Effects of sowing method, coating condition and sowing date on biomass at flowering stag
Under the same sowing method, there were differences in flowering biomass at different sowing dates ( Table 2 ). Under the condition of equidistant sowing, the biomass of S2 was the highest and the aboveground biomass was 22.58% and 67.15% higher than that of S4 and S5, respectively. The underground biomass was significantly higher than that of S3, S4 and S5, which was 68.38% higher than that of S5. At random sowing, the aboveground biomass of S1 and S2 was significantly higher than that of S3, S4 and S5. Among them, S1 and S2 were 54.57% and 68.84% higher than S5, respectively. The underground biomass S1 was significantly higher than that of the other four sowing dates, which was 105.17%, 481.00%, 453.45% and 705.02% higher than that of the other four sowing dates, respectively. In general, the biomass of single seedling was the highest and the growth rate was the best at S2.Under the same seed coating conditions, there were significant differences in flowering biomass at different sowing dates. When the seeds were coated, the biomass was the highest at S1 and the aboveground biomass was 34.46%, 68.19%, 104.81% and 161.61% higher than other sowing dates, respectively. The underground biomass was 110.51%, 107.50%, 139.09% and 226.40 % higher than other sowing dates, respectively. When the seeds were not coated, the biomass was still the highest when S1 was still the highest. The above-ground biomass was 82.64%, 93.52%, 78.75% and 182.94 higher than other sowing dates and the underground biomass was 108.80%, 149.76%, 129.96% and 238.96% higher than other sowing dates, respectively. On the whole, the biomass of single seedling was the highest and the growth was the best at S1.
At the same sowing date, there were some differences in aboveground and underground biomass between soybean equidistant sowing and random sowing (Table 2). The aboveground biomass of soybean under equidistant sowing was higher than that under random sowing. The increase of aboveground biomass S3 and S5 was the most obvious, which was 10.58% and 4.34%, respectively and the average increase of the five sowing dates was 4.49%.
For underground biomass, the biomass of S1-S5 increased by 5.64% on average. Equidistant sowing could obtain higher and more stable biomass than random sowing and the aboveground and underground biomass of S1-S5 increased by 5.07% on average. At the same sowing date, the biomass of coated soybean seeds was generally higher than that of uncoated soybean seeds. Under the five sowing dates, the average above-ground biomass of coated seeds was 15.23% higher than that of uncoated seeds. The underground biomass of coated seeds was 15.64% higher than that of uncoated seeds.
Effects of sowing date on photosynthetic characteristics of leaves
As shown in Table 3, there were differences in chlorophyll content and photosynthetic characteristics of leaves during different sowing periods. The relative chlorophyll content of SPAD was affected by sowing date. The relative content of S2 was the highest, 17.82% higher than that of the lowest S5. The actual photosynthetic efficiency Phi2 of photosystem II also performed best under s2 condition, which was significantly higher than the observed values of other sowing dates. The initial fluorescence yield F0, the maximum fluorescence yield Fm and the steady-state fluorescence yield Fs fluctuated with the delay of the sowing date and the values were higher at the later sowing date. Fv / Fm, NPQ, phiNO and phiNPQ did not change significantly with sowing date.
Effect of sowing date on yield
As shown in Table 4, the yield of S2 sowing date (5.7) was significantly higher than that of other sowing dates under equidistant sowing and coated seeds, equidistant sowing and uncoated seeds, random sowing and coated seeds. For equidistant planting and coated seeds, the yield of S2 was 9.73%, 10.82%, 17.04% and 41.03% higher than that of S1, S3, S4 and S5, respectively, with an average increase of 19.66%. The yield of equidistant sowing and uncoated seeds S2 was 14.59%, 47.8%, 30.2% and 66.73% higher than that of other sowing dates, respectively, with an average of 39.83% higher than that of other sowing dates. The yield of random planting and coated seeds S2 was 8.49%, 32.32%, 73.43% and 51.69% higher than that of other sowing dates, respectively, with an average increase of 41.48%. Regardless of whether the sowing time, sowing method and seed coating are considered individually, or in combinations of two, there are significant differences in soybean yield when all three factors are considered together.
Effect of coating on yield
As shown in Fig 2, coated seeds can obtain more stable and higher yield than uncoated seeds under random sowing conditions. Under the condition of random sowing, the yield of coated seeds was higher than that of uncoated seeds in five sowing periods. The yield of S1-S5 increased by 7.76%, 3.19%, 37.63%, 14.8% and 22%, respectively, with an average increase of 17.08 %. Under the condition of random sowing, the yield of coated sowing was not always higher than that of uncoated sowing. The yield of coated sowing under S1, S2 and S4 was 39.7%, 43.85% and 17.31% higher than that of uncoated sowing, respectively. The yield of uncoated sowing under S3 and S5 was 10.16% and 13.66% higher than that of coated sowing, respectively. The yield of coated sowing under S1-S5 was 15.4% higher than that of uncoated sowing. In general, under random sowing conditions, the number of uncontrollable factors increases, making the yield unstable. Coated sowing can obtain higher and more stable yield.
Effect of the sowing method on yield
Under the condition of seed coating, the yield of different sowing dates was different (Fig 2). The random sowing yield of S1 and S2 was 1.86% and 0.8% higher than that of equidistant sowing, respectively. The yield of S3-S5 was 18.46%, 47% and 6.7% higher than that of random sowing. The average yield of equidistant sowing was higher than that of random sowing, which increased by 13.9%. This shows that under the condition of seed wrapping, the difference between equidistant sowing and random sowing in early sowing date is not significant, but due to the delay of sowing date, equidistant sowing can obtain higher and more stable yield. Under the condition that all seeds are not coated, the yield of different sowing methods will also be different. The yield of equidistant sowing of S1, S2 and S4 was higher than that of random sowing, which increased by 27.28%, 38.29% and 50.22% respectively. The yield of random sowing of S3 and S5 was higher than that of equidistant sowing, which increased by 28% and 29.95%, respectively. On average, the yield of equidistant sowing was higher than that of random sowing.
Previous studies have shown that even when the same variety is planted in the same location, differences in sowing periods can lead to changes in growth stages and biomass (ZHOU Enqiang 2023). This is because changes in sowing period alter the length and intensity of light, accumulated temperature and radiation during various developmental stages of crops
(Allen et al., 2018), affecting the process by which plants transition from vegetative to reproductive growth. It consistent with our experimental results, which found differences in biomass for different sowing periods after measuring aboveground and belowground biomass. The delay of sowing date shortened the growth period of soybean and the effective accumulated temperature may be insufficient, which leads to the low dry matter accumulation rate of grain and then leads to the sharp reduction of grain weight and yield
(Qinghua et al., 2021). In early spring, the temperature is low and the rainfall is abundant, which is easy to make the plants affected by low temperature or frost
(Gupta et al., 2019). At the same time, early sowing will slow down the growth of seedlings and reduce their resistance, making them vulnerable to damage
(Ravensbergen et al., 2024). The SPAD value directly reflects the concentration of chlorophyll in leaves
(Janila et al., 2015) the Phi2 value reflects the effectiveness of photosystem II
(Slattery et al., 2017). In this experiment, the maximum SPAD value and Phi2 value were observed at the optimal sowing period S2, indicating the strongest photosynthetic capacity at this time. The corresponding yield at S2 is also the highest.
Many scholars have proven through practical research that the biomass and yield of crops sown in a grid pattern are higher than those sown randomly for example wheat, corn and rice
(Olsen et al., 2005; Ying et al., 2023; Lu et al., 2020). The sowing method regulates the absorption and utilization of nutrients by affecting the growth morphology of plants
(Mabudi et al., 2016). In this experiment, the advantage of equidistant sowing was not obvious when the seeds were coated and sown earlier. This may be because the appropriate choice of seed coating and sowing date has better protection for plant growth and the sowing method has little effect on yield. However, in the case of uncoated and coated late sowing, the yield of equidistant sowing was higher than that of random sowing. On the whole, equidistant sowing can obtain a higher and more stable yield than random sowing.
Coating agents are used for the coating of seeds or seedlings of crops or other plants. The application of seed coating technology can accurately prevent and control diseases and pests in the early stage of crop growth, regulate seed germination and seedling growth, reduce the use of pesticides
(Kumar et al., 2021) and is conducive to ensure the quality of agricultural products and promote the development of green agriculture (
Halmer, 2008).
Numerous studieshave pointed out that the improvement of biomass and yield by seed coating agents is that seed coating can promote the active defense response of plants while protecting crops from seeds and soil-borne pathogens
(Mnasri et al., 2017) and at the same time, it can make seeds germinate early, improve seedling robustness, enhance photosynthesis at seedling stage, promote the formation and accumulation of substances and enhance the activity of some enzymes in the body
(Tian et al., 2024). As a compound seed coating agent, Maishuping has dual control effects, which can prevention and control of plant diseases and insect pests and increase yield and drought tolerance. It has been widely used in rape and cotton and soybean
(Zhang et al., 2024; Jacob et al., 2023). In this study, the comparison of coated and uncoated was consistent with the previous research conclusions, showing obvious yield advantages.The biomass at the flowering stage increased by 15.64% on average, the yield increased by 17.08% on average when sowing equidistantly and the yield increased by 15.4% on average when sowing randomly.
