Plant Ideotype at Heading for Super High-Yielding Rice in Double-Cropping System in South China

The newly released super high-yielding hybrid rice combinations, Yueza 122, Fengyou 428, Peiza 67, and the super high-yielding conventional cultivars, Guangchao 3 and Shengtai 1, were grown in both early and late seasons. The morphological characters of each population were investigated at the heading stage, and the data were analyzed by using ANOVY and other statistic methods. The plant ideal morphological characters at the heading stage were established as follows： 1 ） for the early-season cropping, 90-105 cm plant height; 11-12 tillers per plant; 35-40 em length and 2.1-2.2 cm width of flag leaf; 46-50 cm length and 1.8-2.1 cm width of the second leaf from the top （L2）; 59-64 cm length and 1.4-1.9 cm width of the third leaf from the top （L3）; 7°-14°, 18° and 200-33° for the ideal leaf angles of the flag leaf, L2 and L3, respectively; 2） for the late-season cropping, 90-100 cm plant height; 9-15 tillers per plant; 30-41 cm length and 1.8-2.0 cm width of flag leaf; 53-61 cm length and 1.3-1.8 cm width of L2; 52-58 cm length and 1.2-1.5 cm width of L3; 9°-19°, 15°-37° and 16°-49° for the ideal leaf angles of the flag leaf, L2 and L3, respectively. The main physiological characteristics of these varieties were also analyzed.

Dissecting Maize Productivity:Ideotypes Associated with Grain Yield under Drought Stress and Well-watered Conditions

To increase maize （Zea mays L.） yields in drought-prone environments and offset predicted maize yield losses under future climates, the development of improved breeding pipelines using a multi-disciplinary approach is essential. Elucidating key growth processes will provide opportunities to improve drought breeding progress through the identification of key phenotypic traits, ideotypes, and donors. In this study, we tested a large set of tropical and subtropical maize inbreds and single cross hybrids under reproductive stage drought stress and well-watered conditions. Patterns of biomass production, senescence, and plant water status were measured throughout the crop cycle. Under drought stress, early biomass production prior to anthesis was important for inbred yield, while delayed senescence was important for hybrid yield. Under well-watered conditions, the ability to maintain a high biomass throughout the growing cycle was crucial for inbred yield, while a stay-green pattern was important for hybrid yield. While new quantitative phenotyping tools such as spectral reflectance （Normalized Difference Vegetation Index, NDVI） allowed for the characterization of growth and senescence patterns as well as yield, qualitative measurements of canopy senescence were also found to be associated with grain yield.

Advances and prospects of super rice breeding in China

Super rice breeding in China has been very successful over the past 3 decades, and the Chinese government has made great efforts to support breeding and cultivation of both conventional and hybrid super rice. In this review, we focus on the progress in and potential of super rice breeding. After the establishment of the breeding theory and strategy of ＂generating an ideotype with strong heterosis through inter-subspecies hybridization, by using gene pyramiding to combine elite traits through composite-crossing to breed super rice varieties with both ideotype and strong hybrid vigor＂, a series of major breakthroughs have been achieved in both conventional and super hybrid rice breeding. A number of new genetic materials with ideotype have been created successfully, and the Ministry of Agriculture of China has approved 156 novel super rice varieties and combinations for commercialization. During the Developing the Super Rice Varieties Program, great attention has also been paid to the integration and demonstration of the rice production technology. Collaboration between industry and university researchers has led to technological innovations and initiation of a demonstration system for super hybrid rice. With widespread cultivation of super rice with higher quality and yield, as well as resistance or tolerance to abiotic or biotic stresses, the yield of rice production per unit has reached a new level. In addition to increased quality and yield, hybrid rice breeding has also led to improvements in many other agronomic traits, such as resistance to pests and diseases, resistance to lodging, and optimized light distribution in population. Achievements in super rice breeding and innovation in rice production have made major contributions to the progress in rice sciences and worldwide food security.

De novo design of future rapeseed crops:Challenges and opportunities

To address the global demand for rapeseed while considering farmers’profit,we face the challenges of making a quantum leap in seed yield and,at the same time,reducing yield loss due to biotic and abiotic stresses.We also face the challenge of efficiently applying new transformative biotechnology tools such as gene editing and breeding by genome design to increase rapeseed productivity and profitability.In this Perspective,we review advances in research on the physiological and genetic bases of both stress factorsaffected yield stability and seed yield potential,focusing on source–sink relationships and allocation of photosynthetic assimilates to vegetative growth and seed development.We propose research directions and highlight the role of plant architecture in the relative contributions of the root system,leaves,and pods to seed yield.We call for de novo design of new rapeseed crops.We review trait variation in existing germplasm and biotechnologies available for crop design.Finally,we discuss opportunities to apply fundamental knowledge and key germplasm to rapeseed production and propose an ideotype for de novo design of future rapeseed cultivars.

Terminal Inflorescence and Restricted Branching Genes in Lupins （L. albus L., L. angustifolius L., L. luteus L.） and Field Bean （Vicia faba L.） Breeding in Poland

The objective of this paper is to present a new ideotype of grain legume cultivar and show improvements in breeding from the introduction of the terminal inflorescence （ti） gene in field bean, and the introduction of the restricted branching （rb） gene in three lupin crops--narrow-leafed lupin, white lupin and yellow lupin. Field trials using control cultivars were conducted at the Research Center for Cultivar Testing in Poland. For each species, different trial periods were selected in which new cultivars with ti/rb genes were registered. A breeding progress was estimated by a comparison of a new cultivar to control--bridge cultivar to the next trial period. Over the past twenty years cultivar improvement using ti/rb genes has proceeded differently in these species. The newest, self-completing legume cultivars have yields comparable to traditional ones and generally are earlier and more uniform when mature. This paper shows that breeding progress in rb yellow lupin is outstanding; in rb narrow-leafed lupin and ti field bean is favorable; and in rb white lupin is moderate.

Breeding Strategies for Improving Rice Yield—A Review

An increase in productivity is always one of the main goals of any crop breeding program including rice. However, many goals can be identified for this crop varying in importance from region to region, country to country, and even within a given country. Increase in grain yield potential is the major goal of almost all rice breeders programs. The major impacts are related to the development of new strategies to increase the genetic grain yield potential of the varieties. Rice breeders have been very successful in improving the crop. Some milestones are the contribution to the green revolution with the semi-dwarf varieties, the new rice plant type and hybrid rice. The main breeding method used to improve rice is the pedigree, but development of hybrids and population improvement are added to the breeder’s portfolio. Breeders have been taking advantage of biotechnology tools to enhance their breeding capacity;however, many programs are still struggling on how to integrate them into the breeding programs and how to balance the allocation of resources between conventional and modern tools.

Validation of Competitive Ability of Diverse Canola Accessions against Annual Ryegrass under Glasshouse and Field Conditions

Weeds are a major constraint in canola (Brassica napus L.) production worldwide, as they cause significant reductions in seed yield and quality. Crop interference is one of the approaches to tackle weed infestation along with other agronomic interventions. In Australia, studies have shown genetic variation in the canola capability to suppress annual ryegrass (Lolium rigidum Gaudin) in the field and under in vitro conditions. Early-season crop biomass accumulation and greater plant height are desired attributes for suppression weeds in canola. However, the canola ideotype for interference traits against this weed has not been studied under glasshouse conditions. In this study, we compared the competitive ability of 26 canola genotypes against annual ryegrass under both glasshouse and field conditions. Five canola genotypes consistently showed the ability to suppress growth of annual ryegrass. Both at glasshouse and field conditions, the shoot biomass, largely contributed by leaf biomass, was significantly associated with suppression ability. Our results suggest that a glasshouse-based evaluation approach can be used to determine the suppressive ability of advanced breeding lines for suppression of ryegrass growth. Based on our analysis, we suggest that initial screening of large collections of germplasm can be conducted under glasshouse conditions, with selected genotypes further evaluated in the field.

A Model Based Ideotyping Approach for Wheat Under Different Environmental Conditions in North China Plain

Before starting a breeding program for a specific crop or variety, it can be helpful to know how traits behave in determining yield under different conditions and environments. Crop growth models can be used to generate valuable information on the relevance of specific traits for an environment of interest. In this paper, the simulation model CMS-Cropsim-CERES- Wheat was used to test the performance of input parameters which describe cultivar differences concerning plant development and grain yield. In so-called ideotyping sequences, the specific cultivar parameters were varied and the model was run with the same management information in four different scenarios. The scenarios consisted of two locations, Wuqiao （37.3°N, 116.3°E） and Quzhou （36.5°N, 115°E） in Hebei Province （North China Plain）, and a dry and a wet growing season for each location. The input parameter G1 （corresponding trait： kernel number per spike） followed by G2 （corresponding trait： kernel weight） had the biggest influence on yield over all scenarios. The input parameters P1V （corresponding trait： vernalization requirement） and P1D （corresponding trait： photoperiod response） also played an important role in determining yield. In the dry scenarios a low response in vernalization and photoperiod generated a higher yield compared to a high response. The lower responses caused earliness and the period of late water stress was avoided. The last relevant parameter that affected yield was PHINT （corresponding trait： leaf area of first leaf）. The simulation showed that with an increasing PHINT, yield was enhanced over all scenarios. Based on the results obtained in this study, plant breeders could carefully select the relevant traits and integrate them in their breeding program for a specific region.

Developing multifunctional crops by engineering Brassicaceae glucosinolate pathways

Glucosinolates(GSLs),found mainly in species of the Brassicaceae family,are one of the most well-studied classes of secondary metabolites.Produced by the action of myrosinase on GSLs,GSL-derived hydrolysis products(GHPs)primarily defend against biotic stress in planta.They also significantly affect the quality of crop products,with a subset of GHPs contributing unique food flavors and multiple therapeutic benefits or causing disagreeable food odors and health risks.Here,we explore the potential of these bioactive functions,which could be exploited for future sustainable agriculture.We first summarize our accumulated understanding of GSL diversity and distribution across representative Brassicaceae species.We then systematically discuss and evaluate the potential of exploited and unutilized genes involved in GSL biosynthesis,transport,and hydrolysis as candidate GSL engineering targets.Benefiting from available information on GSL and GHP functions,we explore options for multifunctional Brassicaceae crop ideotypes to meet future demand for food diversification and sustainable crop production.An integrated roadmap is subsequently proposed to guide ideotype development,in which maximization of beneficial effects and minimization of detrimental effects of GHPs could be combined and associated with various end uses.Based on several use-case examples,we discuss advantages and limitations of available biotechnological approaches that may contribute to effective deployment and could provide novel insights for optimization of future GSL engineering.

Regulation of Leaf Senescence and Crop Genetic Improvement

Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobiliza- tion efficiency and harvest index. The doubling of the grain yield in major cereals in the last 50 years was primarily achieved through the extension of photosynthesis duration and the increase in crop biomass partitioning, two things that are intrinsically coupled with leaf senescence. In this review, we consider the functionality of a leaf as a function of leaf age, and divide a leaf＇s life into three phases： the functionality increasing phase at the early growth stage, the full functionality phase, and the senescence and functionality decreasing phase. A genetic framework is proposed to describe gene actions at various checkpoints to regulate leaf development and senescence. Four categories of genes contribute to crop production： those which regulate （Ⅰ） the speed and transition of early leaf growth, （Ⅱ） photosynthesis rate, （Ⅲ） the onset and （Ⅳ） the progression of leaf senescence. Current advances in isolating and characterizing senescence regulatory genes are discussed in the leaf aging and crop production context. We argue that the breeding of crops with leaf senescence ideotypes should be an essential part of further crop genetic improvement.