At the La Platina Experiment Station (INIA), severa) hundreds of bread wheat lineswerestudied in yield tria)s, under irrigation, every year between 1971 and 1981. In Part I of this paper, theeffects of severa) factors on the differences in yield between bread and durum wheats were analyzed; in this Part II, relations between yield of bread wheats and time of sowing; hectoliter weight; attack of Puccinia graminis, P. recondita, P. striiformis, BYDV, and aphids; accumulated degree-days (base 5ºC); and rainfali are studied. There were large differences in the average annual values for ah these parameters: yields varied between 26.6 and 92.1 quintals/ha; hectohiter weights, between 75.3 and 82.6; P. graminis infections, between traces and 47.4%; P. recondita infections, between 0 and 20%; P. striiformis infections, between traces and 8.5%; notes (0-absence; 10-maximum infection) on BYDV infection, between 0 and 10; notes on aphid infestation, between 1 and 8.
The main factors modifying yleid, in order of importance, were:
1. Date of sowing: years with early sowings gaye better yields;
2. BYDV: years with higher infectations produced lower yields; and
3. Aphids: years with larger infestations gaye lowsr yields.
Rainfali, hectohiter weight, commulative degree-days (base 5ºC), and P. graminis infections, showed no influence on yield.