Effects of Cultivation Measures on Crude Fat Content and Yield of Silage Maize

Yield and quality are two indispensable evaluation factors for silage maize varieties. The quality of silage corn is usually judged by using crude protein content, crude fat content, crude fiber content, nitrogen-free extract and ash content, etc. to determine the nutritional quality of the feed. There are certain deficiencies in this evaluation method. At present, the quality of silage corn is generally classified internationally based on nutrient content, type of cellulose, and animal ex vivo experiments. Commonly used indicators include crude protein content, starch content, neutral and acidic detergent fiber content, lignin content, and Body digestion and cell wall digestion. The crude protein content can be determined by a protein analyzer, crude fat can be measured by a crude fat analyzer, and crude fiber can also be measured by a fiber analyzer. Cultivation measures are important factors affecting the yield and quality of silage corn. The research results at home and abroad show that fertilization has a significant effect on the nutritional quality of corn kernels. In the aspect of the response of the nutritional quality of silage corn to the density and fertilizer, the previous studies are not yet systematic, and the mechanism is not yet clear. This experiment adopted a 3-factor optimal saturation design to study the relationship between N, P and planting density and the crude fat of silage maize at different harvesting stages. The effect of 3 factors on crude fat content and yield of silage corn was simulated by regression. High-yield and high-quality cultivation of silage corn provide theoretical basis.

1 Materials and Methods

1.1 Basic conditions of the test site

The experiment was conducted at the Horticultural Science and Technology Experimental Center in Hohhot in 2005. The soil was a sandy loam soil with a deep soil layer. The basic fertility conditions were: organic matter 1.34%, alkaline dissolved nitrogen 31.25 mg/kg, available phosphorus 16.13 mg/kg, effective potassium 146.25 mg/kg. The maximum water holding capacity in the field is 22.5% and the pH value is 7.7.

1.2 Test Materials and Design

The tested variety was corn silage Jinkun No. 9. The experimental design included three factors of nitrogen application rate (pure N), phosphorus application rate (P2O5) and planting density (D), and 5 levels, with 311-A saturated design and 12 treatment combinations (Table 1, Table 2). Repeat 3 times for a total of 36 trial plots with an area of ​​15 m2 per plot and a 50 cm spacing. The sowing date was April 28, and 22 500 kg/hm2 of organic fertilizer was applied before sowing. Phosphate fertilizer was applied as a base fertilizer at the same time as the sowing, and urea was applied at the small bell mouth stage and the big bell mouth stage according to the total amount of fertilization. % and 70% topdressing, combined with top dressing irrigation during the fertility period 3 times, other management measures with ordinary corn field.

1.3 Sampling and Measurement Methods

Sampling methods: On August 11th, August 26th and September 12th respectively, select 2 m2 representative sampling sites among all treatment plots, harvest all the plants, measure their ear, straw and whole plant fresh weight, and Samples were taken from each organ, and the samples were fixed at 105°C for 30 minutes, then dried at 80°C until constant weight, and samples were taken for nutrient analysis. Measurement method: The crude fat was measured by using the residue (slag) method. Data Analysis: All experimental data were analyzed using SPSS (11.0) statistical analysis software.

2 Results and Analysis

2.1 The relationship between cultivation measures and crude fat content

The results of quadratic regression fitting (Table 3) on the results of the whole plant crude fat content at different harvest periods (Table 3) showed that there was a significant correlation between crude fat content and N, P, and density on August 11. On August 26 and September 12, the test values ​​of the regression equation and the regression coefficient did not reach a significant level, indicating that the crude fat content and the N, P, and plant density individual factors were not closely related. From the test value of regression coefficient t, we can see that at the grain filling stage, N is not significantly related to crude fat content; NP interaction, N density interaction, and crude fat content are not significantly related. At milk ripening stage, N and P single factor had no significant correlation with crude fat content; N density interaction had no significant correlation with crude fat content.

According to the partial regression coefficients and t-values ​​of the primary and secondary terms (Table 5), the relationship between N, P and the single factor of planting density on crude fat content was harvested on August 11 as P(X2)>N (X1 )> Density (X3); Harvested on August 26 as P(X2)> Density (X3)> N(X1); Harvested on September 12 as density (X3)> N(X1)> P(X2). Two-way interaction effect, harvested on August 11 as NP>N density>P density; harvested on August 26 as NP>N density>P density; harvested on September 12 as N density>NP>P density.

It can be seen from Figure 1 that during the three harvest periods, the effects of N, P and planting density on the fat content of the single factor varied with the harvest period. During the loose-flying period, with the increase of N application, the crude fat content showed an increasing trend, and the increase rate gradually decreased. With the increase of P application amount, the trend showed a downward trend, and the greater the P application amount, the more significant the decline was. At this stage, harvest, density The effect on the crude fat content was the smallest, and with the increase of the density, the crude fat content showed a decreasing trend, and the decreasing range gradually decreased. During the grain-filling and milk-mature stages, the crude fat content showed a “unimodal” curve as the N application rate increased. The peak values ​​were 1.23% and 1.47%, respectively, and the optimal application rates for N were 210 kg/hm2 and 165 kg/hm2. During the grain-filling period, the crude fat content showed a downward trend with the increase of application P amount, and the decrease rate gradually decreased; during the milk-maturing period, the crude fat content showed a “unimodal” curve change with the increase of application P amount, with a peak value of 1.46%. , The corresponding optimum application amount is 144 kg/hm2. At the grain-filling and milk-mature stages, the crude fat content changes with the density and shows a "U"-shaped curve.

It can be seen that the crude fat content is not only affected by the N, P and planting density 3 factors, but also by the harvest period. In this experiment, during the loose-powder stage, the highest crude fat content was observed under high N, medium P, and low density conditions, and the crude fat content was highest under medium N, low P, and low density conditions during the grain-filling period; Under medium N, medium P, and low density conditions, the crude fat content is the highest.

2.2 Relationship with crude fat production

The results of the quadratic regression fitting (Table 6 and Table 7) of the crude fat yield at different harvest stages showed that the test value of the regression equation and the regression coefficient did not reach a significant level, indicating that among the three factors affecting crude fat production, Individual factors are not significantly related to crude fat production. On the 11th of August, there was no significant correlation between N, density, single factor and crude fat yield; P density interaction was not significantly related to crude fat production. Harvested on August 26, P had no significant correlation with crude fat production; N density interaction, P density interaction and crude fat yield were not significantly related. On September 12th harvest, N and P single factors were not significantly correlated with crude fat yield; P density interactions were not significantly related to crude fat production.

From the partial regression coefficients and t-values ​​of the primary and secondary terms (Table 7 and Table 8), the relationship between N, P, planting density, single factor, and crude fat production was obtained on August 11 and September 12. Density (X3)>P(X2)>N(X1); Harvested on August 26 as P(X2)>N(X1)>density (X3). The two-factor interaction effect was harvested on August 11 and August 26 as NP>N density>P density; on September 12, the harvest was N density>NP>P density.

As can be seen from Figure 2, in the three different harvest periods, the crude fat production showed a “single-peak” curve change with the increase of N and P application rates. The peak value is the highest value of crude fat production, and the corresponding code value is the best effect value of the fertilizer. Under the experimental conditions, the optimum N application amount was 225, 165, and 225 kg/hm2 as the harvest period was postponed, and the highest yields of crude fat were 170, 185, and 375 kg/hm2, respectively; At 128, 64, and 144 kg/hm2, the highest crude fat yields were 170, 188, and 388 kg/hm2, respectively. During the loose-grained and grain-filling stages, the impact of density on crude fat production was not significant. During grain filling and milk ripening, crude fat production decreased significantly with increasing density.

3 Conclusions and discussions

Fertilizer and density are the main cultivation measures for the high yield and high quality of silage corn. Chen Gang (1989) pointed out that planting density has a significant effect on the dry matter content and fat content of corn silage. At high densities, both dry matter content and fat content are relatively high. Under specific production conditions, higher planting densities are necessary if the digestibility does not decrease significantly as the planting density continues to increase (Greg, 1998). For corn planted as feed, the density of seedlings in the field is required to be 75 000-90 000 plants/hm2, and for silage corn is required to be 105 000-120 000 plants/hm2 (Zhou Fengshan, 1997). This experiment studied and established a regression model of planting density, N application rate and P application amount, and crude fat content and yield of silage maize at different harvesting stages. The effect analysis of each factor showed that N, P, and density are important factors affecting crude fat content and yield. As the harvest period is delayed, the effect of density and N on the content of crude fat gradually increases, and the effect of P gradually decreases. The effect on crude fat production varies with different harvest periods. Harvesting at loose and milky stages showed density (X3)>P(X2)>N(X1); harvesting stage showed P(X2)>N(X1)>density (X3). In general, with the increase of N and P dosages, the whole fat content and yield of the whole plant of silage maize showed a single-peak curve change, and it decreased slightly with the increase of the density.

In the experimental planting density range, the appropriate N application rate was 165-225 kg/hm2, and the P application rate was 65-140 kg/hm2, which could yield 170-390 kg/hm2 higher crude fat yield. This standard can be used as reference fertilization for silage maize production in Hohhot.