SENESCÊNCIA FOLIAR E RESPOSTA DE HÍBRIDOS DE MILHO LIBERADOS COMERCIALMENTE PARA CULTIVO EM DIFERENTES ÉPOCAS AO ADENSAMENTO

Abstract

This work was carried out aiming to evaluate the crowding effects on leaf senescence during grainfilling and productivity of maize hybrids commercially released in different eras. The trial was set in Lages, SC,Brazil, during the 2008/2009 and 2009/2010 growing seasons. Two hybrids were evaluated: AG 303 (old hybrid -OH) and P30F53 (modern hybrid - MH). Each hybrid was tested at five plant densities: 25,000, 50,000, 75,000,100,000 and 125,000 pl ha-1. Floral synchrony, green and senesced leaf area at silking, 56 after silking, grain yieldand its components were determined. OH leaf area at silking was more than 1,000 cm-2 higher than MH leaf area atall plant densities. An opposite behavior was observed 56 days after silking, when MH had greater leaf area than OH.Plant densities that promoted highest grain yields were 53,044 and 86,665 pl ha-1 for OH and MH, respectively. MHpresented better synchrony between anthesis and silking and lower female sterility than OH. Such traits contribute tothe 2.8 smaller leaf senescence rate of MH with the increment in plant density 56 days after silking , increasing theMH tolerance to crowding.

Keywords

• Zea mays
• leaf area
• plant density
• productivity