Urease inhibitor on performance of corn hybrids in second crop in Sinop-MT

Nitrogen is the most demanded element with the most complex management and with the highest responses in productivity in the corn crop, of the principal source of nitrogen supplies, but the urea is inefficient due to its volatilization. The objective of this work was to evaluate the agronomic performance and the efficiency of the urease inhibitor in formulations containing urea, applied in five different commercial corn hybrids in Sinop - MT. The experimental design was in randomized blocks, in a 3 x 5 factorial scheme with three replications. The first factor consisted of three cover fertilizations: control (without application of fertilizer); fertilization with 250 kg ha-1 of urea and fertilization with 250 kg ha-1 of urea with the presence of the urease inhibitor (UREMAX®) NBPT. The second factor was five corn hybrids: 2B433, DKB255, DKB335, NS45 and SYN522. It was found that all hybrids had greater growth and productivity when they received the urease inhibitor, in relation to the treatment without coverage. The hybrids DKB 255, 2B433 and SYN 522, the treatment with UREMAX® reached the highest productivity. The most prominent hybrid in productivity was DKB 255, which reached 9600 kg ha-1, with UREMAX® in cover fertilization, about 31% more than the treatment without urea coverage, and with gains of 18% in relation to urea.

Leaf and Root Growth, Carbon and Nitrogen Contents, and Gene Expression of Perennial Ryegrass to Different Nitrogen Supplies

Nitrogen greatly impacts plant growth and development. The objective of this study was to characterize growth, nitrogen use, and gene expression of perennial ryegrass (Lolium perenne) in response to increasing nitrogen supplies. Perennial ryegrass (cv. Inspire) was grown in sand culture and irrigated with a half-Hoagland solution amended with 0, 0.5, 1.0, 2.5, 5.0, and 7.5 mm nitrogen. Leaf tissues were harvested at 10 days (first cutting) and 20 days (second cutting) and roots were harvested at 20 days. The relatively higher N supply (2.0–7.5 mm) resulted in a larger amount of leaf fresh and dry weight but lower root fresh and dry weight, especially for the second cutting. Root:leaf ratio was higher under low N, but lower under the high N treatment. Leaf N content was relatively higher under 2.5, 5, and 7.5 mm N than under the other three treatments, while 2.5 mm N exhibited relatively higher leaf carbon content for both cuttings. Leaf C:N ratio and leaf nitrogen use efficiency (LNUE) decreased with increasing N supplies for the first cutting but were higher under low N (0–1.0 mm) for both cuttings. Leaf C:N ratio and LNUE did not differ among low N and LNUE also remained unchanged among high N for the second cutting. Root N content increased, but the root C:N ratio and root N use efficiency (RNUE) decreased with increasing N supplies, especially under 2.5, 5.0, and 7.5 mm N. Low (0.5 mm), moderate (2.5 mm), and high (7.5 mm) N were chosen to examine the expression level of NR encoding nitrate reductase and GS1b encoding glutamine synthetase. Treatment of 0.5 mm N had higher expression levels of leaf NR than other two treatments for both cuttings and a higher level of leaf GS for the second cutting. Expression of NR in the roots did not vary among treatments but the expression of GS increased under 2.5 and 7.5 mm, compared with the 0.5 mm N. Differential leaf and root growth and physiological responses to low N (0 to 1 mm) and to moderate to high N (2.5 to 7.5 mm) could be used for examining the natural variation of N use in diverse perennial ryegrass populations.