To determine a suitable nutrient solution for rapid propagation of virus-free sweet potato seedlings, four nutrient solutions at two concentrations each were tested using virus-free seedlings of Longshu No.9 in substrate culture to explore the effects of different treatments on the growth of virus-free seedlings. The results showed that both nutrient solution type and electrical conductivity significantly affected morphology and physiology of the virus-free seedling. The Longjiu treatments showed the best growth performance and root vitality, particularly Longjiu 2 resulted in superior stem vine length, stem node number, and aboveground fresh and dry weights compared with other treatments. These results indicated that Longjiu 2 was a suitable nutrient solution for rapid propagation of virus-free Longshu No.9 sweet potato seedlings.

To address the issues of unreasonable chemical fertilizer management, low fertilizer use efficiency, and escalating environmental risks in the maize production areas of Inner Mongolia, field plot experiments were conducted in two typical production areas, namely the black soil region of Northeast China and the Tumochuan Plain. Six treatments were established: no nitrogen control (CK), 100% chemical fertilizer (M0), and organic fertilizer replacing 25% (M25), 50% (M50), 75% (M75), and 100% (M100) of chemical nitrogen, to clarify the effects of different substitution ratios on maize yield, dry matter accumulation, fertilizer use efficiency, and nitrogen (N), phosphorus (P), and potassium (K) nutrient uptake. The results showed that the M25 treatment significantly increased maize yield, with an increase of 4.69%-36.80% compared with other treatments. The M0 treatment exhibited the highest dry matter accumulation of various organs during the early growth stages of maize; however, the M25 treatment showed a distinct advantage from the large bell-mouth stage to maturity. The M25 treatment promoted the uptake of N, P, and K nutrients and enhanced their utilization efficiency; the partial productivity of fertilizer in M25 was 2.77%-50.51% higher than those of other treatments. In conclusion, the response of maize to organic fertilizer substitution in the Tumochuan Plain was superior to that in the Black Soil Region of Northeast China, and replacing 25% of chemical nitrogen with organic fertilizer can achieve a synergistic improvement in maize yield and fertilizer use efficiency.

In order to explore the appropriate keeping way of tea plants before closing the garden, using “Baojinghuangjincha 1” as the test material, two autumn management treatments were set up, topping before garden closing (T) and no topping (CK). Samples were collected at germination stage, bud head stage as well as one bud and one leaf stage in spring, and the hormone content was determined. The amino acid components and related gene expression levels at one bud and one leaf stage were determined, and the correlation between hormone content and main amino acid components was analyzed. The results showed that budding density, 100-bud weight, and yield of tea plants in T treatment were extremely significantly increased compared with CK treatment. The determination of endogenous hormones in three periods showed that T treatment mainly affected the contents of auxin and cytokinin, the contents of auxin and cytokinin were positively correlated with the content of major amino acids, and the contents of theanine and aspartic acid were significantly positively correlated with the content of IAA-Ala. T treatment was beneficial to the accumulation of auxin and cytokinin in new shoots of tea plants in spring, promoted the germination and growth of lateral buds of tea plants, increased the yield, and T treatment was also beneficial to the accumulation of major amino acid components, such as theanine, aspartic acid, glutamate, serine, and improved the quality of tea.

To explore the effects of silicon (Si) on the physiological characteristics of oat leaves infected by Puccinia graminis f. sp. avenae and clarify the physiological mechanism of silicon-induced resistance to stem rust, a pot experiment was conducted using ʻBayou 1ʼ, an oat cultivar highly susceptible to stem rust, as the experimental material. Four treatments were established: CK (no silicon, no stem rust pathogen inoculation), +Si-P (silicon application, no stem rust pathogen inoculation), -Si+P (no silicon, stem rust pathogen inoculation), and +Si+P (silicon application, stem rust pathogen inoculation). This study investigated the effects of 1.5 mmol/L silicon application on the disease progression, reactive oxygen species content, and antioxidant enzyme activities of oat leaves after stem rust pathogen infection. The results showed that silicon application effectively delayed the disease development process of oat stem rust, and significantly alleviated disease symptoms. Stem rust pathogen infection led to a rapid increase in O₂^-. and hydrogen peroxide content in leaves. Simultaneously, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), malondialdehyde (MDA) content, and relative electrical conductivity of leaves increased rapidly, while ascorbate peroxidase (APX) activity decreased rapidly. Within seven days after stem rust pathogen inoculation, silicon application reduced the reactive oxygen species content in leaves, while increasing the activities of SOD, POD, and CAT, and decreasing APX activity and MDA content. Furthermore, silicon application reduced the relative electrical conductivity of leaves within 11 days after inoculation. Silicon application enhanced the antioxidant defense ability of oat leaves, reduced the degree of membrane lipid peroxidation, and enhanced oat resistance to stem rust.

A total of 24 progenies from Saccharum robustum L. and Nanjian chewing cane through reciprocal crosses were used. Correlation analysis, principal component analysis, cluster analysis, and comprehensive evaluation associated with seven important agronomic traits were performed. The results showed that there were differences in agronomic traits among different germplasm materials in the same planting period experiment, and there were differences in agronomic traits among different planting period experiment in the same germplasm materials. The variation coefficient of agronomic traits ranged from 11.17% to 43.37%. The variation of sugar yield and sugarcane stalk yield was the largest, which was 43.37% and 42.20%, respectively, the variation of plant height was small. The correlation analysis showed that sugarcane stalk yield and sugar yield were significantly positively correlated with single stalk weight and effective stalk number, respectively, and sugarcane stalk yield was significantly positively correlated with sugar yield. The yield-sugar factor, stalk diameter-sugar factor and stalk diameter-quality factor were extracted via principal component analysis, and the cumulative contribution rate was 81.39%. The results of cluster analysis showed that the 24 germplasm materials were divided into three groups at the Euclidean distance of 6.00, which were basically consistent with the results of principal component scores. Among them, the seven agronomic indexes of group III were excellent, with high yield and high sugar. Yunrui 12-38-27, Yunrui 12-38-18, Yunrui 12-9-45, Yunrui 12-9-9 and Yunrui 12-38-29 ranked top five based on their comprehensive evaluation D values.

The effects of nitrogen (N) application on maize yield, root distribution, and N metabolism were analyzed under high-density planting by using the maize cultivar Xianyu 335 as material, setting up a conventional density treatment of 6.75×10⁴ plants/ha (D1) and a high-density treatment of 8.25×10⁴ plants/ha (D2), and applying N at five rates (0, 160, 220, 280, and 340 kg N/ha) per density treatment. The results indicated that with the increasing of N application rate, the maize yield showed a trend of increasing and then decreasing. The yield of D2 treatment was significantly higher than that of D1 treatment and the combination of high-density planting and optimized N application (160-220 kg N/ha) increased the yield by 39.1%-51.8% compared to conventional management. The optimized combination of N rates and planting densities increased root length, root length density, root surface area, root volume, specific root length, as well as the activities of glutamate synthase and glutamine synthetase in roots. The two enzyme activities were positively correlated with root growth distribution. In conclusion, an application of 160-220 kg/ha of N at a planting density of 8.25×10⁴ plants/ha is recommended. This combination enhances nitrogen metabolism enzyme activities, promotes root growth, and increases soil nutrient uptake, thereby improving maize yield. This can serve as a high-yield maize planting model for the Guanzhong region of Shaanxi.

To address the issues of soil structure deterioration, decreased organic carbon content, and low maize yield caused by soil wind erosion in semi-arid aeolian sandy regions, a long-term field positioning experiment was conducted in Durbod Mongolian Autonomous County, Heilongjiang Province. Four treatments were established: rotary tillage with ridging (CK), no-tillage with straw mulching for one year (T1), continuous no-tillage with straw mulching for three years (T2), and continuous no-tillage with straw mulching for seven years (T3). The effects of each treatment on soil aggregate distribution characteristics, organic carbon accumulation, and maize yield across different soil layers were analyzed. The results showed that in the 0-30 cm soil layer, compared with the other treatments, the T3 treatment significantly reduced soil bulk density and significantly increased soil moisture content. Meanwhile, the T3 treatment enhanced the percentage of >0.25 mm water-stable aggregates, the organic carbon content, and the contribution rate within these aggregates, while also increasing the mean weight diameter and geometric mean diameter. No-tillage with straw mulching significantly increased maize yield, with the increase ranging from 14.98% to 39.54% compared with the CK treatment. In summary, no-tillage combined with straw mulching helps improve soil aggregate stability, the organic carbon content of aggregates across all size classes, and maize yield in semi-arid areas, with the T3 treatment yielding the best results.

To identify the distribution of disease resistance functional genes in Xinjiang spring wheat materials and provide materials for genetic improvement of wheat disease resistance breeding, KASP technology was employed to detect genes associated with resistance to stripe rust, leaf rust, powdery mildew, and Fusarium head blight in 549 Xinjiang spring wheat materials. The results showed that 121 materials carried five stripe rust resistance alleles with relatively high frequencies (QYrqin.nwafu-2AL, Yr29, QYrsn.nwafu-1BL, QYrqin.nwafu- 6BS, Yr78); 352 materials carried two leaf rust resistance alleles with relatively high frequencies (Lr67, Lr46); and 142 materials carried three Fusarium head blight resistance alleles with relatively high frequencies (QFhb.Hbaas-5AS, QFhb.hbaas-5AL, QFhb.caas-5AL). No presence of the five powdery mildew resistance genes (Pm12, Pm21, Pm2a, Pm5e, PmV) was detected in any of the materials. In summary, Xinjiang spring wheat varieties exhibited high frequencies of resistance genes for stripe rust, leaf rust, and Fusarium head blight, but a notable lack of resistance sources for powdery mildew. Therefore, it is crucial to focus on introducing and utilizing new powdery mildew resistant materials to improve the disease resistance breeding capacity of Xinjiang spring wheat.

Drought experiments were carried out in different stages of tuberous root differentiation and formation by potting soil cultivation to analyze the changes of reactive oxygen species metabolism and endogenous hormone content in sweetpotato roots. The results showed that drought stress caused the decrease of sweetpotato fresh tuber weight per plant, and the earlier the drought, the greater the effect. Compared with normal irrigation treatment (CK), the O₂^-. content in sweetpotato roots was significantly decreased and H₂O₂ content was significantly increased under drought stress. The increase of H₂O₂ was effectively inhibited after rehydration. Drought stress at different periods resulted in the decrease of activities of peroxidase (POD) and catalase (CAT) in sweetpotato roots, and ascorbate peroxidase (APX) activity increased significantly in early, middle and late stages of sweetpotato root differentiation and formation under drought stress. The results showed that the root system of sweetpotato mainly relied on APX to remove reactive oxygen species under drought stress, and SOD also made great contribution to the removal of reactive oxygen species during the early and middle stages of drought stress. After rehydration, the APX activity in sweetpotato roots decreased, while POD activity increased, indicating that sweetpotato root recovered the damage caused by drought stress by enhancing POD activity to improve antioxidant capacity after rehydration. In addition, the free proline content in sweetpotato roots increased under drought stress, and as an osmotic regulator to resist drought stress, the proline content in sweetpotato roots decreased after rehydration. Compared with CK, the contents of ABA and JA in sweetpotato roots for the treatments of D_8-14 and D_15-21 were significantly increased, while the contents of GA and IAA were significantly decreased, and the decreasing ranges were smaller than the increasing ranges of ABA and JA. When drought treatment (D_22-28) was carried out at late stage of root differentiation and formation, the contents of these four endogenous hormones in sweetpotato roots did not change significantly. These results indicated that when sweetpotato was subjected to drought stress in early and middle stages of tuberous root differentiation and formation, it responded strongly by increasing the contents of JA and ABA in roots. However, when sweetpotato was subjected to drought stress during tuberous root differentiation and formation stage, only JA had a significant increase.

In order to clarify the pathogenicity and the potential risk of major corn pathogens to soybean root rot in corn-soybean inter planting, this study artificially inoculated non-co-occurring pathogens onto soybean roots and observed the symptoms in pots, and identified the infection grades of pathogens on soybean root rot. The results showed that Curvularia lunata causing corn curvularia leaf spot, Bipolaris maydis causing southern corn leaf blight, and Exserohilum turcicum causing northern corn leaf blight were non-co-occurring pathogens and could cause soybean root rot. Isolation and identification confirmed that the isolated strains were identical to the inoculated pathogens; C.lunata could cause soybean root rot up to Grade 5, B.maydis and E.turcicum could lead to soybean root rot up to Grade 3. The above results indicated that all three pathogens were causal agents of soybean root rot, and there was a potential risk of causing soybean root rot.