Tangyuan Ning

POTASSIUM NITRATE APPLICATION ALLEVIATES SODIUM CHLORIDE STRESS IN WINTER WHEAT CULTIVARS DIFFERING IN SALT TOLERANCE

A sand culture experiment was conducted to answer the question whether or not exogenous KNO(3) can alleviate adverse effects of salt stress in winter wheat by monitoring plant growth, K(+)/Na(+) accumulation and the activity of some antioxidant enzymes. Seeds of two wheat cultivars (CVs), DK961 (salt-tolerant) and JN17 (salt-sensitive), were planted in sandboxes and controls germinated and raised with Hoagland nutrient solution (6 mM KNO(3), no NaCl). Experimental seeds were exposed to seven modified Hoagland solutions containing increased levels of KNO(3) (11, 16, 21 mM) or 100 mM NaCl in combination with the four KNO(3) concentrations (6, 11, 16 and 21 mM). Plants were harvested 30 d after imbibition, with controls approximately 22 cm in height. Both CVs showed significant reduction in plant height, root length and dry weight of shoots and roots under KNO(3) or NaCl stress. However, the combination of increased KNO(3) and NaCl alleviated symptoms of the individual salt stresses by improving growth of shoots and roots, reducing electrolyte leakage, malondialdehyde and soluble sugar contents and enhancing the activities of antioxidant enzymes. The salt-tolerant cultivar accumulated more K(+) in both shoots and roots compared with the higher Na(+) accumulation typical for the salt-sensitive cultivar. Soluble sugar content and activities of antioxidant enzymes were found to be more stable in the salt-tolerant cultivar. Our findings suggest that the optimal K(+)/Na(+) ratio of the nutrient solution should be 16:100 for both the salt-tolerant and the salt-sensitive cultivar under the experimental conditions used, and that the alleviation of NaCl stress symptoms through simultaneously applied elevated KNO(3) was more effective in the salt-tolerant than in the salt-sensitive cultivar.

Abscisic acid and aldehyde oxidase activity in maize ear leaf and grain relative to post-flowering photosynthetic capacity and grain-filling rate under different water/nitrogen treatments.

This study investigated changes in leaf abscisic acid (ABA) concentrations and grain ABA concentrations in two maize cultivars and analyzed the following relationships under different water/nitrogen treatments: leaf ABA concentrations and photosynthetic parameters; leaf ABA concentrations and grain ABA concentrations; leaf/grain ABA concentrations and grain-filling parameters; and aldehyde oxidase (AO,xa0EC 1.2.3.1) activities and ABA concentrations. The ear leaf average AO activities and ABA concentrations were lower in the controlled release urea treatments compared with the conventional urea treatments. The average AO activities in the grains were higher in the controlled release urea treatments, and the ABA concentrations were significantly increased at 11-30 DAF. The Pn and ABA concentrations in ear leaves were negatively correlated. And the Gmean were positively correlated with the grain ABA concentrations at 11-30 DAF and negatively correlated with the leaf ABA concentrations at 20 and 40-50 DAF. The grain ABA concentrations and leaf ABA concentrations were positively correlated. Thus, the Gmean were closely related to the AO activities and to the ear leaf and grain ABA concentrations. As compared to other treatments, the subsoiling and controlled release urea treatment promoted the uptake of water and nitrogen by maize, increased the photosynthetic capacity of the ear leaves, increased the grain-filling rate, and improved the movement of photosynthetic assimilates toward the developing grains. In the cultivar Z958, higher ABA concentrations in grains at 11-30 DAF and lower ABA concentrations in ear leaves during the late grain-filling stage, resulted in higher grain-filling rate and increased accumulation of photosynthetic products (relative to the cultivar D3).

Biodiversity management of organic farming enhances agricultural sustainability

Organic farming (OF) has been believed to be capable of curtailing some hazardous effects associated with chemical farming (CF). However, debates also exist on whether OF can feed a world with increasing human population. We hypothesized that some improvements on OF may produce adequate crops and reduce environmental pollutions from CF. This paper makes comparative analysis of crop yield, soil organic matter and economic benefits within the practice on Biodiversity Management of Organic Farming (BMOF) at Hongyi Organic Farm (HOF) over eight years and between BMOF and CF. Linking crop production with livestock to maximal uses of by-products from each production and avoid xenobiotic chemicals, we have achieved beneficial improvement in soil properties, effective pest and weed control, and increased crop yields. After eight years experiment, we have obtained a gradual but stable increase in crop yields with a 9.6-fold increase of net income. The net income of HOF was 258,827 dollars and 24,423 dollars in 2014 and 2007 respectively. Thus, BMOF can not only feed more population, but also increase adaptive capacity of agriculture ecosystems and gain much higher economic benefits.

CO2–C evolution rate in an incubation study with straw input to soil managed by different tillage systems

A laboratory incubation experiment was conducted to assess the impact of straw input on CO2–C emissions. After the winter wheat (Triticum aestivum L.) growing season, soil samples were collected from the 0–20 cm soil layer. The experiment was conducted on a brown loam soil, classified as a Udoll according to the U. S. soil taxonomy. Treatment levels consisted of three tillage practices: sub-soiling (ST), no-till (NT) and the conventional tillage (CT), two straw management (with and without input of straw), three temperature (25, 30 and 35 °C), and three moisture regimes (55%, 65% and 75% of field moisture capacity or FMC). The results showed that the rate of straw decomposition was the highest in the soil under NT management. The relationship between rate of cumulative CO2–C and straw decomposition was significant under NT (R2 = 0.52). The soil CO2–C release under incubation was significantly higher with than without the input of straw (R2 = 0.95). Furthermore, soil respiration increased with increases in incubation temperature and FMC. At 75% FMC, the rate of CO2–C release increased by 21.9 mg kg−1 d−1 at 30 °C and 32.0 mg kg−1 d−1 at 35 °C compared with that at 25 °C. At 35 °C, the rate of CO2–C release increased by 43.6 mg kg−1 d−1 at 65% FMC and 51.2 mg kg−1 d−1 at 75% FMC incubation than that of at 55% FMC under ST. The degree of control on the CO2–C evolution rate during the pre-incubation period and with higher incubation temperature and FMC was better for the soil from NT than that from CT and ST, and better yet for the soil from ST than that from CT.

CO 2 fixation in above-ground biomass of summer maize under different tillage and straw management treatments

This study was conducted to quantify the potential for CO2 fixation in the above-ground biomass of summer maize (Zea mays L.) under different tillage and residue retention treatments. The treatments were paired and included conventional tillage with straw removed (CT0), conventional tillage with straw retained (CTS), no-till with straw removed (NT0), no-till with straw retention (NTS), subsoiling with straw removed (SS0), and subsoiling with straw retained (SSS). The results indicated that NTS and SSS can enhance translocation of photosynthates to grains during the post-anthesis stage. SSS showed the highest total production (average of 7.8 Mg ha−1), carbon absorption by crop (Cd) (average of 9.2 Mg C ha−1), and total C absorption (Ct) (average of 40.4 Mg C ha−1); and NTS showed the highest contribution of post-anthesis dry matter translocation to grain yield (average of 74%). Higher CO2 emission intensity and CO2 fixation efficiency (CFE) were observed for straw retention treatments. In comparison with CTS, the mean CFE (%) over four years increased by 26.3, 19.0, 16.5, and 9.4 for NT0, SS0, NTS, and SSS, respectively. Thus, SSS and NTS systems offer the best options for removing CO2 from the atmosphere while enhancing crop productivity of summer maize in the North China Plain.