Abstract:

A 3-year experiment was conducted to investigate the change pattern of daily yield and its response to sunlight duration and air temperature with different phosphorous rates during cucumber growing season under greenhouse condition. The formation of yield peak，the growth period for nutrient use with the highest efficiency and the appropriate phosphate rate were discussed in order to solve the problem of excessive application of phosphorus in greenhouse production in the North China Plain. Three treatments were designed in this experiment，including a non-phosphorus control（P0），a recommended phosphorus rate（P1）and a farmers’ conventional phosphorus rate（P2）. Based on the basic soil Olsen-P content，the abundance index of soil phosphorus and the target yield，the phosphorous rate was recommended as P₂O₅ 300 kg · hm^-2 in the P1 treatment. Based on the average amount of phosphate applied by farmers planting greenhouse cucumber in Hebei Province，the phosphorus rate of the P2 treatment was designed as P₂O₅ 675 kg · hm^-2. The results showed that：（1）quadratic curve was used for describing the daily yield formation during 3 years：the daily yield peak was observed in 97–104 days after transplanting with the accumulated air temperature（8 am，≥ 10 ℃）1 389.4–1 849.6 ℃ and the accumulated sunlight duration 629.0–866.8 h：the average daily temperature was 23–27 ℃ and the estimated active accumulated air temperature was 1 650–2 050 ℃ at this point.（2）Although 56% of phosphate was reduced，the soil phosphorus supply in the P1 treatment was sufficient for yield formation and no significant change was observed in the yield peak and the total yield compared to the P2 treatment. （3）The yield peak was postponed for 16 days and close to the vine removed stage in the P0 treatments compared to the P2 treatment in 2009，which indicated that continuous non-phosphorus application leaded to the delay of the fruit maturation when high yield was formed. In conclusion，for winter-spring cucumber，the growing stage for nutrient utilization with the highest efficiency was considered from the end of May to the early June，because of forming yield peak during this period. Sufficient fertilizer and water application would be helpful to improve nutrient use efficiency during this period. For the greenhouse with the similar test condition，applying P₂O₅ 300 kg · hm^-2 for the target yield of 170 t · hm^-2，would guarantee no change of the yield peak and the total yield and to reduce over 50% phosphate compared to the farmers’ conventional management.

Key words: cucumber, winter-spring, yield formation, yield response to sunlight duration and air temperature, the growing period of nutrient use with the highest efficiency, phosphate rate