Tatiana Maria da Silva

Agronomic Evaluation of Sweet Sorghum in Semiarid Region: Cultivar and Spacing Effects

The objective of this study was to evaluate the agronomic characteristics of two sweet sorghum varieties for row spacing in the semiarid region of the State of Ceara, Brazil. Hence, an experiment was carried out on the Experimental Farm of the Federal University of Ceara, in two agricultural cycles (2015 and 2016), in sandy loam Planosol during the rainy season. Two sweet sorghum varieties (BRS 506 and SF 15), cultivated at 50, 60, 70, and 80 cm row spacing, were evaluated at different times after sowing (30, 45, 60, 75, and 90 days), in a randomized block design repeated four times in the arrangement of subdivided plots (2 × 4 × 5). The BRS 506 variety had higher mean number of leaves and leaf angle +3 in the two cycles evaluated. The highest mean plant height was observed at 90 DAS (328.11 cm). The stalk diameter at 15.59 mm was greatest with 70 cm spacing between rows. The chlorophyll content of the leaves may be influenced by stress factors, such as water and mineral deficiency, primarily nitrogen. The best results for chlorophyll occurred in the first cycle, in which the greatest mean was observed at 75 days, while in the second cycle, a year that presented low precipitation (water stress), the greatest means were observed at 30 days. Taking into consideration our results, BRS 506 variety is recommended for cultivation in semiarid northeastern Brazil, presenting good agronomic characteristics, when sown with 70 cm spacing between the rows.

Growth and gas exchange in cowpea plants under different managements and saline conditions

The cowpea is one of the main crops of economic and social importance in the northeast of Brazil. However, the growing need to increase crop yield has prompted the use of irrigation water with high levels of salts. The aim of this study therefore, was to evaluate the effects of different irrigation depths and rates of liquid biofertilizer on growth and gas exchange in cowpea plants under saline conditions. The experiment was conducted in a randomized block design, using a scheme of split lots consisting of four irrigation depths with saline water (75, 100, 125 and 150% of crop evapotranspiration - ETc) and sub-lots of four different doses of biofertilizer (0; 5,000; 10,000 and 15,000 L ha-1). At 75 days after sowing (DAS), readings were taken of gas exchange in the plants (photosynthesis, stomatal conductance, internal CO2 concentration and transpiration), and growth analyses were carried out (plant height, leaf area and total dry matter). An increase in irrigation depth gives an increase in total dry weight and leaf area. Increasing irrigation depth causes a significant increase in gas exchange, with quadratic behavior noted for photosynthesis and stomatal conductance, and linear behavior for internal CO2 concentration and transpiration. The application of high doses of biofertilizer gives increased stomatal opening of the cowpea leaves.

MATURAÇÃO FISIOLÓGICA DE SEMENTES DE SORGO SACARINO NO SEMIÁRIDO EM FUNÇÃO DA ADUBAÇÃO FOLIAR SILICATADA

The aim of this study was to evaluate physiological quality in seeds of sweet sorghum grown under semi-arid conditions, and to determine the age of physiological maturity of the seeds as a function of the foliar application of potassium silicate. The experiment was carried out at the Curu Valley Experimental Farm, in Pentecoste in the state of Ceará, during the rainy seasons of 2014 and 2015. The BRS 506 and BRS 511 varieties were used, under foliar fertilisation with potassium silicate at doses of 500, 1000 and 1500 mL.ha , in addition to the control lots (with no application); harvesting was at four periods, 30, 37, 44 and 51 days after full bloom (DAB). The percentage and speed of germination were evaluated, together with the accelerated ageing test and seedling growth. The seeds presented greater than 90% germination from 37 DAB, reaching high seedling vigour at 51 DAB. Foliar fertilisation with potassium silicate under the conditions of the experiment resulted in an increase in the physiological quality of the seeds. The BRS 506 and BRS 511 cultivars displayed the highest physiological quality between 49 and 53 DAF.