Abstract
Faba bean frequently alter the structure and size of their canopy as a consequence of environmental factors. This peculiarity has been taken into account to handle the little information regarding how growth and yield of faba bean respond to significant changes in plant density and how these changes affect yield potential and economic return. The seeds of two faba bean varieties (Giza 716 and Giza 843) were cultivated around the emitters of a drip irrigation system at five densities (4, 6, 8, 10 and 12 plants dripper(-1)). The results showed that the relative growth rate, net assimilation rate, total dry weight per plant and leaf area per plant gradually increased with increasing plant density up to 8 plants dripper(-1) and significantly decreased with 10 and 12 plants dripper-1; however, increasing plant density increased the plant height and decreased the number of branches per plant. The highest leaf area duration and leaf area index were found at 8 plants dripper-1, while the lowest were found at 4 plants dripper(-1). While yield components of individual plants tend to significantly decrease with increased plant density, seed yield per hectare significantly increased with increasing plant density up to 8 plants dripper(-1) and slightly decreased with 10 and 12 plants dripper(-1). Crop production functions with respect to the number of plants per dripper versus all the attributes measured exhibited strong quadratic relationships with the exception of the yield components of individual plants, which exhibited a strong linear relationship. Seed yield per hectare showed a strong relationship with crop growth and vegetative growth parameters but not with the yield components of individual plants. Finally, when the plant densities were converted to seeding rates, simulations indicated that 118.0 (6 plants dripper(-1)) and 118.8 kg ha(-1) (8 plants dripper(-1)) for branched (Giza 716) and non-branched (Giza 843) varieties, respectively, were adequate to lower seed cost without reducing net profit.