A YA-type cytoplasmic male-sterile source in common wheat

A new cytoplasmic male‐sterile (CMS) system for hybrid wheat breeding, YA‐type CMS line with the cytoplasmic mutant from the common wheat variety ‘CA8057’, was developed by the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences. The pollen sterility of YA‐type CMS line was easily maintained but difficult to restore. Some sterile lines with desirable agronomic performance, such as msYA‐‘CA8057’ (BC₁₇), msYA‐‘Yuandong 6’ (BC₉), msYA‐‘Jin 411’ (BC₉), msYA‐‘WL1’ (BC₁₀), msYA‐‘Yanshi 9’ (BC₁₀), msYA‐‘BPm16’ (BC₉), msYA‐‘Jindong 8’ (BC₉) and msYA‐‘Jinmai 33’ (BC₉), were bred and a restorer line GR1 was screened with 26 new restorer lines being developed by transferring restorer genes from GR1. It was found that abnormal phenomena occurred at the uninucleate‐pollen stage and the abortive pollen was poor in starch content and other components. The variance analysis of agronomic traits in eight sterile lines indicated that there was no general negative effect of cytoplasm. The genetic analysis for fertility restoration showed that two pairs of independent major genes (designated YARf₁YARf₁YArf₂YArf₂) and some minor genes could be involved in the fertility restoration in restorer line GR1, and YARf₁ was epistatic over YARf₂ for the genetic effect of fertility restoration. As a new CMS system, the YA‐type CMS line was of potential value for hybrid wheat breeding and should be further studied.     

In vitro tetraploid induction via colchicine treatment from diploid somatic embryos in grapevine (Vitis vinifera L.)

A protocol for in vitro induction of tetraploids via colchicine-treated somatic embryos from immature zygotic embryos of diploid grapevine (Vitis vinifera L.) is reported. Embryogenic callus was initiated from immature zygotic embryos cultured on Nitsch and Nitsch (NN) medium supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). The callus was transferred to NN medium containing 1.0 mg/l α-naphthalene acetic acid (NAA) and 0.5 mg/l benzyladenine (BA) to establish somatic embryogenesis. The vigorously growing globular embryos were selected and treated by 0, 10 or 20 mg/l colchicine for 1, 2 or 3 days, and then immediately transferred to NN medium supplemented with 0.03 mg/l NAA and 0.5 mg/l BA, for somatic embryo conversion and plant regeneration. The number of surviving embryos and regenerated plantlets following colchicine treatment decreased with increasing colchicine concentration and treatment time. Among 29 randomly investigated plantlets regenerated from colchicine-treated somatic embryos, five solid tetraploids (2n = 4× = 76) were identified by chromosome counting analysis; all others were diploid (2n = 2× = 38). Ploidy level of plant regenerated was also determined from leaves using flow cytometry. No chimeras with both 2C and 4C nuclei was produced from colchicine-treated somatic embryos. Significant differences in leaf stomata parameters were observed between diploid and induced tetraploid plantlets.     

Adapting to intersectoral transfers in the Zhanghe Irrigation System, China: Part II: Impacts of in-system storage on water balance and productivity

This paper investigates the impacts of farm ponds in a context of declining supplies in a major canal command within the Zhanghe Irrigation System (ZIS), in Central China. As dam supplies have been diverted to higher-valued uses (hydropower, cities and industry), farmers have responded by constructing small storages within their fields. These farm ponds have given them sufficient flexibility in water supply to practice varying forms of alternate wetting and drying irrigation for rice without compromising yields and incomes. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. Various scenarios of water supply incorporating the main reservoir, in-system reservoirs, farm ponds and irrigation practices were simulated using the OASIS model. OASIS integrates surface and groundwater flows, and contains a crop growth module to aggregate the impacts of different water management regimes. The modelling and sensitivity analysis show that further reductions in main reservoir supplies will have a negative effect on rice production in dry and average years, and that ponds have played a crucial role in adapting agriculture to reduced canal supplies. The flexibility allowed by the ponds has resulted in increased water productivity, except in high rainfall years, but net depletion has not decreased, as local supplies have substituted for water from the main reservoir. The study demonstrates the importance of properly accounting for return flows and the necessity to understand crop production in relation to the actual depletion of water (as evapotranspiration) within an irrigation system.     

Effect of Rainfall Collecting with Ridge and Furrow on Soil Moisture and Root Growth of Corn in Semiarid Northwest China

A plastic‐covered ridge and furrow farming of rainfall collecting (RC) system were designed to increase water availability to corn for improving and stabilizing agricultural production in the semiarid Loess region of northwest China. This system comprised two elements: the ridge mulched by plastic film that acts as a rainfall harvesting zone and the furrow as a planting zone. To adopt this system for large‐scale use in the semiarid region and bring it into full play, it is necessary to test the appropriate rainfall range for RC farming. A field study (using corn as an indicator crop) combined with rainfall simulation was conducted to determine the effect of RC on soil moisture, root characteristic parameters and the yield of corn under three different rainfall levels (230, 340 and 440 mm) during the growing seasons of 2006 and 2007. The results indicated that with the rainfalls ranging within 230–440 mm, the soil moisture at 0–100 cm depth for RC system in furrows was significantly higher (P < 0.05) than that of conventional flat (CF for control) practice. At 100–200 cm soil depth, there was no significant difference (P > 0.05) between soil moisture in the RC₂₃₀ plots and in the CF₂₃₀ plots during the corn growing seasons, while the soil moisture both in the RC₃₄₀ and RC₄₄₀ plots were significantly higher (P < 0.05) than those in the CF₃₄₀ and CF₄₄₀ plots. The root length, root surface area, root volume and root dry weight for RC₂₃₀ and RC₃₄₀ plots all significantly increased (P < 0.05) compared with CF₂₃₀ and CF₃₄₀ plots, but these root characteristic parameters at 440 mm rainfall slightly decreased compared with those of CF practice. Compared with the CF_230–440 pattern, the increasing amplitude of grain yield under the RC_230–440 pattern diminished with the rainfall increase and there was no obvious yield‐incrementing effect (P > 0.05) between two patterns at 440 mm rainfall in 2006. In comparison with these two farming practices, the RC system not only improved soil moisture of dry farmland, but also promoted the development of corn root systems when the rainfall ranged between 230 and 440 mm. Thus, it could be concluded that the optimal upper rainfall limit for the RC system is below 440 mm in the experiment. For corn, the adoption of the RC practice in the 230–440 mm rainfall area will make the system more effective during the whole growth period and offer a sound opportunity for sustainable farming in semiarid areas.     

Estimation of a network irrigation efficiency to cope with reduced water supply

The overall irrigation efficiency, e_p, for the irrigationnetworks in the Thessaloniki plain, in Northern Greece, wasestimated from historical data, spanning eight years. Irrigationnetworks differ regarding the method of water delivery and themethod of field application. Overall irrigation efficiency is theparameter which helps to adjust water supply to meet the actualcrop water requirements. A method is introduced which calculatesnetworks e_p using spatially distributed data. Efficiencyvalues for all systems were calculated using the proposed method.Seasonally averaged e_p values for eight years for 32(surface and sprinkler) irrigation networks ranged from 0.38 to0.81. Analysis of the time series e_p values can identifyoperational factors that might affect network e_p. Sprinklerand surface network irrigation efficiencies did not show anysignificant difference.     

Water resources and water use efficiency in the North China Plain: Current status and agronomic management options

Serious water deficits and deteriorating environmental quality are threatening agricultural sustainability in the North China Plain (NCP). This paper addresses spatial and temporal availability of water resources in the NCP, identifies the effects of soil management, irrigation timing and amounts, and crop genetic improvement on water use efficiency (WUE), and then discusses knowledge gaps and research priorities to further improve WUE. Enhanced irrigation and soil nutrient (mainly nitrogen) management are the focal issues in the NCP for enhancing WUE, which are shown to increase WUE by 10-25% in a wheat-maize double cropping system. Crop breeding has also contributed to increased of WUE and is expected to play an important role in the future as genetic and environmental interactions are understood better. Agricultural system models and remote sensing have been used to evaluate and improve current agronomic management practices for increasing WUE at field and regional scales. The low WUE in farmer's fields compared with well-managed experimental sites indicates that more efforts are needed to transfer water-saving technologies to the farmers. We also identified several knowledge gaps for further increasing WUE in the NCP by: (1) increasing scientific understanding of the effects of agronomic management on WUE across various soil and climate conditions; (2) quantifying the interaction between soil water and nitrogen in water-limited agriculture for improving both water and nitrogen-use efficiency; (3) improving irrigation practices (timing and amounts) based on real-time monitoring of water status in soil-crop systems; and (4) maximizing regional WUE by managing water resources and allocation at regional scales.     

Effect of organic manure on organic phosphorus fractions in two paddy soils

We investigated the transformation of the organic P fractions from organic manure in two paddy soils (Ultisol, Entisol) and the influence of organic manure or cellulose on organic P under anaerobic conditions. The results obtained from the P fractionation experiment indicated that during the incubation labile and moderately labile organic P fractions increased in the Ultisol and decreased in the Entisol, which might be related to the difference in the organic matter content of both soils. Immediately after the application of organic manure, a large part of labile and moderately labile organic P supplied with the manure was transformed into moderately resistant organic P, possibly Ca- or Mg-inositol P were transformed into Fe-inositol P. During anaerobic incubation, the labile forms of organic P in the soils treated with organic manure were increased along with the incubation period in the first 4 weeks. The change in the moderately labile fraction was dramatic. It increased sharply in the first 2 weeks, then decreased, which was more pronounced in the soils treated with pig faeces. The moderately resistant fraction decreased during the whole incubation period. This indicated that under anaerobic conditions, the moderately resistant fraction can be transformed into labile and moderately labile organic P fractions, perhaps as Fe³⁺-inositol P is reduced to Fe⁺²-inositol P. Cellulose as an organic substrate had an increasing effect on organic P, especially when it was combined with inorganic P. Therefore, it is suggested that the application of inorganic P fertilizer combined with organic manure may be an effective way of protecting inorganic P against intensive sorption in soils.     

Automatic segmentation of relevant textures in agricultural images

One important issue emerging strongly in agriculture is related with the automatization of tasks, where the optical sensors play an important role. They provide images that must be conveniently processed. The most relevant image processing procedures require the identification of green plants, in our experiments they come from barley and corn crops including weeds, so that some types of action can be carried out, including site-specific treatments with chemical products or mechanical manipulations. Also the identification of textures belonging to the soil could be useful to know some variables, such as humidity, smoothness or any others. Finally, from the point of view of the autonomous robot navigation, where the robot is equipped with the imaging system, some times it is convenient to know not only the soil information and the plants growing in the soil but also additional information supplied by global references based on specific areas. This implies that the images to be processed contain textures of three main types to be identified: green plants, soil and sky if any. This paper proposes a new automatic approach for segmenting these main textures and also to refine the identification of sub-textures inside the main ones. Concerning the green identification, we propose a new approach that exploits the performance of existing strategies by combining them. The combination takes into account the relevance of the information provided by each strategy based on the intensity variability. This makes an important contribution. The combination of thresholding approaches, for segmenting the soil and the sky, makes the second contribution; finally the adjusting of the supervised fuzzy clustering approach for identifying sub-textures automatically, makes the third finding. The performance of the method allows to verify its viability for automatic tasks in agriculture based on image processing.     

Miocene burrows of extinct bear dogs: indication of early denning behavior of large Mammalian carnivores

Partial skeletons of four species of extinct carnivores have been found in their dens excavated in the floodplain of an early Miocene ephemeral braided stream at Agate Fossil Beds National Monument, Nebraska. Bear dogs (Carnivora: Amphicyonidae) were the principal occupants; their den dimensions and body size are similar to those of living wolves and hyenas. Discovery of this predator community extends the record of denning behavior of large mammalian carnivores to the early Miocene, 20 million years ago.     

Effect of Different Nutrient Factors in the Population Growth of Heterocapsa circularisquama

A marine red tide algae denominated as Heterocapsa circularisquama was cultured under the control factors. And the ecological function of nutrient salts such as nitrogen （mg/L）, phosphorus （rag/L） as well as silicon （rag/L） in different consistency on the population growth of H. circularisquama was investigated. The results showed that overtop or too low consistency of nutrient salts both delayed the population multiplication of the red tide algae, and different nutrient factors as nitrogen, phosphorus and silicon all had significant effects on the population amplification of H.circularisquama （p〈0.01）. The optimal concentration of nitrogen, phosphorus and silicon in the culture medium for the algae propagation and growth were 10 mg/L, 1-5 mg/L and 0 mg/L respectively.