Estudo da influencia do potássio e do cálcio na reprodução do nematoide do cisto da soja

The objective of this work was to evaluate the reproduction of the soybean cyst nematode (SCN) in soybean plants in substract with different potassium (K) and calcium (Ca) doses. The experiment was conducted in a completely randomized block design, with 25 treatments and six replicates. A factorial scheme (5 x 5) was used with five K doses (0; 150; 300; 450; and 600 mg / dm3 ) and five Ca doses (0; 75; 150; 225; and 300 mg / dm3 ). Eighteen days after sowing, plants were inoculated with 4,000 H. glycines race 3 eggs. Thirty days after inoculation a total of three weekly evaluations were performed measuring plant height and stem diameter. Seventy days after inoculation, the following variables were analyzed: measurement of leaf blade, numbers of eggs / pot, cysts / pot, eggs / cyst, females and cysts / root system, eggs / female and the reproduction factor of H. glycines. Root and shoot dry matter were weighed. Then, K and Ca shoot contents of each sample was obtained. There was a significant interaction between K and Ca doses only for number of eggs / female. The K doses significatively influenced the numbers of cysts / pot, eggs / cyst, eggs / pot, females and cysts / root system and reproduction factor. The Ca doses did not influence significatively the nematologic variables analyzed. The K-Ca interaction affected all crop-related variables analyzed. A significative K-Ca interaction was observed for Ca contents in shoot dry matter. The K contents were only influenced by potassium doses amended to the soil.

Cobre via foliar na nutrição e na produção de mudas de cafeeiro

The objective of this study was to evaluate the effect of different sources and doses of copper (Cu) applied to leaves on growth and nutrition of coffee seedlings. The treatments consisted of combinations of two Cu sources (Cupric Sulfate Ammonium - CSA and Copper Sulfate - CS) and four Cu doses (0, 250, 500 and 1000 g ha-1). The sources of Cu in different doses were dissolved in water, calculated for the application volume of 400 L ha-1. The doses were divided in 3 applications at 20 days. The Cu content and concentration in the leaf, stem, and root in were measured. The dry matter of the leaf, stem, root and total and the utilization, absorption and translocation efficiency, in coffee seedlings were evaluated. In general the Cu content and concentration were obtained for the CS at doses of 250, 500 and 1000 g ha-1 Cu. The maximum increase of total dry matter was 48 and 51 g to CSA and CS, when applied 534 and 668 g ha-1, respectively. The highest utilization and absorption efficiency was found to CSA and CS, respectively. The translocation efficiency was similar for both sources.