131. Study on ecological effect and physiological characteristics in apricot and wheat intercropping systems.

• Authors:
  • Nuermaimaiti, T.
  • Zhang, X.
  • Zhao, Q.
  • Gao, Y.
  • Sailihan, S.
  • Qiao, X.
  • Chen, X.
  • Lei, J.
• Source: Xinjiang Agricultural Sciences
• Volume: 47
• Issue: 12
• Year: 2011
• Summary: Objective: The present study was set to discuss ecological effects and physiological characteristics of wheat of apricot and wheat intercropping system. Method: The area from Apricot base point to the middle of two rows of apricot trees are divided into three areas: area under the crown, area near crown, area far away from crown. Study on changes in physiological characteristics of ecological indicators in the apricot and wheat intercropping in wind speed, soil temperature, chlorophyll content. Result: The colser from the distance of the apricot, the lower soil water content in wheat field; The wind speed, plant nutrients in apricot and wheat intercropping field are less than that in wheat monoculture field. Soil temperature under 5 cm for the apricot and wheat intercropping system are less than that in wheat monoculture field before 14:00; soil temperature under 5 cm of wheat monoculture field are higher than that of apricot and wheat intercropping system after 14:00. Wheat booting stage is the obvious contradiction of competition for water between wheat and apricot. Compared with different crown area in intercropping system, the area far away from crown demands for more chlorophyll content of wheat. Compared with wheat monoculture field and intercropping system, there was a fight for nutrient between wheat plants and apricot trees in intercropping field. The efficiency of uptaking nutrient of wheat plants was much lower than that of apricot trees nutrient content of less. Conclusion: Under apricot tree and wheat plant intercropping conditions, the closer from the distance of apricot trees, the less the soil moisture content, the less chlorophyll content of wheat plant. The physiological characteristics of wheat in monoculture field were superior to that in intercropping field.

132. Crop nitrogen use and soil mineral nitrogen accumulation under different crop combinations and patterns of strip intercropping in northwest China.

• Authors:
  • Zhang, F.
  • An, M.
  • Christie, P.
  • Sun, J.
  • Yu, C.
  • Li, Y.
  • Li, C.
  • Li, L.
• Source: Plant and Soil
• Volume: 342
• Issue: 1/2
• Year: 2011
• Summary: Increasing crop nitrogen use efficiency while also simultaneously decreasing nitrogen accumulation in the soil would be key steps in controlling nitrogen pollution from agricultural systems. Long-term field experiments were started in 2003 to study the effects of intercropping on crop N use and soil mineral N accumulation in wheat ( Triticum aestivum L. cv 2014)/maize ( Zea mays L. cv Shendan16), wheat/faba bean ( Vicia faba L. cv Lincan No. 5) and maize/faba bean intercropping and monocropping systems. Monocropping was compared with two types of strip intercropping: continuous intercropping (two crops intercropped continuously on the same strips of land every year) and rotational intercropping (two crops grown adjacently and rotated to the other crop's strip every year). Maize/faba bean intercropping had greater crop N uptake than did wheat/faba bean or wheat/maize. Wheat/maize accumulated more mineral N in the top 140 cm of the soil profile during the co-growth stage from maize emergence to maturity of wheat or faba bean. Continuously intercropped maize substantially decreased soil mineral N accumulation under wheat and faba bean rows (60-100 cm soil depth) at maize harvest. Soil mineral N accumulation under wheat rows increased with rotational intercropping with faba bean. Rotational intercropping may potentially alleviate the adverse effects of wheat on N use by other crops and increase the nitrogen harvest index of wheat, maize and faba bean. Intercropping using species with different maturity dates may be more effective in increasing crop N use efficiency and decreasing soil mineral N accumulation.

133. Overyielding and interspecific interactions mediated by nitrogen fertilization in strip intercropping of maize with faba bean, wheat and barley.

• Authors:
  • Li, L.
  • Zhang, F.
  • Christie, P.
  • Wei, X.
  • Sun, J.
  • Li, Q.
• Source: Plant and Soil
• Volume: 339
• Issue: 1/2
• Year: 2011
• Summary: Interspecific interactions and soil nitrogen supply levels affect intercropping productivity. We hypothesized that interspecific competition can be alleviated by increasing N application rate and yield advantage can be obtained in competitive systems. A field experiment was conducted in Wuwei, Gansu province in 2007 and 2008 to study intercropping of faba bean/maize, wheat/maize, barley/maize and the corresponding monocultures of faba bean ( Vicia faba L.), wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.) and maize ( Zea mays L.) with N application rates of 0, 75, 150, 225 and 300 kg N ha -1. Total land equivalent ratios (TLER) were 1.22 for faba bean/maize, 1.16 for wheat/maize, and 1.13 for barley/maize intercropping over the 2-year study period. Maize was overyielding when intercropped with faba bean, but underyielding when intercropped with wheat or barley according to partial land equivalent ratios (PLER) based on grain yields of individual crops in intercropping and sole cropping. There was an interspecific facilitation between intercropped faba bean and maize, and interspecific competition between maize and either wheat or barley. The underyielding of maize was higher when intercropped with barley than with wheat. Fertilizer N alleviated competitive interactions in intercrops with adequate fertilizer N at 225 kg ha -1. Yield advantage of intercropping can be acquired with adequate nitrogen supply, even in an intensive competitive system such as barley/maize intercropping. This is important when using intercropping to develop intensive farming systems with high inputs and high outputs.

134. Decomposition, nitrogen and phosphorus mineralization from winter-grown cover crop residues and suitability for a smallholder farming system in South Africa.

• Authors:
  • Muchaonyerwa, P.
  • Chiduza, C.
  • Murungu, F. S.
  • Mnkeni, P. N. S.
• Source: Nutrient Cycling in Agroecosystems
• Volume: 89
• Issue: 1
• Year: 2011
• Summary: Increasing land degradation has prompted interest in conservation agriculture which includes growing cover crops. Besides providing soil cover, decaying cover crops may release substantial amounts of nutrients. Decomposition, N and P release from winter cover crops [grazing vetch ( Vicia darsycarpa), forage peas ( Pisum sativum) and oats ( Avena sativa)] were assessed for suitability in a cropping system found in the smallholder irrigation sector of South Africa. Nitrogen and P contribution to maize growth by cover crop residues was also estimated. Decrease in mass of cover crop residues was highest in grazing vetch (7% remaining mass after 124 days) followed by forage peas (16%) and lastly oats (40%). Maximum net mineralized N and P were higher for grazing vetch (84.8 mg N/kg; 3.6 mg P/kg) than for forage peas (66.3 mg N/kg; 2.7 mg P/ha) and oats (13.7 mg N/kg; 2.8 mg P/kg). Grazing vetch and forage pea residues resulted in higher N contribution to maize stover than oat residues. Farmers may use grazing vetch for improvement of soil mineral N while oats may result in enhancement of soil organic matter and reduction land degradation because of their slow decomposition. Terminating legume cover crops a month before planting summer crops synchronizes nutrient release from winter-grown legume cover crops and uptake by summer crops.

135. Mulch effects on soil moisture and nitrogen, weed growth and irrigated maize productivity in a warm-temperate climate of South Africa.

• Authors:
  • Muchaonyerwa, P.
  • Chiduza, C.
  • Murungu, F. S.
  • Mnkeni, P. N. S.
• Source: Soil & Tillage Research
• Volume: 112
• Issue: 1
• Year: 2011
• Summary: Low soil fertility and weeds reduce maize yields on most smallholder (SH) irrigation schemes in South Africa (SA). While cover cropping can increase maize productivity, benefits from different types of mulch are not well understood, leading to challenges in selecting the most appropriate cover crop species to grow. Field experiments investigating the effects of oat ( Avena sativa), grazing vetch ( Vicia dasycarpa), faba bean ( Vicia faba), Lupin ( Lupinus angustifolius) and forage pea ( Pisum sativum) mulch on maize grown at two fertilizer levels (0 and 60 kg N/ha) were undertaken in the 2007/08 and 2008/09 seasons. Plots where maize was grown without mulch were included as controls. Treatments were arranged in a randomised complete block design with three replications. Grazing vetch and forage pea mulch significantly ( P

136. The formation of kernel number per spike and analysis of yield components of wheat under shade condition.

• Authors:
  • Zhou, Y.
  • Zhang, X.
  • Chen, X.
  • Zhao, Q.
  • Lei, J.
  • Zhang, H.
  • Qiao, X.
• Source: Xinjiang Agricultural Sciences
• Volume: 48
• Issue: 10
• Year: 2011
• Summary: Objective: The purpose of this project was to clarify shade condition's effect on the formation of kernel number per spike and analyze yield components of wheat under shade condition so as to take an effective growth measurement on fruit tree-crop intercropping models (Jujube-wheat, Apricot-wheat and Walnut-wheat intercropping). Method: In the present paper, the effects of shading on kernel number per spike were studied and analysis of yield components of wheat under the artificial shade condition was carried out. Result: The results showed that, under the artificial shade condition, the fertile florets, plant weight, grains per spike, grains weight per spike, spike number per hectare and yield were obviously reduced in the course of the wheat growth period. Conclusion: The results indicated that improving the kernel number per spike should be focused on the differentiation, growth and development, degeneration and grain courses of florets. Improving the yield should be focused on the growth and development, spike number per hectare and grain-filling characteristic courses of plants.

137. Spatial distribution characteristics of root system of jujube trees in jujube-wheat intercropping system.

• Authors:
  • Taxi, Z.
  • Song, F.
  • Yishake, H.
  • Yu, T.
  • Shi, Y.
• Source: Journal of Northeast Forestry University
• Volume: 39
• Issue: 10
• Year: 2011
• Summary: A study was conducted to discuss the spatial distribution of root system of jujube trees in jujube-crop intercropping system in Aksu by the layered digging method, in order to provide a theoretical basis for the establishment of root water uptake model for jujube trees, the analysis of ecological characteristics of water, and the determination of application area. Results showed that, in the vertical direction, in the jujube-wheat intercropping system, the jujube roots distributed in the 0-80 cm soil layer, accounting for 82.55% of root biomass and 74.87% of root length density, while in the jujube-cotton intercropping system, the jujube roots distributed in the 0-90 cm soil layer, accounting for 82.66% of root biomass and 66.75% of root length density; in the horizontal direction, in the jujube-wheat intercropping system, the jujube roots distributed in 0-100 cm away from the jujube tree, accounting for 82.10% of root biomass and 56.99% of root length density, while in the jujube-cotton intercropping system, the jujube roots distributed in 0-150 cm away from the jujube tree, accounting for 81.46% of root biomass and 83.80% of root length density. The distribution regularity of root length density of different root diameter classes and total root length density was consistent. Roots of 0- to 1.0-mm root diameter class mainly distributed in the 0-80 cm soil layer and 0-150 cm away from the jujube tree, and the root length density decreased with increasing soil depth and distance from the tree (horizontal direction). Regression equations explaining the relationships between total root length density or total root biomass and the horizontal distance from the tree and soil depth were established.

138. Study on the soil temperature characteristics in early spring under apricot-wheat system in the south of Xinjiang.

• Authors:
  • Fu, L.
  • Jia, Q.
  • Yang, L.
  • Fan, D.
  • Zhang, P.
  • Lu, C.
  • Wang, F,
• Source: Xinjiang Agricultural Sciences
• Volume: 48
• Issue: 8
• Year: 2011
• Summary: Objective: According to the measured data of soil temperature and air temperature in early spring in Kashgar area of Xinjiang, the temperature change characteristic about apricot wheat interplanting and the only wheat monoculture during the 24 h was analyzed. Method: The paper took Saimaiti apricot of 8 years old and Xindong-20 as investigative objects, and carried out a study of phenophase, horizontal distance, soil depth and air temperatures at different levels under the intercrop and monoculture model by ZDR-41. Result: The results showed that: (1) the total changes of soil temperature present the onefold type of "S"; (2) there were differences in the sustained time of temperature extremum under the 20 cm soil layer of different modes. The topmost and lowermost of air temperature did not have sustained time, but it had sustained time of the topmost and lowermost under the different horizontal distance in the intercrop model; (3) in the stages in germination, temperature under monoculture model was higher than intercrop model at the same soil depth. The average temperature of the stages in apricot germination was monoculture > the distance of 2 m to stem of apricot > the distance of 1 m to stem of apricot > air temperature. Conclusion: In the stages in germination of early spring, apricot orchard inter-crop wheat have definite effect to reduce soil temperature. The time change and the soil temperature were gradually ascended. In the period of apricot bloom, the horizontal distance at different levels did not have obvious effect on soil temperature.

139. Stakeholder views on restoring depleted cereal fallows in arid Tunisia: societal barriers and possible crevices.

• Authors:
  • Belgacem, A.
  • Maughan, N.
  • Visser, M.
  • Neffati, M.
• Source: Journal of Arid Environments
• Volume: 75
• Issue: 11
• Year: 2011
• Summary: All dryland countries struggle with manmade dryland degradation and climate change will reinforce this trend. In arid Tunisia (100-200 mm annual rainfall), depleted cereal fallows are a prominent feature of the desertified landscape. Based on long-term agro-ecological work with promising native steppe grasses, this work explores the societal barriers to restoring cereal fallows with these species. Interviews were conducted with 23 stakeholders (researchers, local decision makers of development agencies and land users) and 40 statements were drawn from these interviews as well as from written sources. These were sorted by 27 stakeholders (some of whom were interviewed before) following a distinct Q-sorting technique inspired by Q-methodology. Principal Components Analysis of these Q-sorts revealed three major types of barriers. (1) A widespread knowledge barrier was obvious since opinion on several agro-ecological statements was often opposite to the scientific evidence. (2) Strong convictions about the sacred nature of barley cropping and olive growing pointed to a cultural barrier to sowing steppe grasses on cereal fallows; (3) Finally, especially non-scientific agropastoralists expressed a lack of trust in any state-backed project aimed at combating desertification. Without the living proof of economic benefits of reseeding, no spontaneous uptake of reseeding can be expected.

140. Study of host range of Hishimonus phycitis (Dist.) and effect of lime growth conditions on its reproduction and WBDL intensity.

• Authors:
  • Hoshiar, H.
  • Samih, M.
  • Abbaszadeh, G.
  • Bagheri, A.
• Source: Annals of Plant Protection Sciences
• Volume: 19
• Issue: 2
• Year: 2011
• Summary: Witches broom disease is one of the most important phytoplasma diseases of lime that threaten lime orchards in south of Iran. It causes by Candidatus Phytoplasma aurantifolia and transmitted by the leafhopper vector, Hishimonus phycitis. The results of present study showed that H. phycitis reproduced only on Citrus and Ziziphus species. It is reported in some sources that H. phycitis is a disease vector and a pest on some plant species like eggplant, sesame, and cotton. This indicate that there is a probable variation among H. phycitis population in Iran and the populations reported from other countries like India. It was also found that H. phycitis prefered young and fresh shoots for feeding and egg laying. This caused an increase in population of H. phycitis on twigs and also in local massively infected trees. Because of this preference, the vector and thereby the disease was more prevalent in orchards with good horticultural management than the other orchards.