Qiang LI,Puxing LIANG*,Baige ZHANG,Biao LIANG,Xiangni LI

1.Foshan Institute of Agricultural Science/Foshan Promotion Center of Agricultural Technology,Guangdong 510640,China;2.Vegetable Research Institute,Guangdong Academy of Agricultural Science,Guangzhou 510640,China

Luffa acutangulaRoxb.,a major luffa species,is one of characteristic vegetables grown in South China.It is a genus of vines with green ridges,yielding highly.It tastes sweet and crisp,and is cooked in various dishes.Therefore,it is one of popular vegetables in summer and autumn,dominating vegetable production in South China[1-3].

Fertilization effect is a basic work of standardization production of luffa.The research conducted"3414"fertilization effect in farmlands to determine the relationship of nutrient supplying capacity and demanded fertilizer quantity of crops and concluded the fertilizer quantity should be applied in Foshan,providing references for scientific fertilization and formulated fertilizer of luffa in Foshan.

Materials and Methods

Test materials

Luyuan luffa was determined as test materials and the test was conducted in Datang Town,Sanshui District,Foshan City.Datang Town is a major vegetable producing area in Foshan.

Test soils contained 82.9,37.2 and 134.9 mg/kg available N,available P and available K,with pH of 7.58[4-7].

Design of experimental scheme

According to"3414"test scheme,the research designed three fertilization factors (N,P and K)and 4 fertilization quantities for each fertilizer(Table 1).With consideration of local fertilization quantity and pre-experiment,the research proposed target yield of 37 500 kg/hm2and N,P2O5and K2O fertilizers were designed at 240,180 and 202.5 kg/hm2.The test plot has an area of 20 m2and planting spacing was 0.60 m×0.60 m.Besides,the test was conducted as per randomized block design with three replications.

Data analysis

The test data were analyzed with Excel 2007 and SG2.2.

Results and Analysis

Yield-increasing effects of fertilizers

N fertilizer effectIn the treatment of N0P2K2,luffa yield reached 31 747.95 kg/hm2,increasing by 24.55% compared with the control(N0P0K0)and the treatments N1P2K2,N2P2K2and N3P2K2grew by 45.93%,53.36% and 54.07%,respectively, which indicated that yield-increasing effect is so significant within a certain range,but the latter two treatments increased not so much.

P fertilizer effectIn the treatment of N0P0K2,luffa yield reached 38 816.1 kg/hm2,increasing by 52.28% compared with the control(N0P0K0)and the treatment without P,the treatments N2P1K2,N2P2K2and N2P3K2grew by 53.23%,53.36% and 52.42%,respectively.Besides,the treatment N2P0K2grew significantly;the treatments N2P1K2and N2P2K2increased fairly;the treatment N2P3K2declined a little.These indicated that P fertilizers had insignificant effects on luffa yield,and the yield even decreased when excessive P fertilizers were applied.

K fertilizer effectIn the treatment of N2P2,luffa yield reached 38 853.30 kg/hm2,increasing by 52.43% compared with the control(N2P2K0)and the treatments N2P2K2and N2P2K3grew by 53.36% and 53.93%,respectively.Besides,N2P2K2increased more than that of treatment N2P2K0,and thegrowth of treatment N2P2K3declined compared with N2P2K2.

Table 1 Experimental scheme of luffa fertilization kg/hm2

Comparisons of economic benefits by different fertilization quantities

Economic benefits from N fertilizerAs shown in Table 2,yields grew by 42.35,30.59 and 20.91 kg in N1P2K2,N2P2K2and N3P2K2contributed by 1 kg nutrient,respectively.Besides,output value reached 127.05,91.77 and 62.73 yuan,and the increased benefits were 15.88,5.74 and 2.61 yuan by every unit nutrient.It can be concluded that economic benefits of N fertilizer in low quantity keeps higher than that in high quantity.Therefore,it is necessary for increasing yield to control N fertility quantity in a rational range.

Economic benefits from P fertilizerAs shown in Table 2,yield increased by 16.13 kg and output value increased by 48.39 yuan in N2P1K2contributed by per unit nutrient,indicating the enhanced benefits reached 8.06 yuan by nutrients per unit.In N2P2K2,yield increased by 18.28 kg and output value increased by 54.84 yuan contributed by per unit nutrient,indicating the enhanced benefits reached 4.57 yuan by nutrients per unit.In N2P3K2,yield almost grew none by per unit nutrient.However,compared with N fertilizer,economic benefits increased less by P fertilizer.

Table 2 Averaged yield and economic benefits in different areas under experimental schemes

Economic benefits from K fertilizerAs shown in Table 2,yield increased by 15.8 kg and output value increased by 47.4 yuan in N2P2K2contributed by per unit nutrient,indicating the enhanced benefits reached 3.51 yuan by nutrients per unit.In N2P2K3,yield increased by 8.46 kg and the enhanced benefits reached 1.25 yuan by nutrients per unit.Compared with N fertilizer,yield-increasing effect was not so significant,and high quantity of K fertilizer would reduce the rate of return.

Analysis on fertilizer response equation

It was analyzed that yield-increasing range of N fertilizer was directly proportional to fertilizer quantity,and negative yield even occurs if excessive P fertilizer is applied.In general,fertilizer effects from high to low were N fertilizer＞K fertilizer＞P fertilizer.On basis of"3414"experiment,regression analysis was conducted on relative yield and fertilizer quantity,and a regression equation was established,as follows:Y=1 699.09+52.89N-3.82P+59.27K-1.17N2-0.11P2+0.06K2+2.02NP-2.16NK-1.97PK (R2=0.98).The results ofregression analysis showedF＞F0.05,indicating that fertilizer quantity is of significant regression relationship with yield.Besides,based on equation analysis,it was proposed the optimal fertilizer quantities included N fertilizer(N)of 270 kg,P fertilizer(P2O5)of 165 kg and K fertilizer(K2O)of 225 kg for achieving ideal yield of 2 500 kg/hm2of luffa in Foshan.

Conclusion and Discussion

Currently,traditionalcultivation model featured by excessive water and fertilizer still dominates in luffa producing areas in Foshan,without high-quality and high-yield safe cultivation technology.Consequently,products available tend to be volatile in terms of quality and economic benefits are lower,which disappoints farmers.In contrast,soil testing and formulated fertilization would effectively resolve the conflicts of fertilization with fertilizer supplements and demanded fertilizer to improve economic benefits and yield by supplying missing nutrient elements of crops specifically.

The research analyzed yield-increasing effect and economic benefits of luffa production in Foshan and established a fertilization index system.What’s more,it was concludedY=1 699.09+52.89N-3.82P+59.27K-1.17N2-0.11P2+0.06K2+2.02NP-2.16NK-1.97PK(R2=0.98)and concluded N fertilizer(N)of 270 kg,P fertilizer(P2O5)of 165 kg and K fertilizer(K2O)of 225 kg for achieving ideal yield of 2 500 kg/hm2of luffa in Foshan.For luffa,vegetative growth and reproductive growth proceed simultaneously,and the required fertilizers would be higher.Besides,soil conditions differ in Foshan,and attention should be paid to N fertilizer in barren areas.

In addition,the research concluded that P and K fertilizers have little effects on luffa yield than that of N fertilizers,which coincides with researches made by Houet al[8].In early stage,especially in peak-fruiting stage,more N fertilizer would reduce yield.In production,it is recommended to apply P and K fertilizers as base fertilizer to reduce fertilization time and production cost and improve production benefits.

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