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Improving Weed Management and Crop Productivity in Maize Systems in Zimbabwe

Arnold Bray Mashingaidze

出版	Wageningen University and Research Centre, 2004
ISBN	90850409579789085040958
URL	http://books.google.com.hk/books?id=yRNIAAAAYAAJ&hl=&source=gbs_api

註釋

Span lang=EN-GB style='mso-ansi-language:EN-GB'Maize-pumpkin and maize-bean intercropping reduced weed biomass by 50-66% when established at a density of 12,300 plants ha span lang=EN-GB style='font-family: Symbol;mso-ansi-language:EN-GB'- span lang=EN-GB style='mso-ansi-language:EN-GB'1 span lang=EN-GB style='mso-ansi-language:EN-GB'for pumpkins equivalent to 33% of the maize density (37,000 plants ha span lang=EN-GB style='font-family:Symbol; mso-ansi-language:EN-GB'- span lang=EN-GB style='mso-ansi-language: EN-GB'1 span lang=EN-GB style='mso-ansi-language:EN-GB'), and 222,000 plants ha span lang=EN-GB style='font-family:Symbol; mso-ansi-language:EN-GB'- span lang=EN-GB style='mso-ansi-language: EN-GB'1 span lang=EN-GB style='mso-ansi-language:EN-GB'for beans. Lower densities of pumpkins than 33% of the maize density failed to reduce weed biomass more than that achieved by sole maize. Sole maize crops were weeded twice or thrice to achieve the same weed biomass as intercrops weeded once showed that intercropping could reduce the weeding requirements of maize by 33 to 67%. Maize grain yield was reduced by 20% in one out of four seasons in the first study on maize-pumpkin intercropping. Maize grain yield was not reduced in three seasons when the maize-pumpkin intercropping treatments were leaf stripped and/or detasselled and the trend of leaf stripping and detasselling alleviating the effects of companion crop competition on maize grain was shown in the maize-bean intercrop experiments as well. Intercrop productivity increased with leaf stripping and detasselling as a result of greater penetration of radiation to the companion crop and their effects of increasing dry matter distributed to the maize cob (indicated by 1000-grain weight, cob weight, and kernel weight cob span lang=EN-GB style='font-family: Symbol;mso-ansi-language:EN-GB'- span lang=EN-GB style='mso-ansi-language:EN-GB'1 span lang=EN-GB style='mso-ansi-language:EN-GB'). Leaf stripping maize at anthesis focused on the removal of leaves that were beginning to senesce. If they would remain on the plant they would compete with the cob for assimilates as they senesce further, until necrosis. Detasselling is known to remove apical dominance and to increase radiation penetration to the middle leaves on the maize plant that produce most assimilates destined for the cob. Leaf stripping did not affect the ability of the intercrop to suppress weed growth and seed production. In maize monocrops more weed biomass and weed seeds were produced with leaf stripping and detasselling..