Cu、Zn制剂对油橄榄容器苗生长和根系的影响

[目的]针对油橄榄容器苗存在主根较为粗大、须根极少、根系盘绕等现象开展化学制剂控根试验,找出适宜油橄榄容器苗的化学控根试剂,从而解决根系畸形导致的油橄榄苗木质量差等问题。[方法]采用4种不同浓度的CuSO_4制剂及ZnSO_4制剂对油橄榄2年生容器苗进行控根试验,测定苗高、地径及地上部、下部生物量,通过根系扫描仪分析根系生长特点,探讨各项生长指标以及生理指标对控根效果的影响。[结果]显示:(1)20 g·L^(-1)和60 g·L^(-1)的Cu制剂可提高容器苗的地上部分生长量;60 g·L^(-1)和200 g·L^(-1)的Cu制剂可显著增加生物量的积累。(2)200 g·L^(-1)的Cu制剂对苗木新根着生效果最为显著;120 g·L^(-1)的Cu制剂对根系的直径、表面积和体积有良好的促进作用;而不同ZnSO_4控根制剂处理对苗木侧根的各指标产生抑制作用。(3)枝条生长量与侧根长度呈显著正相关性;地径、枝条生长量与侧根表面积呈极显著正相关关系。(4)120 g·L^(-1)的Cu制剂处理后叶片的可溶性蛋白质含量最高,Cu制剂浓度为20 g·L^(-1)时,叶片的叶绿素含量增加。[结论]试验发现质量浓度为120 g·L^(-1)和200g·L^(-1)CuSO_4制剂控根效果良好,可运用于实际生产。

Farmer Participatory Evaluation of Nursery Bed Treatments for the Control of Root-Knot Nematodes [Meloidogynejavanica （Treub） Chitwood and Meloidogyne incognita （Kofoid and White） Chitwood] in Smallholder Farms in Kenya

Root-knot nematodes （Meloidogvne spp.） constrain the production of high value vegetable crops, such as tomato, on smallholder farms in Kenya. For several years, control of root-knot nematodes largely depended on the use of synthetic nematicides, most of which have been banned due to their toxicity to humans and the environment. Farmer-participatory trials were established, for two consecutive growing seasons on farmers＇ fields infested with root-knot nematodes （A4eloidogvne javanica and Meloidogyne incognita）, at two sites in central Kenya （Maragua and Kirinyaga districts）, representing two contrasting group of farmers （low-input and high-input）. The trials aimed at evaluating the potential of using biological control agents （BCAs）, i.e. Poehonia ehlamydosporia and Pasteuria penetrans, antagonistic plants （Crotalaria grahamiana and Tagetes minuta）, ＂＇trash burning＂ and chemical control （dazomet 98% = Basamid~ Granular） in the management of root-knot nematodes in tomato nursery beds, and quantify the associated net benefits, compared to an untreated control. Crotalaria grahamiana, ＂trash burning＂ and dazomet, significantly （P 〈 0.05） reduced the number of second-stage juveniles （J2s） of the root-knot nematodes in the soil in nursery beds during the first season at Karigui-ini, but there was no significant （P 〉 0.05） increase in yield after transplanting tomato seedlings from the respective treatment. Similarly, one of the BCAs （P. ehlamydosporia）, was effectively transferred to the field with seedlings from the BCA-treated nursery beds, but there was no significant （P 〉 0.05） increase in yield due to slow proliferation of the BCA, after transplanting. Participatory partial budgets were successfully developed with srnallholder farmers, and proved to be a vital tool in making informed decisions on management options for root-knot nematodes. In general, labour was considered by all farmers as the major input that contributed to the overall additional cost of the different treatments at both sites. This necessitates improvement in efficiency of labour resource use.

Bacillus cereus X5 Enhanced Bio-Organic Fertilizers Effectively Control Root-Knot Nematodes(Meloidogyne sp.)

The efficacy of Bacillus cereus X5 as a potential biological control agent against root-knot nematodes was evaluated in vitro by examining second-stage juvenile mortality and egg hatching rate under addition of culture filtrate and in planta by application of bio-organic fertilizers enhanced with B. cereus X5, B. thuringiensis BTG, or Trichoderma harzianum SQR-T037 alone or together in greenhouse and field experiments. The biofumigation of the root-knot nematode-infested soil with organic materials (chicken manure, pig manure and rice straw) alone or in combination with B. cereus X5 was also conducted in greenhouse experiments. In laboratory, the filtrate of B. cereus X5 more effectively reduced egg hatching rates during the incubation period for 14 d and more effectively killed the second-stage juvenile during the incubation period of 24 h than that of B. thuringiensis BTG. The highest dry shoot weights for greenhouse tomatoes and field muskmelons were found in both the treatment consisting of the bio-organic fertilizer enhanced with the three biocontrol agents and the treatment consisting of the bio-organic fertilizer enhanced only with B. cereus X5. The two bio-organic fertilizers achieved better nematicidal effects than those enhanced only with B. thuringiensis BTG or T. harzianum SQR-T037. B. cereus X5 also enhanced effect of biofumigation, which resulted in increased plant biomass and reduced nematode counts in the roots and rhizosphere soil. Therefore, these results suggested that biological control of root-knot nematodes both in greenhouses and fields could be effectively achieved by using B. cereus X5 and agricultural wastes.

Arbuscular Mycorrhizal Fungal Inoculation Enhances Suppression of Cucumber Fusarium Wilt in Greenhouse Soils

A pot experiment was conducted to study the plant growth and fruit yields of cucumber （Cucumis sativus L.） on a greenhouse soil with or without inoculation of arbuscular mycorrhizal fungi （AMFs） and Fusarium oxysporum f. sp, cucumerinum under unsterilized conditions. Two AMF inocula were tested： only one AMF strain Glomus caledonium 90036 and an AMF consortium mainly consisting of Glornus spp. and Acaulospora spp. There were four treatments including no inoculation （control）, inoculation with F. oxysporum but without mycorrhizae （FO）, inoculation with F. oxysporum and G. caledonium （FO＋M1）, and inoculation with F. oxysporum and the AMF consortium （FO＋M2）. Cucumber plants were harvested at weeks 3 and 9 after transplanting. Compared with the control, the FO treatment without AMF inoculation had less biomass both at weeks 3 and 9 （P 〈 0.05） and had higher incidence of Fusarium wilt and produced no cucumber fruit at week 9. Both FO＋M1 and FO＋M2 treatments had higher mycorrhizal colonization than the treatments which received no AMF inoculation at week 3 （P 〈 0.05）, but only the FO＋M2 treatment elevated plant biomass, decreased the incidence of Fusarium wilt, and improved cucumber yields to the same level as the control at week 9. The results indicated that the AMF consortium could suppress Fusarium wilt of cucumber and, therefore, showed potential as a biological control agent in greenhouse agroecosystems.