Sorghum (Sorghum Bicolor L. Moench) yield compensation processes under different plant densities and variable water supply

Sorghum, which is tolerant to high temperatures and drought, can be an alternative crop to maize in marginal irrigated areas where the irrigation water supply is limited during crop development. The objective of this work was to study the productive response and the compensation phenomena between the sorghum yield components sown at four densities under variable water supply in the climatic conditions of the Middle Ebro Valley (Spain). The technique of the sprinkler line source was used. This technique produces a continuous and diminishing gradient of water applied. The results showed that the differential irrigation treatments significantly affected the productive parameters and the grain yield of sorghum. Water stress produced a decrease of the seasonal evapotranspiration, total dry matter, grain yield and harvest index. The relationships between the total dry matter, grain yield and harvest index versus the seasonal irrigation water applied was linear in the four sorghum plant densities. The different established plant densities did not significantly affect sorghum aerial dry matter, grain yield and harvest index. The results showed that important yield compensation processes occurred when the sorghum crop was grown under limited conditions of irrigation water and plant population. In fact, a greater tiller production, a greater number of grains per panicle and a higher weight of grains compensated the smaller number of plants per m2 of the lower plant densities. These results indicated that a high plant density did not present productive advantages in the sorghum grain yield.