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Grain yield, nitrogen use efficiency and physiological performance of indica/japonica hybrid rice in response to various nitrogen rates

ZHOU Qun, YUAN Rui, ZHANG Wei-yang, GU Jun-fei, LIU Li-jun, ZHANG Hao, WANG Zhi-qin, YANG Jian-chang

2023, 22 (1): 63-79. DOI: 10.1016/j.jia.2022.08.076

Abstract （471） PDF in ScienceDirect

Utilizing the heterosis of indica/japonica hybrid rice (IJHR) is an effective way to further increase rice grain yield. Rational application of nitrogen (N) fertilizer plays a very important role in using the heterosis of IJHR to achieve its great yield potential. However, the responses of the grain yield and N utilization of IJHR to N application rates and the underlying physiological mechanism remain elusive. The purpose of this study was to clarify these issues. Three rice cultivars currently used in rice production, an IJHR cultivar Yongyou 2640 (YY2640), a japonica cultivar Lianjing 7 (LJ-7) and an indica cultivar Yangdao 6 (YD-6), were grown in the field with six N rates (0, 100, 200, 300, 400, and 500 kg ha^–1) in 2018 and 2019. The results showed that with the increase in N application rates, the grain yield of each test cultivar increased at first and then decreased, and the highest grain yield was at the N rate of 400 kg ha^–1 for YY2640, with a grain yield of 13.4 t ha^–1, and at 300 kg ha^–1 for LJ-7 and YD-6, with grain yields of 9.4–10.6 t ha^–1. The grain yield and N use efficiency (NUE) of YY2640 were higher than those of LJ-7 or YD-6 at the same N rate, especially at the higher N rates. When compared with LJ-7 or YD-6, YY2640 exhibited better physiological traits, including greater root oxidation activity and leaf photosynthetic rate, higher cytokinin content in the roots and leaves, and more remobilization of assimilates from the stem to the grain during grain filling. The results suggest that IJHR could attain both higher grain yield and higher NUE than inbred rice at either low or high N application rates. Improved shoot and root traits of the IJHR contribute to its higher grain yield and NUE, and a higher content of cytokinins in the IJHR plants plays a vital role in their responses to N application rates and also benefits other physiological processes.

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Optimization of nitrogen fertilization improves rice quality by affecting the structure and physicochemical properties of starch at high yield levels

ZHOU Tian-yang, LI Zhi-kang, LI En-peng, WANG Wei-lu, YUAN Li-min, ZHANG Hao, LIU Li-jun, WANG Zhi-qin, GU Jun-fei, YANG Jian-chang

2022, 21 (6): 1576-1592. DOI: 10.1016/S2095-3119(21)63678-X

Abstract （268） PDF in ScienceDirect

A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs. This study was designed to determine whether optimized nitrogen (N) fertilization could fulfill these multiple goals. In two-year experiments, two high yielding ‘super’ rice cultivars were grown with different N fertilization management regimes, including zero N input, local farmers’ practice (LFP) with heavy N inputs, and optimized N fertilization (ONF). In ONF, by reducing N input, increasing planting density, and optimizing the ratio of urea application at different stages, N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels. Compared with LFP, yield and partial factor productivity of applied N (PFP) under ONF were increased (on average) by 1.70 and 13.06%, respectively. ONF increased starch and amylose content, and significantly decreased protein content. The contents of the short chains of A chain (degree of polymerization (DP) 6–12) and B1 chain (DP 13–25) of amylopectin were significantly increased under ONF, which resulted in a decrease in the stability of rice starch crystals. ONF increased viscosity values and improved the thermodynamic properties of starch, which resulted in better eating and cooking quality of the rice. Thus, ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency (NUE) at high yield levels. These results will be useful for applications of high quality rice production at high yield levels.

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Deciphering the morpho–physiological traits for high yield potential in nitrogen efficient varieties (NEVs): A japonica rice case study

ZHU Kuan-yu, YAN Jia-qian, SHEN Yong, ZHANG Wei-yang, XU Yun-ji, WANG Zhi-qin, YANG Jian-chang

2022, 21 (4): 947-963. DOI: 10.1016/S2095-3119(20)63600-0

Abstract （202） PDF in ScienceDirect

The use of nitrogen (N)-efficient rice (Oryza sativa L.) varieties could reduce excessive N input without sacrificing yields. However, the plant traits associated with N-efficient rice varieties have not been fully defined or comprehensively explored. Here, three japonica N-efficient varieties (NEVs) and three japonica N-inefficient varieties (NIVs) of rice were grown in a paddy field under N omission (0 N, 0 kg N ha^–1) and normal N (NN, 180 or 200 kg N ha⁻¹) treatments. Results showed that NEVs exhibited higher grain yield and nitrogen use efficiency (NUE) than NIVs under both treatments, due to improved sink size and filled-grains percentage in the former which had higher root oxidation activity and greater root dry weight, root length and root diameter at panicle initiation (PI), as well as higher spikelet–leaf ratio and more productive tillers during the grain-filling stage. Compared with NIVs, NEVs also exhibited enhanced N translocation and dry matter accumulation after heading and improved flag leaf morpho–physiological traits, including greater leaf thickness and specific leaf weight and higher contents of ribulose-1,5-bisphosphate carboxylase/oxygenase, chlorophyll, nitrogen, and soluble sugars, leading to better photosynthetic performance. Additionally, NEVs had a better canopy structure, as reflected by a higher ratio of the extinction coefficient for effective leaf N to the light extinction coefficient, leading to enhanced canopy photosynthesis and dry matter accumulation. These improved agronomic and physiological traits were positively and significantly correlated with grain yield and internal NUE, which could be used to select and breed N-efficient rice varieties.

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Characterization and fine mapping of RTMS10, a semi-dominant reverse thermo-sensitive genic male sterile locus in rice

NI Jin-long, WANG De-zheng, NI Da-hu, SONG Feng-shun, YANG Jian-bo, YAO Da-nian

2022, 21 (2): 316-325. DOI: 10.1016/S2095-3119(20)63563-8

Abstract （270） PDF in ScienceDirect

The discovery and application of environment-sensitive genic male sterile (EGMS) rice germplasm provide an easy method for hybrid rice breeding and have made great contributions to hybrid rice production. Typically, the photoperiod- and thermo-sensitive GMS (P/TGMS) lines utilized in two-line hybrid systems are male sterile under long day or/and high temperature but fertile under short day or/and low temperature conditions. However, YannongS (YnS), a reverse TGMS (rTGMS) line, is sterile under low temperature (<29°C) and fertile under high temperature (>29.5°C). Here, we report a genetic study on the rTGMS trait in YnS. Interestingly, the F₁ plants of the cross between YnS and a cultivar, L422, were male sterile at 22°C and completely fertile at 27°C. Moreover, the segregation ratio of fertile and sterile individuals in YnS/L422 F₂ populations changed from 1:3.05 to 2.95:1 when the ambient temperature increased, showing that the rTGMS trait exhibits semi-dominance in YnS. We further found a locus on chromosome 10, termed RTMS10, which controls the rTGMS trait in YnS. We then finely mapped RTMS10 to a ~68 kb interval between markers ID13116 and ID1318 by YnS/L422 BC₆F₂ populations. A near iso-genic line (NIL) NL1 from the BC₆F₃ generation was developed and the pollen of NL1 became abnormal from the meiosis stage under low temperature. In summary, we identified an rTGMS locus, RTMS10, and provided co-segregated markers, which could help to accelerate molecular breeding of rTGMS lines and better understand the rTGMS trait in rice.

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Genome-wide identification and analysis of the regulation wheat DnaJ family genes following wheat yellow mosaic virus infection

LIU Ting-ting, XU Miao-ze, GAO Shi-qi, ZHANG Yang, HU Yang, JIN Peng, CAI Lin-na, CHENG Ye, CHEN Jian-ping, YANG Jian, ZHONG Kai-li

2022, 21 (1): 153-169. DOI: 10.1016/S2095-3119(21)63619-5

Abstract （258） PDF in ScienceDirect

The co-chaperone DnaJ plays an important role in protein folding and regulation of various physiological activities, and participates in several pathological processes. DnaJ has been extensively studied in many species including humans, drosophila, mushrooms, tomatoes, and Arabidopsis. However, few studies have examined the role of DnaJ in wheat (Triticum aestivum), and the interaction mechanism between TaDnaJs and plant viruses. Here, we identified 236 TaDnaJs and performed a comprehensive genome-wide analysis of conserved domains, gene structure and protein motifs, chromosomal positions and duplication relationships, and cis-acting elements. We grouped these TaDnaJs according to their domains, and randomly selected six genes from the groups for tissue-specific analysis, and expression profiles analysis under hormone stress, and 17 genes for plant virus infection stress. In qRT-PCR, we found that among the 17 TaDnaJ genes tested, 16 genes were up-regulated after wheat yellow mosaic virus (WYMV) infection, indicating that the TaDnaJ family is involved in plant defense response. Subsequent yeast two-hybrid assays verified the WYMV NIa, NIb and 7KD proteins interacted with TaDJC (TraesCS7A02G506000), which had the most significant changes in gene expression levels after WYMV infection. Insights into the molecular mechanisms of TaDnaJ-mediated stress tolerance and sensitivity could inform different strategies designed to improve crop resistance to abiotic and biotic stress. This study provides a basis for future investigation of the TaDnaJ family and plant defense mechanisms.

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Genome-wide identification and expression analysis of StPP2C gene family in response to multiple stresses in potato (Solanum tuberosum L.)

WANG Yi-fan, LIAO Yu-qiu, WANG Ya-peng, YANG Jiang-wei, ZHANG Ning, SI Huai-jun

2020, 19 (6): 1609-1624. DOI: 10.1016/S2095-3119(20)63181-1

Abstract （153） PDF in ScienceDirect

The plant protein phosphatase 2Cs (PP2Cs) play an essential role in response to stress and abscisic acid (ABA) signaling pathway. However, to date, no systemic characterization of the PP2Cs has yet been conducted in potato (Solanum tuberosum L.). In the study, a comprehensive research was performed on genome-wide identification and expression analysis of StPP2C genes in potato. A total of 78 potato StPP2C genes were identified based on specific structure of PP2C domain, which were distributed across 11 out of 12 potato chromosomes and divided into 12 (A–L) phylogenetic branches. The result from gene duplication analysis showed that 14 StPP2Cs were involved in gene tandem duplication and 8 genes formed fragment duplication events, which indicated that both tandem and fragment duplication contributed to the expansion of the gene family in evolution. Exon–intron structural analysis showed that they had a wide range of exon numbers. Analysis of protein conservative motif demonstrated that StPP2Cs contained more similar motif structures in the same phylogenetic branches. The cis-elements in StPP2C gene promoter regions were mainly responded to light, phytohormone and abiotic stress. Most of them exhibited tissue-specific expression patterns, and some members could differentially express under abiotic stress. The evidence suggested that StPP2C genes may contribute to different functions in several physiological stress and environmental stress conditions. This study could provide new insights to further investigate StPP2C functional characteristics responding to various stresses in potato.

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The effects of water and nitrogen on the roots and yield of upland and paddy rice

ZHANG Ya-jie, XU Jing-nan, CHENG Ya-dan, WANG Chen, LIU Gao-sheng, YANG Jian-chang

2020, 19 (5): 1363-1374. DOI: 10.1016/S2095-3119(19)62811-X

Abstract （109） PDF in ScienceDirect

It is of great significance to study the root characteristics of rice to improve water and nitrogen (N) use efficiency and reduce environmental pollution. This study investigated whether root traits and architecture of rice influence grain yield, as well as water and N utilization efficiency. An experiment was conducted using the upland rice cultivar Zhonghan 3 (a japonica cultivar) and paddy rice cultivar Huaidao 5 (also a japonica cultivar) using three N levels, namely, 2 g urea/pot (low amount, LN), 3 g urea/pot (normal amount, NN), and 4 g urea/pot (high amount, HN), and three soil water potentials (SWPs, namely, well-watered (0 kPa), mildly dried (–20 kPa) and severely dried (–40 kPa). The results showed that with decreasing SWP, the percentage of upland rice roots increased in the 0–5 cm tillage layer, and decreased in the 5–10 and 10–20 cm tillage layers, whereas paddy rice roots showed the opposite trend. With increasing amounts of N, the yield of upland and paddy rice increased, and the percentage of root volume ratios of the two rice cultivars in the 0–5 and 5–10 cm tillage layers increased, whereas that in the 10–20 cm tillage layer decreased. The roots of upland rice are mainly distributed in the 10–20 cm tillage layer, whereas most paddy rice roots are in the 0–5 cm tillage layer. These results indicate that the combination of −20 kPa SWP and NN in upland rice and 0 kPa SWP and LN in paddy rice promotes the growth of the root system during the middle and late stages, which in turn may decrease the requirements for water and N fertilizer and increase rice yield.

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Changes in starch quality of mid-season indica rice varieties in the lower reaches of the Yangtze River in last 80 years

ZHANG Hao, JING Wen-jiang, XU Jing-ju, MA Bing-ju, WANG Wei-lu, ZHANG Wei-yang, GU Jun-fei, LIU Li-jun, WANG Zhi-qin, YANG Jian-chang

2020, 19 (12): 2983-2996. DOI: 10.1016/S2095-3119(20)63431-1

Abstract （119） PDF in ScienceDirect

Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm^–1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm^–1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and root bleedings at grain filling stage during the improvement of mid-season indica rice.

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Optimizing integrative cultivation management improves grain quality while increasing yield and nitrogen use efficiency in rice

ZHANG Hao, HOU Dan-ping, PENG Xian-long, MA Bing-ju, SHAO Shi-mei, JING Wen-jiang, GU Jun-fei, LIU Li-jun, WANG Zhi-qin, LIU Yuan-ying, YANG Jian-chang

2019, 18 (12): 2716-2731. DOI: 10.1016/S2095-3119(19)62836-4

Abstract （202） PDF in ScienceDirect

A major challenge in rice (Oryza sativa L.) production is to cope with increasing grain yield and fertilizer use efficiency without compromising grain quality. This study was designed to determine if optimizing integrative cultivation management in rice could improve grain quality while increase yield and nitrogen use efficiency (NUE). An indica-japonica hybrid rice cultivar and a japonica rice cultivar were grown in the field, with five cultivation managements including no N application (0 N), local farmer’s practice (LFP), and three optimizing integrative cultivation managements, reducing N rate and increasing plant density (ND), ND+alternate wetting and moderate soil drying irrigation (NDW), and NDW+applying rapeseed cake fertilizer (NDWR). The results showed that the optimizing integrative cultivation managements could not only increase grain yield, but also enhance NUE compared to LFP. Compared to LFP, NDWR significantly increased brown, milled, head milled rice rate, ratio of the kernel length to breadth and breakdown value of starch, whereas decreased amylose content, gel consistency, prolamin content, setback value, percentage of chalky kernels, and chalkiness. The three optimizing integrative cultivation managements increased contents of total proteins, albumin and glutelin, activities of the key enzymes involved in the sucrose-starch conversion in grains, root oxidation activity, and malic and succinic acid concentrations in root exudates during the grain-filling period. The results suggested that optimizing integrative cultivation managements could improve grain quality meanwhile increase grain yield and NUE by enhancing physiological activities of rice plants.

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Physiological mechanism underlying spikelet degeneration in rice

WANG Zhi-qin, ZHANG Wei-yang, YANG Jian-chang

2018, 17 (07): 1475-1481. DOI: 10.1016/S2095-3119(18)61981-1

Abstract （446） PDF （716KB）（364）

The phenomenon of degenerated spikelets is very common in cereals, and considered as a serious physiological defect and a main constraint to grain production. Understanding the physiological mechanism in which spikelet degeneration occurs would have great significance in enhancing yield potential in grain crops. Taking rice as an example, the paper reviewed the physiological mechanism underlying spikelet degeneration, with focus on the roles of phytohormones in regulating the process. There are several hypotheses for the spikelet degeneration, such as resource limitation, self-organization, and primigenic dominance. However, convincing evidences are not enough to support the assumptions. Phytohormones including auxins, cytokinins, gibberellins, abscisic acid, and ethylene are involved in regulating spikelet degeneration in cereals. The new phytohormones of brassinosteroids and polyamines have been observed to suppress spikelet degeneration in rice. The interactions among or between plant hormones may play a more important role in regulating spikelet degeneration. However, the information on such interactions is very limited. Some agronomic practices, especially proper water and nitrogen management, could reduce spikelet degeneration but the mechanism underlying remains unclear. Further research is needed to understand the cross-talk among/between phytohormones on spikelet degeneration, to reveal the physiological and molecular mechanism in which phytohormones and their interactions regulate the degeneration of spikelets, to exploit approaches to decrease spikelet degeneration and to elucidate their mechanism.

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Grain yield and water use efficiency of super rice under soil water deficit and alternate wetting and drying irrigation

ZHOU Qun, JU Cheng-xin, WANG Zhi-qin, ZHANG Hao, LIU Li-jun, YANG Jian-chang, ZHANG Jian-hua

2017, 16 (05): 1028-1043. DOI: 10.1016/S2095-3119(16)61506-X

Abstract （941） PDF in ScienceDirect

This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency (WUE) under alternate wetting and drying (AWD) irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered (WW), moderate water deficit (MWD) and severe water deficit (SWD). Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying (AWMD), alternate wetting and severe drying (AWSD) and conventional irrigation (CI). Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI, AWMD increased, whereas AWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and either AWMD or AWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.

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Water consumption in summer maize and winter wheat cropping system based on SEBAL model in Huang-Huai-Hai Plain, China

YANG Jian-ying, MEI Xu-rong, HUO Zhi-guo, YAN Chang-rong, JU Hui, ZHAO Feng-hua, LIU Qin

2015, 14 (10): 2065-2076. DOI: 10.1016/S2095-3119(14)60951-5

Abstract （1918） PDF in ScienceDirect

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model (SEBAL) and crop information for assessment of regional crop (summer maize and winter wheat) actual evapotranspiration (ETa) in Huang-Huai-Hai (3H) Plain, China. The average seasonal ETa of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ETa belt of summer maize occurs in piedmont plain, while a low ETa area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ETa area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ETa, normalized difference vegetation index (NDVI), and the land surface temperature (LST). A stronger relationship between ETa and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ETa and LST than that between ETa and NDVI, and this significant relationship ran through the entire crop growing season. ETa in the summer maize growing season showed a significant relationship with longitude, while ETa in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

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Spatiotemporal Characteristics of Reference Evapotranspiration and Its Sensitivity Coefficients to Climate Factors in Huang-Huai-Hai Plain, China

YANG Jian-ying, LIU Qin, MEI Xu-rong, YAN Chang-rong, JU Hui, XU Jian-wen

2013, 12 (12): 2280-2291. DOI: 10.1016/S2095-3119(13)60561-4

Abstract （1325） PDF in ScienceDirect

Climate change will have important implications in water shore regions, such as Huang-Huai-Hai (3H) plain, where expected warmer and drier conditions might augment crop water demand. Sensitivity analysis is important in understanding the relative importance of climatic variables to the variation in reference evapotranspiration (ET0). In this study, the 51-yr ET0 during winter wheat and summer maize growing season were calculated from a data set of daily climate variables in 40 meteorological stations. Sensitivity maps for key climate variables were estimated according to Kriging method and the spatial pattern of sensitivity coefficients for these key variables was plotted. In addition, the slopes of the linear regression lines for sensitivity coefficients were obtained. Results showed that ET0 during winter wheat growing season accounted for the largest proportion of annual ET0, due to its long phenological days, while ET0 was detected to decrease significantly with the magnitude of 0.5 mm yr-1 in summer maize growing season. Solar radiation is considered to be the most sensitive and primarily controlling variable for negative trend in ET0 for summer maize season, and higher sensitive coefficient value of ET0 to solar radiation and temperature were detected in east part and southwest part of 3H plain respectively. Relative humidity was demonstrated as the most sensitive factor for ET0 in winter wheat growing season and declining relativity humidity also primarily controlled a negative trend in ET0, furthermore the sensitivity coefficient to relative humidity increased from west to southeast. The eight sensitivity centrals were all found located in Shandong Province. These ET0 along with its sensitivity maps under winter wheat-summer maize rotation system can be applied to predict the agricultural water demand and will assist water resources planning and management for this region.

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Performance in Grain Yield and Physiological Traits of Rice in the Yangtze River Basin of China During the Last 60 yr

ZHANG Hao, CHEN Ting-ting, LIU Li-jun, WANG Zhi-qin, YANG Jian-chang , ZHANG Jian-hua

2013, 12 (1): 57-66. DOI: 10.1016/S2095-3119(13)60205-1

Abstract （1963） PDF in ScienceDirect

Knowledge on the performance in grain yield and physiological traits is essential to understand the main yield-limiting factor and make strategies for breeding and crop management in rice (Oryza sativa L.). This study investigated the changes in grain yield and associated physiological traits of rice in the Yangtze River Basin of China during the last 60 yr. Thirteen mid-season indica and 12 japonica rice cultivars that were popularly used were grown in the field in 2008 and 2009. The grain yield and yield components, biomass, leaf area, leaf photosynthesis, root oxidation activity, and harvest index were examined. The results showed that grain yield and grain yield per day have progressively increased during the years and such increases are mainly attributed to the expanded sink size as a result of more spikelets per panicle, especially for the case of super rice. Both biomass and harvest index were increased with the improvement of cultivars. Increase in biomass for modern rice cultivars was associated with an enhancement of leaf area and photosynthesis, root dry weight, and root oxidation activity, although the indica super rice cultivars showed a lower leaf photosynthetic rate and root oxidation activity than the semi-dwarf cultivars during the grain filling period. Both indica and japonica super rice cultivars exhibited a low percentage of filled grains, which may limit their great yield potential. All the data suggested that grain yield have been substantially improved during the 60 yr of rice breeding in the Yangtze River Basin. Expanded sink size, increased dry matter production and harvest index, and enhanced leaf area and photosynthesis, root dry weight, and root oxidation activity contribute to the improvement in grain yield. Increase in filling efficiency could realize the great yield potential in super rice.

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The Effects of Different Sex-Linked Dwarf Variations on Chinese Native Chickens

OUYANG Jian-hua, XIE Liang, NIE Qing-hua, ZENG Hua, PENG Zhi-jun, ZHANG De-xiang, ZHANG Xi-quan

2012, 12 (9): 1500-1508. DOI: 10.1016/S1671-2927(00)8682

Abstract （1431） PDF in ScienceDirect

Variants in chicken growth hormone receptor (GHR) gene lead to sex-linked dwarf (SLD) chickens, but effects of different variants are distinct. In this study, 11 SLD chicken breeds or strains including 3 Chinese native breeds and 8 breeding strains were studied in order to investigate the effects of different sex-linked dwarf variations on growth performance. The results showed that there were three reasons which could lead to dwarfism in the 11 breeds or strains. Firstly, an about 1.7 kb deletion of growth hormone receptor (GHR) gene leads to dwarfism in Jiangxi dwarf chicken, strains GF24, GF26, N308, N309, and N310. Secondly, a T354C mutation in exon 5 of the GHR gene leads to dwarfism in strains N301 and N305. Thirdly, an unknown variant leads to dwarfism in Guizhou Yellow Dwarf chicken and Yixing Bantam chicken. In addition, all individuals of N303 had the 1.7 kb deletion of the GHR gene, and additionally, some of them also carried the T354C mutation. As far as the performance of individuals were compared among T354C homozygote, deletion homozygote, and heterozygote carrying both T354C and deletion, it was found that the T354C’s impacts on body weight of Chinese chickens were maximum, the body weight of chickens with homozygote T354C was 92.12% of those with heterozygote, and the difference of the body weight between deletion homozygote and heterozygote was not significant. There was no significant difference of shank length among three genotypes.

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Root Morphology and Physiology in Relation to the Yield Formation of Rice

YANG Jian-chang, ZHANG Hao, ZHANG Jian-hua

2012, 12 (6): 920-926. DOI: 10.1016/S1671-2927(00)8614

Abstract （2291） PDF in ScienceDirect

Root system is a vital part of plant and regulates many aspects of shoot growth and development. This paper reviews how some traits of root morphology and physiology are related to the formation of grain yield in rice (Oryza sativa L.). Higher root biomass, root oxidation activity, and cytokinin contents in roots are required for achieving more panicle number, more spikelets per panicle, greater grain-filling percentage, and higher grain yield. However, these root traits are not linearly correlated with yield components. When these traits reach very high levels, grain filling and grain yield are not necessarily enhanced. High numbers of mitochondria, Golgi bodies, and amyloplasts in root tip cells benefit root and shoot growth and yield formation. Proper crop management, such as an alternate wetting and moderate soil drying irrigation, can significantly improve ultra-structure of root tip cells, increase root length density and concentration of cytokinins in root bleedings, and consequently, increase grain-filling percentage, grain yield, and water use efficiency. Further studies are needed to investigate the mechanism underlying root-shoot and root-soil interactions for high grain yield, the roles of root-sourced hormones in regulating crop growth and development and the effects of soil moisture and nutrient management on the root architecture and physiology.

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Modeling the Potential Geographic Distribution of Black Pepper (Piper nigrum) in Asia Using GIS Tools

HAO Chao-yun, FAN Rui, Milton Cezar Ribeiro, TAN Le-he, WU Hua-song, YANG Jian-feng, ZHENG Wei-quan , YU Huan

2012, 12 (4): 593-599. DOI: 10.1016/S1671-2927(00)8579

Abstract （1947） PDF in ScienceDirect

Known as the “king of spices”, black pepper (Piper nigrum), a perennial crop of the tropics, is economically the most important and the most widely used spice crop in the world. To understand its suitable bioclimatic distribution, maximum entropy based on ecological niche modeling was used to model the bioclimatic niches of the species in its Asian range. Based on known occurrences, bioclimatic areas with higher probabilities are mainly located in the eastern and western coasts of the Indian Peninsula, the east of Sumatra Island, some areas in the Malay Archipelago, and the southeast coastal areas of China. Some undocumented places were also predicted as suitable areas. According to the jackknife procedure, the minimum temperature of the coldest month, the mean monthly temperature range, and the precipitation of the wettest month were identified as highly effective factors in the distribution of black pepper and could possibly account for the crop’s distribution pattern. Such climatic requirements inhibited this species from dispersing and gaining a larger geographical range.

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