Interference of Volunteer Corn on Stress Metabolism and Yield of Dry Beans

ABSTRACT: Dry bean cultivation after corn favors the occurrence of volunteer corn plants which interfere with the crop and cause yield losses of dry bean. Yield losses resulting from interferences caused by corn may be related to oxidative stress, which, in turn, is caused by the higher production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2). This work aimed to quantify H2O2 contents, and the activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) in dry beans under interference with densities of volunteer corn F2 originated from individual plants and clumps (seven corn plants emerged at the same point). Two experiments were carried out in a randomized blocks design with three replicates in Passo Fundo - RS, Brazil. Enzyme analysis was performed in a laboratory at 21, 35 and 46 days after dry bean emergence (DAE). Corn densities were 0, 0.5, 1, 2, 4, 8 and 12 plants or clumps m-2. The results show changes in H2O2 levels and in the activity of SOD, CAT, and APX enzymes with the increase of corn densities, in which the highest activity occurred for SOD. The interference of volunteer corn with dry beans alters the stress metabolism of dry bean but does not cause oxidative stress. The yield of dry beans reduced under interference with volunteer corn F2, but it is higher when the corn was originated from clumps.

摘要：玉米后茬种植干菜豆时，易滋生自生玉米植株，这类植株会对干菜豆作物造成干扰，引发产量损失。玉米干扰引发的产量损失可能与氧化应激相关，而氧化应激由过氧化氢（hydrogen peroxide, H₂O₂）等活性氧（reactive oxygen species, ROS）的过量生成所诱发。本研究旨在定量分析干菜豆在受来源于单株及丛株（同一萌发点萌发7株玉米）的F2代自生玉米不同密度干扰时，其体内过氧化氢（H₂O₂）含量，以及超氧化物歧化酶（superoxide dismutase, SOD）、过氧化氢酶（catalase, CAT）与抗坏血酸过氧化物酶（ascorbate peroxidase, APX）的活性。本研究在巴西南里奥格兰德州帕索丰杜地区开展两项随机区组设计（randomized blocks design）试验，每组设置3次重复。分别于干菜豆出苗后21 d、35 d及46 d（DAE）在实验室完成酶活性检测。自生玉米的处理密度设置为0、0.5、1、2、4、8及12株/丛·m⁻²。结果显示，随着自生玉米密度升高，干菜豆体内H₂O₂含量及SOD、CAT、APX的酶活性均发生改变，其中超氧化物歧化酶（SOD）的活性变化最为显著。自生玉米对干菜豆的干扰会改变其应激代谢，但并未诱发氧化应激。受F2代自生玉米干扰时，干菜豆产量会下降，但当干扰源为丛株自生玉米时，干菜豆产量相对更高。