fitri yani - Academia.edu (original) (raw)

Papers by fitri yani

Agronomy Journal, 2000

Rice (Oryza sativa L.) is one of the world's mosl important crops. The present investigation vvas... more Rice (Oryza sativa L.) is one of the world's mosl important crops. The present investigation vvas designed lo assess the range of growthpromoting activities of various diazotrophic bacteria on rice seedling vigor, its carryover elfect on strew and grain yield, and the persistence of an inoculant strain on rice roots under greenhouse conditions. Growth responses to inoculation exhibited bocterid straindce variety specificity thal were either stimulrtory or inhibitory. Growih responses included changes in rates of seedling emergence, radical elongation, height and drymatterrplumule length, cumutrtive leaf and root arers, and grain and straw yields. Most notable were the inocrrlation responscs lo Rhlzobium leguminosarum bv. trttolii E11 and Rhizobtum sp.IRBG74, which stimulnted early rice growth resulting in a carryover efiect of significantly (P : 0,05) incressed grain and straw yields rt meturity, even though their culturable populations on roots diminished to below detectrble vrlues st 6i0 d after planting. The test strains were positive for indole-}.acetic acid production in vitro, but onlysome reduced ecetylene to ethylene in associntion with rice under laboratory grou{h conditions. These studies indicate that certain shains of nonphotosynthetic diazotrophs, including rhizobia, can promote grorth and vigor of rice seedlings, and this benefit of early seedling development can carryover to significantly increased grnin yield ot maturity. Qenor-rnc vrcoR is critical when competition for light, t.J nutrients, air, and water becomes strong. Seedlings with a vigorous g:owth pattern can compete iuccessfufly under stress, influencing stand establiJhment and ultimately grain yield. The vigor parameters of a crop varie.ty can be influenced by genetic manipulations that are time-consuming and costly, and cultuial manipulations that can provide quicker, short-term boosts in irop yield by changing the physiological status of young ptantjttrat persists throughout their life cycle (Teng, tqgO). Cultural manipulations under field conditions can be achieved by delivery of a balanced fertilization, optimum water management, seed treatment, etc. Treatment of seeds with beneficial microbes can help to control disease incidence and severity (O,Sullivan and O'Gara, L99?),improve nutrient uptake efficiency (Bashan et al., 1990), and promote growth leading to enhanced yield (De Freitas and Germida, 1990).-The growth-promoting activities (GpA) of bacterial inoculants on crop plants may be manifesied in several yayq.-For example, their production of iron-sequesteringsiderophores and antimicrobial compounds niay hinder colonization of hosts by phytopathbgens (Neilands

Agronomy Journal, 2000

Rice (Oryza sativa L.) is one of the world's mosl important crops. The present investigation vvas... more Rice (Oryza sativa L.) is one of the world's mosl important crops. The present investigation vvas designed lo assess the range of growthpromoting activities of various diazotrophic bacteria on rice seedling vigor, its carryover elfect on strew and grain yield, and the persistence of an inoculant strain on rice roots under greenhouse conditions. Growth responses to inoculation exhibited bocterid straindce variety specificity thal were either stimulrtory or inhibitory. Growih responses included changes in rates of seedling emergence, radical elongation, height and drymatterrplumule length, cumutrtive leaf and root arers, and grain and straw yields. Most notable were the inocrrlation responscs lo Rhlzobium leguminosarum bv. trttolii E11 and Rhizobtum sp.IRBG74, which stimulnted early rice growth resulting in a carryover efiect of significantly (P : 0,05) incressed grain and straw yields rt meturity, even though their culturable populations on roots diminished to below detectrble vrlues st 6i0 d after planting. The test strains were positive for indole-}.acetic acid production in vitro, but onlysome reduced ecetylene to ethylene in associntion with rice under laboratory grou{h conditions. These studies indicate that certain shains of nonphotosynthetic diazotrophs, including rhizobia, can promote grorth and vigor of rice seedlings, and this benefit of early seedling development can carryover to significantly increased grnin yield ot maturity. Qenor-rnc vrcoR is critical when competition for light, t.J nutrients, air, and water becomes strong. Seedlings with a vigorous g:owth pattern can compete iuccessfufly under stress, influencing stand establiJhment and ultimately grain yield. The vigor parameters of a crop varie.ty can be influenced by genetic manipulations that are time-consuming and costly, and cultuial manipulations that can provide quicker, short-term boosts in irop yield by changing the physiological status of young ptantjttrat persists throughout their life cycle (Teng, tqgO). Cultural manipulations under field conditions can be achieved by delivery of a balanced fertilization, optimum water management, seed treatment, etc. Treatment of seeds with beneficial microbes can help to control disease incidence and severity (O,Sullivan and O'Gara, L99?),improve nutrient uptake efficiency (Bashan et al., 1990), and promote growth leading to enhanced yield (De Freitas and Germida, 1990).-The growth-promoting activities (GpA) of bacterial inoculants on crop plants may be manifesied in several yayq.-For example, their production of iron-sequesteringsiderophores and antimicrobial compounds niay hinder colonization of hosts by phytopathbgens (Neilands