Border effects enhance lodging resistance of spring wheat in narrowing-row-space enlarged-lateral-space drip irrigation patterns

Lodging results in severe yield loss and harvest difficulty in wheat production, especially in the drip-irrigation technique dominated wheat system in arid area of North-west China. We assume that our previously developed enlarging lateral space (ELS) drip irrigation pattern benefits plant lodging resistance due to the enlarged border row space (BRS) by narrowing row space (NRS). In a three-year field experiment, we compared spring wheat lodging resistance of the ELS patterns with the conventional drip irrigation pattern of TR4 (one drip tube serves plant rows (TR) of four, with normal row space (RS) of 15 cm, as control). Six ELS patterns included the normal ELS patterns of TR6 and TR8 (expanding TR from four to six and eight, with normal RS of 15 cm), large BRS ELS patterns of TR6L (BRS of 35 cm) and TR8L (BRS of 45 cm) by narrowing RS to 10 cm, and shorter BRS ELS patterns of TR6S and TR8S with BRS of 25 cm and RS of 10 cm. The normal ELS patterns with even RS (TR6 & TR8) (10.82–48.21%) significantly increased lodging rate as compared with TR4 (7.22–42.41%). Reversely, patterns with broadened BRS effectively reduced lodging rate (5.62–39.55% for TR6L & TR8L, 6.18–41.73% for TR6S & TR8S). The much improved lodging resistance of the outermost or the border rows essentially contributed to the much lower lodging rate of the modified ELS patterns. The border plants in the modified ELS patterns performed higher photosynthesis of leaf and lignin content in basal stems, subsequently increased stem pole substantial degree and finally improved stem mechanical properties. In addition, the modified ELS patterns also optimized accumulation and redistribution of dry matter in stems in the outermost rows. Therefore, the modified ELS drip irrigation patterns via NRS which leaved border effects were recommended as low lodging risks approach towards stabilized wheat productivity, of which TR6S was strongly recommended.