ABSTRACT The stabilization process necessary for leather tanning, in the leather industry, generates a great deal of collagenic solid waste, which is a likely pollutant. This solid waste has high nitrogen content, which suggests potential for agricultural use. To evaluate the feasibility of application of industrial leather waste as an N source for wheat and rice crops, a greenhouse experiment was conducted with five application rates of N from collagen (0, 225, 450, 675, and 900 mg kg-1) and three […]

Incorporation of rice straw into the soil just before flooding for water-seeded rice can immobilize mineral nitrogen (N) and lead to the production of acetic acid harmful to the rice seedlings, which negatively affects grain yield. This study aimed to evaluate the formation of organic acids and variation in pH and to quantify the mineral N concentration in the soil as a function of different times of incorporation of rice straw or of ashes from burning the straw before flooding. […]

Establishment of the water layer in an irrigated rice crop leads to consumption of free oxygen in the soil which enters in a chemical reduction process mediated by anaerobic microorganisms, changing the crop environment. To maintain optimal growth in an environment without O2, rice plants develop pore spaces (aerenchyma) that allow O2 transport from air to the roots. Carrying capacity is determined by the rice genome and it may vary among cultivars. Plants that have higher capacity for formation of […]

The efficiency of uptake of a nutrient by plants is a function of their physiological and morphological properties, which may vary between cultivars of the same species. A study was carried out to determine root morphology and kinetic parameters of potassium (K) uptake in rice genotypes. The experiment was conducted in a laboratory and the plants cultivated in pots under artificial light. Treatments were represented by 11 rice genotypes (Avaxi, BRS Atalanta, BRS Bojuru, BRS Fronteira, BRS Querência, CNA 10754, […]

Nitrogen is the most important nutrient for rice (Oryza sativa L) yields. This study aimed to evaluate the response of upland rice cultivars to N rate and application times in a randomized block design, in subdivided plots with four replications. The studied factors were five rice cultivars (BRS MG Curinga, BRS Monarca, BRS Pepita, BRS Primavera, and BRS Sertaneja), three application times (100 % at planting, 50 % at planting – 50 % at tillering and 100 % at tillering) […]

Silicon is considered an important chemical element for rice, because it can improve tolerance to biotic and abiotic stress. However, in many situations no positive effect of silicon was observed, probably due to genetic factors. The objective of this research was to monitor Si uptake kinetics and identify responses of rice cultivars in terms of Si uptake capacity and use. The experiment was carried out in a greenhouse of the São Paulo State University (UNESP), Brazil. The experiment was arranged […]

Rice is classified as an ammonium (NH4+)- tolerant plant due the predominance of this ion in flooded soils. However, in the oxygenated zones of flooded soil and in the rice rhizosphere, nitrate (NO3–) can be formed and become an important nitrogen (N) source for the crop. This experiment was carried out to evaluate the effect of different ammonium:nitrate proportions on rice development in nutrient solution. The experiment was carried out in a greenhouse, from January until February 2008 in a […]

Soils of the coastal plains of Rio Grande do Sul, Brazil, are affected by salinization, which can hamper the establishment and development of crops in general, including rice. The application of high doses of KCl may aggravate the crop damage, due to the high saline content of this fertilizer. This study aimed to evaluate the effect of K fertilizer management on some properties of rice plant, grown in soils with different sodicity levels, and determine which attribute is best related […]

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), […]

The high oxygen diffusion in different materials makes the establishment and maintenance of oxygen-free environments difficult. The techniques used to obtain oxygen-free environments are little efficient and not representative of flooded soil conditions. The purpose of this study was to develop a method for obtaining roots in a hypoxic environment to evaluate iron plaque and aerenchyma formation in rice plants. A hypoxic condition similar to that of flooded soils was created in 50 L tanks, based on the oxygen diffusion capacity […]