Effect of Burial Depth on Tuber Sprouting and Growth of Purple Nutsedge (Cyperus rotundus L.) Ecotypes

Purple nutsedge (Cyperus rotundus L.) is a problematic weed in tropical regions particularly in Jiroft, Kahnooj and Birjand, so that farmers annually suffer severe damage to their vegetable and cucurbit crops. Currently, very little research on the biological basis of this noxious weed has been don.This study was conducted to evaluate the effect of burial depth on tubes germination and emergence of different purple nutsedge ecotypes. Purple nutsedge tubers were collected from birjand, kahnooj and jiroft regions. A factorial experiment was conducted based on randomized complete block design in University of Birjand with three replications. To investigate the viability of tubers before being used for bioassays, their germination potentials were examined in a growth chamber set at 25/15°C. Then, ten tubers of each ecotype with almost equal weight (3.6gr) and size were planted in polyethylene tubes with 25 cm in diameter and 50 cm in height. Ten tubers of each purple nutsedge ecotype were sown at 8 different depths, including 0, 2.5, 5, 10, 20, 30, 40 and 50 cm. At the termination of experiment, number of tubers and pre tubers, underground tuber dry weight, shoot number and above ground dry weight were recorded. Results showed that purple nutsedge tubers were able to emerge from very deep burial depths (up to a depth of 50 cm), and in this regard, there were some differences among the three ecotypes. Generally, as depth increases, the number and weight of tubers, and shoots decreased; whereas the burial depth showed no effect on the shoot height and pre-tuber production. Therefore, in addition to deep plowing, other control methods such as cultural control and chemical methods should be used in an integrated management.