QTL Mapping of Yield and Yield Components for Elite Hybrid Derived-RILs in Upland Cotton

A population of 180 recombinant inbred lines （RILs） was developed by single seed descended from the cross of high yield Upland cotton （Gossypium hirsutum L.） varieties Zhongmiansuo12 （ZMSI2） and 8891, the two parents of Xiangzamian2 （XZM2）. A genetic linkage map consisting of 132 loci and covering 865.20 cM was constructed using the RIL population chiefly with SSR markers. Yield and yield components were investigated for RILs in three environments in China. The purpose of the present research was to analyze the relationship between yield and its components and to map QTL for yield and yield components in cotton. QTL were tagged with data sets from single environment （separate analysis） and a set of data from means of the three environments （joint analysis）. A total of 34 QTL for yield and yield components were independently detected in three environments, whereas fifteen QTL were found in joint analysis. Notably, a stable lint percentage QTL qLP-A10-1 was detected both in joint analysis and in two environments of separate analysis, which might be of special value for marker-assisted selection. The QTL detected in the present study provide new information on improving yield and yield components. Results of path analysis showed that bolls/plant had the largest contribution to lint yield, which is consistent with the mid-parent heterosis value in F1. Accordingly, in cotton breeding, bolls/plant can be considered first and other yield components measured as a whole to implement variety enhancement and hybrid selection of cotton.

Combining Ability Analysis for Yield and Yield Components of Yinshui-type Japonica Hybrid Rice

[Objective] This study aimed to analyze the yield potential of newly developed Yinshui-type japonica hybrid rice parents and provide the theoretical basis for breeding of Yinshui-type japonica hybrid rice. [Method] An incomplete diallel cross of four cytoplasmic male sterile （CMS） lines and four restorer lines was designed to investigate the combining ability for yield and yield components of Yinshui-type japonica hybrid rice. [Result] The variances of general combining ability （GCA） for yield traits were extremely significantly different. GCA variances of male parents were higher than that of female parents except for seed-setting rate. The variances of specific combining ability （SCA） for grain yield per plant, number of effective spikes and seed-setting rate were significantly or extremely significantly different. 139A and Wanlun 422 exhibited higher GCA effects. Most yield traits of these two parents be- longed to type II. Combinations 139AxWanlun 422 and Liaojingl0AxWanlun 422 had relatively high grain yield per plant and SCA effects. GCA effects of restorer lines and SCA effects of combinations greatly affected yield traits, while GCA ef- fects of CMS lines slightly affected yield traits. [Conclusion] In this study, restorer lines exhibited greater genetic differences and impact on yield traits than CMS lines; 139A and Wanlun 422 possessed higher application potential.

Effect of Limited Single Irrigation on Yield of Winter Wheat and Spring Maize Relay Intercropping

A field experiment was conducted during the 2002/2003 cropping season of winter wheat （Triticum aestivum） and spring maize （Zea mays） to evaluate the effect of limited single drip irrigation on the yield and water use of both crops under relay intercropping in a semi-arid area of northwestern China. A controlled 35 mm single irrigation, either early or late, was applied to each crop at a certain growth stage. Soil water, leaf area, final grain yield and yield components such as the thousand-grain weight, length of spike, fertile spikelet number, number of grains per spike, and grain weight per spike were measured, and water use efficiency and leaf area index were calculated for the irrigated and non-irrigated relay intercropping treatments and sole cropping controls. The results showed that yield, yield components, water use efficiency, and leaf area index in the relay intercropping treatments were affected by limited single drip irrigation during various growth stages of wheat and maize. The total yields in the relay intercropping treatment irrigated during the heading stage of wheat and the heading and anthesis stage of maize were the highest among all the treatments, followed by that irrigated during the anthesis stage of wheat and silking stage of maize; so was the water use efficiency. Significant differences occurred in most yield components between the irrigated and non-irrigated relay-intercropping treatments. The dynamics of the leaf area index in the relay-intercropped or solely cropped wheat and maize showed a type of single-peak pattern, whereas that of the relay intercropping treatments showed a type of double-peak pattern. Appropriately, limited single irrigation and controlled soil water content level could result in higher total yield, water use efficiency, and leaf area index, and improved yield components in relay intercropping. This practice saved the amount of water used for irrigation and also increased the yield. Therefore, heading stage of wheat and heading and anthesis stage of maize were suggested to be the optimum limited single irrigation time for relay-intercropped wheat and maize in the semi-arid area.

Effects of Plant Population on Growth, Development and Oil Yield of Safflower

Two field trials were clone to evaluate the effects of plant density on the growth, development and yield of safflower. The results showed that plant density and season of growth had significant （P ≤ 0.01） effects on growth, development, yield components, yield and oil content of safflower. Increasing safflower plant density from 100,000 to 250,000 plants ha^- significantly reduced plant height （13.2%-21.3%）, branch number plant^-1 （37%-54.7%）, leaf number plant^-1 （39%-39.2%）, leaf area （19.5%-53%）, plant spread （39.6%-54.4%）, root length （28.1%-54.4%）, plant biomass （17%-50%）, capitula size （12%-12.7%）, capitula number plant^-1 （39.5%-50.5%）, seed number capitula~ （39%-45%）, capitula weight （3.3%-3.6%）, seed yield （67.9%-69.8%） and seed oil content （14.7%-20.8%）. The reduction in vegetative growth, yield components, yield and oil content of safflower due to increased plant density was attributed to inter and intra-plant competition for light, nutrients and water necessary for growth and development. The differences between winter and summer grown safflower were attributed to difference in day and night temperature （DIF） and the average daily temperature which were optimum for safflower growth in winter. It was concluded that under Botswana conditions or in semi-arid areas, safflower should be planted at 50 cm × 20 cm or wider in order to maximize yield and oil content and allow the plants to express their maximum genetic potential.

Influence of potassium fertilization and foliar application of zinc and phosphorus on growth,yield components,yield and fiber properties of Egyptian cotton(Gossypium barbadense L.)

Aims Supplying optimal quantities of mineral nutrients to growing crop plants is one way to improve crop yields.Nutrients need to be used rationally in order to avoid a negative ecological impact and undesirable effects on the sustainability of agricultural production systems.Excessive application of nutrients also affects the farmer’s economy.In order to calculate the amount of fertilizer to be applied to crops,it is necessary to develop recommendation programmers that adjust nutrient rates to crop requirements.Methods Experiments in two successive seasons were conducted to investigate the effect of K fertilization and foliar application of Zn and P on yield and fiber properties of cotton cv.Giza 86.Potassium(0.0 and 47.4 kg of K ha^(-1))was soil applied,while chelated zinc(0.0 and 57.6 g of Zn ha^(-1),applied twice at 70 and 85 days after sowing‘DAS’)and phosphorus(0.0,576,1152 and 1728 g of P ha^(-1),applied twice at 80 and 95 DAS)were applied to the foliage.Important findings Dry matter yield,total chlorophyll concentration,K,Zn and P uptake per plant,number of opened bolls per plant,boll weight,seed index,lint index,seed cotton yield per plant,seed cotton and lint yield ha^(-1) and earliness of harvest increased with the application of K,Zn and P.Treatments generally had no significant effect on lint percentage and fiber properties,with exceptions,for micronaire reading and flat bundle strength,and uniformity ratio,where the mean values of these characters were significantly increased over the untreated control by applying K,and for the micronaire reading in the first season,when applying P at 1728 g ha^(-1),and uniformity ratio in the second season,when applying Pat 1152 and 1728 g ha^(-1),where the mean values of these characters were significantly increased over the untreated control by applying P.Under the conditions of this study,applying K fertilization at 47.4 kg ha^(-1) combined with spraying cotton plants with zinc at 57.6 g ha^(-1) and also with P at 1728 g ha^(-1) improved growth and yield of Egyptian cotton.

Effects of plant density and mepiquat chloride application on cotton boll setting in wheat–cotton double cropping system

Sowing cotton directly after harvesting wheat in the Yangtze River Valley of China requires early mature of cotton without yield reduction.Boll-setting period synchronisation and more yield bolls distributed at the upper and middle canopy layers are also required for harvesting.The objective of this study is to quantify the individual and interaction effects of plant density and plant growth regulator mepiquat chloride(MC)on temporal and spatial distributions of yield bolls,as well as yield and yield components.During the 2013–2016 cotton growing seasons,the experiments were conducted on a shortseason cotton cultivar CRRI50 at Yangzhou University,China.Various combinations of plant density(12.0,13.5 and 15.0 plants m^(–2))and MC dose(180,270 and 360 g ha^(–1))were applied on cotton plants.The combination of 13.5 plants m^(–2)and 270 g ha^(–1)MC resulted in the greatest boll number per unit area,the highest daily boll setting number and more than 90%of bolls positioned within 45–80 cm above the ground.In conclusion,appropriate MC dose in combination of high plant density could synchronize boll-setting period and retain more bolls at the upper and middle canopy layers without yield reduction in the system of direct-seeded cotton after wheat harvest,and thus overcome the labor-intensive problem in current transplanting cropping system.

Evaluation of Cassava Genotypes for Resistance to Cassava Mosaic Disease and Agronomic Traits

Sixteen cassava genotypes comprising introductions, local landraces and improved genotypes were evaluated for two seasons in Mansa, Zambia, for their reaction to cassava mosaic disease (CMD). The study was conducted in 2009/10 and 2010/11 seasons to evaluate the reaction of cassava cultivars to CMD and agronomic traits. Cassava mosaic disease severity and leaf retention were scored at 6 months after planting (MAP) and data on yield and yield components were recorded at harvest (7 MAP). Significant genotype x season interaction for CMD, harvest index, fresh root yield, biomass, plant height, root size and leaf retention was recorded. Bangweulu, Kalaba, Chikula, Mwakamoya and Chila-7 were the most susceptible genotypes over the two seasons. Mweru, Kampolombo, TMS190, TMS3001, Tanganyika and Nalumino had low severity scores. Harvest index ranged from 0.36 (Mwakamoya) to 0.55 (Chila-7) for the combined seasons. Chila-7 had the highest fresh root yield with a mean of 0.87 kg plant-1 for the combined seasons. The resistant genotypes might be used to improve the CMD resistance of local cultivars through hybridisation.

Effects of External Chemical Regulation on Bt Transgenic Cotton Plants under Combined Stress of High Temperature and Water Deficit

[Objective] The study aimed to find a possible way to combat or alleviate the negative effects caused by high temperature and water deficit at the growth stage of peak boll-setting.[Method] With Bt transgenic cotton GK22 as the test cultivar,a potted experiment was carried out to investigate the effects of the regulation of external substances(the water solutions of pix,urea and their mixture) on the physiological parameters,insecticidal protein content,yield and yield component of cotton plants in artificial climate chambers treated with high temperature and water deficit.[Result] The application of external pix,urea or their mixture was effective in stabilizing the physiological parameters of cotton plants,insecticidal protein content,yield and yield components.Compared with the exclusive application of pix and urea,the mixture of pix and urea played the most effective role in stabilizing the content of chlorophyll,soluble sugar and insecticidal protein,alleviating the increase of the content of free amino acids and proline,and increasing boll number per plant,boll weight and seed cotton yield.[Conclusion] The water solutions of pix,urea or their mixtures can be used to combat or alleviate the stress of high temperature and water deficit if they are sprayed onto cotton plants prior to stress occurrence.