Improved Water-use Efficiency in Dryland Grain Sorghum by Promoted Plant Competition
1976
Blum, A. | Naveh, M.
Field experiments evaluated the hypothesis that competition-suppressed plant growth might improve the water-use efficiency and yield of dryland grain sorghum [Sorghum bicolor (L.) Moench.] grown on stored soil moisture. Plant competition was promoted by planting sorghum in double rows (DR), i.e., 40 cm between rows within a pair, and 160 cm between row pairs, as compared with regular-spaced rows (RR) (100 cm between rows), with the same number of plants/unit area. The effect of competition in DR was observed, beginning at 20 to 35 days after emergence, in reduced total stover dry matter/plant, and reduced tillering and LAI, as compared with the RR arrangement. In two out of four experiments, grain yield was significantly increased by DR configuration, as compared with RR, and was associated with a reduced number of panicles/plant, and an increased number of grains/panicle and 1,000-grain weight. Leaf water potential prior to the grain-filling period did not differ between treatments. During the grain-filling period, leaf water potential was significantly lower in RR than in DR plants. Leaf diffusive resistance prior to the grain-filling period was significantly higher in DR than in RR plants, during late afternoon. During grain-filling period, leaf diffusive resistance was significantly higher in RR than in DR plants, beginning at noon. During the boot to full bloom growth stages, less soil water was extracted in DR than in RR plots. Consequently, more soil water was available in DR plots during the grain-filling period.
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