Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativ...Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.展开更多
Prospects for deploying perennial grasses that are currently considered leading candidates for dedicated energy crops over large acreages are debatable because of several limitations, including vegetative propagation ...Prospects for deploying perennial grasses that are currently considered leading candidates for dedicated energy crops over large acreages are debatable because of several limitations, including vegetative propagation or small seed size, low biomass production during the first growing season, and incomplete assessments of crop invasiveness risk. Pearl Millet-Napiergrass hybrids (“PMN”;Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), in contrast, are large-seeded, sterile feedstocks capable of high biomass production during establishment year. Novel methods are warranted for confirmation of PMN hybrids, as traditional morphological observations can be inconclusive and chromosome number determination using cytological methods is laborious and time consuming. Six putative PMN lines were produced in this study, and 10 progeny from each line were evaluated using morphological traits, seed fertility, flow cytometry, and expressed sequence tag-simple sequence repeat (EST-SSR) markers. All putative hybrid lines were sterile and failed to produce seed. The PMN hybrids could not be distinguished from either parent using flow cytometry due to highly similar nuclear genome DNA contents. A number of paternal napiergrass-specific EST-SSRs were identified for each PMN line, and four paternal-specific EST-SSRs conserved across all napiergrass accessions were selected to screen the putative PMN hybrids. These EST-SSRs confirmed that all F1 individuals analyzed were PMN hybrids. The use of paternal-specific markers therefore provides a valuable tool in the development of both “Seeded-yet-Sterile” biofuel PMN feedstocks and additional PMN cultivar-and parental species-specific markers.展开更多
文摘Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.
文摘Prospects for deploying perennial grasses that are currently considered leading candidates for dedicated energy crops over large acreages are debatable because of several limitations, including vegetative propagation or small seed size, low biomass production during the first growing season, and incomplete assessments of crop invasiveness risk. Pearl Millet-Napiergrass hybrids (“PMN”;Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), in contrast, are large-seeded, sterile feedstocks capable of high biomass production during establishment year. Novel methods are warranted for confirmation of PMN hybrids, as traditional morphological observations can be inconclusive and chromosome number determination using cytological methods is laborious and time consuming. Six putative PMN lines were produced in this study, and 10 progeny from each line were evaluated using morphological traits, seed fertility, flow cytometry, and expressed sequence tag-simple sequence repeat (EST-SSR) markers. All putative hybrid lines were sterile and failed to produce seed. The PMN hybrids could not be distinguished from either parent using flow cytometry due to highly similar nuclear genome DNA contents. A number of paternal napiergrass-specific EST-SSRs were identified for each PMN line, and four paternal-specific EST-SSRs conserved across all napiergrass accessions were selected to screen the putative PMN hybrids. These EST-SSRs confirmed that all F1 individuals analyzed were PMN hybrids. The use of paternal-specific markers therefore provides a valuable tool in the development of both “Seeded-yet-Sterile” biofuel PMN feedstocks and additional PMN cultivar-and parental species-specific markers.
