Cell Wall Fixation,Translocation,and Vacuolar Detoxification of Cadmium Contribute to Differential Grain Cadmium Accumulation in Two Rice Cultivars

Cadmium(Cd)toxicity in rice is a major concern for human health and the environment,as it can accumulate in rice grains when grown in Cd-contaminated soils.To mitigate the risk of Cd toxicity,it is crucial to cultivate rice varieties with low grain Cd accumulation.In the summers of 2021 and 2022,we conducted Cd analysis on two rice cultivars,Tianyouhuazhan(TYHZ)and Xiushui 14,grown in fields with varying Cd pollution levels.These cultivars were also subjected to hydroponic treatment with or without 1μmol/L Cd for 7 d to assess Cd accumulation,nitric oxide(NO)production。

Yield and Nutritive Values of Semi- and Non-Fall Dormant Alfalfa Cultivars under Late-Cutting Schedule in California’s Central Valley

California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.

Increasing root-lower characteristics improves drought tolerance in cotton cultivars at the seedling stage

Drought is an important abiotic stress factor in cotton production.The root system architecture(RSA)of cotton shows high plasticity which can alleviate drought-related stress under drought stress(DS)conditions;however,this alleviation is cultivar dependent.Therefore,this study estimated the genetic variability of RSA in cotton under DS.Using the paper-based growth system,we assessed the RSA variability in 80 cotton cultivars at the seedling stage,with 0 and10%polyethylene glycol 6000(PEG6000)as the control(CK)and DS treatment,respectively.An analysis of 23 aboveground and root traits in the 80 cotton cultivars revealed different responses to DS.On the 10th day after DS treatment,the degree of variation in the RSA traits under DS(5–55%)was greater than that of CK(5–49%).The 80 cultivars were divided into drought-tolerant cultivars(group 1),intermediate drought-tolerant cultivars(group 2),and drought-sensitive cultivars(group 3)based on their comprehensive evaluation values of drought resistance.Under DS,the root lengthlower,root area-lower,root volume-lower,and root length density-lower were significantly reduced by 63,71,76,and 4%in the drought-sensitive cultivars compared to CK.Notably,the drought-tolerant cultivars maintained their root lengthlower,root area-lower,root volume-lower,and root length density–lower attributes.Compared to CK,the root diameter(0–2 mm)-lower increased by 21%in group 1 but decreased by 3 and 64%in groups 2 and 3,respectively,under DS.Additionally,the drought-tolerant cultivars displayed a plastic response under DS that was characterized by an increase in the root-lower characteristics.Drought resistance was positively correlated with the root area-lower and root length density-lower.Overall,the RSA of the different cotton cultivars varied greatly under DS.Therefore,important root traits,such as the root-lower traits,provide great insights for exploring whether drought-tolerant cotton cultivars can effectively withstand adverse environments.

Analysis on Genetic Diversity of 40 Flowering Cherry Cultivars and Construction of Molecular ID Based on SSR Markers

Studying on the genetic diversity and genetic relationship of flowering cherry cultivars is extremely important for germplasm conservation, cultivar identification and breeding. Flowering cherry is widely cultivated as an important woody ornamental plant in worldwide, especially Japan, China. However, owning to the morphological similarity, many cultivars are distinguished hardly in non-flowering season. Here, we evaluated the genetic diversity and genetic relationship of 40 flowering cherry cultivars, which are mainly cultivated in China. We selected 13 polymorphicprimers to amplify to allele fragments with fluorescent-labeled capillary electrophoresis technology. The population structure analysis results show that these cultivars could be divided into 4 subpopulations. At the population level, Na and Ne were 6.062, 4.326, respectively. Ho and He were 0.458 and 0.670, respectively. The Shannon’s information index (I) was 1.417. The Pop3, which originated from P. serrulata, had the highest Ho, He, and I among the 4 subpopulations. AMOVA showed that only 4% of genetic variation came from populations, the 39% variation came from individuals and 57% (p < 0.05) came from intra-individuals. 5 polymorphic SSR primers were selected to construct molecular ID code system of these cultivars. This analysis on the genetic diversity and relationship of the 40 flowering cherry cultivars will help to insight into the genetic background, relationship of these flowering cherry cultivars and promote to identify similar cultivars.

Effect of Different Mulch Materials on Yield and Nutrition Profile of Common Capsicum (Capsicum annuum) Cultivars in Bangladesh

Capsicum is a nutritious vegetable and its cultivation in farms is getting popular in Bangladesh. Although many efforts have lain to explore better yielding and nutritionally rich cultivars with suitable modern cultivation techniques but still have to find the desired outcome. Thus, it’s necessary to conduct further research to identify the high-yielding and nutritious capsicum cultivars in Bangladesh. An experiment was conducted from July 2021 to June 2022 at the Bangladesh Institute of Research and Training on Applied Nutrition (BIRTAN) research field with three cultivars of capsicum: B0 = California Wonder, B1 = BARI Misti Morich-1 and B2 = BARI Misti Morich-2 and three mulching: T0 = No mulching, T1 = Water hyacinth, T2 = Poly Mulching in randomized complete block design with three replications to identify better quality capsicum cultivar and suitable mulching material. Among cultivars the BARI Misti Morich-2 (B2) showed increased agronomic parameters like number of branches and effective branches per plant, leaves length and width, consequently yield and yield contributing traits were also enhanced like fruits per plant, fruit length, fruit diameter and yield per plant (25.97%, 4.54%, 3.64% and 21.43%, respectively). Poly Mulching (T2) increased agronomic traits, yield traits and yield (0.61 kg) than BARI Misti Morich-1 (T1). The combined effect of B2T2 increased the number of branches per plant, effective branches per plant, leaves length and breadth by 40%, 90%, 15.57% and 26.22%, respectively, hence resulting in an increased yield of 20%. BARI Misti Morich-2 cultivar showed an increase in Fe, Zn and Vitamin-C content of 26.24% and 23.10%, 8.82% and 5.14%, and 6.03% and 5.74% than B0 and B1 cultivars, respectively. Therefore, BARI Misti Morich-2 exhibited the improved agronomic, yield and nutritional traits of capsicum under poly mulching among other cultivars in Bangladesh.

Study on Germplasm Resources of Peach Cultivars

[Objectives]To study the germplasm resources of excellent peach cultivars.[Methods]Five peach cultivars were introduced,in-cluding‘Jinxiu’peach,‘Jinxiang’peach,‘Chunxiao’peach,‘Hujingmilu’peach and‘018 nectarine’peach.Then,these five cultivars were used to study the biological characteristics of peach trees,namely,as phenology,fruit quality,heat resistance,cold resistance and other resistance.[Results]Five cultivars of peach plants grew fast and robust,among which‘018 nectarine’had very crisp fruit,‘Jinxiu’,‘Jinxiang’,‘Chunxiao’and‘Hujingmilu’had very sweet fruitꎻthe peach trees of these five cultivars have good water resistance,heat resist-ance and cold resistance.[Conclusions]The results of this study can not only provide a reference for the introduction of peach trees,but also provide a practical basis for the large-scale planting of peach trees.

Optimizing the transplanting window for higher productivity of short and medium duration rice cultivars in Punjab,India using CERES-Rice model

The CERES-Rice(V4.7.5)model was used to identify the optimum transplanting window for higher productivity of rice in Indian Punjab.The model was first sensitized for 11 genetic coefficients and then these values were used for calibrating and validating the model for rice cultivars.The Normalized Root Mean Square Error was in excellent range(<10%)for all the parameters—the coefficient of determination(R2)for CVS.PR126 and PR127 for days taken to anthesis and maturity were 0.94 and 0.89−0.96,respectively while grain yield and LAI(leaf area index)were 0.89−0.98 and 0.87−0.89,respectively.The optimum transplanting window of 24−30 June for PR126 and 20−26 June for PR127 simulated the grain yield/LAI ranging from 8,425−8,473 kg·ha^(−1)/4.23−4.24 for PR126 and 8,298−8,356 kg·ha^(−1)/4.20−4.21 for PR127.The early transplantation of rice cultivars on 7th June resulted in the lowest yield/LAI of 6,702 kg·ha^(−1)/3.8 for PR126 and 6,865 kg·ha^(−1)/3.9 for PR127.The deviation for the grain yield and HI(harvest index)of PR126 was between−14.2%to+8.2%and−15.1%to+10.5%,respectively,and of PR127 varied between−11.2%to+8.1%and−14.2%to+10.6%,respectively.The decline in the yield/HI from the average was observed during early transplantation in 2^(nd)week of June(before the 15^(th)of June for PR126 and the 13^(th)of June for PR127)as well as late transplantation in the 1st week of July(after 11^(th)July for PR126 and 6^(th)July for PR127)for rice cultivars.The negative effect on yield and HI of both varieties during early and late transplantation could be due to unfavorable climatic conditions.

Difference of Nitrogen Uptake and Use Efficiency in Conventional Indica Rice Cultivars with Different Nitrogen Use Efficiency for Grain Output

[Objective] The study aimed to confirm difference of nitrogen uptake and used efficiency with different nitrogen use efficiency for grain output (NUEg) types of indica rice.[Method] 88 and 122 conventional indica rice cultivars were solution-cultured in 2001 and 2002, respectively. Dry matter weight (including root system, culm and sheath, leaves, panicle), nitrogen content of different organs, yield and its components were measured. The tested rice cultivars were classified into 6 types (i.e. A, B, C, D, E and F, A was the lowest, and F was the highest) based on their NUEg level by the MinSSw method.[Result](1)Difference of NUEg of the cultivars used in this study were very large; (2) No significant difference of N content at heading stage was observed among different NUEg types of indica rice. In the cultivars with higher NUEg, however, N content in leaf, stem-sheath and entire rice plant were lower at mature stage. (3)Cultivars with higher NUEg were characterized with lower N uptake before heading and at mature stage; (4) Cultivars with higher NUEg were characterized with higher N use efficiency in biomass production and harvest index. [Conclusion] The cultivars with higher NUEg showed lower N uptake and N content, while nitrogen use efficiency was higher.

Observation for Leaf Epidermal Characteristics of Four Different Pomegranate Cultivars under Scanning Electron Microscope

[Objective] The research aimed to provide reference for classification of pomegranate cultivars and studies of genetic relationship among pomegranate cultivars.[Method] The electron microscope scanning was used to comparatively observe leaf epidermal structures of 4 pomegranate cultivars.[Result] The upper epidermal structures of 4 pomegranate cultivars were similar and showed reticular structure .However, the differences existed in lower epidermis,such as cell shape,cell size and arrangement mode of cell as well as stomatal density,while the structures of leaf vein in lower epidermis of 4 pomegranate cultivars were similar.[Conclusion] The research provided morphological references for studying heterosis of pomegranate to some extent.

Evaluation of the Adaptability of 28 Green Asparagus Cultivars

[Objective] This study aimed to evaluate the adaptability of 28 green asparagus cultivars under the climatic conditions in Poland and to select cultivars most suitable for growing in Poland. [Method] Based on an overview of asparagus, spears of 28 cultivars from the six year’s harvest in 2008 were evaluated at the Marcelin Experimental Station. During the harvest period, spears were cut daily and trimmed to 22 cm, followed by grading and weigh. In addition, general appearance, anthocyan discolouration, head tightness, colour and smoothness of the spears were also evaluated. [Result] In terms of total yield, ‘Gynlim’ was the best cultivar, followed by ‘Hannibal’, ‘Ravel’, ‘Grolim’ and ‘Ramada’; ‘Gloria’ was the worst cultivar, followed by ‘Tsuki-kho 3’, ‘Purple Passion’, ‘Jacq. Ma 2014’, ‘Sartaguda’, and ‘Jacq. Ma 2004’. ‘Gynlim’, ‘Hannibal’, ‘Ravel’, ‘Ramada’ and ‘Ariane’ were the top five cultivars in early yield, and the worst cultivar concerning early yield was ‘PLA-2132’, followed by ‘Ramos’, ‘Tsuki-kho 3’ and ‘Purple Passion’. ‘Ariane’, ‘Cipress’, ‘Grolim’, ‘Gynlim’ and ‘Hannibal’ were five best culivars considering spear quality, and the four worst cultivars were ‘Jacq. Ma 2004’, ‘Gloria’, ‘Jacq. Ma 2014’ and ‘Tsuki-kho 3’. [Conclusion] Taken both the yield and quality of spears into consideration, the most suitable cultivars of green spears for growing under the climatic conditions in Poland should be ‘Gynlim’, ‘Hannibal’, ‘Ravel’ and ‘Grolim’, while ‘Gloria’, ‘Tsuki-kho 3’, ‘Purple Passion’, ‘Jacq. Ma 2014’ and ‘Sartaguda’ were not suitable for growing in Poland.

Resistance of Major and Backup Rice Cultivars against Ustilaginoidea virens in Anhui Province

[Objective] The aim was to study resistance of major and backup rice cul- tivars against Ustilaginoidea virens. [Method] Experiments and surveys were made on resistance of seventeen backup rice cultivars and some major cultivars in Anhui Province to identify resistance of different rice cultivars. [Result] Yanjing No.9, 80You 226, Tianxie No.l, A01 Xian, Lvjingnuo No.6 were moderate resistant; A03 Xian and Yangjing 636 were susceptible and the rest ten showed moderate susceptibility. Based on surveys on major rice cultivars, most of Liangyou rice series are suscept- able and novel Liangyou Xiang 4 enjoys resistance to certain extent. [Conclusion] The research provided references for resistance of rice against diseases in Anhui Province.

Genetic Diversity Analysis and Fingerprint Construction of Major Mango Cultivars in China

[Objective] The genetic diversity of major mango cultivars in China was analyzed by using SSR markers, and their fingerprints were constructed so as to provide theoretical basis for germplasm innovation and breeding of mango. [Method] With 115 pairs of SSR primers, genetic diversity analysis and cluster analysis were performed for 30 mango cultivars, among which the genetic relationships were analyzed. [Result] Total 64 pairs of polymorphic primers were screened out from the 115 pairs of primers, and total 343 bands were amplified from the 30 cultivars with 73.2% of polymorphic bands. On average, 3.9 allelic loci were detected for each pair of primers with genetic diversity index of 0.5, Shannon＇s diversity index of 1.00 and polymorphism information content of 0.49, indicating higher genetic diversity. The cluster analysis showed that the 30 major cultivars could be classified into four categories. The first category included 14 cultivars; the second category included 11 cultivars, most of which were introduced from abroad; the third category included 4 cultivars, Le., Miansan, Parayinda, Baiyu and Hongxiangya： the fourth category included only one cultivar Maqiesu.By using 7 pairs of SSR markers, i.e., M42, M49, M54, M55, M96, M99 and M103, digital fingerprints were constructed for the 30 mango cultivars. [Conclusion] The 30 mango cultivars present more complex genomic genetics and abundant genetic information, and they have higher genetic diversity.

Relationship between Pepper Cultivars' Yields and High Temperatures with Pepper in Different Genotypes

[Objective] The aim was to research effects of high temperature stress on pepper yield by cultivation of peppers in different genotypes and provide theoretical references for pepper breeding and high-yield cultivation. [Method] Four pepper va- rieties were studied with varied genotypes to explore effects of temperatures on pepper fruiting and yield in the whole growth stage. [Result] The optimal-temperatre term for pepper blooming and fruiting were shorter. For example, the periods from June 16 to July 15 and from August 16 to September 15 would be the best, with temperature ranging from 20.70 ℃ to 30.74 ℃. In the stage from July 16 to August 15, the temperature range of 24.22 ℃-32.17 ℃ would severely affect pepper growth and yield. Pepper No. 1 and pepper No. 1-1＇s yields were just 38.21% and 51.74% of the yields in the stage 1st and 52.01% and 62.35% in the stage 3rd and eady No. 1 and late No. 1 were 48.1% and 72.38%, respectively. Under high tem- perature stress in summer, pepper No. 1, pepper No. 1-1, and late No. 1 showed extremely significant differences with early No. 1 （P〈0.01）. The yield ratios of pep- per No. 1 and pepper No. 1-1 in stage 1st （May 25-July 15） and the later three stages were 42.34：57.66 and 39.50：60.50; the ratio was 47.99：52.21 of early No. 1; the ratio of late No. 1 was 20.25：79.75. [Conclusion] The cultivation approaches should vary upon pepper variety, necessitating the focus on pepper management, fertilization, and irrigation, and locating peak-blooming term in moderate-temperature stage to accelerate pepper growth.

Separation and Identification of Differentially Expressed Proteins in Pistillate Flowers between Different Mulberry Cultivars

[Objective] This study aimed to explore the proteins related to pistillate flower development in different mulberry cultivars. [Method] The total proteins of the pistillate flowers of two mulberry cultivars Dal0 （Morus atropurpurea Roxb.） and SG01 （Morus muIticaulis Perr.） were extracted, separated and detected through two- dimensional electrophoresis （2-DE） and mass spectrometry. [Result] There was sig- nificant difference in the expression of proteins from the pistillate flowers of different mulberry cultivars. From the 2-DE images of Dal0 and SG01, 445_＋17 and 425_＋12 protein spots were respectively detected. The expression levels of 75 protein spots differed significantly. Thirteen spots those were expressed at high levels and well separated were analyzed by mass spectrometry, and nine of them were identified successfully. The nine proteins are involved in the glycometabolism, protein and amino acid metabolism and defense responses during the development of mulberry pistillate flower after they were pollinated. [Conclusion] The findings will provide reference for further study on the molecular mechanism of mulberry pistillate flower de- velopment.

Study on in vitro Culture and Germination of Three Cultivars of Lagerstroemia indica L.

[Objective] The research aimed at investigating the in vitro culture and germination of three cultivars of Lagerstroemia indica L.[Method] The pollen of three L.indica cultivars Hongdiefeiwu,Cuipanjinwei and Zizhuayinwei in full flowering stage was collected as materials to study the effects of in vitro culture on pollen viability and germination.[Result] The optimum medium for L.indica pollen germination was 150 g/L sucrose ＋ 60 mg/L boric acid ＋ 20 mg/L CaCl2＋20 mg/L MgSO4 ＋100 mg/L KNO3,in which,the concentrations of sucrose and boric acid could significantly influence the pollen germination.In addition,the vitality of pollen at long filament differed from that at short filament,wherein,the vitality of pollen at short filament of Zizhuayinwei and Hongdiefeiwu was higher than that at their long filament,while Cuipanjinwei showed the opposite result.Within 2-6 h after pollination self,pollen germinated to form pollen tube,which grew fast firstly and then slowly.[Conclusion] The study provided theoretical reference for breeding new L.indica cultivar.

Comparative Test for New Watermelon Cultivars

Comparative test was conducted on 11 （including the cultivar as control） new watermelon cultivars to identify the yielding ability, stability, adaptability, stress resistance and other important characteristics of the new watermelon oultivars, to thereby obtain new watermelon cultivars with good comprehensive characters suit- able for different regions and different cultivation manners. The results showed that Dali Qilin, Jingangerhao Hemeiren, Hongli Dahonghu, Hongli Baowang, Longjing Heibao and XJ-I had outstanding performance in yield, resistance and quality, and thus were worthy of further experiment demonstration and certification.

Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years

Three winter wheat cultivars ( Triticum aestivum L.), representatives of those widely cultivated in Beijing over the past six decades, were grown in the same environmental condition, and their physiological features were investigated. Daily changes of net photosynthetic rate (P-n), transpiration (T-r) in different growth stages were measured in order to find the relationship between leaf photosynthesis and yield. Instantaneous water use efficiency (WUE) of leaf was calculated from P-n/T-r. It is suggested that relationship between photosynthetic rate and yield changed with the developing stages of wheat. High yield wheat cultivar Jingdong 8 (released in the 1990s) had a higher photosynthetic rate ( the maximal P-n increased by 77%) and transpiration rate (the maximal T-r increased by 69%), but a lower WUE than the low yield cultivar Yanda 1817 (released in the 1940s) during the day time at stem elongation stage. However; difference of P-n among the three cultivars changed with wheat growth process. Before 10 o'clock P-n in leaves of Jingdong 8 usually was the highest of the three cultivars, but P-n of Yanda 1817 was the highest after 10 o'clock. At dough ripe stage, P-n in leaves of Yanda. 1817 was the highest among the three cultivars during the whole day. The difference of changing trend of transpiration in three wheat cultivars was similar to P,, but WUE of Yanda 1817 was the highest in those three cultivars, indicating that the higher yield of Jingdong 8 was achieved via a greater consumption of water. Contrary to the cultivars released in the later period, midday depression of photosynthesis was small in Yanda 1817, which might suggest that Yanda 1817 was resistant to photoinhibition. It is possible that photosynthetic potential in leaves of wheat increased as wheat cultivars was improved over the past six decades. However, it became less resistant to photoinhibition.

Comprehensive Evaluation on Drought Resistance of Different Flue-cured Tobacco Cultivars in Bijie Tobacco Growing Area

Based on pot experiments, major agronomic traits, biomass accumulation, leaf water-holding capacity, relative water content, root MDA content, root proline content and other physiological indicators of four different flue-cured tobacco culti-vars under drought stress were investigated, and drought resistance in various flue-cured tobacco cultivars was comprehensively analyzed with subordinate function method, aiming at clarifying the differences in drought resistance among various flue-cured tobacco cultivars. The results indicated that under drought stress, major agronomic traits, fresh and dry mass accumulation, and leaf relative water content of four different flue-cured tobacco cultivars were reduced significantly; the decreas-ing range of Yunyan 87 reached the minimum, fol owed by Bina 1, while Qianxi 1 demonstrated the maximum decreasing range. Leaf water-holding capacity of various flue-cured tobacco cultivars showed a descending order of Yunyan 87 〉 Bina 1 〉Qianxi 1 〉 Jiucaiping 2. MDA content and proline content in roots of various flue-cured tobacco cultivars increased significantly; to be specific, Yunyan 87 and Bina 1 exhibited a slight increase in root MDA content and a significant increase in root proline content, while Jiucaiping 2 and Qianxi 1 showed an opposite trend. Accord-ing to the results of comprehensive analysis with subordinate function method, drought resistance in various flue-cured tobacco cultivars showed a descending or-der of Yunyan 87 〉 Bina 1 〉 Jiucaiping 2 〉 Qianxi 1.

Comparison of Absorption Capacity of Different Flue-cured Tobacco Cultivars for Six Kinds of Heavy Metals

[Objective] This study aimed to analyze the differences in absorption capacity of different flue-cured tobacco cultivars for chromium （Cr）, arsenic （As）, cadmium （Cd）, lead （Pb）, mercury （Hg） and copper （Cu）. [Method] With 4 flue-cured tobacco cultivars as the experimental materials, their absorption capacity for 6 kinds of heavy metals was compared by pot experiment. [Result] There were great differences in absorption capacity of different flue-cured tobacco cultivars for the six kinds of heavy metals. According to the absorption capacity of different flue-cured tobacco cultivars for the heavy metals, the six heavy metals could be classified into three categories. The first category included only Cd with average enrichment coefficient of 8.564; the second category included Hg with average enrichment coefficient of 0.753; and the third category included Cr, As, Pb and Cu with average enrichment coefficients below or equivalent to 0.114. [Conclusion] The absorption capacity of different flue-cured tobacco cultivars for heavy metals was grasped by this study, thereby providing reference data for screening of high-yielding and high-quality flue-cured tobacco cultivars.

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the difference in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil （Entic Haplaquept） with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer （GFAAS） and flame atomic adsorption spectrophotometer （AAS） respectively. Wide variation of Cd content in grain was found in a range of 0.004-0.057 mg/kg, while the Zn content in a range of 10.25-30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods （MOHC and SSC, 2005）, calculated potential risk of food Cd exposure with ＂Zn hungry＂ through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.