Prohexadione-Calcium and Nitrogen Topdressing Fertilisation on Productive Performance of Maize with Late Sowing

Background: The growing use of nitrogen topdressing fertilisation, combined with late sowing of maize crops, causes greater sensitivity to lodging and breaking of plant stems, and poses risks to yield and grain quality. Thus, plant growth retardants are currently an option to mitigate losses resulting from adverse effects.

Aims: The objective of this work was to evaluate the influence of using the plant growth retardant prohexadione-calcium (Pro.Ca) in response to application of different nitrogen levels on morphometric and productive characteristics of maize after late sowing.

Study Design: The experiment used a randomized block design (RBD) with four replications.

Place and Duration of Study: The field research was conducted at Lages, Santa Catarina State, Brazil, in Santa Catarina State University farm (27° 52’S; 50° 18’E and 930 m elevation), from February to June of 2017.

Methodology: The treatments were composed of two levels of nitrogen: 135 and 270 kg N ha-1, and three doses of the plant growth retardant Pro.Ca: 0, 100 and 200 g a.i. ha-1.

Results: The results showed that the tested nitrogen levels significantly affected (P = .05) ear height and plant height while number of grains per spike, stem diameter, thousand-grain weight and final yield were not affected (P > .05). The 135 kg of N ha-1 (100% level) show better results for agronomic traits of maize. The plant growth retardant Pro.Ca applied on maize plants at V12 stage at a 100 g a.i. ha-1 lead to a decrease in 8.9% and 5.3% in plant and ear height, respectively, which point to its use with high level of nitrogen topdressing fertilisation associated with Pro.Ca to avoid excessive vegetative growth in plant and ear height, maintaining the yield component number of grains per ear and final yield.

Conclusion: The recommended dose of nitrogen (135 kg ha-1) topdressing a V4 stage are adequately for achieve higher grain yield and plant height at late sowing; but Pro.Ca (100 g a.i. ha-1, applied at V12 stage) can effectively retard maize plant growth, which results in shorter plants with lower ear height, without affecting grain yield; which helps to minimise the occurrence of breaking and lodging of the stem.