The contradiction between the supply and demand of edible vegetable oil in China is prominent, and the self-sufficiency rate is less than 35%.  Peanut has a very outstanding status in ensuring the security of edible oil and food.  The emphasis of increasing peanut yield should be the improvement of pod yield per unit area, because the total yield of peanut has not increased as required.  This is attributed to mainly two factors - low increase in the crop productivity and the competition for land for grain and cotton crops.  For traditional double-seed sowing pattern, it is difficult to further increase the peanut yield due to the serious contradiction between populations and individuals and the declining population quality under high-yield conditions.  Single-seed precision sowing was proven to be a new way to increase the economic coefficient (economic yield/biological yield) with the basic stability of the total biomass, which could make plants distribute evenly, reduce the competition among individuals and attain the full production potential of single plant.  In order to reveal the mechanism of increasing peanut yield by single-seed precision sowing, the effects on the ontogenetic development (plant character, physiological characteristic and nutrient utilization) and population structure (population uniformity and photosynthesis, source-sink relationship and yield composition) were systematically expounded.  This study reports establishment of the high-yield cultivation technology system with the key technology of single-seed precision sowing and the supporting technology of fertilizing and management.  We anticipate its wider application for the improvement of peanut yield.

 

Double-seed sowing (two seeds per hole) is the dominant pattern of peanut sowing in China, but within-hole plant competition usually limits their growth and yield formation.  Besides, the traditional double-seed sowing method does not facilitate mechanization during sowing.  The objective of this study was to determine if single-seed sowing at a proper seeding rate yielded better than traditional double-seed sowing pattern and the differences of physiological metabolism of roots.  A field experiment was conducted in two consecutive years to compare pod yields of single-seed sowing at 180 000 (S180), 225 000 (S225), and 270 000 seeds ha^–1 (S270) with that of double-seed sowing at 270 000 seeds ha^–1 (D270) using a completely randomized block design with four replications.  And the root bleeding sap rate, nutrient content, and the main hormone contents in root bleeding sap were also comparatively investigated.  Although the pod yields of single-seed sowing at the three densities were higher than that of traditional double-seed sowing (D270), S225 yielded better than the other two single-seed sowing treatments (S180 and S270).  The increased pod yield in single-seed sowing at 225 000 seeds ha^–1 was mainly due to the higher pod dry weight per plant and harvest index.  The improved pod dry weight and shoot growth had closely relationship with the enhanced root physiological traits such as the increased root bleeding sap rate, content of free amino acids, soluble sugars, K⁺, Mg^2+, Zn²⁺, and Ca²⁺ of the individual plant root.  The improved activity of root reductive, nitrate reductase (NR) and ATPase and higher zeatin and zeatin riboside (Z+ZR) content of root bleeding sap were also crucial to the pod and shoot growth of peanut.  Single-seed sowing at a moderate seeding rate (S225) is a potential practice to increase pod yield and to save seed cost.

 

Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide.  To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and deflation of its spermathecae as a function of time and copulation duration, and the quantitative impact of copulation termination on volume of spermatheca vesicle, fecundity, and offspring sex ratio.  After mating started, at least one spermatheca started to inflate immediately, but no egg was produced until spermatheca volume reached 1 021 μm3.  Beyond this size, cumulative fecundity was linearly correlated with vesicle volume.  Producing one egg required 36 μm3 volume increase of the vesicle.  Each spermatheca vesicle reached its peak size at the end of mating duration (ca. 2.38 h after mating started), and started to shrink immediately.  In 24 h, ca. 71% individuals had one completely shriveled spermatheca, while in 72 h all individuals had at least one shriveled spermatheca.  The estimated maximum cumulative fecundity per female after a single mating is (69.4±7.7) eggs.  No significant impact of mating termination on offspring sex ratio was observed after mating duration reached 60 min, while higher proportion of male offspring was observed when mating duration is 15 or 30 min.  This study is the first step to investigate possible male impact on offspring sex ratio in P. persimilis.  Our results suggested the number of sperms received during mating be a restriction factor of P. persimilis offspring sex ratio regulation.

The growth and yield of peanut are negatively affected by continuous cropping.  Arbuscular mycorrhizal fungi (AMF) and calcium ions (Ca²⁺) have been used to improve stress resistance in other plants, but little is known about their roles in peanut seedling growth under continuous cropping.  This study investigated the possible roles of the AMF Glomus mosseae combined with exogenous Ca²⁺ in improving the physiological responses of peanut seedlings under continuous cropping.  G. mosseae combined with exogenous Ca²⁺ can enhance plant biomass, Ca²⁺ level, and total chlorophyll content.  Under exogenous Ca²⁺ application, the F_v/F_m in arbuscular mycorrhizal (AM) plant leaves was higher than that in the control plants when they were exposed to high irradiance levels.  The peroxidase, superoxide dismutase, and catalase activities in AM plant leaves also reached their maximums, and accordingly, the malondialdehyde content was the lowest compared to other treatments.  Additionally, root activity, and content of total phenolics and flavonoids were significantly increased in AM plant roots treated by Ca²⁺ compared to either G. mosseae inoculation or Ca²⁺ treatment alone.  Transcription levels of AhCaM, AhCDPK, AhRAM1, and AhRAM2 were significantly improved in AM plant roots under exogenous Ca²⁺ treatment.  This implied that exogenous Ca²⁺ might be involved in the regulation of G. mosseae colonization of peanut plants, and in turn, AM symbiosis might activate the Ca²⁺ signal transduction pathway.  The combination of AMF and Ca²⁺ benefitted plant growth and development under continuous cropping, suggesting that it is a promising method to cope with the stress caused by continuous cropping.