Crop planting patterns are an important component of agricultural land systems.  These patterns have been significantly changed due to the combined impacts of climatic changes and socioeconomic developments.  However, the extent of these changes and their possible impacts on the environment, terrestrial landscapes and rural livelihoods are largely unknown due to the lack of spatially explicit datasets including crop planting patterns.  To fill this gap, this study proposes a new method for spatializing statistical data to generate multitemporal crop planting pattern datasets.  This method features a two-level model that combines a land-use simulation and a crop pattern simulation.  The output of the first level is the spatial distribution of the cropland, which is then used as the input for the second level, which allocates crop censuses to individual gridded cells according to certain rules.  The method was tested using data from 2000 to 2019 from Heilongjiang Province, China, and was validated using remote sensing images.  The results show that this method has high accuracy for crop area spatialization.  Spatial crop pattern datasets over a given time period can be important supplementary information for remote sensing and thus support a wide range of application in agricultural land systems.

The successful launched Gaofen satellite no. 1 wide field-of-view (GF-1 WFV) camera is characterized by its high spatial resolution and may provide some potential for regional crop mapping.  This study, taking the Bei’an City, Northeast China as the study area, aims to investigate the potential of GF-1 WFV images for crop identification and explore how to fully use its spectral, textural and temporal information to improve classification accuracy.  In doing so, an object-based and Random Forest (RF) algorithm was used for crop mapping.  The results showed that classification based on an optimized single temporal GF-1 image can achieve an overall accuracy of about 83%, and the addition of textural features can improve the accuracy by 8.14%.  Moreover, the multi-temporal GF-1 data can produce a classification map of crops with an overall accuracy of 93.08% and the introduction of textural variables into multi-temporal GF-1 data can only increase the accuracy by about 1%, which suggests the importance of temporal information of GF-1 for crop mapping in comparison with single temporal data.  By comparing classification results of GF-1 data with different feature inputs, it is concluded that GF-1 WFV data in general can meet the mapping efficiency and accuracy requirements of regional crop.  But given the unique spectral characteristics of the GF-1 WFV imagery, the use of textual and temporal information is needed to yield a satisfactory accuracy.

How to fully use spectral and temporal information for efficient identification of crops becomes a crucial issue since each crop has its specific seasonal dynamics.  A thorough understanding on the relative usefulness of spectral and temporal features is thus essential for better organization of crop classification information.  This study, taking Heilongjiang Province as the study area, aims to use time-series moderate resolution imaging spectroradiometer (MODIS) surface reflectance product (MOD09A1) data to evaluate the importance of spectral and temporal features for crop classification.  In doing so, a feature selection strategy based on separability index (SI) was first used to rank the most important spectro-temporal features for crop classification.  Ten feature scenarios with different spectral and temporal variable combinations were then devised, which were used for crop classification using the support vector machine and their accuracies were finally assessed with the same crop samples.  The results show that the normalized difference tillage index (NDTI), land surface water index (LSWI) and enhanced vegetation index (EVI) are the most informative spectral features and late August to early September is the most informative temporal window for identifying crops in Heilongjiang for the observed year 2011.  Spectral diversity and time variety are both vital for crop classification, and their combined use can improve the accuracy by about 30% in comparison with single image.  The feature selection technique based on SI analysis is superior for achieving high crop classification accuracy (producers’ accuracy of 94.03% and users’ accuracy of 93.77%) with a small number of features.  Increasing temporal resolution is not necessarily important for improving the classification accuracies for crops, and a relatively high classification accuracy can be achieved as long as the images associated with key phenological phrases are retained.

   Metarhizium anisopliae as an essential entomopathogenic fungus has been known to produce destruxins (a kind of cyclo-peptidic mycotoxins) and blastospores in submerged culture. Blastospores and destruxins are candidates for insecticides, but the relations of both productions and the impact factors are unclear yet. In this study, we investigated the effects of inoculums, rotation, dissolved oxygen (DO) on the productions of blastospores and destruxins A and B (DA and DB) in submerged culture of M. anisopliae strain MaQ01. The results indicated that DO levels were regulated by inoculum amounts and rotation speeds, meanwhile, the productions of DA, DB and blastospores were also closely influenced by those factors. Totally, when DO value was more than 40%, the higher productions of destruxins and blastospores were achieved, by contrast, lower than 40% of DO values resulted in lower productions. The regression analysis suggested that the productions of DA, DB and blastospores were positively correlated with the DO levels. Meanwhile, the positive correlations between the productions of DA or DB and blastospores were also found. Briefly, when the rotation is 150 r min–1 and the inoculum is 1.0×10⁶ spore mL^–1, the DA, DB and blastospores achieved the best production of 61.81 mg mL^–1, 24.74 mg mL^–1 and 5.73×10⁶ spore mL^–1, respectively. In addition, the pathogenicities of blastospores and conidia against Plutella xylostella were bioassayed. The higher mortalities of P. xylostella were totally recorded in blastospore treatments than in conidia treatments, especially in lower dosages and earlier periods. Our research will give some new insights to production of destruxins and blastospores by using M. anisopliae.  

Destruxin A (DA), a kind of cyclo-hexadepsipeptide isolated from entomopathogenic fungus, Metarhizium anisopliae, is an inhibitor of insect’s immunity. But its mechanism has not been clarified yet. In this study, the effects of DA on morphologic changes of in vivo and in vitro hemocytes of silkworm, Bombyx mori, were investigated by means of inverted phase contrast microscopy (IPCM), fluorescence microscopy (FCM) and environmental scanning electron microscopy (ESEM). The results indicated that DA was cytotoxic to granulohemocytes (GR) and plasmatocytes (PL). The LC50 values of DA against in vitro GR and PL of silkworm were 68.77 and 84.11 μg mL-1, respectively. However, the hemocytes in vivo were more susceptible to DA, although at the extremely low dose of 10 μL of 12.5 μg mL-1 for each insect (i.e., 0.036 μg g-1 body weight, or approximately 0.25 μg mL-1 hemolymph), DA could induce obviously morphologic alterations of hemocytes in vivo. The results imply that there might be some factors in silkworm’s hemolymph, which influence the interaction of DA and hemocytes.

Pod shatter resistance of rapeseed is of great importance for modern farming practice. In order to determine the combining ability of elite inbred lines and the breeding potential of rapeseed hybrids in terms of pod shatter resistance, analysis of a 6×6 incomplete diallel cross was conducted at two locations. Results showed that a significant variation existed among breeding lines and their F1 hybrids for pod shatter resistant index (SRI), pod length and width. Pod shatter resistance was significantly positively correlated with pod length. The general combining ability (GCA) effects (GCA=1.58) played a more important role than specific combining ability (SCA) effects (SCA=0.20) for pod shatter trait. The elite lines R1, 1019B and 1055B displayed significant positive GCA effects for pod shatter resistance. Four crosses (1019B×R1, 1015B×R1, 6098B×R1, and 8908B×R1) with high mean performance and positive SCA effects were recommended for developing new hybrids for mechanical harvest in the middle reaches of the Yangtze River.