000			03034nab a22004457a 4500
001			G61684
003			MX-TxCIM
005			20211006080139.0
008			121211b |||p||p||||||| |z||| |
040			_aMX-TxCIM
072		0	_aF01
072		0	_aU10
090			_aCIS-1948
100	1		_aBell, M.A.
245	0	0	_aGenetic and agronomic contributions to yield gains: _b A case study for wheat
260			_c1995
340			_aPrinted
500			_aPeer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=0378-4290
520			_aGenetic and agronomic contributions to yield gains for wheat (Triticum aestivum L.) in the Yaqui Valley of northwest Mexico were estimated for the period from 1968-1990. Five problems associated with estimating sources of yield gains were considered, namely: (1) adjusting yield gains for variation in weather over the study period; (2) considering annual cultivar-by-weather interactions, which are potentially problematic when relative yields of cultivars are generated over only part of the study period; (3) overestimating relative yields of cultivars if the check cultivar(s) become susceptible to disease; (4) ensuring that yields as estimated from research station trials represent cultivar performance under farmers' conditions; and (5) allowing for cultivar-by-management interactions. With these factors considered, 28% of the weather-adjusted yield gain of 103 kg ha(-1) y(-1) was attributed to genetic gain (i.e., cultivar improvement). If the yield gains had not been adjusted for annual weather variation, genetic gain would have been overestimated at 50%. By contrast, 48% of the gain was attributed to increased use of N fertilizer, driven at least in part by a decline in N prices; no N-by-cultivar interactions were apparent. The remainder of the yield gap (24%) could not be attributed to specific factors, although P application rates increased over time, and negative deviations from linearity were associated with years having greater than normal rainfall in November and December (a phenomenon which can delay sowing and/or reduce crop stand). In addition to identifying factors contributing to yield gains, technologies that have contributed benefits not measured by yield are discussed
536			_aConservation Agriculture Program
546			_aEnglish
591			_aR95ANALY|Elsevier|EconomicsPubs|3
594			_aCSAY01
595			_aCSC
650	1	7	_aAgronomic characters _gAGROVOC _2 _91008
650	1	0	_aEnvironmental factors
650	1	0	_92091 _aGenetic gain _gAGROVOC
650	1	0	_aMexico
650	1	0	_aResearch projects _91237
650	1	0	_aYield factors
653	0		_aCIMMYT
650	1	0	_91296 _aTriticum aestivum _gAGROVOC
650	1	7	_aWheat _gAGROVOC _2 _91310
650	1	0	_91313 _aYields _gAGROVOC
700	1		_aByerlee, D. _9455
700	1		_aFischer, R.A., _ecoaut.
700	1		_aSayre, K.D., _ecoaut.
773	0		_tField Crops Research _n649145 _gv. 44, no. 2-3, p. 55-65
942			_cJA
999			_c17640 _d17640