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.

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.

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.

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.

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.

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.

Gene expression pattern of K transporter GhHAK5 gene of potassium efficient and in-efficient cotton cultivars based on morphological physiognomies as affected by potassium nutrition and reduced irrigation

Background Under K deficiency the uptake and distribution pattern in plant cells is mediated through different transport proteins and channels which were controlled by specific gene family.Therefore,a hydroponic experiment was conducted under control condition for testing the gene expression pattern of the K transporter under adequate and low K supply levels.After that,a 2-year field experiment was conducted to evaluate five selected cotton cultivars(four K-efficient cultivars,viz.,CIM-554,CYTO-124,FH-142,IUB-2013,and one K non-efficient,BH-212) screened from the initial hydroponics culture experiment and two levels of potassium(0 K_(2)O kg·ha^(-1) and 50 K_(2)O kg·ha^(-1)) were tested under reduced irrigation(50% available water content;50 AWC) and normal irrigation conditions(100% available water content;100 AWC).Result Results revealed that the transcript levels of GhHAK5aD in roots were significantly higher in K^(+) efficient cultivars than that in K^(+) non-efficient cultivars.The GhHAK5aD expression upon K^(+) deficiency was higher in roots but lower in shoots,indicating that GhHAK5aD could have a role in K^(+) uptake in roots,instead of transport of K^(+) from root to shoot.Similarly,under field conditions the cultivar FH-142 showed an increase of 22.3%,4.9%,2.4%,and 1.4% as compared with BH-212,IUB-2013,CYTO-124,and CIM-554,respectively,in seed cotton yield(SCY) with K application under reduced irrigation conditions.With applied K,the FH-142 showed an increase in net photosynthetic rate by 57.3% as compared with the rest of the cultivars under reduced irrigation over K control.However,the overall performance indicators of K-efficient cultivars like FH-142,CYTO-124,CIM-554,and IUB-2013 were better than BH-212(K in-efficient) under reduced irrigation conditions with applied K at 50 kg·ha^(-1).Fiber quality trait improved significantly with K application under water deficit.The increase in micronaire was 3.6%,4.7%,7.8%,3.4%,and 6.7% in BH-212,IUB-2013,CIM-554,CYTO-124,and FH-142,respectively,with K application at 50 kg·ha^(-1) over without K application under reduced irrigation conditions during the cotton growing season.Similarly,the cultivars FH-142 increased by 12% with K application under reduced irrigation as compared with other cultivars.The performance of K-efficient cultivars under reduced irrigation conditions was 30% better in SCY and quality traits with the application of K at 50 kg·ha^(-1) as compared with K-non-efficient cultivars.Similarly,water use efficiency(WUE)(40.1%) and potassium use efficiency(KUE)(20.2%) were also noted higher in case of FH-142 as compared with other cultivar with K application under reduced conditions.Conclusion Higher expression of GhHAK5aD gene was observed in K-efficient cultivars as compared with K-nonefficient cultivars in roots indicates that GhHAK5aD may be contributing to genotypic differences for K^(+) efficiency in cotton.K-efficient cotton cultivars can be used for the low-K environments and can also be recommended for general cultivars.

Characterization of wheat monogenic lines with known Sr genes and wheat cultivars for resistance to three new races of Puccinia graminis f. sp. tritici in China

Wheat stem rust, caused by Puccinia graminis f. sp. tritici(Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known stem rust resistance(Sr) genes and 69 wheat cultivars to three new Pgt races(34C0MRGQM, 34C3MKGQM, and 34C6MTGSM)identified from aeciospores at the seedling and adult-plant stages. The phenotyping results revealed that monogenic lines harboring resistance genes Sr9e, Sr17, Sr21, Sr22, Sr26, Sr30, Sr31, Sr33, Sr35, Sr36, Sr37, Sr38, Sr47, SrTmp,and SrTt3 were effectively resistant to all three Pgt races at the seedling and adult-plant stages. In contrast, monogenic lines containing Sr5, Sr6, Sr7b, Sr9a, Sr9d, Sr9f, Sr9g, Sr9b, Sr16, Sr24, Sr28, and Sr39 were highly susceptible to these races at both seedling and adult-plant stages. The other lines with Sr8a, Sr10, Sr11, Sr13, Sr14, Sr15, Sr18, Sr20,Sr19, Sr23, Sr25, Sr27, Sr29, Sr32, and Sr34, displayed variable levels of resistance to one or two of the tested races.Seedling infection types(ITs) and adult-plant infection responses(IRs) indicated that 41(59.4%) of the wheat cultivars showed high resistance to all the three races. Molecular marker analysis showed that four wheat culitvars likely carried Sr2, 20 wheat culitvars likely carried Sr31, 9 wheat culitvars likely carried Sr38, and none of the cultivars carried Sr24,Sr25, and Sr26. Our results provide a scientific basis for rational utilization of the tested Sr genes and wheat cultivars against these novel Pgt races.

Skim resequencing finely maps the downy mildew resistance loci RPF2 and RPF3 in spinach cultivars whale and Lazio

Commercial production of spinach(Spinacia oleracea L.)is centered in California and Arizona in the US,where downy mildew caused by Peronospora effusa is the most destructive disease.Nineteen typical races of P.effusa have been reported to infect spinach,with 16 identified after 1990.The regular appearance of new pathogen races breaks the resistance gene introgressed in spinach.We attempted to map and delineate the RPF2 locus at a finer resolution,identify linked single nucleotide polymorphism(SNP)markers,and report candidate downy mildew resistance(R)genes.Progeny populations segregating for RPF2 locus derived from resistant differential cultivar Lazio were infected using race 5 of P.effusa and were used to study for genetic transmission and mapping analysis in this study.Association analysis performed with low coverage whole genome resequencing-generated SNP markers mapped the RPF2 locus between 0.47 to 1.46 Mb of chromosome 3 with peak SNP(Chr3_1,221,009)showing a LOD value of 61.6 in the GLM model in TASSEL,which was within 1.08 Kb from Spo12821,a gene that encodes CC-NBS-LRR plant disease resistance protein.In addition,a combined analysis of progeny panels of Lazio and Whale segregating for RPF2 and RPF3 loci delineated the resistance section in chromosome 3 between 1.18–1.23 and 1.75–1.76 Mb.This study provides valuable information on the RPF2 resistance region in the spinach cultivar Lazio compared to RPF3 loci in the cultivar Whale.The RPF2 and RPF3 specific SNP markers,plus the resistant genes reported here,could add value to breeding efforts to develop downy mildew resistant cultivars in the future.

Mixing trait-based corn(Zea mays L.)cultivars increases yield through pollination synchronization and increased cross-fertilization

Abiotic stress such as high temperature at flowering is one of many conditions reducing yield of corn(Zea mays L.).Mixing corn cultivars with diverse functional traits increases within-crop diversity and provides a potential means of mitigating yield losses under stress conditions.We conducted a three-year field study to investigate the effects of cultivar mixtures on kernel setting rate,pollen sources,and yield.This study consisted of six treatments,including two high temperature-tolerant(HTT)monocrops of WK702 and DH701,two high temperature-sensitive(HTS)monocrops of DH605 and DH662,and two HTT–HTS mixtures of WK702-DH605 and DH701-DH662.The anthesis–silking interval(ASI)was 0.9–1.6 days shorter in mixtures than in monocrops.Kernel setting rate was increased in mixtures(86.4%–88.7%)compared with those in monocrops(74.7%–84.1%)as a result of synchrony and complementarity of pollination.Grain yields of the HTT–HTS mixtures increased by 13.3%–18.7%,equivalent to 1169 to1605 kg ha^(-1),in comparison with HTS corn monocrops.The results of SSR markers showed that crossfertilization percentage in corn cultivar mixtures ranged from 29.3%to 47.8%,partially explaining yield improvement.Land equivalent ratio(LER)was 1.12 for corn mixtures and the partial land equivalent ratio(e.g.,>0.5)showed the complementary benefits in corn mixtures.The results indicated that mixing corn cultivars with diverse flowering and drought-tolerance traits increased yields via pollination synchrony.

Stay-Green Panicle Branches Improve Processing Quality of Elite Rice Cultivars

Rice panicle branches are key routes for transportation of photo synthetic products to grains.Branch senescence is an important trait that the breeders considered when breeding elite rice cultivars in South China.However,little is known about the mechanisms underlying the contributions of stay-green panicle branches to rice yield and quality.Here,we reported stay-green branches that continuously maintained transportation function and provided carbohydrates for basal grain development at the late stages of rice development.This ensured the coordination of development between apical and basal grains,and further improved the processing quality of elite rice.These findings provided strategies for improving the fullness and quality of rice grains and presented an important basis for cultivating elite rice.

Genetic diversity, population structure, and genome-wide association analysis of ginkgo cultivars

Ginkgo biloba is an economically valuable tree worldwide.The species has nearly become extinct during the Quaternary,which has likely resulted in reduction of its genetic variability.The genetic variability is now conserved in few natural populations in China and a number of cultivars that are,however,derived from a few ancient trees,helping the species survive in China through medieval times.Despite the recent interest in ginkgo,however,detailed knowledge of its genetic diversity,conserved in cultivated trees and cultivars,has remained poor.This limits efficient conservation of its diversity as well as efficient use of the existing germplasm resources.Here we performed genotyping-by-sequencing(GBS)on 102 cultivated germplasms of ginkgo collected to explore their genetic structure,kinship,and inbreeding prediction.For the first time in ginkgo,a genome-wide association analysis study(GWAS)was used to attempt gene mapping of seed traits.The results showed that most of the germplasms did not show any obvious genetic relationship.The size of the ginkgo germplasm population expanded significantly around 1500 years ago during the Sui and Tang dynasties.Classification of seed cultivars based on a phylogenetic perspective does not support the current classification criteria based on phenotype.Twenty-four candidate genes were localized after performing GWAS on the seed traits.Overall,this study reveals the genetic basis of ginkgo seed traits and provides insights into its cultivation history.These findings will facilitate the conservation and utilization of the domesticated germplasms of this living fossil plant.

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.

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.

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.

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.