Spanish Journal of Agricultural Research
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X-ray computerized tomography for characterization of pick-up destruction and pick-up parameter optimization of tomato root lumps
No full textThis study was aimed to find the causes of pick-up destruction of tomato root lumps using X-ray microcomputed tomography, and to identify the pick-up parameters of low root lump destruction. The roots and pores were reconstructed three-dimensionally and analyzed quantitatively. It was found that the roots acted winding and wraping the root lumps and thus preventing the substrate from loosening. The major causes for root lump destruction were pore aggregation and crack formation. The apex and circumference of pick-up pins were areas where root lumps were prone to fracture and breakage, respectively. Lacunarities of these two areas were used as index to quantify the root lump destruction. Single-factor analysis of variance was conducted with pick-up pin shape (circular, flat), diameter (2, 2.5, 3 mm) and initial pick-up angle (18°, 21°, 24°) as the test factors and then the effects of these three factors on root lump destruction were studied. It was found the lacunarities at the fracturable area and breakable area both increased with the rise of pick-up pin diameter and decreased with the rise of initial pick-up angle. At the same pick-up conditions, lacunarities with the use of flat pins always surpassed that of circular pins. When circular pick-up pins with diameter of 2 mm and initial pick-up angle of 24° were used, the destruction rate of root lumps (6.63%) was smaller than under other test conditions. The optimized pick-up parameters can be used to guide gripper design and to improve the working performance of automatic transplanters
Isolation and evaluation of endophytic bacteria from root nodules of Glycine max L. (Merr.) and their potential use as biofertilizers
No full textAim of study: To isolate and characterize endophytic bacteria inhabiting soybean root nodules collected from two tropical cropping systems in Mexico, and to evaluate the bacterial effects in soybean plants under controlled conditions.Area of study: The study was carried out at two locations (San Antonio Cayal and Nuevo Progreso municipalities) of Campeche State, Mexico.Material and methods: Two experimental stages were performed: 1) isolation, morphological and biochemical characterization, and molecular identification of endophytic bacteria from root-nodules of four soybean varieties grown at field conditions; and 2) evaluation of the effects of endophytic isolates on soybean growth and nodule development, and the effects of bacterial co-inoculation on soybean plants, under controlled conditions.Main results: Twenty-three endophytic bacteria were isolated from root nodules, and identified as Agrobacterium, Bradyrhizobium, Rhizobium, Ensifer, Massilia, Chryseobacterium, Enterobacter, Microbacterium, Serratia, and Xanthomonas. Under controlled conditions, Rhizobium sp. CPO4.13C or Agrobacterium tumefaciens CPO4.15C significantly increased the plant height (46% and 41%, respectively), whereas Bradyrhizobium sp. CPO4.24C promoted the nodule formation (36 nodules/plant). The co-inoculation of B. japonicum USDA110 and Bradyrhizobium sp. CPO4.24C enhanced plant growth, height (33.87 cm), root nodulation (69 nodules/plant) and N-fixation (3.10 µmol C2H4 h-1 plant-1) in comparison to the negative control.Research highlights: Results suggest that the native Bradyrhizobium sp. CPO4.24C may be used as a biofertilizer directed to developing sustainable soybean cropping at tropical regions
Harvest chronological planning using a method based on satellite-derived vegetation indices and artificial neural networks
No full textAim of study: Wheat appropriate harvest date (WAHD) is an important factor in farm monitoring and harvest campaign schedule. Satellite remote sensing provides the possibility of continuous monitoring of large areas. In this study, we aimed to investigate the strength of vegetation indices (VIs) derived from Landsat-8 for generating the harvest schedule regional (HSR) map using Artificial Neural Network (ANN), a robust prediction tool in the agriculture sector.Area of study: Qorveh plain, Iran.Material and methods: During 2015 and 2016, a total of 100 plots was selected. WAHD was determined by sampling of plots and specifying wheat maximum yield for each plot. The strength of eight Landsat-8 derived spectral VIs (NDVI, SAVI, GreenNDVI, NDWI, EVI, EVI2, CVI and CIgreen) was investigated during wheat growth stages using correlation coefficients between these VIs and observed WAHD. The derived VIs from the required images were used as inputs of ANNs and WAHD was considered as output. Several ANN models were designed by combining various VIs data.Main results: The temporal stage in agreement with dough development stage had the highest correlation with WAHD. The optimum model for predicting WAHD was a Multi-Layer Perceptron model including one hidden layer with ten neurons in it when the inputs were NDVI, NDWI, and EVI2. To evaluate the difference between measured and predicted values of ANNs, MAE, RMSE, and R2 were calculated. For the 3-10-1 topology, the value of R2 was estimated 0.925. A HSR map was generated with RMSE of 0.86 days.Research highlights: Integrated satellite-derived VIs and ANNs is a novel and remarkable methodology to predict WAHD, optimize harvest campaign scheduling and farm management
Use of root pruning, paclobutrazol, and prohexadione-Ca combination strategies to control growth and improve productivity on pear trees
No full textGrowth control in pear orchards is essential, not just to reduce competition between vegetative and reproductive sinks, but also to improve return bloom, yield and fruit quality. The goal to optimize growth control, return bloom and yield must be pursued with the integration or combination of several strategies. Aim of this study was to assess the use of root pruning, paclobutrazol, and prohexadione-Ca (ProCa) either alone or in combination, to control growth and improve productivity on pear trees. The experiment was conducted during three years in a 10 year-old pear orchard with ‘Blanquilla’ as the scion cultivar. All of the different strategies that were assessed improved growth control in pear trees, with different grade depending on the strategy. Control trees had about 50% of the shoots shorter than 60 cm, root pruning 63%, ProCa 70%, paclobutrazol and root pruning plus ProCa 83%, and root pruning plus paclobutrazol 86%. In addition, yield, fruit weight and return bloom were more affected by applications of ProCa than paclobutrazol. Use of paclobutrazol either alone or in combination with root pruning seems to be most suitable for situations of high-vigor cultivars. The fact that use of paclobutrazol may be challenged again in the future, leave combinations of root pruning plus ProCa as the best shot for vigorous cultivars. In other situations of medium-low vigor, ProCa alone would be the best strategy
Effects of Cry toxins on non-target soil bacteria during a 2-year follow up study
No full textGenetically modified (GM) plants with insecticidal Bacillus thuringiensis (Bt) genes are widely accepted but their commercial utilization highlights the biosafety issues worldwide. The risk assessment of GM crops demonstrates their impact on the ecosystem as well as non-target organisms (NTOs). Among the NTOs, plant growth promoting rhizobacteria (PGPR) demand more critical experimental studies as they play a significant role in plant growth. A comparative study of Bt with non-Bt cotton rhizosphere was conducted, on selected bacterial strains. During the course of the study, biochemical characterization, auxin biosynthesis and molecular characterization was done to assess the effect of Bt toxins (Cry1Ac and Cry2A) on non-target PGPR strains. A significant decrease (p<0.05) in phosphatase activity was recorded in some of the experimental bacterial strains as compared to those of control strains. However, no significant differences (p>0.05) were observed in other parameters like bacterial population, colony morphologies as well as biochemical activities. Thus, our study demonstrates the safe plantation of Bt crops with respect to soil bacteria
Development of a riding-type fully automatic transplanter for vegetable plug seedlings
No full text Aim of study: The aim of this study was to develop a riding-type fully automatic vegetable seedling transplanter enabling continuous transplanting work on 2 rows simultaneously with plug seedlings fed automatically.Material and methods: In design, the transplanter consists of a 4-wheel drive system, a seedling pick-up mechanism, a seedling feeding mechanism, a rotation discharging mechanism, a 2-row planting mechanisms, and a multi-source control unit. The 4-wheel drive system is a riding type well adapting to slops. The seedling pick-up mechanism could extract several seedlings at a time from the tray cells conveyed by the feeding mechanism, and then transfer them to the rotation discharging mechanism where they would be released into the 2-row planting mechanisms. The multi-source control unit was constructed to carry out the flexible automation of seedling transplanting. Being the first prototype, the performance tests under actual production conditions were conducted on a vegetable base.Main results: The testing results showed that the developed fully automatic transplanter could well grasp seedlings from the trays, transfer them, discharge them, and plant them into the ground. The success ratio in picking up seedlings and the qualified percent in planting seedlings were all up to 90%, and the coefficient of variation of plant spacing was less than 5% at the working speed of 60 plants row-1 min-1.Research highlights: The overall planting effects could well meet the requirements of agronomy cultivation, and the quality of automatic transplanting was satisfactor
Effect of artificial seawater and feeding frequency on the larval culture of freshwater Amazonian ornamental fish banded cichlid Heros severus (Heckel, 1840) and angelfish Pterophyllum scalare (Schultze, 1823)
No full textThe present study aimed to evaluate the effect of salinity and feeding frequency on zootechnical performance of Pterophyllum scalare and Heros severus five-day-old post-larvae. Two experiments were performed in a completely randomized experimental design in a 5 × 2 factorial scheme, with 5 different NaCl concentrations (0, 2, 4, 6 and 8 g/L) and 2 feeding frequencies (2 and 4 times a day). P. scalare showed the highest survival rates (p<0.05) when subjected to salinities of 0, 2 and 4 g/L (97.50–96.25%), and higher values (p<0.05) for standard length (13.22 mm), weight (64.64 mg) and specific growth rate (15.41% per day) when fed 4 times a day. For this species, feeding frequency did not influence survival rates. H. severus, in turn, showed higher survival rates in water without the addition of salt (96.25%) and the highest standard length in salinity of 2 g/L (11.80 mm). H. severus fed 4 times a day and presented the highest values (p<0.05) for most of the growth variables (weight: 57.28 mg, specific growth rate: 18.30% per day). The results of the present study suggest that banded cichlid post-larvae showed higher survival rates in water without salt addition, however, the best growth of this species occurred at the salinity of 2 g/L. In contrast, angelfish post-larvae can be cultivated in salinities of up to 4 g/LNaCl. A feeding frequency of 4 times per day is recommended for both species
Modelling of the leaf area for various pear cultivars using neuro computing approaches
No full textAim of study: Leaf area (LA) is an important variable for many stages of plant growth and development such as light interception, water and nutrient use, photosynthetic efficiency, respiration, and yield potential. This study aimed to determine the easiest, most accurate and most reliable LA estimation model for the pear using linear measurements of leaf geometry and comparing their performance with artificial neural networks (ANN).Area of study: Samsun, Turkey. Material and methods: Different numbers of leaves were collected from 12 pear cultivars to measure leaf length (L), and width (W) as well as LA. The multiple linear regression (MLR) was used to predict the LA by using L and W. Different ANN models comprising different number of neuron were trained and used to predict LA.Main results: The general linear regression LA estimation model was found to be LA = -0.433 + 0.715LW (R2 = 0.987). In each pear cultivar, ANN models were found to be more accurate in terms of both the training and testing phase than MLR models.Research highlights: In the prediction of LA for different pear cultivars, ANN can thus be used in addition to MLR, as effective tools to circumvent difficulties met in the direct measurement of LA in the laboratory
Effects of white shrimp (Litopenaeus vannamei) and tilapia nilotica (Oreochromis niloticus var. Spring) in monoculture and co-culture systems on water quality variables and production in brackish low-salinity water earthen ponds during rainy and dry seasons
No full textAim of study: To determine the effects of white shrimp (Litopenaeus vannamei) and tilapia nilotica (Oreochromis niloticus var. Spring) in monoculture and co-culture on water quality variables and production in earthen ponds during dry and rainy seasons.Area of study: A shrimp farm (total area 20 ha) at Chiripa, San Blas Nayarit, Northwest coast of Mexico (21° 37' 34.53 " N; 105° 18' 16.31" W).Material and methods: Two production cycles were performed in a completely randomized design consisting of two treatments and three replications each during rainy season (September-December) and dry season (February-May). Shrimp was the main crop and tilapia the secondary species.Main results: White shrimp (10 org/m2) can be co-cultured with Nile tilapia at a stocking high density (4 org/m2), leading to improved water quality and better utilization of nutrients in dry season than in rainy season. However, the shrimp’ highest weight was recorded in the tilapia-shrimp co-culture ponds during rainy season due to higher water temperature and better quality of live food. The mean individual weight, biomass and survival of the shrimp, in co-culture ponds were greater than those of the shrimp monoculture, in the two seasons studied.Research highlights: There was a trend towards greater concentration of nutrients in the water of the monoculture ponds and, lower dissolved oxygen and higher BOD5 in co-culture ponds in the dry season than in the rainy season
Morphological and physiological responses and some WRKY genes expression in cherry rootstocks under salt stress
No full textAim of study: To determine morphological, physiological and molecular responses of cherry rootstocks under salt stress condition.Area of study: Konya, Turkey.Material and methods: A pot trial was conducted to assess moderate salt stress (35 mM NaCl) effects on cherry rootstocks (CAB-6P, MaxMa 14 and Mazzard). We have evaluated many morphological and physiological parameters and analyzed WRKY genes (WRKY25, WRKY33 and WRKY38) under salinity conditions.Main results: All rootstocks survived with slight leaf burn under salinity conditions and the plant growth and physiological parameters, except membrane permeability, decreased in all rootstocks. The membrane permeability increased with salinity and the lowest increment in the membrane permeability (12.17%) was in MaxMa 14, while CAB-6P and Mazzard showed higher levels of increases reaching 46.81 and 56.42%, respectively. Furthermore, the expression of WRKY25, WRKY33 and WRKY38 genes was significantly increased by salinity. The rankings of the WRKY genes expression levels among control rootstocks were: MaxMa 14 < CAB-6P < Mazzard.Research highlights: CAB-6P, MaxMa 14 and Mazzard rootstocks were found relative salt-tolerant at the moderate salinity levels and there is a cross-talk between physiological and molecular responses. Mazzard had higher tolerance to salinity shown in molecular responses. The study possesses importance for plant physiologists and cherry growers as it showed how cherry rootstocks respond to salt stress