[Effects of exogenous methylglyoxal on chesnut seedlings under drought stress]. / å¤–æºç”²åŸºä¹™äºŒé†›å¯¹å¹²æ—±èƒè¿«ä¸‹æ¿æ —å¹¼è‹—çš„å½±å“.

Methylglyoxal (MG) is a novel signaling molecule with multiple functions in plants. To explore the effects of MG on Chinese chestnut (Castanea mollissima) under drought stress, two-year-old 'Huangpeng' chestnut seedlings were treated with 15% polyethylene glycol (PEG) coupled with MG or its scavenger N-acetyl-L-cys-teine (NAC). We measured the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), and glyoxalase enzymes, including glyoxalase Ⅰ (GlyⅠ) and glyoxalase Ⅱ(GlyⅡ). Contents of antioxidants such as endogenous MG, malondialdehyde (MDA), H2O2, and O2-· as well as the osmotic adjustment substances including proline (Pro), soluble sugar (SS), glycine betaine (GB) were also detected. The results showed that 0.5 mmol·L-1 MG significantly increased the activities of antioxidant enzymes (SOD, POD, CAT, APX, GR) and glyoxalase enzymes (GlyⅠ, GlyⅡ) in leaves of chestnut seedlings under drought stress, elevated the contents of osmotic adjustment substances (Pro, SS, GB) and antioxidant substances (ASA, GSH), and reduced the contents of MG, MDA, H2O2, O2-· and dehydroascorbate (DHA). Drought stress induced damages such as membrane lipid peroxidation and osmotic stress was alleviated by MG, leading to an overall improved adaptability of chestnut to drought stress. Moreover, the addition of MG scavenger NAC could reverse the effects induced by MG, indicating that MG had positive impacts on drought resistance of chestnut plants. Our study provided a theoretical basis for further exploring the mechanism of MG in alleviating drought stress induced symptoms in chestnut.

[Effects of compound fertilizer of (NH2)2CO and KH2PO4 on the chestnut photosynthesis characteristics, growth and fruiting].

Compound fertilizer can improve the fertilizer use efficiency and tree nutrition status to ensure balanced fertilization. Taking 7 year-old chestnut trees as test material, with (NH2)2CO and KH2PO4 being mixed at the different ratios, the effects of different compound fertilizers on the photosynthesis characteristics as well as the growth and fruiting of chestnut were studied quantitatively by trunk injection method. Results showed that compound fertilizer of (NH2)2CO and KH2PO4 induced positive synergistic effects to enhance photosynthetic capacity, yield and quality of chestnut obviously. The content of chlorophyll was decreased by (NH2)2CO and increased by KH2PO4, but increased obviously by the compound fertilizer. The contents of N, P, K of leaf and branch rose under the four compounded fertilization treatments, among which 0.3%(NH2)2CO+0.3%KH2PO4 was the best. All fertilizer treatments could advance the photosynthetic parameters, while the compound fertilizer performed better. 0.3% (NH2)2CO + 0.3% KH2PO4 treatment significantly increased the photosynthetic rate, the maximum net photosynthesis, apparent quantum yield, carboxylation efficiency, instantaneous water use efficiency and nitrogen use efficiency. Compound fertilizer could promote the growth of branch in diameter and length synchronously, and increase the number of mixed buds, while (NH2)2CO only promoted the growth of branch in length, and did little in the number of mixed buds. The compound fertilizer did better in advancing nuts yield and quality than single fertilization of N or P. The nuts yield, mass and total sugar were increased by 68.2%, 25.5% and 14.9% respectively under 0.3% (NH2)2CO+0.3%KH2PO4 treatment compared with the control.

[Effects of different water-saving irrigation modes on chestnut growth and fruiting in drought hilly land].

Taking the chestnut trees in a semi-arid and semi-humid hilly orchard of Tai' an, Shandong Province of East China as test objects, a field experiment was conducted to study the effects of different water-saving irrigation modes (pottery jar storing water, small hole storing water, and border irrigation with covering) on the soil moisture characteristics and the growth, fruiting, and development of chestnut roots. Comparing with the control (border irrigation), all the three water-saving irrigation modes could prolong the period of soil keeping moist, and the best effect came from pottery, jar treatment, with the soil keeping moist for 32 days, 13 days longer than the control. Under water-saving irrigations, the bearing branches length and number, leaf area and mass, and shoot mixed buds all increased obviously. Both pottery jar storing water and small hole storing water could irrigate deeper roots and induce root growth in deeper soil layers, and thus, relieve the drought stress on superficial roots. The three water-saving irrigation modes could increase chestnut yield markedly, with an increment of 18.8%, 16.5%, and 14.2%, respectively, as compared with the control.