Changes in Cultivated Land Resources and Grain Potential in China's Mainland between 1996 and 2007

Analysis of recent changes in the amount and nature of cultivated land and grain potential, and the impacts of these changes on grain security in China's Mainland provides vital information for revising and developing strategies regarding protection of cultivated land and national grain security. This study examined changes in the area of cultivated land and in grain potential in agro-ecological zones using the "change rate" method. Agro-ecological subzones were used as the basic units and agro-ecological zones as the research units. We then studied changes for all of China's Mainland using the "gravity centre model" and analyzed the structural change of cultivated lands in each agro-ecological zone to investigate the changes in detail. The results show that both cultivated land and grain potential in China's Mainland decreased from 1996 to 2007. The structural and quantitative changes in each zone have caused the shift of the gravity centres of cultivated land and grain potential in China's Mainland to the northeast. Unfortunately, it is unlikely that natural and economic resources can keep up with this change. Although a large gap remains between the grain potential and the actual grain yield, the rapid loss of grain potential and the direction of change pose great threats to grain security. To ensure comprehensive grain security in China, it is vital to rethink the regional patterns of grain production according to natural conditions without jeopardising cultivated land protection(quantitative and qualitative), and consider the direction of cultivated land use and reconstruction according to local natural conditions, water and soil resources, and the level of economic development, and then work steadily to improve the grain potential.

A novel Effective Panicle Number per Plant 4 haplotype enhances grain yield by coordinating panicle number and grain number in rice

Increasing effective panicle number per plant(EPN)is one approach to increase yield potential in rice.However,molecular mechanisms underlying EPN remain unclear.In this study,we integrated mapbased cloning and genome-wide association analysis to identify the EPN4 gene,which is allelic to NARROW LEAF1(NAL1).Overexpression lines containing the Teqing allele(TQ)of EPN4 had significantly increased EPN.NIL-EPN4^(TQ) in japonica(geng)cultivar Lemont(LT)exhibited significantly improved EPN but decreased grain number and flag leaf size relative to LT.Haplotype analysis indicated that accessions with EPN4-1 had medium EPN,medium grain number,and medium grain weight,but had the highest grain yield among seven haplotypes,indicating that EPN4-1 is an elite haplotype of EPN4 for positive coordination of the three components of grain yield.Furthermore,accessions carrying the combination of EPN4-1 and haplotype GNP1-6 of GNP1 for grain number per panicle showed higher grain yield than those with other allele combinations.Therefore,pyramiding of EPN4-1 and GNP1-6 could be a preferred approach to obtain high yield potential in breeding.

China’s Potential of Grain Production Due to Changes in Agricultural Land Utilization in Recent Years

The changes in utilization of agricultural land have gradually grown into one of the major factors impacting grain output in China. This study explores the various components of agricultural production in China from the land utilization perspective, involving changes in grain production per unit area, multi-cropping index, and adjustment of agricultural structure. Compared with the record values, different research methodologies are used to analyze the po- tential of above three components. The results indicate that grain production potential of 65.68×109kg was unexploited in 2006, in which 45.8×109kg came from the restructuring in agriculture. So we can infer that the reduction of grain production in China could be primarily attributed to agricultural restructuring in recent years. So the productive poten- tial can be fully restored by increasing agricultural investment, or recovering agricultural structure in favorable condi- tions. So we can say that China’s current condition of food security is good.

Nanoscale control of grain boundary potential barrier, dopant density and filled trap state density for higher efficiency perovskite solar cells

In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity(RH)environments.Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains.The averageΔφGB,Pnet,and PGB,trap in the perovskite films decreased from 0%RH to 25%RH exposure,but increased when the RH increased to 35%RH and 45%RH.This clearly indicated that perovskite solar cells fabricated at 25%RH led to the lowest average GB potential,smallest dopant density,and least filled trap states density.This is consistent with the highest photovoltaic efficiency of 18.16%at 25%RH among the different relative humidities from 0%to 45%RH.