Narrowing row space improves productivity and profit of enlarged lateral space drip irrigated spring wheat system in Xinjiang, China

Abstract

Enlarging lateral space (ELS) saves cost of drip tubes, however, it is challenged by risks of heterogeneity of productivity between different rows of plants in drip irrigated wheat systems. In a two-year field experiment, we expanded the number of wheat rows served by single drip tube (TR, one Tube serves number of wheat Rows) from four (TR4) to six (TR6) and eight (TR8). To maximize grain yield and profit, we modified the ELS patterns by narrowing plant row space (NRS) and shortening inter-block space between planting blocks (SIBS). We then performed six ELS patterns, including normal ELS patterns with row space of 15 cm (TR6 and TR8), narrowed row space of 10 cm with large inter-block space (TR6L and TR8L), narrowed row space of 10 cm with shortened inter-block space (TR6S and TR8S). Compared with TR4 (control), the normal ELS patterns (TR6 and TR8) resulted in yield loss of 5.60–13.75% and WUE reduction of 6.93–15.89% due to the weak performances of plants distant to the drip tube, with a profit loss of 1.03–8.71%. NRS (TR6L and TR8L) caused yield and WUE reductions of only 1.85–10.71% and 2.92–12.41%, and received net profit increase of 0.44–5.07%. NRS in combination with SIBS (TR6S and TR8S) received the best yield and WUE, and much better profit than TR4. The overall yield was closely correlated to yield performance of plants distant to drip tube, though the later received much less irrigation water than the 1st row adjacent to the drip tube (R1). Moreover, the dry matter pre-stored in vegetative organs before anthesis which was further redistributed into grains during grain filling, was improved to well compensate the much less received irrigation water (RIW) in the distant rows to drip tube under ELS patterns. The modified ELS patterns performed better soil water status in distant rows in relation to the normal ELS patterns of TR6 and TR8. The marginal effect also conferred the improved grain yield and WUE to distant rows. In conclusion, narrowing row space in combination with shortening inter-block space were recommended in the enlarged lateral space drip irrigated wheat system in terms of better yield, WUE and profit.