Awan Tahir Hussain, Chauhan Bhagirath Singh, Cruz Pompe C Sta
Weed Science, Crop and Environmental Sciences Division, International Rice Research Institute (IRRI), Los Baños, Philippines.
Crop Science Cluster, Department of Agronomy, College of Agriculture, University of Philippines, Los Baños, Philippines.
PLoS One. 2014 Jun 9;9(6):e98255. doi: 10.1371/journal.pone.0098255. eCollection 2014.
Ischaemum rugosum is a competitive weed in direct-seeded rice systems. Developing integrated weed management strategies that promote the suppression of weeds by crop density, cultivar selection, and nutrition requires better understanding of the extent to which rice interferes with the growth of this weed and how it responds to resource limitation due to rice interference. The growth of I. rugosum was studied when grown with four rice seeding rates (0, 25, 50, and 100 kg ha(-1)) and four nitrogen (N) rates (0, 50, 100, and 150 kg ha(-1)). Compared to the weed plants grown alone, weed tiller number was reduced by 63-80%, leaf number by 68-77%, leaf area by 69-77%, leaf biomass by 72-84%, and inflorescence biomass by 81-93% at the rice seeding rates of 25-100 kg ha(-1). All these parameters increased with increasing rates of N from 0 to 150 kg ha(-1). At weed maturity, I. rugosum plants were 100% taller than rice at 0 kg N ha(-1), whereas, with added N, the weeds were only 50% taller than rice. Weed biomass increased by 82-160%, whereas rice biomass increased by 92-229%, with the application of 50-150 kg N ha(-1). Added N favored rice biomass production more than it did the weed. Rice interference reduced the height and biomass of I. rugosum, but did not suppress its growth completely. I. rugosum showed the ability to reduce the effects of rice interference by increasing leaf area, leaf weight ratio, and specific leaf area, and by decreasing the root-shoot weight ratio in comparison to the weed plants grown alone. The results suggest that rice crop interference alone may reduce I. rugosum growth but may not provide complete control of this weed. The need for integrated weed management practices to effectively control this weed species is highlighted.
皱稃草是直播水稻系统中的一种竞争性杂草。制定综合杂草管理策略，通过作物密度、品种选择和养分管理来促进对杂草的抑制，需要更好地了解水稻对这种杂草生长的干扰程度，以及它如何应对因水稻干扰而导致的资源限制。研究了皱稃草在四种水稻播种量（0、25、50和100千克/公顷）和四种氮素施用量（0、50、100和150千克/公顷）条件下的生长情况。与单独生长的杂草植株相比，在水稻播种量为25 - 100千克/公顷时，杂草分蘖数减少了63 - 80%，叶片数减少了68 - 77%，叶面积减少了69 - 77%，叶生物量减少了72 - 84%，花序生物量减少了81 - 93%。随着氮素施用量从0增加到150千克/公顷，所有这些参数都有所增加。在杂草成熟时，在不施氮（0千克氮/公顷）的情况下，皱稃草植株比水稻高100%，而在增施氮肥后，杂草仅比水稻高50%。施用50 - 150千克氮/公顷时，杂草生物量增加了82 - 160%，而水稻生物量增加了92 - 229%。增施氮肥对水稻生物量生产的促进作用大于对杂草的促进作用。水稻干扰降低了皱稃草的高度和生物量，但并未完全抑制其生长。与单独生长的杂草植株相比，皱稃草表现出通过增加叶面积、叶重比和比叶面积，以及降低根冠比来减轻水稻干扰影响的能力。结果表明，仅靠水稻作物干扰可能会降低皱稃草的生长，但可能无法完全防除这种杂草。这凸显了采用综合杂草管理措施有效防除这种杂草的必要性。
