Days After Transplanting Research Articles

Endophytic actinomycetes promote growth and fruits quality of tomato (Solanum lycopersicum): an approach for sustainable tomato production.

Tomato, a fruit with a high vitamin content, is popular for consumption and economically important in Thailand. However, in the past year, the extensive usage of chemicals has significantly decreased tomato yields. Plant Growth-Promoting Rhizobacteria (PGPR) is an alternative that can help improve tomato production system growth and yield quality while using fewer chemicals. The present study aimed to determine whether endophytic actinomycetes promote growth and fruit quality of tomato (Solanum lycopersicum). The experiment was conducted in a net-houses at the Center for Agricultural Resource System Research, Faculty of Agriculture, Chiang Mai University, Chiang Mai province, Thailand. The randomized completely block design (RCBD) was carried out for four treatments with three replications, which was control, inoculation with TGsR-03-04, TGsL-02-05 and TGsR-03-04 with TGsL-02-05 in tomato plant. Isolated Actinomycetes spp. of each treatment was then inoculated into the root zone of tomato seedlings and analyzed by Scanning Electron Microscopy (SEM). The height of tomato plants was measured at 14, 28, 56, and 112 days after transplanting. Final yield and yield quality of tomato was assessed at the maturity phase. The SEM result illustrated that the roots of tomato seedlings from all treatments were colonized by endophytic actinomycetes species. This contributed to a significant increase in plant height at 14 days after transplanting (DAT), as found in the TGsR-03-04 treatment (19.40 cm) compared to the control. Besides, all inoculated treatments enhanced tomato yield and yield quality. The highest weight per fruit (47.38 g), fruit length (52.37 mm), vitamin C content (23.30 mg 100g-1), and lycopene content (145.92µg g-1) were obtained by inoculation with TGsR-03-04. Moreover, the highest yield (1.47 kg plant-1) was obtained by inoculation with TGsL-02-05. There was no statistically significant difference in the number of fruits per plant, fruit width, brix, and antioxidant activity when various inoculations of endophytic actinomycetes were applied. Therefore, the use of endophytic actinomycetes in tomato cultivation may be an alternative to increase tomato yield and yield quality.

Productivity and profitability of black rice as affected by transplanting methods and crop geometry

Black rice is a highly nutritious cereal that has been introduced to Nepal recently. Due to its late introduction, only a few agronomic research have been conducted so far. Hence, farmers are not aware about the appropriate transplanting methods and cropping geometry for profitable black rice cultivation. To fulfill the research gap and to establish a basic benchmark for further studies, the research focuses on responses of two black rice genotypes at different transplanting methods and cropping geometry. The profitability analysis with respect to transplanting methods and cropping geometry revealed, transplanting 21 days old seedlings with any geometrical pattern would yield and profit more as compared to SRI. Similarly, farmers can get a highest net revenue of 9379.3 $ at the B/C ratio of 12.07 from fine black rice as compared to coarse black rice that has a net revenue of 4485.7 $ at the B/C of 7.38. The highest productivity (2.70 t ha−1), net revenue (6018.5 $), and B/C ratio (13.7) were observed at the crop geometry of 20 cm × 15 cm for coarse black rice. Whereas, the highest yield (4.60 t ha−1), net revenue (10889.8 $), and B/C ratio (19.5) was observed in 20 cm × 10 cm for fine black rice. The higher net revenue and B/C ratio of premium black rice genotypes was due to their higher market price. The correlation analysis suggested tillering index (Ti) and net biomass accumulated up to 60 days after transplanting (DAT) had the highest positive correlation with yield of both black rice genotypes. Hence, the authors recommend researchers to work on additional agronomic practices that enhance the tillering index and net biomass production up to 60 DAT considering transplanting methods yield more as compared to SRI and crop geometry of 20 cm × 15 cm and 20 cm × 10 cm are the most productive and profitable cropping geometry for coarse and fine black rice genotypes, respectively.

Effect of integrated nutrient management on the growth and productivity of four high-yielding rice varieties of Eastern India

Aim: To investigate the integrated nutrient management in agricultural fields using cow dung manure and poultry manure as organic, and NPK as inorganic fertilizer at varied ratios. Methodology: Four rice varieties were selected for the experiment viz., MTU 1010, IET 4786, IET 17430, and IET 9947 under nine organic manure and inorganic fertilizer combinations in different ratios with one control treatment. The cultivation was carried out in three replications in a randomized complete block design. The biometric observations were noted at 30, 55, and 80 days after transplant (DAT). Leaf Area Index (LAI), Crop Growth Rate (CGR), and grain yield were calculated for the varieties under varied treatments. Results: Biometric observation and growth indices confirmed that the treatment T3 showed the highest value among all other treatments for shoot length, dry matter, LAI and LAD for all varieties. Treatment T7 recorded the maximum root length. For CGR treatment T2 and T3 recorded highest value for different varieties. Soil nutrient results suggest that treatment T2-T4 and T6-T8 showed the highest N, P and K content. The results showed significant difference (p<0.05) in grain yield for all the treatments in all varieties, where T3 recorded the highest value. Interpretation: The year experiment revealed that integrated nutrient application resulted in considerably greater growth and productivity compared to the control and 100% inorganic fertilizer-treated cultivation. Key words: Cow dung, Integrated nutrient management, Poultry manure, Plant growth indices, Rice productivity Aim: To investigate the integrated nutrient management in agricultural fields using cow dung manure and poultry manure as organic, and NPK as inorganic fertilizer at varied ratios. Methodology: Four rice varieties were selected for the experiment viz., MTU 1010, IET 4786, IET 17430, and IET 9947 under nine organic manure and inorganic fertilizer combinations in different ratios with one control treatment. The cultivation was carried out in three replications in a randomized complete block design. The biometric observations were noted at 30, 55, and 80 days after transplant (DAT). Leaf Area Index (LAI), Crop Growth Rate (CGR), and grain yield were calculated for the varieties under varied treatments. Results: Biometric observation and growth indices confirmed that the treatment T3 showed the highest value among all other treatments for shoot length, dry matter, LAI and LAD for all varieties. Treatment T7 recorded the maximum root length. For CGR treatment T2 and T3 recorded highest value for different varieties. Soil nutrient results suggest that treatment T2-T4 and T6-T8 showed the highest N, P and K content. The results showed significant difference (p<0.05) in grain yield for all the treatments in all varieties, where T3 recorded the highest value. Interpretation: The year experiment revealed that integrated nutrient application resulted in considerably greater growth and productivity compared to the control and 100% inorganic fertilizer-treated cultivation. Key words: Cow dung, Integrated nutrient management, Poultry manure, Plant growth indices, Rice productivity

Cross-talk between antioxidant production and secondary metabolite biosynthesis under combined effects of ozone stress and nitrogen amendments: A case study of lemongrass

The present experiment was done to study the interactive effects of soil nitrogen (N) amendments and elevated ozone (O3) (N–O3) on a medicinal plant, lemongrass [Cymbopogon flexuosus (Steud.) (Wats.)]. The experiment used two doses of inorganic soil nitrogen (N1, recommended and N2, 1.5-times recommended dose) in open-top chambers under ambient and elevated (ambient + 15 ppb and ambient + 30 ppb) O3 conditions. To analyze various characteristics, samples were collected at 45 and 90 days after transplantation (DAT). Additionally, at 110 days after transplantation (DAT), the metabolite contents of the leaves and essential oils were analyzed. The present study aims to investigate the mechanistic approach involving the crosstalk between antioxidant production and secondary metabolite biosynthesis in lemongrass upon N–O3 interactions. The present experiment showed that N amendments can be an efficient measure to manage O3 injury in plants, along with ensuring a balance between primary and secondary metabolic pathways, thus sustaining the plant defense and production of bioactive compounds, simultaneously. Under N–O3, not only the Halliwell asada pathway was stimulated resulting in the increased activities and concentrations of antioxidant pools; the shikimate, phenylpropanoid and mevalonic acid pathways were also invigorated, producing more number and contents of secondary metabolites (SMs), compared with plants that were not treated with N doses. This study suggests that soil nitrogen amendments will improve the therapeutic qualities of lemongrass, along with the strengthening of its antioxidant machinery, upon exposure to O3 stress.

Impact of integrated nutrient management and foliar zinc supplementation on rice (Oryza sativa L.) nutrient uptake and yield in the Cauvery Delta Zone

In 2023, rice production reached 523.9 million tons, making it the fourth most produced crop globally. Accounting for 14% of global fertilizer use, the demand for rice continues to increase. However, the unbalanced application of NPK fertilizers poses significant environmental risks. An integrated nutrient management approach, combining organic and inorganic sources, offers a cost-effective solution to meet crop nutritional needs while enhancing soil health. Therefore, a field experiment was conducted in Experimental Farm of Annamalai University during kuruvai (June-September) 2023 to evaluate the effect of different levels of inorganic fertilizers with different sources of organic manures along with foliar zinc sulphate on the yield and yield components in lowland rice. The experiment was laid out in randomized block design with nine treatments. These treatments included different sources of organic manures viz., farm yard manure, vermicompost, press mud and poultry manure and foliar application of zinc sulphate. The results revealed that combining 75% nitrogen through urea and 25% nitrogen from vermicompost and 100 % P and K along with foliar application of zinc sulphate (0.5%) at 25 and 50 days after transplanting (DAT) significantly improved all nutrient uptake of nitrogen, phosphorous and potassium and also yield parameters viz., number of productive tillers m-2, number of filled grains/panicle, grain yield, straw yield and harvest index of rice.

Changes in Carotenoids and Polyphenols during the Growth Stages of Orange-Fleshed Sweet Potato (Ipomoea batatas (L.) Lam.)

The storage roots of orange-fleshed sweet potato contain high levels of polyphenols and carotenoids. Little information is available on changes in the content and composition of these secondary metabolites during the growth stages of the root system. We investigated changes in carotenoids, polyphenols, and anthocyanins in the root system of the orange-fleshed sweet potato ‘Tamaakane’ from the post-planting stage. Carotenoids and polyphenols accumulated immediately after root-system formation at 15 days after transplanting (DAT). The levels of carotenoids increased by 45 DAT and decreased once the storage root enlargement began, but increased rapidly thereafter. After 90 DAT, β-carotene accounted for >90% of the total carotenoids, and the frequency remained stable until maturity. Total polyphenol content increased significantly towards 45 DAT and then gradually decreased as the storage roots began to thicken. No anthocyanin was detected in the root systems of ‘Tamaakane’ at any stage. The content and composition of these secondary metabolites are discussed in terms of agronomic aspects, as they might contribute to a strategy to protect storage roots while engaging with each other against biotic or abiotic stresses at the growth stage of the root system.

Enhancing Yield and Nitrogen Utilization of Boro Rice with Urea Super Granules

A field experiment was conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during boro season to assess the comparative performance of prilled urea (PU) and urea super granule (USG) on the growth, yield, and nitrogen uptake of BRRI dhan29. The experiment was laid out in a randomized complete block design with three replications. The treatment combinations were T1: Control, T2: PU at 7 days after transplanting (DAT)+27 DAT+47 DAT, T3: PU at 10 DAT+30 DAT+50 DAT, T4: PU at 15 DAT+35 DAT+55 DAT, T5: USG at transplanting, T6: USG at 7 DAT, T7: USG at 10 DAT and T8: USG at 10 DAT+30 DAT where PU and USG were applied @ 216 kg N ha-1. PU was applied as surface broadcasting whereas USG was placed at 6-8 cm depth by hand between four hills at every alternate row. The results revealed that all the treatments showed better performances than control (T1). Results found that yield components, yield, and nitrogen uptake of BRRI dhan29 responded significantly to deep placement of USG than PU. Treatment T6 (USG at 7 DAT) produced the highest grain and straw yields of 6.56 t ha-1 and 6.95 t ha-1 respectively. Treatment T6 (USG at 7 DAT) also showed the highest grain yield increase (57.16%) and straw yield increase (52.37%) over control. The highest grain, straw, and total N uptake of 87.28, 32.71 and 120 kg ha-1 respectively were obtained in the treatment T6 (USG at 7 DAT). The overall results clearly indicate that deep placement of USG at 7 DAT in rice field increases rice yield and efficient uptake of the applied N. So, treatment T6 (USG at 7 DAT) could be recommended as best treatment for reducing N losses, conserving environment and improving sustainable production of rice.

THE EFFECT OF ZINC ON WHITE-BACKED PLANTHOPPER INFESTATION, RICE PLANT BIOCHEMICAL RESPONSES CROP YIELD, AND INSIGHTS FOR SUSTAINABLE PEST MANAGEMENT

The white-backed planthopper (WBPH), Sogatella furcifera, has emerged as a highly destructive rice crop pest, leading to significant annual yield losses. Excessive zinc (Zn) can be detrimental to plants, but the role of Zn on herbivorous insects remains uncertain. In this research, we conducted a pot culture experiment in the Kharif season 2017 at the Department of Entomology, College of Agriculture, OUAT, Bhubaneswar, Odisha, India. The aim was to investigate the effect of Zn (in the form of Zn EDTA or ZnSO4) when applied as a basal or foliar spray, either alone or in various combinations, on the WBPH. Our findings revealed that the population of WBPH in the control group of rice plants was at its highest (79.20) at 60 days after transplanting (DAT) compared to the groups treated with Zn. Further, an analysis of 60-day-old plant samples showed that applying Zn increased levels of chlorophyll, phenols, and soluble protein content. In addition, there was an elevation in the activity of superoxide dismutase (SOD), peroxidase (POD), and phenylalanine ammonia-lyase (PAL). Simultaneously, this treatment decreased the levels of total free amino acids, total soluble sugars, and proline content. Both increase and decrease in respective biochemical parameters were indicators of an induced antibiosis mechanism in rice plants against the WBPH. The correlation analysis between the WBPH population and various plant biochemical parameters showed that the WBPH population was inversely correlated with total chlorophyll, phenol, soluble protein content, as well as the activities of SOD, POD, and PAL. Conversely, it positively correlated with total free amino acids, soluble sugars, and proline content. Therefore, this research has provided valuable insights into the presence of Zn, which significantly influences the population of WBPH, suggesting a potential avenue for WBPH control and rice yield improvement through strategic Zn application.. KEYWORDS :Antibiosis, Biochemical parameters, Enzymes, Rice, Zinc

Far-red radiation management for lettuce growth: Physiological and morphological features leading to energy optimization in vertical farming

Recently, far-red wavelengths (FR, 700–750 nm) have been largely investigated in indoor cultivation systems due to their morphological effects on plants (e.g., leaf expansion and stem elongation), resulting also in increasing yield. This work investigated the effect of substituting part of the red (R) and blue (B) radiation with far-red radiation, while keeping constant the photon flux density, in the light spectrum for lettuce grown in a vertical farm. Lettuce (Lactuca sativa var. Canasta) plants were transplanted and grown in an ebb-and-flow system for 29 days. During the cycle, plants were subjected to five different light treatments: a control treatment consisting of an optimized R and B spectrum (ratio of 3; RB3) with a photosynthetic photon flux density of 200 µmol m−2 s−1, and four treatments in which R and B were partially replaced by 10, 30, 50 and 70 µmol m−2 s−1 of FR light, resulting in an increasing FR fraction. Biomass production and most of the morphological parameters were affected from 15 days after transplanting (DAT), while stomatal conductance from 22 DAT. Leaf greenness and specific leaf area values were influenced by the FR radiation starting from 8 DAT. At 29 DAT, substitution of an amount of R and B photons equal to 30 (RB3–30) or 50 (RB3–50) µmol m−2 s−1 with the same amount of FR radiation resulted in increased leaf biomass in both fresh (+49 and +47%, respectively) and dry weight (+45 and +42%, respectively). With RB3–30, the increase was due to leaf area expansion (+103%), whereas stomatal conductance (gs) and quantum efficiency of photosystem II (ΦPSII) did not change compared with the spectrum with only R and B. With RB3–50, gs and ΦPSII decreased compared with RB3 (-27 and -6%, respectively), but the greater biomass accumulation was supported by the greater leaf expansion (+119 %). The adoption of RB3–30 and RB3–50 also promoted light use efficiency (+45 and +42 %, respectively), lighting energy use efficiency (+48 and +53 %, respectively) and therefore the overall energy performance of the system. The adoption of RB3–30 and RB3–50 is a valid strategy to increase yield for lettuce production, but further studies, also in relation to blue radiation intensity, are needed to avoid the negative effect on leaf pigmentation.

Melon cultivation under agrotextile increases production and reduces phytosanitary products

Abiotic and biotic factors influence the productivity and quality of melon fruit; therefore, the protection of plants using agrotextile mesh is a solution that can be agronomically viable, as it reduces the use phytosanitary pesticides and allows for greater productivity and, consequently, quality. The objective this study was to evaluate the influence of coverage time with an agrotextile (0, 21, 26 and 31 days after transplanting (DAT)) in melon hybrids ‘Gold Mine’, ‘Soleares’, ‘Lual’ and ‘Natal’ on productivity and fruit quality attributes. The plants that were protected with agrotextile mesh for 21 and 26 DAT had higher productivity (53.5 and 52.1 t ha−1). Among the hybrids, all excellent plots produced above 42.4 1 t ha−1. Of the observed hybrid quality parameters, 'Natal' protected for 21 DAT showed a better total phenol content and a higher maturation index, and 'Soleares' protected for 21 DAT showed a higher DPPH antioxidant activity and flavonoid content.

Response of Potassium Humate Extracted from Different Organic Sources on Yield and Quality of Green Chilli

Aim: In recent trend of organic farming, use of humic substances plays important role, as it act as biostimulants to boost the yield of crop. Humic substances can be easily obtained by locally available organic sources. Hence, three different organic sources viz. Farm Yard Manure (FYM), vermicompost, lignite were characterized for their physico-chemical properties and quality parameters along with nutrients to judge their quality and maturity to extract humic substances. The potassium salt of humic acid extracted from these three sources were used as foliar application at different concentrations to study their effects on yield and quality of green chilli. Study Design: The pot culture experiment was conducted in Completely Randomized Design comprising eleven treatments with three replications. Place and Duration of the Study: The experiment was conducted in rabi season 2021-22 at College of Agriculture, Karad, Maharashtra, India. Methodology: Three organic sources viz. Farm Yard Manure (FYM), vermicompost and lignite were used to extract humic substances (humic and fulvic acid). These organic sources were studied for their physico-chemical properties and quality parameters along with their nutrient status to compare their quality and maturity for extraction of humic substances. Humic substances obtained from these different sources were studied for their content and characteristics. The potassium humate extracted from these organic sources were used in a pot culture study on green chilli, comprising eleven treatments and three replications. The different levels of potassium humate (200 to 600 ppm) were used as foliar application on transplanted chilli at 30 and 45 days after transplanting (DAT) along with recommended dose of fertilizers (GRDF) for studying its effects on yield and quality of green chilli. Results: Among all the three organic sources, vermicompost was reported as the best organic source to extract humic substances from its physico-chemical properties viz. pH (6.9), EC (0.3 dS m-1), water soluble organic carbon (0.76 %) and C:N ratio (18.0), which are considered as quality and maturity parameters to obtain good quality humic substances. Nutrient status for macro and micronutrients were reported to be higher in vermicompost followed by FYM and least content in lignite. In the pot culture experiment, the foliar application of potassium humate extracted from vermicompost resulted in significant improvement in fresh and dry yield of chilli fruit and stalk as compared to potassium humate application extracted from FYM and lignite. Among the various concentrations used (200-600 ppm) for the foliar application of potassium humate, application @ 400 ppm extracted from vermicompost along with GRDF (T7) was reported as the best treatment resulting in significantly increase in the fresh and dry yield of chilli fruits and stalk. Further, it was noticed that the same treatment was observed to be effective in significant improvement of the ascorbic acid content as quality parameter in fresh green chilli fruits.

Seedling Growth, Field Performance and Economics of Production of Early Cauliflower as Influenced by Different Sowing Media and Variety under Greenhouse Condition in Assam, India

An experiment was conducted at the greenhouse and in the field of the Experimental Farm, Department of Horticulture, College of Agriculture, Assam Agricultural University, Jorhat for two consecutive years (2018 and 2019) to assess the effect of sowing media and variety on growth of early cauliflower seedling and subsequent performance of seedling in the main field. The results revealed that seedlings raised in different sowing media surpassed the conventional sowing media (soil, sand and farm yard manure) for growth attributes and yield. The media M1 i.e., cocopeat (60): vermiculite (20): perlite (20) recorded the highest seedling emergence whereas minimum days to transplanting and maximum leaf area was recorded in M2 i.e., cocopeat (50): vermicompost (50). Minimum days to 2-true leaf emergence was recorded in both M2 and M3 [cocopeat (50): vermicompost (50): microbial consortium@ 1:100] and M3 recorded the highest seedling height in nursery. Minimum days for 2-true leaf emergence was recorded by variety V2 (CFL1522) while highest leaf area was found in V1(White Diamond). Among interactions, M1V1 recorded maximum emergence, M2V2 recorded minimum number of days for 2-true leaf stage and to transplanting respectively, maximum leaf area in M2V1 and M3V2 produced the tallest seedling. In field, the seedlings that were grown in M3 media in nursery recorded significantly higher value of growth parameters and yield. Variety white Diamond took minimum days for establishment and recorded maximum leaf area index at 30 Days After Transplanting (DAT) as well as at harvest. Though treatment combination, M3V2 recorded the highest curd yield the highest cost benefit ratio was obtained in M3V1 (3.95) and the lowest (2.42) in M1V1. Considering the cost benefit ratio, for producing good quality seedlings of early cauliflower under green house, which will further give best performance in field condition, cocopeat (50): vermicompost (50): microbial consortium (1:100) as sowing media and variety White Diamond can be used in Assam.

Influence of transplanting date and integrated weed management in system of rice intensification of aromatic black rice (Oryza sativa)

A field experiment was conducted during rainy seasons (kharif) of 2019 and 2020 at the research farm of School of Agricultural Sciences, Nagaland University, Nagaland to study the effect of transplanting date and weed management practices on productivity and profitability of aromatic black rice (Oryza sativa L.) under system of rice intensification. The experiment was conducted in a split plot design (SPD) with 3 transplanting dates (D1, 15th June; D2, 30th June; and D3, 15th July) in main plot and 5 weed managements practices [W1, Weedy check; W2, Conoweeding at 20 and 40 DAT (days after transplanting); W3, Pretilachlor @0.75 kg/ha (PE) fb hand weeding (HW) at 40 DAT; W4, Pretilachlor @0.75 kg/ha (PE) fb conoweeder at 40 DAT; and W5, Pretilachlor at 0.75 kg/ha (PE) fb bispyribac-sodium @ 25 g/ha (PoE)] in sub-plot, replicated thrice. Results showed that the most abundant weed flora observed in the experimental field were Fimbristylis quinquangularis (Vahl) Kunth, Cyperus esculentus (L.), Cyperus iria (L.), Rhynchospora colorata (L.) H.Pfeiff., Ludwigia linifolia Poir, Mimosa pudica (L.), Mimosa diplotricha Sauvalle, Scoparia dulcis (L.) and Eriochloa villosa (Thunb.) Kunth. Transplanting on 15th June recorded highest growth and yield of black rice. The improvement in the grain yield was about 39% under 15th June over 15th July transplanting date. Among weed management practices, pretilachlor @0.75 kg/ha at 3 DAT fb HW at 40 DAT recorded minimum density of weeds resulting in higher growth attributes and yield of black rice. Economic analysis showed that highest benefit cost (B:C) ratio was obtained when black rice was transplanted on 15th June along with application of pretilachlor @0.75 kg/ha at 3 DAT fb bispyribac-sodium @25 g/ha at 20 DAT and demonstrated to be the best treatment for profitable production of black rice under system of rice intensification.

Design and evaluation of slow sand and UV filters for effective nutrient recycling in closed soilless cultivation

Nutrient and water use efficiency can be improved in soilless cultivation systems by recirculating the leachate. However, untreated leachate contains particulate matter that may clog drip emitters and root pathogens which can pose a threat to the crop health if reintroduced into the system. To address this issue, an ultraviolet (UV) filter was developed to complement the slow sand filter to enhance its treatment efficiency in removing root pathogens. The experiment was conducted during 2019 and 2020 at Punjab Agicultural University, Ludhiana, Punjab to assess the effectiveness of the UV filter in removing pathogens, specifically Dickey zeae and Xanthomonas, from the leachate in a closed soilless cultivation system. Pre and post-treatment measurements were made 40 days after transplanting (DAT) and 80 DAT to evaluate the efficiency of the UV filter. The results revealed that combined UV and slow sand filters substantially treated the raw leachate. At 40 DAT, the pathogen removal efficiency was 94.8%, while it was 92% at 80 DAT. The findings highlight the importance and effectiveness of using the UV filter as an additional treatment step in closed soilless cultivation systems with significant improvement in the overall removal efficiency of root pathogens from the leachate.

Improving the estimation of rice above-ground biomass based on spatio-temporal UAV imagery and phenological stages.

Unmanned aerial vehicles (UAVs) equipped with visible and multispectral cameras provide reliable and efficient methods for remote crop monitoring and above-ground biomass (AGB) estimation in rice fields. However, existing research predominantly focuses on AGB estimation based on canopy spectral features or by incorporating plant height (PH) as a parameter. Insufficient consideration has been given to the spatial structure and the phenological stages of rice in these studies. In this study, a novel method was introduced by fully considering the three-dimensional growth dynamics of rice, integrating both horizontal (canopy cover, CC) and vertical (PH) aspects of canopy development, and accounting for the growing days of rice. To investigate the synergistic effects of combining spectral, spatial and temporal parameters, both small-scale plot experiments and large-scale field testing were conducted in Jiangsu Province, China from 2021 to 2022. Twenty vegetation indices (VIs) were used as spectral features, PH and CC as spatial parameters, and days after transplanting (DAT) as a temporal parameter. AGB estimation models were built with five regression methods (MSR, ENet, PLSR, RF and SVR), using the derived data from six feature combinations (VIs, PH+CC, PH+CC+DAT, VIs+PH +CC, VIs+DAT, VIs+PH+CC+DAT). The results showed a strong correlation between extracted and ground-measured PH (R2 = 0.89, RMSE=5.08 cm). Furthermore, VIs, PH and CC exhibit strong correlations with AGB during the mid-tillering to flowering stages. The optimal AGB estimation results during the mid-tillering to flowering stages on plot data were from the PLSR model with VIs and DAT as inputs (R 2 = 0.88, RMSE=1111kg/ha, NRMSE=9.76%), and with VIs, PH, CC, and DAT all as inputs (R 2 = 0.88, RMSE=1131 kg/ha, NRMSE=9.94%). For the field sampling data, the ENet model combined with different feature inputs had the best estimation results (%error=0.6%-13.5%), demonstrating excellent practical applicability. Model evaluation and feature importance ranking demonstrated that augmenting VIs with temporal and spatial parameters significantly enhanced the AGB estimation accuracy. In summary, the fusion of spectral and spatio-temporal features enhanced the actual physical significance of the AGB estimation models and showed great potential for accurate rice AGB estimation during the main phenological stages.

Weed dynamics, yield and economics of winter transplanted organic chia (Salvia hispanica L.) under nutrient and weed management

An experiment was conducted during winter (rabi) season of 2021–22 at Agricultural Research Station, Chhatabar, Institute of Agricultural Sciences, Siksha ‘O’ Anusandhan (Deemed to be) University, Bhubaneswar, Odisha to study the effect of weed and nutrient management practices on weed dynamics, yield and economics of winter transplanted organic chia (Salvia hispanica L.). The experiment was conducted in split plot design having 6 weed and 5 nutrient management practices with three replications. Among 6 weed management practices, hoeing and weeding twice at 20 and 35 days after transplanting (DAT) recorded the minimum density and biomass of weeds with weed control efficiency of 85 and 79.4% at 40 DAT and harvest, respectively. Nerium leaf aqueous extract (NLAE) 5% + castor leaf aqueous extract (CLAE) 5% + manual weeding at 35 DAT proved equally effective in weed control. Hoeing and weeding twice with 9 t/ha FYM + green manuring + Jeevamrit gave the seed, oil and protein yield of 730, 204 and 145 kg/ha, as against 720, 205 and 136 kg/ha, respectively. Weed management by NLAE 5% + CLAE 5% + manual weeding integrated with 9 t/ha FYM + green manuring + Jeevamrit and both, being statistically at par, proved to be significantly superior to all other treatment combinations. These two treatment combinations recorded statistically similar net return and return per rupee investment, and proved significantly superior to all others.

Weed and nitrogen management effects on weed flora and productivity of transplanted rice (Oryza sativa) in North-Eastern region of India

A field study was conducted during rainy (kharif) season of 2017 at Barapani, Meghalaya, to find out the effects of weed and nitrogen management on weed flora and yield of transplanted rice (Oryza sativa L.) in North-Eastern region of India. The experiment was taken in split-plot design with 3 replications. In the main plot, 4 weed management practices, viz. unweeded control; oxadiargyl 0.08 kg/ha followed by (fb) bispyribac-Na 0.02 kg/ha; oxadiargyl 0.08 kg/ha fb hand weeding (HW) at 40 days after transplanting (DAT), and 2 HW at 20 and 40 DAT was taken, while 4 N levels, viz. 0, 30, 60 and 90 kg N/ha were taken in sub-plots. At 60 DAT, total weed population and weed density were remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. The grain yield also followed the same trend and remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. However, in terms of net returns, application of oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha recorded the highest followed by oxadiargyl 0.08 kg/ha fb HW at 40 DAT. Application of N at higher level reduced the total weed population at 60 DAT and a reverse trend was found with weed dry weight. Application of 90 kg N/ha recorded higher grain yield, net returns and benefit: cost ratio. It may be concluded that oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha with 90 kg N/ha could be an alternative for HW to enhance the productivity in transplanted rice for North-Eastern region of India.

Effect of establishment methods on aromatic rice (Oryza sativa) genotypes in lower Gangetic plains of West Bengal

A field experiment was conducted at Jaguli, Nadia, West Bengal, India, during the rainy (kharif) season of 2016, to study the response of four aromatic (Oryza sativa L.) rice genotypes (‘Gobindabhog’, ‘Radhunipagal’, ‘Tulaipanji’ and ‘Kalonunia’) under 3 establishment methods [conventional planting, drum seeding and modified system of rice intensification (SRI)].The plants raised under modified SRI showed the maximum plant height at harvesting (136.7 cm), tiller production (298/m2 ) at 63 days after transplanting (DAT), and dry-matter production at 33 DAT (194 g/m2 /day) and 63 DAT (444 g/m2 /day). Conventional planting resulted in the highest grain yield (2.24 t/ha), head rice recovery (HRR) (55.2%) and net income (`32,593/ha), which were greater over the modified SRI (2.09 t/ha, 53.5% and `30,901/ha) and drum seeding method (2.0 t/ha, 53.2% and `32,192/ha). ‘Gobindabhog’ had the highest grain yield (2.35 t/ha), HRR (56.5%), net income (`39,754/ha) and benefit: cost (B:C) ratio (2.13) compared to the other genotypes; but ‘Kalonunia’ might be tried as a second option in New Alluvial Zone of West Bengal.

Carpochron: a concept for the time interval between the appearance of fruits in consecutive harvests

The aim of this research was to estimate the base temperature for the appearance of fruits at harvest point in the strawberry and to propose a concept to represent the time required for the appearance of fruits in consecutive harvests. The experiment was conducted in 2021 in four seedling transplanting seasons: May (season 1), June (season 2), July (season 3) and August (season 4) of two cultivars: Fronteras and Merced. Twenty-four consecutive fruit harvests were carried out from September 9, 2021, to December 1, 2021, when the number, length (cm), diameter (mm), and fresh weight of the fruits (g) were evaluated. The base temperature for the fruit emission of the strawberry was calculated using the method of the smallest mean square error. Carpochron was estimated at each season and for each cultivar, obtaining a simple linear regression between the number of fruits and the accumulated thermal sum (ºC day) and the number of days after transplanting (DAT), using as base temperature the one estimated in this work. The base temperature for the appearance of consecutive fruits at the harvest point in the strawberry is 11ºC. Carpochron increases with the delay of the transplanting season and the values ranged from 81.97ºC fruit day to 144.93ºC fruit day for cultivars Merced and Fronteras.

Effect of weed management practices on weeds, nutrient depletion and yield of rice (Oryza sativa)

Field experiments were conducted during Navarai (rabi) seasons of 2011 and 2012 with ADT-36 rice (Oryza sativa L.) variety to evaluate the effect of weed management practices. Pooled data of the two years revealed that application of butachlor @ 1.5 kg a.i/ha followed by weekly cono-weeding from 21 to 42 days after transplanting (DAT) resulted in least weed count, dry-matter production and nutrient removal which resulted in the highest weed control efficiency, productive tillers/hill, grains/panicle, number of filled grains/panicle and enhanced the grain yield, which was 0.73 and 0.46 t/ha more compared to twice hand weeding and conventional method of butachlor application followed by hand weeding.