Crotalaria Juncea Research Articles

Effects of tree species and planting density on the total yield of an agroforestry system in the Brazilian Cerrado

ABSTRACT This study aimed to evaluate the effects of spacing and population density of three tree species on the primary yield of an agroforestry system in the Cerrado. The experiment was conducted in the experimental area of the State University of Goiás, São Luís de Montes Belos, Brazil. The experiment was designed to assess the effects of tree species, density, and spacing in a factorial scheme of 3 × 2 × 3, totaling 18 treatments with two tree rows each. The tree species assessed were Corymbia citriodora (seedlings), Eucalyptus cloeziana (seedlings), and an Eucalyptus urophylla clone. The trees were planted in single and triple rows (Trees planted in single and triple rows, varying density). In the first year of the experiment, maize (Zea mays) and Crotalaria juncea were sown, maize and Marandu palisadegrass (Uroclhoa brizantha cv. Marandu) in the second year, and a monoculture of Marandu palisadegrass during the third and fourth years. Due to the larger tree-covered area, the arrangement in triple rows reduced maize yield by 36% in the first year, silage yield by 40% in the second year, and pasture yield by approximately 30%. Reducing tree density is crucial to ensure the functionality of the agroforestry system.

Experimental Design to Optimize the Extraction and Properties of an Alternative Gum from Crotalaria Juncea Seeds

Experimental Design to Optimize the Extraction and Properties of an Alternative Gum from Crotalaria Juncea Seeds

Short-Term Agronomic and Economic Responses to the Adoption of Cover Crops for Corn Rotation in the Brazilian Semiarid Region

Cover crops (CCs) have demonstrated their significance in enhancing the agronomic and economic performance of corn in succession. In this paper, we assess the agronomic responses and short-term economic returns of adopting cover crops (CCs) for corn cultivation in the sandy soils of the semiarid region of northeast Brazil, with the aim of addressing the additional challenges of CCs adoption in semiarid regions. The field study was conducted in Arapiraca, Alagoas, under no-tillage conditions for two cropping seasons. A randomized complete block design was employed, comprising six CCs (sunn hemp, spectabilis, jack bean, pigeon pea, lab lab, and millet) treatments and one fallow, with 18 replications. The CCs were cultivated for 60 days before corn planting. Drip irrigation was applied during the grain-filling stage of corn growth. Over the two cropping seasons, the biomass and nutrient cycling of the CCs, corn yield, and economic returns were determined, as well as the total organic carbon (TOC) and Mehlich-1 extractable P levels in the soil after corn harvest. The grain yields with sunn hemp, spectabilis, and jack bean were superior (~10%) to that of the fallow (7.7 vs. 7.1 Mg ha−1), irrespective of the cropping season. Sunn hemp exhibited a higher biomass accumulation and ensured greater nutrient cycling, except for K, while lab lab and millet displayed a similar potential, although substantial variations were observed between seasons. Under sunn hemp and jack bean, the TOC increased by ~9%, particularly in the second season. Regarding the available P, spectabilis and jack bean exhibited the highest levels, with an increase of ~74% compared to the fallow (~31.1 vs. 17.9 mg dm−3). Spectabilis and lab lab demonstrated more promising results, both agronomically and economically. However, millet and sunn hemp have the potential to reduce costs over multiple cropping seasons. Therefore, the adoption of cover crops is a sustainable and economically viable agricultural practice. However, it is essential to acknowledge that our results do not represent rainfed conditions and require further investigation.

Green manuring with sunn hemp and the production of the sugarcane variety RB867515, in the cane-plant cycle

Several managerial and agricultural techniques have been proposed for the implantation and management of sugarcane fields, aiming at high productivity in the cane-plant cycle and small decreases in regrowth. Green manuring with sunn hemp is one of these techniques. Thus, the objective of the present study was to evaluate in a small rural property, in the edaphoclimatic environment of Mercês, Zona da Mata Mineira, the accumulation of dry matter and nutrient cycling by sunn hemp and by plants in the fallow area, on the nutritional status, the production of forage and industrializable stems using the RB867515 variety. In September, limestone and gypsum were applied based on the results of soil samples in the 0 to 20 cm and 20 to 40 cm layers. Then the soil was plowed and harrowed. At the beginning of October, shortly after the first rains, the study was installed, consisting of an area with sunn hemp sowing and another fallow area. At the beginning of February of the year following sowing, the accumulation of dry matter and nutrients in the aerial part of sunn hemp and in the plants in the fallow area was evaluated. Subsequently, sunn hemp and vegetation from the fallow area were incorporated into the soil, followed by planting RB867515. In January of the year following planting, the nutritional status of the sugarcane was evaluated in the area previously cultivated with fertilizer and in the fallow area, systematically sampling at seven points in the crop. In July, when the sugarcane was mature, the production of forage and industrializable stems was evaluated, sampling in the same places used for the evaluation of the nutritional status. The results obtained were subjected to analysis of variance and means compared by the t test at 5% probability. Crotalaria juncea cultivation resulted in greater nutrient cycling than the vegetation in the fallow area, especially for nitrogen. No difference was observed in the nutritional status of RB867515, comparing the plants from the area previously cultivated with Sunn hemp and those from the fallow area, both of which were well nourished. Green manuring with Sunn hemp increased forage production and the production of industrializable stems. In the area formerly with crotalaria juncea, the plant's aerial biomass production was 20.30 t of natural matter more than in the fallow area. For the production of industrialable stalks, green manuring increased production by 16.7 t per hectare.

Cover crops on soil quality and yield of cowpea under no-tillage in the Amazon savanna

Conservation practices such as no-tillage are necessary to maintain, and/or improve agricultural soil quality. However, straw formation and maintenance in tropical regions is a limiting factor to adopting this system. In this sense, this research aimed to study the effect of cover crops on straw formation, soil quality indicators, and cowpea yield under no-tillage in the Amazon savanna. Two experiments were carried out in consecutive years, on a Latossolo Amarelo. The treatments consisted of the straw of cover crops in a single (S) and intercrop (I) system, as follows: Urochloa brizantha (UBS), Pennisetum glaucum (PGS), Crotalaria juncea (CJS), Canavalia ensiformis (CES), Mucuna aterrima (MAS), U. brizantha and C. juncea (UBCJI), U. brizantha and C. ensiformis (UBCEI), P. glaucum and C. juncea (PGCJI), P. glaucum and C. ensiformis (PGCEI), and spontaneous vegetation (SV). Cowpea was cultivated after desiccation of the cover crops. Most of the straw favored soil particle aggregation, except for C. juncea and SV, which negatively influenced this variable. Basal soil respiration, organic carbon content, potassium, base saturation, geometric mean diameter, macroaggregates, and macroporosity at layer of 0-0.10 m were the most sensitive indicators for improving soil quality in a savanna environment. UBS, UBCJI, and UBCEI were superior to the other treatments in improving soil quality. Almost all treatments increased cowpea yield by up to 29%, except for CJS and SV.

Molecular and Biological Characterization of a Novel Tobamovirus Infecting Sunn Hemp (Crotalaria juncea) in Hawaii.

Sunn hemp (Crotalaria juncea L.) cultivar Tropic Sun plants, stunted and displaying mottle and mosaic symptoms on foliage, were observed at a seed farm in Maui County, Hawaii. Lateral flow assays indicated the presence of either tobacco mosaic virus or a serologically related virus. High-throughput sequencing results coupled with real-time PCR experiments recovered the 6,455-nucleotide genome of a virus with an organization typical of tobamoviruses. Nucleotide and amino acid sequence comparisons and phylogenetic analyses indicated that this virus was most closely related to sunn-hemp mosaic virus but represents a distinct species. Sunn-hemp mottle virus (SHMoV) is being proposed as the common name of this virus. Transmission electron microscopy of virus extracts purified from symptomatic leaves revealed rod-shaped particles approximately 320 by 22 nm in size. In inoculation studies, the experimental host range of SHMoV appeared limited to members of the plant families Fabaceae and Solanaceae. Greenhouse experiments demonstrated plant-to-plant transmission of SHMoV that increased with ambient wind speed. Seeds from SHMoV-infected Tropic Sun were collected and were either surface disinfested or directly planted. A total of 924 seedlings germinated; 2 were positive for the virus, resulting in a seed transmission rate of 0.2%. Both infected plants came from the surface disinfestation treatment, suggesting that the virus might be unaffected by the treatment.

PHYSICAL ATTRIBUTES OF SOIL AND WHEAT PRODUCTIVITY AS A FUNCTION OF COVERING PLANTS AND MECHANICAL CHISELING

Soil compaction is a main physical problem in many growing areas. The use of ground cover crops for soil decompaction has been a subject of many studies. That has promising results both used alone and in association with mechanical chiseling. The objective of this study was to evaluate the influence of cover crops associated or not with mechanical chiseling, for that, on the physical attributes of the soil, and the wheat grain yield, in an Ultisol from the Central Depression of RS. The experimental design used was randomized blocks with 3 replications in each block, in a 2 x 5 factorial scheme. Where the factor A: soil chiseling - chiseled and non-chiseled, and P fator: cover crops – pigeon pea (Cajanus cajan), Crotalaria juncea (Crotalaria juncea), pearl millet (Pennisetum americanum) and velvet bean (Mucuna aterrima). The chiseling was adjusted to a depth of 0.30m, with 5 rods spaced 0.3m apart. The determinations carried out were: macroporosity, microporosity, total soil porosity, bulk density (BD), penetration resistance (RP), and grain yield. The physical attributes of the soil showed improvements in the second year evaluated, highlighting the treatments with pearl millet and velvet bean that showed higher differences. The maximum RP of the Soil was observed at a depth of 0.25m with 1.64 Mpa. There was a significant difference in the RP of the soil between the treatments of factor A at depths of 0.15 - 0.20 and 0.25m. Mechanical chiseling provided a 15% increase in wheat grain yield compared to non-chiseling treatment, while P factor treatments did not provide any gain.

Fermentative parameters and chemical composition of mixed silages from corn-crotalaria intercropping

The objective of the study was to evaluate the influence of corn-crotalaria intercropping on the fermentative process, the organic acid profile, and the chemical composition of the silages produced. The trial was implemented in a randomized block design, in a 3 × 2 factorial scheme, with three types of intercrops [single corn (CSC), corn + Crotalaria juncea (CCJ), and corn + Crotalaria ochroleuca (CCO)] in two spatial arrangements [A1 (corn and legume sown in the same row) and A2 (corn and legume sown in alternate rows)], with six repetitions per treatment, evaluated in two agricultural years. The silages were evaluated for fermentative losses, pH, organic acids, ammonia nitrogen, chemical composition, and in vitro dry matter degradability. The least amount of gas loss was observed in the silages produced in the first year with CCJ and the CCO (11.6 g/kg dry matter for both). The lowest pH values were verified in the silage of the treatments CSC and CCJ (3.46 and 3.44, respectively) in the second year, and for ammoniacal nitrogen (NH3-N), the lowest concentrations were observed for CSC and CCO (120.7 and 138 g/kg total nitrogen, respectively). Higher levels of lactic acid and crude protein were obtained in the silage produced with CCJ, in both years of evaluation, whereas lower contents of acid detergent fiber were observed in the silage of the treatments CSC and CCO in the spatial arrangement A2. The largest coefficients of in vitro dry matter degradability were observed in the silages originated from CSC and CCO (820.6 and 798.0 g/kg dry matter, respectively). These results suggest that the intercropping of corn with C. ochroleuca sown in alternate rows increase the crude protein content without reducing the fermentative and nutritional quality of the silages. The planting of both legumes in the same row with corn negatively influenced the fermentative and nutritional characteristics of the silages, and this method is not recommended.

Increasing phosphorus rate alters microbial dynamics and soil available P in a Lixisol of Zimbabwe.

Soil phosphorus (P) deficiency is a major challenge to food security in most parts of sub-Saharan Africa, including Zimbabwe, where farmers largely depend on local organic nutrient resources as fertilizer in the production of crops. Soil microorganisms can contribute to synchronous availability of soil P to plants through regulating immobilization and mineralization cycles of soil P pools but their activity may be influenced by antecedent soil P, P fertilizer application regimes and P uptake by plants. Using soils collected from plots where Crotalaria juncea (high quality), Calliandra calothyrsus (medium quality), cattle manure (variable quality), maize stover and Pinus patula sawdust (both low quality) were applied at the rate of 4 t C ha-1 with 16 kg P ha-1 at the start of every season over 16 seasons. A pot study was conducted to evaluate the influence of increasing inorganic P fertilizer rates (26 and 36 kg P ha-1) on soil microbial dynamics, soil P pools, and maize P uptake. Results indicated that nineteen (19) fungal and forty-two (42) bacterial colonies were identified over the study period. Fungi dominated bacteria on day one, with Aspergillus niger showing a 30-98% abundance that depends on organic resource quality. Overall, microbial diversity peaked activity characterized succession on day 29, which coincided with a significant (P<0.05) increase in P availability. Increasing P rate to 26 kg P ha-1 amplified the microbial diverse peak activity under medium-high quality resources while under the control the peak emerged earlier on day 15. Mucor and Bacillus had peak abundances on day 43 and 57, respectively, across treatments regardless of P rates. Treatment and P rate had a significant (P<0.01) effect on microbial P. Bacteria were more responsive to added P than fungi. Increasing P to 36 kg P ha-1 also stimulated an earlier microbial diverse peak activity under maize stover on day 15. Addition of P alone, without supplying complementary nutrients such as N, did not have a positive effect on maize P uptake. Farmers need to co-apply medium-high quality organic resources with high fertilizer P rates to increase microbial diversity, plant available P and maize growth on sandy soils (Lixisols). Our results suggest that there is a need to reconsider existing P fertilizer recommendations, currently pegged at between 26 and 30 kg P ha-1, for maize production on sandy soils as well as develop new fertilizer formulations to intensify crop production in Zimbabwe.

Growth rates and nutrient accumulation in aerial biomass of sunn hemp juncea and spectabilis sown in spring

Crotalaria juncea and spectabilis have been widely used in green manuring, mainly due to the fact that they incorporate large amounts of N into the soil, through biological fixation of atmospheric N2, and also because they have a vigorous and branched root system, characteristics that help to recycle nutrients from the deeper layers of the soil. The present work was carried out in the municipality of Mercês, in the Mata Mineira area. Growth rates and nutrient accumulation were evaluated in the aerial part of sunn hemp and sunn hemp, grown in soil with good nutrient availability. The soil in the chosen area had good fertility, with no exchangeable aluminum in the 0 to 20 cm layer. Soon after the first spring rains, the soil was subsoiled, plowed, and harrowed, and the study was then installed, conducted in an experimental design in randomized blocks with five replications. The plots consisted of six furrows of five meters in length with 0.50 meters of spacing. Sowing was carried out in the first week of October. Evaluations of dry matter accumulation and plant height were carried out in the four central furrows of the plots, at 30; 45; 60; 75; 90 and 105 days after emergence (D.A.E.), with a sample area of 1.0 m of furrow (0.5 m2). In the biomass collected at 105 D.A.E, phenological stage of grain filling, the contents of nitrogen, phosphorus, potassium, calcium, magnesium and sulfur were determined, with the objective of quantifying the accumulation of these elements in the aerial part of sunn hemp. The results obtained in this edaphoclimatic environment led to the conclusion that sunn hemp juncea had faster vegetative development than sunn hemp spectabilis, therefore, a plant with greater soil protection potential against the impact of raindrops than sunn hemp spectabilis. Although they have very different growth rates, both for sunn hemp and sunn hemp, the highest rates of growth and dry matter accumulation in the shoots occurred in the periods from 45 to 60 D.A.E., with mean values, respectively, of 406, 7 and 140.0 kg per hectare per day. The accumulation of dry matter in the aerial part, as a function of the age of the plants, can be described by the quadratic equation, y = 0.0024 x2 + 0.5267x -11.8086 (R2= 0.9888), for sunn hemp, and y = 0.0008 x2 + 0.2003x -4.4657 (R2= 0.9928), for sunn hemp spectabilis. For the adopted production system, and in this climatic environment, sunn hemp was a better recycled/fixing plant than sunn hemp spectabilis, thus, green manuring with sunn hemp was more advantageous than with sunn hemp spectabilis.

Modification of sunnhemp (Crotalaria juncea) protein isolate by high intensity ultrasound: Impact on the molecular structure, amino acid composition and nutritional profiling

In the present study, sunnhemp protein isolate (SHPI) was prepared by alkaline extraction followed by acid precipitation method. The prepared sunnhemp protein isolate was subjected to high-intensity ultrasound treatment at 40 and 50% ultrasound amplitude for 10, 20, and 30 min. The effect of ultrasound treatment on molecular flexibility, available lysine content, antioxidant properties, and molecular weight distribution was investigated. The antioxidant activity of ultrasound treated SHPIs was found to be higher than the untreated sample. The optimum ultrasound treatment condition (50% amplitude and 20 min) had the highest molecular flexibility and antioxidant properties among all the sunnhemp protein isolates. The available lysine content of all SHPI samples decreased after ultrasound treatment. SDS-PAGE results demonstrated that there was no change in the electrophoresis patterns of ultrasound treated SHPI samples over the untreated sample, thus indicating the primary structure of the sunnhemp protein isolate was intact. Hydrophobic amino acid content was improved after ultrasound treatment in US5 (50% amplitude for 20 min) sample, thereby resulting in increase in total amino acid content than SHPI without ultrasound treatment. Biological value and essential amino acid index were also improved due to ultrasound treatment in US5 sample. Leucine and isoleucine were the first and second limiting amino acids found in SHPI according to FAO/WHO scoring patterns. Overall, it can be concluded that ultrasound treated SHPI can be a valuable source of plant-based protein with desirable nutritional characteristics at a low cost. The current findings speculated that high-intensity ultrasound treatment can be a valuable technique for the modification of sunnhemp protein isolate with its promising utilization in food supplements.

EKSPLORASI TANAMAN YANG BERPOTENSI SEBAGAI SUMBER BAHAN BAKAR NABATI DI BUKIT JIMBARAN, BALI

The continuously increasing oil prices make us realize that petroleum supplies are dwindling, therefore governments around the world are supporting the development of alternative fuels that are cheaper and more environmentally friendly, known as biodiesel. The research aims to measure the oil content of plants found on Jimbaran Hill. The method used is the exploration method by walking around Bukit Jimbaran. The oil is extracted from the seeds which have been dried by the soxhletation method using hexane as a solvent. The results showed that there were 14 species found on Jimbaran Hill. The highest oil content was obtained from mahogany (Swietenia mahagoni L.), namely 45.26%. This was followed by the kapok plant (Ceiba pentandra) with an oil content of 34.13%. While the lowest oil content was obtained from the orok-orok plant (Crotalaria juncea), namely 2.13%. Other non-food plants found in Bukit Jimbaran that have potential as biodiesel are the Ketapang plant (Terminalia catappa) and the butterfly plant (Bauhinia purpurea L.) with yields of 28.23% and 25.20% respectively.

Planting time and stand density effect on radiation interception and use efficiency of maize and sunn hemp intercropping in semi-arid South Africa

Solar radiation must be efficiently utilised to enhance dry matter accumulation and carbon sequestration capacity within dryland agroecosystems. The study evaluated the effects of sunn hemp (Crotalaria juncea L.) intercropping time and stand density on radiation interception and radiation use efficiency (RUE) in a maize-based system. Field experiments were conducted under the in-field rainwater harvesting (IRWH) technique for two consecutive growing seasons, 2019/20 and 2020/21. Radiation interception and productivity were measured and calculated for maize and sunn hemp, sole and intercrops. The intercrops were identified by the sunn hemp intercropping times [simultaneous with maize planting (P1), at V15 maize growth stage (P2), at R1 maize growth stage (P3)] and stand densities [16 plants m–2 (D1-low), 32 plants m–2 (D2-medium), 48 plants m–2 (D3-high)]. Total radiation interception was calculated using a row-crop radiation transmission (RCRT) model from strip width of component crops, extinction coefficient (k), plant height, and leaf area index (LAI) measurements taken throughout the growing season. The results showed that the LAI of sunn hemp was high when intercrop was planted simultaneous with maize planting and at 48 plants m–2. The overall k for the sole sunn hemp (SSH) cropping system was 0.37. The correlations (r2) between the modelled and measured fractions of photosynthetic active radiation (PAR) in simultaneous maize planting, V15 maize growth stage, and R1 maize growth stage intercropping treatments were 0.87, 0.97 and 0.93, respectively. Simultaneous planting of sunn hemp intercrop with maize captured the most growing season PAR of 798.70 MJ m–2 and had the highest RUE of 1.42 g MJ−1. These results suggest that intercropped sunn hemp planted simultaneously with maize would help to increase production through the more efficient use of solar radiation. Optimising planting time and density can help plan the planting time to increase radiation utilisation in maize/sunn hemp intercropping systems.

Different nanocellulose morphologies (cellulose nanofibers, nanocrystals and nanospheres) extracted from Sunn hemp (Crotalaria Juncea)

Nanocellulose of different morphologies was extracted from Sunn Hemp (Crotalaria Juncea) using acid hydrolysis. The work focused on two objectives: first, to valorize the Sunn Hemp fibers for nanocellulose (NC) production, and second, to study the effects of acid concentration on different morphologies of NC and their properties. The study extracted nanocellulose at five different concentrations of H2SO4: 16 %, 32 %, 48 %, 64 %, and 72 %. Obtained nanocellulose was characterized by Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). AFM and FE-SEM confirmed the production of three different morphologies of nanocellulose. The NC-32 had a web-like structure typically observed for cellulose nanofibrils (CNF), whereas NC-48 and NC-64 were observed as cellulose nanocrystals (CNC) with rod-like and needle-like shapes, respectively, and NC-72 displayed spherical particles termed cellulose nanospheres (CNS). The total crystallinity index of NC was calculated using FTIR, and a similar trend of crystallinity was also observed from XRD analysis. NC-32 was obtained with the highest yield of 94.83 %, followed by 91.40 % and 81.70 % for NC-48 and NC-64, respectively, whereas NC-72 yielded the lowest yield of 12.03 %. NC-72 had the highest thermal stability among other NC morphologies.

Decomposition and nutrient release of green manure biomass in a passion fruit orchard in the brazilian semiarid region.

Green manure decomposition and nutrient recycling improve soil quality and productivity of different crops, but information on irrigated fruit orchards in the Brazilian semi-arid region is still scarce. Decomposition and nitrogen, phosphate, and potassium release from the cut biomass of three green manure legumes (sunn hemp, pigeon pea and jack bean) placed in litterbags, and spontaneous vegetation grown for 90 days in the rows of a passion fruit orchard were followed for 150 days. Biomasses decreased exponentially, reaching 12 (sunn hemp) to 25% (jack beans and spontaneous vegetation) after 150 days. K was rapidly released (< 21 and 4% of the original content remaining after 7 and 150 days, respectively), contrasting with more than half of the P and one third of the N remaining after 150 days. The amounts released were more influenced by the amounts of biomass produced (sunn hemp, 1583); (Jack bean 5152 kg ha-1); (Pigeon pea 822 kg ha-1); (Spontaneous plants 3175 kg ha-1); (spontaneous legumes 744 kg ha-1) than by variation in decomposition proportions among species. N release represented a liquid input to the soil, since more than 80% of the green manure and spontaneous vegetation contents came from N2-symbiotic fixation. Therefore, green manure is an effective technique to incorporate N and recycle K and P in irrigated orchards in the Brazilian semi-arid region.

Implementation and Use of Green Manures for Weed Suppression in Sequential Maize Cropping

The ground cover produced by green manures has a direct influence on weed suppression and, in addition, the biomass produced by these same plants influences crop growth. This study was carried out to compare the effect of green manure species on the incidence of weeds, in sequence, in order to evaluate the effects of the use of green manure cover on the productive characteristics of maize plants. A completely randomised experimental design was used, with 11 treatments and 4 replications. The treatments were cover crops Canavalia ensiformis (T1), Cajanus cajan (T2), Stizolobium pruriens (T3), Crotalaria juncea (T4), Phaseolus vulgaris (T5), Stizolobium trigre (T6), Stizolobium aterrimum (T7), Crotalaria retusa (T8), Crotalaria breviflora (T9), Dolichos lablab (T10), and conventional system (T11). Ninety days after sowing, the green manures were cut, and 30 days after the green manures were cut, the hybrid maize Crop Top 520 was sown. The variables evaluated in relation to the planting of green manures were the green and dry biomass of green manures, alongside the green biomass of weeds and suppression of weeds. Concerning maize plants, the variables evaluated were plant height at 60 DAS, stalk diameter at 60 DAS, number of grain rows per ear, number of grains per grain row, and yield. The averages were subsequently analyzed using Tukey’s test at 95% significance level. The use of green manure significantly reduces the green mass of weeds up to 90 days due to lack of access to light of the weeds, which reduces their appearance and growth. Stizolobium aterrimum showed the best results both as a dry mass producer and weed suppressor and also as a yield enhancer in maize crops.

Sunn hemp hessian cloth reinforced thermoplastic composites: Effects of chemical treatment and gamma-ray irradiation

Untreated and alkali-treated Sunn hemp hessian cloth-reinforced high-density polyethylene (HDPE) composites were prepared by the compression molding method. The fabricated composites contained 40, 45, 50, 55, 60, and 65wt% fiber contents and were optimized. 55wt% fiber contents reinforced composites showed better mechanical properties. This composite was alkali treated and irradiated under gamma-ray at doses 2.5‒7.5 kGy at the rate of 6 kGy/h. The X-ray diffraction (XRD) result indicates that the crystallinity of the alkali-treated Sunn hemp-reinforced HDPE composites shows a higher value than those of untreated and irradiated composites. Better adhesion between fiber and matrix was observed from surface micrographs. Fourier-transform infrared (FTIR) spectroscopy reveals cross-linking between fiber and matrix. The water intake properties of irradiated composite show more hydrophobic nature than that of untreated and alkali-treated composites. The tensile strength of the gamma-ray irradiated composites are 20% and 33% greater than that of untreated and alkali-treated composites. Similar results are found for Young’s modulus. At a certain dose of 5 kGy, the irradiated composites show improved thermal, mechanical, and structural properties than untreated and alkali-treated composites.

Long-term effects of cover crops on physical-hydric properties of compacted soil

The screening of cover crops is essential for improving the physical-hydric properties of compacted soils. This study aimed to evaluate the effects of mixed or single cover crops on improving the physical-hydric properties of compacted Oxisol. Species with tap-rooted and fibrous-rooted rooting patterns were evaluated. The species included pearl millet (Pennisetum americanum), pigeon pea (Cajanus cajan), sunn hemp (Crotalaria spectabilis), velvet bean (Mucuna pruriens), white oat (Avena sativa), black oat (Avena strigosa), rye (Secale cereale), black oat + forage turnip (Raphanus sativus), black oat + white lupin (Lupinus albus L.), and black oat + group pea (Pisum arvense L.). Mixing cover crops did not improve the physical properties of the soil. The tap-rooted pigeon pea effectively reduces bulk density and increases porosity and saturated hydraulic conductivity (Ksat) in compact soils. The selection of cover crops with characteristics that improve soil physical-hydric properties is crucial for compacted areas.

Fitness and population build-up of a native predatory bug, &lt;i&gt;Nesidiocoris tenuis&lt;/i&gt;, on tomato pinworm, &lt;i&gt;Phthorimaea absoluta&lt;/i&gt;, in a modified crop habitat

The tomato pinworm damage, population build-up, the damage and longevity of native predatory bug, Nesidiocoris tenuis in sole crop and diversified crop of tomato (pumpkin and sunn hemp as border crop + a patch of sunn hemp as hedgerow) were studied. Infestation of tomato pinworm, Phthorimaea absoluta was found to be the highest in the sole crop (5.60 live mines/plant at 20 DAP) compared to the diversified crop of tomato (1.50 live mines per plant). No significant difference in the number of necrotic rings per plant was observed between the sole crop and the diversified crop of tomatoes. The development period of nymphs of N. tenuis was the shortest in tomatoes followed by pumpkin. The results of the present study confirmed the role of crop diversification in supporting the population build-up of predatory bug N. tenuis in effecting the biological control of pinworm in tomato crop.

Strategies for reducing the impact of clubroot on broccoli cultivation in tropical mountain regions

Brassica spp. production can be negatively affected by clubroot, which is caused by the protozoan Plasmodiophora brassicae Woronin. Most of the information on clubroot control is derived from studies in temperate regions. Here, management strategies were evaluated to reduce broccoli (Brassica oleracea L. var. italica Plenck) crop losses owing to clubroot in tropical mountain regions. The first experiment revealed the effect of green manure from coriander (Coriandrum sativum L.), sunn hemp (Crotalaria juncea L.), sweet corn (Zea mays L.), and spontaneous vegetation (control) associated with broccoli seedlings of 4 different sizes. In the second experiment, the effect of soil amendments (limestone and steel slag) in conjunction with poultry litter (fresh or composted for 45 days) and without poultry litter (control), was assessed. Both field experiments sought to evaluate the disease intensity, plant development (root growth, biomass, and nutrient accumulation), and yield. Sunn hemp and coriander biomass resulted in higher healthy root volumes and dry weights of broccoli. However, such benefits were not derived from corn treatment. Compared to smaller seedlings (10 mL cell and 20 days of age, and 16 mL cell and 24 days of age), the use of larger seedlings (35 mL cell and 28 days of age, and 50 mL cell and 32 days of age) resulted in lower intensity of clubroot and increased the average yield by 143% in summer crops. Steel slag, like limestone, corrected soil acidity and resulted in plant growth; however, clubroot intensity was not significantly affected. Fresh and composted poultry litter increased the percentage of diseased roots compared with the control; however, broccoli yield was not affected by the treatments. Using green manure (sunn hemp or coriander) and well-developed seedlings is recommended as a strategy to reduce losses induced by clubroot during broccoli cultivation.