Trichoderma is an important and widely used plant growth-promoting fungus (PGPF).  In this study, stevia residue amended with amino acids hydrolyzed from animal carcasses was used for the production of Trichoderma guizhouense NJAU 4742 by solid-state fermentation, and then its potential to promote corn plant growth was evaluated in combination with chemical fertilizer (CF) or organic fertilizer (OF).  The highest spore number of 7×10⁹ CFU g^–1 fresh weight was obtained under the following optimal parameters: material ratio of 50% (stevia residue:rice bran=1:1), pH value of 3.0 (amended with 6.67% amino acids), initial moisture content of 60%, inoculum size of 10%, material thickness of 3 cm and an incubation time of 4 days.  The aboveground corn plant biomass obtained with T. guizhouense applied alone and with CF treatments were slightly higher than those of no fertilizer control and CF treatments, respectively.  However, T. guizhouense applied with OF significantly (P<0.05) increased aboveground biomass compared to OF and yielded the highest aboveground biomass among all the treatments.  Moreover, T. guizhouense applications primarily in?uenced the fungal bulk soil community composition, among which three OTUs (OTU_2 and OTU_9 classified as Chaetomium, and OTU_4 classified as Trichoderma) were stimulated in both bulk and rhizosphere soil.  Notably, a specific OTU_3 (Phymatotrichopsis) was only stimulated by T. guizhouense applied with OF, possibly leading to high soil productivity.  These results show that it is feasible to employ stevia residue in the eco-friendly fermentation of T. guizhouense, which is strongly suggested for enhancing OF applications.

 

In order to improve the management of nitrogen (N) fertilization in pear orchards, we investigated the effects of application timing on the distribution, storage, and remobilization of N in mature pear trees in a field experiment at Jingtai County, Gansu Province, China.  Nine trees were selected for the experiment and each received equal aliquots of 83.33 g N in the autumn, spring, and summer, with ¹⁵N-labeled (NH₄)₂SO₄ used in one of the aliquots each season.  Results showed that the (¹⁵NH₄)₂SO₄ applied in the autumn remained in the soil during the winter.  In the following spring this N was absorbed and rapidly remobilized into each organ, especially new organs (leaves, fruit and new shoots).  The ¹⁵N supplied in spring was rapidly transported to developing fruit between the young fruit and fruit enlargement stages.  ¹⁵N from the summer application of fertilizer was mainly stored in the coarse roots over the winter, then was mobilized to support growth of new organs in spring.  In conclusion, for pear trees we recommend that the autumn application of N-fertilizer be soon after fruit harvest in order to increase N stores in fine roots.  Spring application should be between full bloom and the young fruit stages to meet the high N demands of developing fruit.  Summer application of fertilizer at the fruit enlargement stage does not contemporaneously affect the growth of pears, but increases the N stored in coarse roots, and in turn the amount available for remobilization in spring.

 

Solving high-temperature plastic mulching film-induced leaf burning in the first week during tobacco cultivation would take much time and effort.  In the present study, the growth as well as the leaf sugar and nicotine contents of seedlings with or without leaf burning induced by high-temperature plastic mulching film were tested at two independent sites in 2015 and 2016 to identify the influence of leaf burning on seedling growth.  The results showed that the growth of seedlings with leaf burning was improved with increased leaf area, leaf number and plant height compared to those without leaf burning, combined with an increased seedling survival rate at two sites in two years.  In seedlings with leaf burning, the contents of fructose and glucose increased and peaked at 11:00 and 13:00 in the leaf and root, respectively, with an increased root nicotine content beginning at 13:00, highlighting the signalling role of sugars.  Activities of antioxidant enzymes including peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were all increased in seedlings with leaf burning.  More plant biomass was allocated to roots in seedlings with leaf burning with increased root volume compared to control seedlings, which might facilitate the absorption of water and nutrients from the soil.  Our findings demonstrate that high-temperature plastic mulching film-induced leaf burning not inhibited but benefited seedling survival and growth, suggesting that the time and labour-consuming manual plucking of burnt leaves can be avoided during tobacco cultivation.