for aboveground extract ofcanola plants (Table 1), while the lowest values of seedlings emerged in soil were observed for root system residues. Effects of root canolaresidues were observed by Yasumoto et al. (2011) in sunflower plants. These authors identified the presence of some volatile substances and other soluble in water, in roots. These substances are able to self-inhibit canola seed germination. According the authors, these substances are released from plants during development stage or even during initial decomposition, after harvesting. Jafariehyazdi & Javidfar (2011) demonstrated reducing on sunflower seed germination and root and hypocolyl length, in aqueous extract ofcanolaand other Brassica species, as B. rapa e B. juncea. These effects were more pronounced in higher concentrations of the extracts, manly those obtained from full flowering plants. A dose-dependent inhibition of B. nigra extract was related by Al-Sherif et al. (2013) in wheat seeds. Higher glucosinolates concentration was found in aboveground parts of a mixture of Brassica juncea and Sinapsis alba (Norsworthy et al., 2005). This result could explain the higher effect of aboveground extract under seed germination in laboratory conditions, where seeds were in direct contact with the extract. In this case, a joint effect of the compounds glucosinolates and phenolic compounds is expected. Whereas the glucosinolates and the products
Al-organic complexes (Miyazawa et al., 2000). According to Miyazawa et al. (1993) and Franchini et al. (2001) residuesof cash crops have on average only one third of the neutralizing capacity of cover crops. This lower capacity to neutralize the soil acidity ofresiduesof crops such as soybean, wheatand maize is related to the reduction in soluble nutrient and C contents with the advancing physiological plant age (Franchini et al., 2004). However, it is noteworthy that the plants in this study were sampled to determine soluble cations at flowering, which is a stage of high metabolic activity. Most likely, this factor contributed to the high contents of water-soluble basic reaction nutrients observed in peanut. It is however unclear whether these nutrients were complexed to the plant or released into the soil during the crop cycle; further studies on the dynamics of these compounds within the plant are required.
Another possibility is the use of bacterial inoculants, which promote plant growthand increase productivity. Brazil has a tradition of research in biological N fixation (BNF) using Azospirillum spp. in graminaceous plants. However, until recently, no commercial inoculants with this bacterial strain were available in Brazil (Hungria, 2011). The observed effects after inoculation were increased uptake of water and minerals and increased tolerance to stress such as drought and salinity, which increased plant robustness andyield (Bashan et al., 2004). Barassi et al. (2008) reported an improvement in the photosynthetic parametersof leaves, including chlorophyll content and stomatal conductance, increased proline content in aerial parts and roots, improvement in water potential, increased water content of the apoplast, increased elasticity of the cellular wall, and greater plant biomass.
In view of the high uniformity, a series of lines were planted in an experimental field in the cold growing season of 2004, in Internal Preliminary tests for grain yield, which included three whiteoat cultivars regarded as controls (standard genotypes recommended for this purpose by the Brazilian Oat Research Commission). In this test, the line was called CGF 03-005. In the cold growing season of 2005, CGF 03-005 was tested again in the Internal Preliminary tests for grain yieldand for other desirable agronomic traits. The Internal Preliminary tests in 2004 and 2005 were evaluated in a randomized complete block design, with four replications, at a density of 300 viable plants per square meter. Each replication consisted of one plot with five 5- m rows spaced 0.20 m apart, and the yield was as- sessed from the production of the three central rows, i.e., of an evaluation area of 3.0 m 2 . In the cold growing season
importance of nitrogen fertilization was reported by Broadley et al. (2000) who noted a negative relation between plants under normal conditions of available nitrogen and deficient plants, where a reduction in leaf weight occurred under conditions limiting this nutrient. The results obtained, however, are still a level lower than the recommended rates of nitrogen utilized in the United States, which according to Thompson & Doerge (1996a, b), vary from 224.0 to 370.0 kg ha -1 , probably due to the cultivar,
average of 20 mg L -1 in the soil solution (ERNANI et al., 2007). The potassium is the macronutrient that is most extracted by carrot plant, and may interpose with the absorption of other nutrients such as nitrogen, calcium, sulfur, phosphorus and magnesium (BISSANI et al., 2008). Potassium fertilization is usually carried out under topdressing method as described by Raij et al. (1997), and should be divided according to the efficient use of the nutrient by plants and avoiding wounding the leaves due to their salt content. Büll et al. (2001) verified that the elevation of potassium levels at the planting-soil provided an increase in the production of bulbs on garlic crop, and this was not influenced by changing potassium levels fertilization on topdressing.
Results of this research show technological implications. Firstly, the crown diameter itself is not an efficient quality descriptor of strawberry transplants. It should be used together with other variables such as number of leaves or size of the transplant. Secondly, the environmental conditions at the time runner tips are collected should be considered. This imposes additional practical difficulties for nurseries in the commercial production of strawberry plug transplants. They search for extending the production time period of transplant production by collecting runner tips early in summer and rooting them in big tray cells or containers. In face of the present results, when this is accomplished, the inhibitory effect of high temperatures on flowering should be considered. Conditioning by artificial chilling, as in Unites States (Bish et al., 1997, 2002; Durner et al., 2002) and Europe (Faby, 1997; Lieten, 2000) for glasshouse forcing in winter, may be an alternative, but further research is needed to evaluate local conditions.
Abstract – The objective of this work was to evaluate methods of intercropping corn and Panicum spp. forages and their effects on corn yieldand forage development. Two experiments with Panicum spp. were conducted, one with 'Tanzania' and other with 'Massai' in the municipality of Piracicaba, in the state of São Paulo, Brazil, in the 2012/2013 growing season. In both experiments, the treatments were: broadcast seeding of Panicum spp. at the same time of corn sowing; corn with Panicum spp. between rows; Panicum spp. sown with fertilizer; Panicum spp. sown between corn rows after corn establishment; broadcast seeding of Panicum spp. after corn establishment; and sole corn sowing. For corn, leaf nitrogen content, ear height, and grain yield were evaluated. For Panicum spp. cultivars, height, dry mass, tiller density, and leaf:stem ratio were evaluated. The intercropping establishment methods used do not affect corn growth, grain yield, and N leaf content. The seeding of both cultivars of Panicum spp. when corn plants had four expanded leaves reduces forage dry mass production and increases the leaf:stem ratio. The Panicum spp. broadcast method, performed after corn was established, does not allow appropriate establishment, with few plants in the area.
Soil chemical characteristics were evaluated at 6 (April, 2007), 12 (October, 2007) and 18 months (April, 2008) after the application of liming materials, at 0.00–0.05, 0.05–0.10, 0.10–0.20, 0.20–0.40, and 0.40–0.60 m soil depths. Six simple samples were taken at random, in order to form a composite sample, in the useful area of plots, in between rows of the previous crop. The samples were dried, sieved (2 mm sieves) and analyzed according to Raij et al. (2001) and Korndörfer et al. (2004).
The adoption of new technologies (agronomy, breeding, and mechanization) requires updated information on root distribution, but there are methodological difficulties associated with nondestructive root sampling and imaging (Muñoz-Romero et al. 2010). A minirhizotron miniature video camera technique was developed to characterize root dynamics (Box Junior 1993), but it was seldom used in sugarcane. Soil core sampling combined with root intersection analysis was used to analyze root distribution at three sugarcane growth stages (Azevedo et al. 2011) and during the crop cycle (Laclau and Laclau 2009). Azevedo et al. (2011) and Laclau and Laclau (2009) found a strong genetic control of root growth in deep soil layers, and that it was necessary to account for the development of sugarcane roots in deep soil layers to improve the understanding of net primary production. https://doi.org/10.1590/1678-4499.20190407
Maximum stem length was reached faster for 150DD treatment as a natural plant response for light competition. However, the effect of closer spacing on increasing stem height at temperate sites may dif- fer at tropical sites as pointed out by Zaag et al. (1990). On the other hand, final stem size for 200SD treat- ment was reduced in favor of stem thickness and load capacity without changing much partitioning coefficients for this plant part (Fig. 3A and 3B). This was most probably due to the increased production of apical branches and leaves observed for this high N level. Thus, besides being cultivar and site depen- dent, maximum stem length is more drastically af- fected by soil nutrient availability (N level) than by competition for light (plant density).
by Rosolem et al. (2002) for Pennisetum glaucum (0.73 MPa), Sorghum bicolor (0.30 MPa), Crotalaria juncea (0.97 MPa) and Helianthus annuus (0.86 MPa), andby Foloni et al. (2006) for Glycine max (1.22 MPa) and Dolichos lablab (1.46 MPa), and close to the values found by Sarto et al. (2018) for Carthamus tinctorius L. (1.77 MPa and 1.55 MPa, respectively for the IMA-2106 and IMA-4904 genotypes). Thus, the characterization of soil mechanical impedance, in which 50 % of the root growth is impaired (Q 1/2 index), is a way of measuring the sensitivity of a given species to compaction. However, the quantity of roots penetrating a certain volume of compacted soil defines the potential of a plant to form biopores and improve the soil physical conditions for subsequent crops (Silva et al. 2006). Dexter (1987), in a study on Pisum sativum, and Materechera et al. (1992), in a study on Lupinus angustifolius and Vicia faba (which are also drought-tolerant leguminous plants from the Fabaceae family), reported that these plants showed the largest tolerance to high compaction (4.2 MPa), among more than 20 studied species.
In this example, we suppose that the epitopes in BMP-2 are unknown and we used our method for evaluat- ing all surface residuesof a monomer. The analysis resulted in 29 residues predicted as hot spots, from a total of 101 sur- face residues. After that, we filtered the set of predicted res- idues using a sequential window of five adjacent residues so that a positive prediction was kept only if among its two left and two right sequential neighbors at least two of them were also positive predictions. This kind of post-processing is quite common for interface region prediction methods (Yuan et al., 2004; Res et al., 2005). A total of 13 positive predictions survived this filtering process, 5 of them corre- sponding to residues in the first epitope (true positives). There were also 14 false negatives, 5 false positives and 83 true negatives, resulting in an F-Measure of 34.5% corre- sponding to a Precision of 50% and a Recall of 26.3%. If only the strongest epitope is considered, it results in an F-Measure of 43.5%, corresponding to a Precision of 50% and a Recall of 38.5%. Even though these levels of cover- age (Recall) are quite low, they are typical for interface re- gion prediction methods (Bradford et al., 2006; Neuvirth et al., 2004) and, at a level of Precision of 50%, are considered as satisfactory for locating interface regions (Bradford and Westhead, 2005). Figure 3 summarizes these predictions. While no residue in the second epitope was found, all false positive predictions are close to those in the true positive in the first epitope.
A higher exchangeable Ca contents in the soil (Figure 1 and Table 2) was related to Ca contents in plant residues only in the case of oilseed radish. Also, for Mg, there was no relationship between the residuesand soil contents. Hence, a cover crop with high Ca or Mg contents would not always result in higher soil Ca and/or Mg contents. As a result of an intensified K leaching from the straw into the soil, a higher K content in the uppermost soil layer would be expected. This has been previously observed (Rosolem et al., 2003, 2005). The same was true for black oatand oilseed radisch that showed higher K tissue contents. A negative relation between N rates and K content in the 0 – 5 cm soil layer (Figure 2) could be understood considering that nitrification was favored by N applications andby pH values above 5.5, supplying NO 3
The adequacy of agronomic practices plays a key role in the development of integrated systems. The hypothesis of this work is that the oat grain yield is not modified by the nitrogen in positions between eucalyptus tracks in alley cropping agroforestry system (ACS), thus the nitrogen does not improve the oatyield in ACS. The objective of this study was to determine how the phytomass accumulation, yield compounds andyieldofoat (Avena sativa L. cv. IPR 126) are influenced by nitrogen levels (12 and 80 kg N ha -1 ), in five equidistant positions between two adjacent eucalyptus (Eucalyptus dunnii Maiden) double line tracks [20 m (4 m x 3 m)] in ACS and traditional no till agriculture in subtropical Brazil. The experiment was carried out in a split-block randomized block design with four replicates. At the end ofoat cycle, there was compensation of the lower number of spikelets per panicle by the greater number of grains per spikelet, as well as higher harvest indexes where less phytomass was accumulated, in environments with high interspecific interaction. The nitrogen levels increase the oatyield differently at positions relative to the trees in the ACS.
higher PW actually results in higher PGW (Fig. 2); that is, selected for one of these traits there are gains for the other. The cluster analysis by UPGMA method formed three distinct groups. The group 1 was composed by black oat populations from Condor, Ajuricaba, Taquaruçu do Sul, Tenente Portela, Palmeira das Missões 2, Alto Alegre, Palmeira das Missões 1, Campos Borges and Santa Rosa; group 2 by populations from Boa Vista das Missões, Espumoso, Chapada and Planalto; and population from Salvador das Missões composed a single group. The cophenetic correlation coefficient was r = 0.728, p < 0.05, showing a good fit between cophenetic and original matrix distances (Fig. 3). Although the black oat populations were collected in a relatively restricted area of the state, with relatively similar climate conditions we found variability between populations. The groups highlighted in the map are useful and show the pattern of variability between black oat populations in the northwestern of the Rio Grande do Sul State (Fig. 1). The population that formed a single group comes from Salvador das Missões; this municipality is located in the most extreme west region among the studied municipalities. Thus, our findings can provide important information for breeders that will be starting a black oat breeding program.
Dry matter accumulation in the main stem ofwheat plants shows significant correlation with soluble sugar levels, which in turn correlate to grain yield (EHDAIE et al., 2008). High assimilate availability right before anthesis may increase flower fertility and, consequently, the number and size of seeds as well as grain filling capacity (EGLI; BRUENING, 2002). There are two main photoassimilate sources for developing grains: one directly originated from photosynthesis and another from photoassimilate remobilization previously stored in other plant organs, mainly stems. The proportion between those two vary according to genotype and cropping conditions (INOUE et al., 2004).
common bean cultivars (BRS Requinte, BRS Cometa, Diamante Negro, BRS Grafite, BRS Valente, and Corrente) as subplots, with three replications. Common bean cultivars did not differ regarding grain yield response to sulfur rates, which fitted to a quadratic equation. Among the cultivars tested, only BRS Requinte and BRS Valente differed in grain yield for S fertilization, the first being more productive. Moreover, S fertilization allows significant increases in common bean grain yield in average of six cultivars and must be considered in cropping systems aiming for high yields.
Even though the difference was small, T5 had the greatest crown diameters, during the entire evaluation period, having practically the same thermal units as T3, in the vicinity of 3,000°C d. Thus, in general papaya trees tend to reduce their crown diameters with time; however, the values verified in this work seem to be related to the lack of soil water (T1), which was also verified by Aiyelaagbe et al. (1986), and to the low winter tempera- tures influencing all evaluated treatments, a condition also found by Silva (1999). No other reductions were detected. Variations in the number of emitted leaves were obtained during the evaluated period in relation to ther- mal units, in all irrigation treatments and their interac- tions; the respective regression equations were estimated, and the coefficients were significant at 5%, by the t test (Figure 5). The estimated regressions did not present suf- ficiently high coefficients of determination, demonstrat- ing that they do little to explain the data obtained, de- spite the observed significance. This could probably be related to the fact that in studies conducted by Aiyelaagbe et al. (1986) and Awada et al. (1979), while studying wa- ter stress in papaya trees, found that the no. of leaves of plants submitted to water stress decreases only due to leaf abcission and not because of the number of emitted leaves, since the numbers of nodes in the plants were the same, and only the distance between nodes was differ- ent, under the different moisture regimes.