ABSTRACT
A split plot experiment was conducted in greenhouse to investigate the effects of irrigation lower limit and maize straw returning on the yield, quality, and water use efficiency (WUE) of tomato. Maize straw was applied for 1 (2018, A1), 2(2017, A2), and 3 (2016, A3) years at different amounts (0, 1.5×104, 3×104, 4.5×104 kg·hm-2) and different irrigation lower limits (50%θf, 60%θf, 70%θf, 80%θf, θf was the field water capacity). Variance analysis, entropy-weight and TOPSIS methods were used to examine the responses of yield, quality and water use efficiency (WUE) of tomato. The results showed that tomato yield was enhanced by the increases of irrigation lower limit. The maximum value of yield was observed in the 80%θf treatments, with the maximum average yield of 93.55 t·hm-2 in A1, 87.23 t·hm-2 in A2, and 99.34 t·hm-2 in A3, respectively. WUE and quality of tomato decreased with increasing irrigation lower limit. In the first year of straw returning, the maximum average yield of tomato was 99.60 t·hm-2 in straw returning 1.5×104 kg·hm-2 . In the second and third years, 4.5×104 kg·hm-2 straw returning had the highest average yield of tomato, which was 92.50 and 107.75 t·hm-2, respectively. The maximum WUE was observed with the straw returning of 1.5×104 kg·hm-2 in A1 and A2, while in the A3 treatment it happened in straw returning of 4.5×104 kg·hm-2. The quality index of tomato showed different trends with the increases of straw returning years and amount.
Subject(s)
Solanum lycopersicum , Water , Agricultural Irrigation , Agriculture , Fertilizers , Soil , Zea maysABSTRACT
Based on the greenhouse experiment in Shenyang, the growth, development, and yield formation of tomato under different irrigation levels were simulated by growth model DSSAT-CROPGRO-Tomato. The optimal scheme of parameter estimation and model validation was determined. There were four treatments in this experiment. Irrigation upper limit of whole growth season was set as field capacity, while the lower limit was 50% (W1), 60% (W2), 70% (W3), and 80% of field capacity (CK), respectively. The relevant genetic coefficients were estimated by DSSAT-GLUE, a program package for parameter estimation in DSSAT. The differences between simulated and observed values of phenological phase, canopy height, shoot dry matter, tomato fresh mass, leaf area index (LAI), and soil moisture were analyzed to determine the accuracy of simulation. The results showed that the estimated value of genetic parameter of tomato (thermal time for final pod load appeared greater variability under optimal genetic coefficient of tomato, PODUR) had large variability, with the coefficient of variation being 11.5%. When the CROPGRO-Tomato model was applied to the greenhouse in different regions, the PODUR should be estimated adequately. Otherwise, the accuracy of simulation would be affected. In the process of model application, the observation data of sufficient irrigation treatment should be selected for estimating genetic parameters, which could improve the simulation precision. The absolute relative error and standard root mean square error were 8.7% and 10.5%, respectively. The simulation results of LAI and soil moisture showed that the higher the irrigation level was, the higher accuracy of simulation was. By leave-one-out cross validation, the overall error validation ranged from 10.5% to 12.5%. Our results indicated that the growth, development, and yield formation of tomato could be accurately simulated by DSSAT CROPGRO-Tomato model under different irrigation conditions in Shenyang greenhouse.
Subject(s)
Solanum lycopersicum/growth & development , Agricultural Irrigation , Plant Leaves , Soil , WaterABSTRACT
A codon-optimized Escherichia coli appA phytase gene was synthesized and expressed in Pichia pastoris. Two residue substitutions (Q258N, Q349N) were sequentially introduced to enhance its glycosylation activity. Secretion of appA-Q258N/Q349N was approx. 0.3 mg ml(-1) and enzyme activity reached 1,030 U ml(-1). Purified appA-Q258N/Q349N had a specific activity of 3,137 U mg(-1) with an MW of approx. 53 kDa. Compared with appA-WT, appA-Q258N/Q349N showed over 40 % enhancement in thermostability (85 °C for 10 min) and 4-5 °C increases in the melting temperatures (Tm). The Km and Kcat of appA-Q258N/Q349N were 0.43 mM and 3,058 s(-1), respectively, which are similar with that of appA-WT. The mutant appA-Q258N/Q349N obtained in this study could be used for the large-scale commercial production of phytase.
