Economic crop plays an important role in the national economy and rural revitalization. Vegetables, fruit trees, tea trees, tropical crops, sugar and flowers are important economic crops. Due to human interference, climate change, population structure and the instability of ecological communities, the wild endangered resources are rapidly reduced, and some important rare resources are on the verge of extinction. However, the rare and endangered resources of economic crops such as vegetables are faced with bottleneck problems such as lack of collection and protection technology and imperfect protection system. It is urgent to carry out research and development of relevant technologies for rescue and protection. This paper mainly introduces the rare and endangered resources of the main economic crops including vegetables, fruit trees, tea, flowers and tropical crops about their protection, monitoring and utilization status, besides we also analyze their main endangerment mechanisms, put forward the protection strategies of the rare and endangered germplasm resources of the main economic crops.

Tree peonies are deciduous subshrubs in the Paeonia section of Moutan from the Paeoniaceae and include nine wildspecies and one cultivated specie with more than one thousand cultivars. All of tree peony wild species are native to China, andthey are the important parental resources for excellent variety breeding of tree peony. In view of severely damaged and endangered status of wild tree peony species, based on the reference of literatures, investigation of their original habitat,telephone consulting, and team research findings about wild tree peony species, we summarized the classification, current distribution regions and numbers of wild species, and its application in genetic breeding of tree peony. In addition, we reviewedthe contribution of wild species on phylogenetic evolution of tree peony, and the development of their oil and edible value.Finally, according to the current status of collection and conservation of wild species and research progress of wild species in ourteam, we summarized the conservation strategies of wild tree peony species and it provides reference for conserving wild treepeony species in the future.

This paper reviewed the distribution patterns, diversity hotspots, research status and protection of rare species related to chrysanthemum. The survival and protection status of Chrysanthemum, Ajania and other rare or endemic Asteraceae species in China was reported. Then, the research progress and proposed protection levels of a number of rare germplasm resources were put forward, mainly including C. rhombifolium, C. zhuozishanense, A. sericea, Opisthopappus taihangensis, Formania mekongensis, Leucomeris decora and Nouelia insignis. In addition, we systematically expounded the research progress of rare species protection from two aspects: habitats investigation and endangered mechanism research. Finally, from the perspectives of advanced monitoring technology system excavation and interdisciplinary analysis, the research methods and future prospects for the protection of chrysanthemum related wild germplasm resources were suggested.

Sugarcane is an important sugar crop with important economic value. The complexity of genetic background, theunclear origin and evolution and the lag of genomics research make it impossible to optimize the selection of parental materialsin sugarcane breeding, seriously restricting the development of sugarcane industry. In this paper, we reviews the research progress of the origin, systematic classification and evolution of sugarcane germplasm resources, the current situation ofconservation at home and abroad, as well as genomics in analyzing the genetic relationship and evolutionary history of sugar can especies and genera. The results will provide important references for the conservation, genetic diversity evaluation and industrial application & development of sugarcane germplasm resources.

The situation of lychee(Litchi chinensis Sonn.) germplasm resources abroad and the investigation, collection and preservation of lychee germplasms in China were introduced in this paper. The phenotypic evaluation, genetic diversity research and the construction of core collection of lychee germplasms in recent years were summarized, and some points for improving lychee germplasm research were recommended.

Endangered plants are an important part of the biosphere, a precious resource of the country, and an extremely important material for scientific research. In this paper, C. tachangensis, an endangered resource, was studied and its protection status was analyzed. The results showed that C. tachangensis in Guizhou was mainly distributed in 12 counties, and its morphological characteristics were significantly different from those of cultivated tea plants. The content of soluble pectin in C. tachangensis was higher than that of cultivars, and the content of catechin component was also different from that of cultivars, indicating that C. tachangensis germplasm has the potential of new variety breeding. The ECG content of C. tachangensis was significantly positively correlated with DFR gene, and five transcription factors of DFR gene were excavated. The AtMPK4 gene of 8 insect resistance factors associated SNPs and 6 negative regulators of systemic acquired resistance (SAR) in C. tachangensis were detected. These results suggested that C. tachangensis has great protection value and development potential.

With the continuous expansion of grape planting area, the leaf chlorosis of grape often occurs in China and other grape producing areas in the world, which seriously affects the yield and quality of grape fruits and seriously restricts the development of grape industry. The occurrence of this phenomenon is often affected by many factors. In this paper, the causes of chlorosis are mainly divided into two categories: pathological chlorosis and physiological chlorosis. The pathological chlorosis is mainly induced by phytoplasma and virus disease. The physiological chlorosis is mainly induced by salt stress and alkali stress. The chlorosis of leaves caused by salt stress was mainly due to the reduction of chlorophyll synthesis by the toxic effect of single salts, while the chlorosis caused by alkaline stress was mainly due to the blockage of iron transport in the plant caused by the accumulation of NO₃^- and HCO₃^- induced by alkaline soil conditions. In addition, this paper also summarizes the influence of the grape leaf chlorosis on plants, the prevention and correction techniques, the physiological mechanism of grape resistance to iron deficiency and the screening of varieties resistant to iron deficiency, and briefly summarizes the shortcomings of the current research on the grape leaf chlorosis, in order to provide a theoretical basis for the further research on the grape leaf chlorosis and the prevention and correction of chlorosis in grape production.

In order to study the effect of the composite substrate added with decomposed wheat straw on cucumber seedling cultivation, six kinds of substrate were obtained by compounding decomposed wheat straw, coconut bran and vermiculite in different proportions, with coconut bran∶vermiculite = 5∶5 (volume ratio) as the control and Jinzao 198 cucumber as the test material. By analyzing the phenotypic traits, biomass accumulation and physiological indexes of seedlings, and using principal component analysis for comprehensive evaluation, a suitable compound substrate formula was screened out. The results showed that: adding decomposed wheat straw was beneficial to the growth of cucumber seedlings, and low addition amount was better than medium and high addition amount. The seedling emergence rate of cucumber seedlings treated with T6（decomposed wheat straw∶ coconut bran∶ vermiculite = 1∶3∶5）was the highest, reaching 98.67%, which was 4.77% higher than that of the CK; the phenotypic traits such as stem diameter, hypocotyl length and maximum root length were the best; the biomass accumulation was the highest, and the seedling strength index was the highest, reached 0.15 and were 50% higher than control; Chlorophyll value, root activity, leaf soluble protein, and soluble sugar content were significantly higher than those of the CK，It increased by 6.68%, 41.70%, 6.69% and 15.38% respectively, and the activities of sucrose phosphate synthase, sucrose synthase, and nitrate reductase were significantly better than those of other treatments. The comprehensive ranking of different evaluation indicators for each treatment is: T6>T5>T3>T4>T2>T1>CK. In conclusion, T6 (decomposed wheat straw∶coconut bran∶vermiculite=1∶3∶5) treatment significantly promoted the growth of cucumber seedlings, and could be used as the best substrate formula for cucumber plug seedlings. This paper provides a theoretical reference for the use of rotted wheat straw in vegetable seedlings, thereby reducing the cost of factory seedlings and improving the quality of seedlings.