Ridge-furrow rainwater harvesting (RFRH) planting pattern can lessen the effect of water deficits throughout all crop growth stages, but water shortage would remain unavoidable during some stages of crop growth in arid and semiarid areas.  Supplemental irrigation would still be needed to achieve a higher production.  Field experiments were conducted for two growing seasons (2012–2013 and 2013–2014) to determine an appropriate amount of supplemental irrigation to be applied to winter oilseed rape at the stem-elongation stage with RFRH planting pattern.  Four treatments, including supplemental irrigation amount of 0 (I1), 60 mm (I2) and 120 mm (I3) with RFRH planting pattern and a control (CK) irrigated with 120 mm with flat planting pattern, were set up to evaluate the effects of supplemental irrigation on aboveground dry matter (ADM), nitrogen nutrition index (NNI), radiation use efficiency (RUE), water use efficiency (WUE), and seed yield and oil content of the oilseed rape.  Results showed that supplemental irrigation improved NNI, RUE, seed yield and oil content, and WUE.  However, the NNI, RUE, seed yield and oil content, and WUE did not increase significantly or even showed a downward trend with excessive irrigation.  Seed yield was the highest in I3 for both growing seasons.  Seed yield and WUE in I3 averaged 3 235 kg ha^–1 and 8.85 kg ha^–1 mm^–1, respectively.  The highest WUE was occurred in I2 for both growing seasons.  Seed yield and WUE in I2 averaged 3 089 kg ha^–1 and 9.63 kg ha^–1 mm^–1, respectively.  Compared to I3, I2 used 60 mm less irrigation amount, had an 8.9% higher WUE, but only 4.5 and 0.4% lower seed yield and oil content, respectively.  I2 saved water without substantially sacrificing yield or oil content, so it is recommended as an appropriate cultivation and irrigation schedule for winter oilseed rape at the stem-elongation stage.

The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrogen use efficiency (NUE) of drip-irrigated greenhouse tomatoes in northwestern China.  The plants were irrigated every seven days at various proportions of 20-cm pan evaporation (E_p).  The experiment consisted of three irrigation levels (I1, 50% E_p; I2, 75% E_p; and I3, 100% E_p) and three N application levels (N1, 150 kg N ha^–1; N2, 250 kg N ha^–1; and N3, 350 kg N ha^–1).  Tomato yield increased with the amount of applied irrigation water in I2 and then decreased in I3.  WUE and IWUE were the highest in I1.  WUE was 16.5% lower in I2 than that in I1, but yield was 26.6% higher in I2 than that in I1.  Tomato yield, WUE, and IWUE were significantly higher in N2 than that in N1 and N3.  NUE decreased with increasing N levels but NUE increased with increase the amount of water applied.  Increasing both water and N levels increased the foliar net photosynthetic rate.  I1 and I2 treatments significantly increased the contents of total soluble solids (TSS), vitamin C (VC), lycopene, soluble sugars (SS), and organic acids (OA) and the sugar:acid ratio in the fruit and decreased the nitrate content.  TSS, VC, lycopene, and SS contents were the highest in N2.  The harvest index (HI) was the highest in I2N2.  I2N2 provided the optimal combination of tomato yield, fruit quality, and WUE.  The irrigation and fertilisation regime of 75% E_p and 250 kg N ha^–1 was the best strategy of water and N management for the production of drip-irrigated greenhouse tomato.