Fernando Felipe Ferreyra Hernandez

Acumulação de biomassa e extração de nutrientes por plantas de feijão-de-corda irrigadas com água salina em diferentes estádios de desenvolvimento

Due to the limited availability of low salinity waters, the use of water of moderate to high salinity in agriculture is a close reality in the expansion of irrigated farms. The objective of this research was to evaluate the effect of irrigation with saline water, applied at different development stages of cowpea plants, on growth and nutrient uptake. The experiment was set up in the field during the dry season. A completely randomized block design, with five treatments and five replications was adopted. The treatments studied were: T1 - groundwater with electrical conductivity (ECw) of 0.8dS m-1 during the whole crop cycle; T2 - saline water (ECw = 5.0dS m-1) during the whole crop cycle; T3, T4 and T5 - saline water from 0 to the 22nd day after sowing (DAS), from the 23rd to the 42nd DAS and from the 43rd to 62nd DAS, respectively. The plants subjected to T3, T4 and T5 were irrigated with groundwater in the other stages of the crop cycle. At 8, 23, 43 and 63DAS plants were collected for evaluation of plant growth, Na, Cl, K, Ca, N, P, Fe, Cu, Zn and Mn contents and distribution in plant parts. The application of saline water during the whole crop cycle (T2) and during the germination and initial plant development (T3) caused, respectively, inhibition and retardation of plant growth. Cowpea plants removed the minerals in the following decreasing sequence: N > K > Cl > Ca > Na > P > Fe > Mn > Zn > Cu, but the continuous use of saline water (T2) reduced the total uptake of all nutrients, except for Na. The minerals Na, Cl, K, Ca, Fe and Mn were distributed preferentially in the vegetative parts of the plant, while most of the N and P were translocated to the pods.

Distribuição da matéria seca e composição química das raízes, caule e folhas de goiabeira submetida a estresse salino

A greenhouse experiment was conducted with the objective of studying the response of guava plants (Psidium guajavaL.) to increasing levels of NaCl concentrations. Plants were grown in nutrient solutions, with 0, 25, 50, 75, 100, 125 and 150mM of NaCl, and harvested 30 and 50 days after saline stress in a complete randomized design. The following traits were studied: shoot, root and total plant dry matter and the percentage of Na, Cl, K, Ca and Mg in plant dry matter. Dry matter yield decreased when salinity increased. The root/shoot ratio decreased with the saline treatment. Salinity stress caused an increase in the levels of Na+ and Cl-. The highest ion accumulation was found in the leaves followed by the roots. The Ca levels were stable in the roots, but decreased in stems and leaves. The K content was reduced with the increased levels of salinity, particularly in the leaves. On the other hand, Mg levels were not affected by salinity in stems and roots but decreased in the leaves. There was a positive relationship between Na and Cl and a negative relationship between Na and K concentration in roots and leaves. Mg concentration in leaves and roots did not vary with the concentration of Na. The concentration of Ca did not vary with Na in the leaves but showed an inverse relationship in the roots.

Rotação cultural feijão caupi/milho utilizando-se águas de salinidades diferentes

The objective of this study was to evaluate the changes in chemical properties of soil, growth and productivity of crops in a cowpea/corn rotation irrigated with water of different salinities. The experiment was conducted under field conditions in randomized block design in a factorial scheme with four treatments and five replications totaling twenty plots. The treatments consisted of plants irrigated with well water of ECw of 0.8 (T1), 2.2 (T2), 3.6 (T3) and 5.0dS m-1 (T4). In the first crop with cowpea (dry season) the space used was 0.8m between rows and 0.3m between plants, with two plants per hole. The same plots were utilized for the cultivation of corn (rainy season), using a spacing between rows of 0.8m and 0.2m between plants and one plant per hole. During the trial period, the chemical properties of soil, plant growth, productivity and partitioning of dry matter were evaluated. The use of saline water during cultivation of the cowpea in the dry season increased the salinity and sodicity of the soil, which reduced the growth and productivity of cowpea. High rainfall before and during the cultivation of corn eliminated the possible negative effects of salinity in this crop. The high yield of crops and the relatively small alteration in the salt content of the soil suggest the feasibility of using cowpea/corn crop rotation under conditions similar to this study.

Absorção de macronutrientes por explantes de bananeira in vitro

The absorption of the nutrients (N, P, K, Ca, Mg and S) by banana (Musa sp.) cv. Prata Ana explants on the basic medium of Murashige & Skoog (1962) supplemented with sucrose (30 g/L) and BAP (3.5 mg/L) were evaluated at 0, 10, 20, 30, 40, 50 and 60 days after inoculation. The seven treatments were arranged on a completely randomized design with three replicates. The sequence of nutrient absorption by the explants was K > N > Ca ³ P > Mg @ S. The P was the nutrient with the fastest absorption rate and at the 30th day the explants had already absorbed 75% of the P from the medium. The P absorption stopped by the 50th day. The S absorption stopped at the 50th day with 66% of it remaining in the medium. The results suggested a close relationship between these two nutrients. The highest rates of nutrient absorption were observed during the first 20 days of culture. The rhizome, pseudostem and leaves behaved differently to the extraction and accumulation of nutrients.

Yield and ion content in maize irrigated with saline water in a continuous or alternating system

Irrigation with water containing salt in excess can affect crop development. However, management strategies can be used in order to reduce the impacts of salinity, providing increased efficiency in the use of good quality water. The objective of this research was to study the effects of use of high salinity water for irrigation, in continuous or cyclic manner, on vegetative growth, yield, and accumulation of ions in maize plants. Two experiments were conducted during the months from October to January of the years 2008/2009 and 2009/2010, in the same area, adopting a completely randomized block design with four replications. Irrigation was performed with three types of water with electrical conductivities (ECw) of 0.8 (A1), 2.25 (A2) and 4.5 (A3) dS m-1, combined in seven treatments including the control with low salinity water (A1) throughout the crop cycle (T1). Saline waters (A2 and A3) were applied continuously (T2 and T5) or in a cyclic way, the latter being formed by six irrigations with A1 water followed by six irrigations by eitherA2 or A3 water, starting with A1 at sowing (T3 and T6) or 6 irrigations with A2 or A3 water followed by 6 irrigations with A1 water (T4 and T7) . The use of low and high salinity water resulted in lower accumulation of potentially toxic ions (Na and Cl) and improvement in the Na/K balance in the shoots of maize plants. Application of saline water in a cyclic way also allows the substitution of about 50% of water of low salinity in irrigation, without negative impacts on maize yield.

Regional Substrates of the Brazilian Northeast on Acclimatization and Development Morphological of Minirose

The transition from heterotrophism to autotrophism in acclimatization is a delicate process for most species. The objective of this work was to evaluate combinations of regional substrates of the Brazilian Northeast in the acclimatization and morphological development of minirose ( Rosa chinensis ‘Minima’) seedlings. The experiment was carried out in a greenhouse using seedlings with 30 days of in vitro culture. The treatments were constituted by: 1) dry coconut powder; 2) 75% dry coconut powder + 25% rice husk; 3) 50% dry coconut powder + 50% rice husk; 4) 75% dry coconut powder + 25% charcoal rice husk; 5) 50% dry coconut powder + 50% carbonized rice husk; 6) 100% vermiculite; 7) 50% vermiculite + 50% dry coconut powder; 8) commercial substrate; 9) 75% sand + 25% dry coconut powder and 10) 50% sand + 50% dry coconut powder. After 21 days, the following characteristics were evaluated: survival percentage, leaf number, shoot height, dry matter of shoot and root and total dry matter. The regional materials tested showed a good choice of substrates to be used in the acclimatization of minirose seedlings. The vermiculite presented the worst results in the characteristics evaluated. Dry coconut powder as substrate should be used in mixtures with other materials to provide better acclimatization conditions. The use of 50% dry coconut powder + 50% rice husk provided a best development and growth of minirose seedlings ( Rosa chinensis ‘Minima’) than other tested substrates

Phosphorus and Zinc Extractable and Total in Substrate Enriched Coconut Powder and Tomato Cultivation

Phosphorus (P) and Zinc (Zn) stand out for their interactions, however, little is known about the interaction of these elements in organic substrates used in the development of plants. The objective of this work was to evaluate the extractable and total P and Zn of the enriched coconut powder substrate and the development of tomato seedlings grown on the same substrate. The work consisted of 10 treatments and 4 replicates with different doses of P and Zn. The substrate used was coconut powder enriched with nutrient solutions in a ratio of 10:1 (v/m). Then, the experiment was conducted using the enriched substrate to observe the effect of P and Zn doses on the development of tomato seedlings in trays. The height, number of leaves and the dry matter of the plants were evaluated. For the water and Mehlich-1 extractors the highest values of P and Zn were for treatments with the highest doses and only the quadratic positive effect of P did not differ statistically in the enriched coconut powder substrate. The results showed that the coconut powder used as substrate is deficient in P and Zn. The highest development of the seedlings was obtained at the doses of 74 mg L -1 P and 3.25 and 4.75 mg L -1 Zn of the substrate enrichment solution.