Objectives In order to establish a high efficiency peanut cultivation technology system for water and fertilizer saving, this paper studied the effect of different topdressing timings and frequencies on peanut growth and yield under underneath film mulched drip fertigation. Based on the results, it was determined the suitable topdressing timings and frequencies for high-yield peanut under mulched drip fertigation, and explored a high-efficiency integrated water and fertilizer management mode for peanut production.
Methods A field experiment was conducted using peanut cultivar of Arachis hypogaea Linn. cv. Qinghua7 as material in Jiaozhou Modern Science and Technology Demonstrative Plantation of Qingdao Agricultural University in 2017. Plastic film was mulched on one ridge and a drip irrigation tube was underneath for 2 rows of peanut water supply. Taking no fertigation as control (CK), seven topdressing treatments were set with the same amount of fertilizer, they were: once topdressing in needling period (N), in podding period (P) and in full fruiting period (F), and twice topdressings in needling + podding periods (NP), in needling + full fruiting periods (NF), and in podding + full fruiting periods (PF), and thrice topdressings in needling + podding + full fruiting periods (NPF). Seven samplings were made at 1 day before flower needle stage fertigation and 12 days after, 1 day before podding stage fertigation and 12 days after, 1 day before full fruiting stage fertigation and 12 days after, and harvest period. Needle number intruding soil surface and that still stagnated on ground and fruit number per plant of peanut under different topdressing treatments were investigated and analyzed, and the pod yield, 100-pod weight, 100-seed weight, valid pod number, seed weight per plant and shelling percentage were measured at harvest time.
Results As to topdressing timing, the effect of topdressing in the flowering needle period was better than that in pod-setting and full fruiting periods, but as for the topdressing frequency, the effects of twice or thrice topdressings were better than once. In case of once topdressing, treatment N made the highest yield, next to it was P and the lowest was F. Compared to CK, the yield increased by 18.3%, 15.4% and 8.1%, respectively. As for twice topdressing, the highest yield increase was with NP, followed by NF and the lowest was PF. Their yields were increased by 38.0%, 23.7% and 19.7% respectively. The yield under NPF was increased by 26.5%. Compared to CK, the peanut 100-pod weights in treatment N, P, F, NP, NF, PF and NPF were increased by 5%, 6%, 7%, 15%, 11%, 11% and 15%, respectively; 100-seed weights increased by 1%, 3%, 2%, 5%, 5%, 6% and 7%, respectively; the pod number per plant increased by 23%, 21%, 17%, 51%, 30%, 36% and 49%, respectively; seed weights per plant increased by 14%, 21%, 18%, 43%, 23%, 27% and 30%, respectively; and percentage of shelling increased by 5%, 2%, 2%, 5%, 3%, 3% and 5%, respectively.
Conclusions Under the conditions of this experiment, earlier and more frequencies of topdressing are conducive to promote the fruit needle formation and intrusion, thus lead to higher biomass and pod yield. Considering the cost and benefit of topdressing, twice topdressings in flowering needle and pod-setting periods is recommended as a high-efficient fertigation measurement for peanut production.
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