yield. Path analysis confirmed that growth and generative features were the main contributors that could be the good indicators of increased yield.

QTL mapping for plant height and ear height using bi-parental immortalized heterozygous populations in maize.

Plant height (PH) and ear height (EH) are key plant architectural traits in maize, which will affect the photosynthetic efficiency, high plant density tolerance, suitability for mechanical harvesting. QTL mapping were conducted for PH and EH using a recombinant inbred line (RIL) population and two corresponding immortalized backcross (IB) populations obtained from crosses between the RIL population and the two parental lines. A total of 17 and 15 QTL were detected in the RIL and IB populations, respectively. Two QTL, qPH1-1 (qEH1-1) and qPH1-2 (qEH1-4) in the RIL, were simultaneously identified for PH and EH. Combing reported genome-wide association and cloned PH-related genes, co-expression network analyses were constructed, then five candidate genes with high confidence in major QTL were identified including Zm00001d011117 and Zm00001d011108, whose homologs have been confirmed to play a role in determining PH in maize and soybean. QTL mapping used a immortalized backcross population is a new strategy. These identified genes in this study can provide new insights for improving the plant architecture in maize.

Reducing nitrogen application at high planting density enhances secondary cell wall formation and decreases stem lodging in rapeseed

Reducing the rate of nitrogen fertilizer (N rate) and achieving high plant density is an effective and economically beneficial approach to enhance rapeseed productivity. However, it is unclear how N rate affects stem lodging in rapeseed directly-sown at high densities. In this study, the effect of different N rates on stem lodging at high plant density was examined in field trial and pot experiments using two modern hybrid rapeseed varieties, Fengyou520 (FY520) and Huayouza62 (HYZ62). Increasing N fertilizer from low level to adequate level significantly increased yield by 39% in FY520 and 43% in HYZ62. However, with elevated N yield increases were limited by an increase in stem lodging. At T1 (the first inflorescence branch below the apex has the first flowers open) phloroglucinol-HCl staining for lignin was weaker under high N (N4: 4 g N pot−1) compared with adequate N (N2: 2 g N pot−1), and was correlated with weaker stem strength. Differences in stem lignin were also associated with variations in gene expression as revealed by transcriptomic profiling of middle stems at T1. Differentially expressed genes indicated significant enrichment for cell wall. Several genes encoding known transcriptional regulators of secondary cell walls (SCWs) biosynthesis and deposition were down-regulated with high N compared with adequate N. Many genes putatively involved in lignin biosynthesis, cellulose biosynthesis and assembly and xylan biosynthesis are down-regulated with high N, corresponding to lower accumulation of lignin, cellulose and hemicellulose in these plants. These findings not only provide us with gene candidates potentially affecting stem lodging in direct sown rapeseed, but also reveal that reducing N at high plant density enhances biosynthesis of stem cell walls to alleviate stem lodging.

Chemical Composition and Bioactivity of Dill Seed (Anethum graveolens L.) Essential Oil from Plants Grown under Shading

This study determined the content and composition of dill seed (Anethum graveolens L.) essential oil under varying light conditions: non-shaded plants in open fields and plants covered with pearl shade nets (40% shade index). Essential oil was extracted using Clevenger hydrodistillation. The essential oil content was 4.63% for non-shaded plants and 4.81% for shaded plants. GC/MS analysis revealed twenty-one and twenty-two components in dill seed from non-shaded and shaded plants, respectively. The terpenic fraction of essential oil from non-shaded plants consisted mainly of oxygen-containing monoterpene derivatives (53.6%), with carvone (46.1%) as the primary component, followed by monoterpene hydrocarbons (46.4%), predominantly limonene (43.8%). Essential oil from shaded plants contained a higher content of carvone (49.8%) and a lower content of limonene (37.8%) compared to essential oil from non-shaded plants. Non-shaded plant essential oil exhibited stronger antioxidant activity (EC50 value: 26.04 mg mL−1) than shaded plant essential oil (54.23 mg mL−1). Dill seed essential oil showed the most potent antimicrobial activity (disc diffusion method) against Escherichia coli (inhibition zone: 15–18 mm). Shaded plants demonstrated a positive influence of essential oil against Klebsiella pneumoniae. Carvone and its derivatives, as the main components, hold significant potential in the food industry and alternative medicines. A practical implication of this study could be higher plant densities or intercropping of dill, as it thrives with minimal light.

Root-shoot ratio and its relationships with physiological characteristics, growth and biomass yield of Gynura procumbens under different shade levels and plant density

Gynura procumbens is one of the most common medicinal plants in the Asteraceae family, with extensive pharmacological properties. The experiment was conducted to evaluate the effects of different shade levels (0 and 30% shade) and plant density (9, 15, and 25 plants m-2) on root-shoot ratio and it is a relationship with physiology, growth, and biomass yield using split-plot design with three replications. Increasing shade level to 30% shade significantly decreased root-shoot ratio (RSR) by22.54%, while total leaf dry weight per plant (TLDW) and total leaf dry weight per square meter (TLDW m-2) increased by 35.64, 11.58, and 32.18%, respectively due to negative correlation with RSR. Increasing plant density from 9 to 25 plants m-2 significantly increased RSR and TLDW m-2 by 67.71 and 18.54%, respectively, while TLDW decreased by 57.31%. There was a negative correlation between RSR and biomass yield per plant. Under stressed conditions (full sunlight and high plant density), G. procumbent plants appeared to change strategy to absorb limited resources, allocate more biomass to the root system, and reduce aboveground parts' size to survive, resulting in high RSR. Keywords: Gynura procumbens, shade, plant density, root-shoot ratio, physiology, growth, biomass

Annual Weeds Suppression and Oat Forage Yield Responses to Crop Density Management in an Oat-Cultivated Grassland: A Case Study in Eastern China

Although weeds can be inhibited by high planting densities, canopy shading, elemental balance and soil microbial recruitment are not yet adequately considered when measuring competitive effects on weed control. The effects of oat (Avena sativa) planting density (60 to 600 plants m−2) on the biomass and shoot element balance of oat and weeds were evaluated in a field experiment. The shift in the microbial community of the dominant weed species was examined in a pot experiment by growing the weed alone and in competition with 360 oat plants m−2 (recommended planting density) under greenhouse conditions. Increasing oat planting density beyond 360 plants m−2 did not improve oat forage yield or weed suppression. Compared to 60 plants m−2, the biomass of broadleaf and grass weeds decreased by 1122% and 111%, respectively, at a density of 360 plants m−2, while oat forage biomass increased by 60% and leaf area index by 24%. The improved canopy properties suppressed competing weeds through increased shading. Typically, the C:N and C:P ratios of shoots of Echinochloa crus-galli and Digitaria sanguinalis were higher than those of Portulaca oleracea and Chenopodium album. At high planting densities, E. crus-galli and D. sanguinalis exhibited high P contents and low N:P ratios, suggesting a limited supply of N nutrients for growth. Soil bacterial community assay showed that the composition of microbial communities of the two grass weeds were shaped by the presence of oat competition, which also considerably depleted several important functional microbes associated with nutrient cycling in the weeds’ rhizosphere. These results highlight that increased crop density significantly improves the crop competitive advantage over weeds through increased shading, reduced elemental balance, and beneficial microorganisms of weeds, thereby reducing the need for herbicides or physical weed control in oat cropping system.

Effect of planting density on yield and architecture suitability of groundnut (Arachis hypogaea) varieties

A field experiment was conducted during rainy (kharif) seasons of 2018 and 2019 at the research farm of Sri Venkateswara Agricultural College (Acharya N. G. Ranga Agricultural University), Tirupati, Andhra Pradesh, to study the effect of planting density on yield and architecture suitability of groundnut (Arachis hypogaea L.) varieties. The experiment included 4 sowing densities (D1, 33.3 plants/m2; D2, 50 plants/m2; D3, 66.6 plants/m2 and D4, 100 plants/m2) and 3 genotypes with varying architecture (G1, Kadiri 6-erect; G2, Kadiri 9-decumbent 2; and G3, Dharani-decumbent 3). The results showed that across planting densities, Dharani and Kadiri 9 genotypes showed higher architectural traits, structural carbohydrates and kernel yield compared to the Kadiri 6. A significant positive correlation was detected between the lodging percentage and both plant height (r = 0.88**) and internodal length (r = 0.61*). Significant negative correlations, were identified between lodging percentage and several parameters, including leaf thickness (r = -0.92**), specific leaf weight (r = -0.93**), stem diameter (r = -0.79**), specific stem weight (r = -0.97**), number of branches (r = -0.72**), cellulose content (r = -0.80**), and lignin content (r = -0.79**). These findings indicate that the decumbent architecture is optimal for achieving groundnut lodging resistance and kernel yield in high-density planting systems.

Effect of sodium dodecyl sulfate (SDS) on microbial community structure and function in lake–terrestrial ecotones: A simulation experiment

Even a low concentration of sodium dodecyl sulfate (SDS), a widely used bactericidal surfactant, can significantly change the species, quantity and genetic functions of microorganism communities in natural waters. Lake–terrestrial ecotones are areas where microorganisms are highly active, and they are also the lake areas most vulnerable to SDS pollution. Because microorganisms are very sensitive to environmental changes, their activities vary greatly among lakes and laboratories, so it is difficult to simulate their real dynamics using small-scale experiments. To study the interaction between SDS and microorganisms in a lake–terrestrial ecotone, a large artificial simulation device was used to analyse microbial community structure, phospholipid fatty acid (PLFA) content, gene function and ability to degrade SDS in a lake–terrestrial ecotone contaminated with SDS. The results showed that (1) the period from 2 to 4 days after the beginning of the experiment was the key stage for the biodegradation of SDS. The biodegradation cycle of SDS in the natural environment is shorter than that in small-scale experimental setups, and more than 90% of SDS was removed within 4 days in the simulation device. (2) Low-level SDS pollution (≤ 6 mg/L) has different effects on different types of lacustrine microorganisms. The presence of SDS can lead to a significant decrease in microbial diversity and biomass in lake–terrestrial ecotones with a high density of aquatic plants, but the opposite is true in ecosystems with degraded aquatic plant communities. (3) After SDS pollution occurred, pollution-resistant bacteria such as Chitinophaga and Flavobacterium became dominant. The relative abundance of carbon cycle functional genes increased rapidly in microorganisms, while the relative abundance of nitrogen cycle functional genes decreased. These changes were not readily reverse even after 20 days, although the communities recovered to a certain extent.

Transcriptome and metabolome profiling reveal the effects of hormones on current-year shoot growth in Chinese ‘Cuiguan’ pear grafted onto vigorous rootstock ‘Duli’ and dwarf rootstock ‘Quince A’

BackgroundDwarf rootstocks have important practical significance for high-density planting in pear orchards. The shoots of ‘Cuiguan’ grafted onto the dwarf rootstock were shorter than those grafted onto the vigorous rootstock. However, the mechanism of shorter shoot formation is not clear.ResultsIn this study, the current-year shoot transcriptomes and phytohormone contents of ‘CG‒QA’ (‘Cuiguan’ was grafted onto ‘Quince A’, and ‘Hardy’ was used as interstock) and ‘CG‒DL’ (‘Cuiguan’ was grafted onto ‘Duli’, and ‘Hardy’ was used as interstock) were compared. The transcriptome results showed that a total of 452 differentially expressed genes (DEGs) were identified, including 248 downregulated genes and 204 upregulated genes; the plant hormone signal transduction and zeatin biosynthesis pathways were significantly enriched in the top 20 KEGG enrichment terms. Abscisic acid (ABA) was the most abundant hormone in ‘CG‒QA’ and ‘CG‒DL’; auxin and cytokinin (CTK) were the most diverse hormones; additionally, the contents of ABA, auxin, and CTK in ‘CG‒DL’ were higher than those in ‘CG‒QA’, while the fresh shoot of ‘CG‒QA’ accumulated more gibberellin (GA) and salicylic acid (SA). Metabolome and transcriptome co-analysis identified three key hormone-related DEGs, of which two (Aldehyde dehydrogenase gene ALDH3F1 and YUCCA2) were upregulated and one (Cytokinin oxidase/dehydrogenase gene CKX3) was downregulated.ConclusionsBased on the results of transcriptomic and metabolomic analysis, we found that auxin and CTK mainly regulated the shoot differences of ‘CG–QA’ and ‘CG–DL’, and other hormones such as ABA, GA, and SA synergistically regulated this process. Three hormone-related genes ALDH3F1, YUCCA2, and CKX3 were the key genes contributing to the difference in shoot growth between ‘CG–QA’ and ‘CG–DL’ pear. This research provides new insight into the molecular mechanism underlying shoot shortening after grafted onto dwarf rootstocks.

Origin of yield gains in maize hybrids

AbstractIncreasing grain yields in maize (Zea mays L.) have been widely witnessed over the lifespan of many aging farmers. This paper aims to capture and summarize the overlapping explanations for the significant increases in maize yields. Changes in management practices have resulted in higher planting densities; however, genetic alterations allowed for maize varieties to tolerate increased stress levels. Increased stress levels, such as light availability, prompted genetic changes to leaf area index, radiation use efficiency, and leaf angles. The narrowing of the anthesis–silking interval is more significant in maize planted in higher densities. Stress factors affecting maize grain yields can be managed by both management changes such as water or pesticide application, and breeding modifications, such as genetic resistance to abiotic, temperature, or moisture, and biotic, pest, disease, and insect stressors. The increase in maize grain yields over the past century can be attributed to a combination of achievements in crop breeding and alternations of management practices.

Integrated nutrient management practices in Mrig bahar crop of guava under high density plantation

Integrated nutrient management practices in Mrig bahar crop of guava under high density plantation

Effects of pan evaporation-based drip irrigation levels on performance of guava grown in Udaipur and Rewa regions of India

A field experiment was conducted for three years (2019-20, 2020-21 and 2021-22) on 4 years old guava orchard established at 3×2 m spacing with drip irrigation treatments at two locations viz. Udaipur Rajasthan and, Rewa, Madhya Pradesh. Plant growth, yield contributing parameters, fruit yield and water use efficiency was significantly affected by different pan evaporation-based drip irrigation levels (70, 80, 90 & 100% of Epan) over local control. In existing climatic conditions of Udaipur and Rewa regions, the daily irrigation water requirement of high-density planting guava tree was varied from 7.8 to 26.3 and 4.5 to 26.5 liter/plant/day, respectively. Among all the pan evaporation-based drip irrigation levels, the irrigation supplied at 80% and 90% of daily pan evaporation were found as best approach for irrigating high density plantation (HDP) guava orchard through drip irrigation in Udaipur & Rewa regions with maximum fruit yield (37.3 & 30.7tha-1), irrigation water use efficiency (0.359 & 0.263tha-1-cm) along with significant water saving (29.2 & 22.2%), respectively over local control. Results will help farmers, policy makers and irrigation managers to conserve available fresh water resources in water scares regions of Rajasthan and Madhya Pradesh.

Apple Growing in Norway—Ecologic Factors, Current Fertilization Practices and Fruit Quality: A Case Study

This paper presents some features of apple production in Norway, the northernmost apple-growing country in the world. Acceptable growing conditions prevail along the fjords in western Norway and around the lakes in eastern Norway at 60° north. These specific mesic climate conditions are associated with very long summer days (18 h daylight mid-summer) and short winter days (6 h daylight), with frost rarely occurring in the spring along the fjord areas. The present apple-growing technique in Norway is similar to that of other developed apple-growing countries, taking into account that all local growing phases involve a considerable delay in progress (1.5–2 months). Therefore, high-density planting systems based on the use of dwarf rootstocks (mainly M.9) with imported early maturing international apple cultivars are used in most orchards. The most common soil type has high organic matter content (2–18%), which persists due to the cool climate and low mineralization, and a clay content of <15%, which results from the formation of the soil from bedrock. The increase in average temperatures caused by current climatic changes leads to a complex combination of different physiological effects on apples, which can have positive or negative effects on the phenology of the trees. The main advantage of Norwegian apple production is that the quality and aroma of the fruit meet the current demands of the local market.

Apple (Malus × domestica Borkh.) production and quality in response to anti-hail nets.

Anti-hail nets are the best way to mitigate the effects of hailstorms in the orchards. Apple trees covered with nets may exhibit a variety of vegetative and reproductive responses, inclusive of changes in tree vigour, cropping, sugar contents, and fruit colour. The present study was conducted to assess the effect of timing of installation and colour of anti-hail net on cropping and fruit quality in high-density apple orchard for two consecutive seasons (2021 and 2022). White and blue colour nets of size (9m × 30m) 80 GSM (square mesh with non-sliding threaded, leno weave, and < 30% shading factor) were installed at three different time intervals (15days before estimated full bloom, at full bloom, and 15days after full bloom) on apple cultivar 'Jeromine'. The installation at different time and colour of anti-hail nets significantly exhibit variability in cropping, fruit quality, and bio-chemical metrics. The significant highest cropping (fruit yield, productivity, and yield efficiency) and fruit biochemical parameters (total soluble solids) were recorded in T3C2 (15days after full bloom + white colour anti-hail net) followed by T2C2 (installed at full bloom + white colour anti-hail net). Hence, white colour anti-hail nets installed 15days after full bloom increased fruit production and improved quality in comparison to blue colour anti-hail net in apple under high-density plantations.

EFFECT OF AGRONOMIC AMENDMENTS ON GROWTH AND YIELD OF SUNFLOWER

Proper planting geometry helps in obtaining optimum plant population and crop yield; while irrigation at right time results in improved higher crop yields and quality of the produce. Two years field experiments were conducted during (2019 and 2020) at Tandojam to examined the effect of sowing methods (Raised bed, Ridge, Drilling and Broadcasting); planting densities (Recommended, high density and ultra-high density) and nutrient management (90+60+60+0, 90+60+60+10 and 90+60+ 60+20 kg ha-1 NPK+FeSO4). The experimental design was randomized complete block design with three replicates. The best result in all parameters on average factors including drilling method, high density planting (66,666 plants ha-1), NPK+FeSO4: 90+60+60+20 kg ha-1 and their interaction resulted in economically superior overall sunflower performance in relation to its growth, seed yield and quality attributes. The drilling method was highly effective to improve seed yield apart from the lower biological yield due to greater harvest index as compared to rest of the sowing methods. Although, recommended plant spacing (55,555 plants ha-1) produced better individual plant based results, but due to lesser plant population, the overall seed yield was greater under high density planting (66,666 plants ha-1).Ultra high density plantation (83,333 plants ha-1) did not prove beneficial due to crowded plant population where harvest index became poor but biological yield increased. Higher FeSO4 improved the grain quality and no effect on foliage; hence 20 kg FeSO4 remained economically most beneficial to achieve desired seed production.