Crop Diversity Measurement at Dufuya Gardens and Insukamini Irrigation Scheme in Lower Gweru Communal Lands

Dufuya wetland gardens and Insukamini irrigation scheme in Lower Gweru communal areas of Gweru district are two examples of how rural communities can be self-reliant if they are capacitated. This study sought to compare crop diversity between these two vegetable producing schemes. The location of the two areas and the selected plots were determined using the GPS （global positioning system） hand receiver. Maps of the quadrants were produced in a GIS （geographic information system） on a computer. Simpson＇s index D = sum （pi2） was used to measure crop diversity while the Shannon-Weiner index （/4） was used to measure crop evenness. Results show that although both schemes are viable, Dufuya Gardens have higher crop diversity than Insukamini irrigation scheme. The study recommends that AGRITEX officers at Insukamini must advise farmers to diversify their crops in order for their produce to be more competitive on the market and also to cushion farmers against the effects of natural hazards. Given the success of the two schemes, the government must seriously consider sustainable utilization of the many small-scale dams and wetlands lying idle across the country for crop production in order to empower poor rural communities as well as alleviate poverty.

Crop Diversity for Ecological Disease Control in Potato and Maize

本文针对中国西南山区作物病害发病高峰与降雨高峰重叠难以防治的难点,进行了生态调控马铃薯与玉米种植结构避雨避病的试验。试验结果表明,时间上提前和推后马铃薯种植避开了降雨高峰,平均降低晚疫病病情指数44.3%。空间上行距拉宽株距缩小,通风透光减轻病害,套种玉米的大斑病平均降低病情指数为14.8%,小斑病平均降低22.5%。本试验的另一重要结果表明,通过调整马铃薯种植结构可以大幅度提高耕地产出率,马铃薯与玉米套种,提前和推后种植马铃薯分别提高土地利用率1.738-1.766。本文研究结果对作物病害的生态防治和增加粮食产量有重要现实意义。通过时空优化作物与环境的配置,合理利用农业生态结构,适应最佳生态环境,实现优质高产高效。

Wheat, maize and sunflower cropping systems selectively influence bacteria community structure and diversity in their and succeeding crop's rhizosphere

supported by the Special Fund for Agro-scientific Research in the Public Interest in China （201103001）

INTERCROPPING:FEED MORE PEOPLE AND BUILD MORE SUSTAINABLE AGROECOSYSTEMS

Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production.Intercropping is currently considerable interest because of its importance in sustainable agriculture.Here,we synthesize the factors that make intercropping a sustainable means of food production by integrating biodiversity of natural ecosystems and crop diversity.In addition to well-known yield increases,intercropping can also increase yield stability over the long term and increase systemic resistance to plant diseases,pests and other unfavorable factors(e.g.,nutrient deficiencies).The efficient use of resources can save mineral fertilizer inputs,reduce environmental pollution risks and greenhouse gas emissions caused by agriculture,thus mitigating global climate change.Intercropping potentially increases above-and belowground biodiversity of various taxa at field scale,consequently it enhances ecosystem services.Complementarity and selection effects allow a better understanding the mechanisms behind enhanced ecosystem functioning.The development of mechanization is essential for largescale application of intercropping.Agroecosystem multifunctionality and soil health should be priority topics in future research on intercropping.

Orphan Crops and their Wild Relatives in the Genomic Era

More than half of the calories consumed by humans are provided by three major cereal crops(rice,maize,and wheat).Orphan crops are usually well adapted to low-input agricultural conditions,and they not only play vital roles in local areas but can also contribute to food and nutritional needs worldwide.Interestingly,many wild relatives of orphan crops are important weeds of major crops.Although orphan crops and their wild relatives have received little attentions from researchers for many years,genomic studies have recently been performed on these plants.Here,we provide an overview of genomic studies on orphan crops,with a focus on orphan cereals and their wild relatives.The genomes of at least 12 orphan cereals and/or their wild relatives have been sequenced.In addition to genomic benefits for orphan crop breeding,we discuss the potential ways for mutual utilization of genomic data from major crops,orphan crops,and their wild relatives(including weeds)and provide perspectives on genetic improvement of both orphan and major crops(including de novo domestication of orphan crops)in the coming genomic era.

Effects of Waxy Maize Relay Intercropping and Residue Retention on Rhizosphere Microbial Communities and Vegetable Yield in a Continuous Cropping System

Intercropping and residue retention contribute to high yield and quality of crops. However, their coupled effects on rhizospheric microbial communities under a continuous vegetable cropping system have not been adequately addressed. The objective of the present study was to assess the effects on soil microbial community and yields of waxy maize（Zea mays L.） intercropped with or without residue retention in a continuous broccoli（Brassica oleracea L.） cropping system, i.e., relay intercropping of broccoli and waxy maize（B/M-B）, relay intercropping of broccoli and waxy maize with residue retention（B/MR-B）, and broccoli monoculture（B-B）. The biomass yields of spring and autumn vegetables in B/MR-B were 16.3%–32.5% and 30.1%–46.1% higher than those of B-B,respectively. Autumn vegetable economic yields of B/MR-B were 28.2%–40.3% higher than B-B. The average well color development followed the order： B/MR-B ＆gt; B/M-B ＆gt; B-B. The Shannon index, Simpson index, and Mc Intosh index were higher in B/MR-B than under monoculture. A principal component analysis showed that microbial communities of B/MR-B soils differed from those of B/M-B and B-B soils. Carbon（C） sources utilized by the rhizosphere microorganisms were mainly carbohydrates, carboxylic acids, amino acids, and polymers; however, the C sources for the soil microbial community differed between intercropping and monoculture. The communities from B/MR-B preferred amino acids and polymers. Available nitrogen（N）, potassium（K）, and phosphorus（P） had an obvious impact on soil microbial community. Additionally, the C source utilization by microorganisms was significantly affected by p H and available K and P. Cropping system diversification through relay intercropping and residue retention effectively improved the functional diversity of the soil microbial communities and increased the yields of vegetables.