Effect of shading on yield,fiber quality and physiological characteristics of cotton subtending leaves on different fruiting positions

Little is known regarding to impact of simulated shading conditions on cotton yield and fiber quality at different fruiting positions. In this 2-year study, our field experiments investigated the effects of shading percentage on the cotton yield, fiber properties, photosynthesis, and carbohydrate concentrations in boll’s subtending leaves during various growing stages at different fruiting positions (FP). Net photosynthetic rate and effective quantum yield of PSII photochemistry decreased in response to shading on both FP1 and FP3 of the 7^th sympodial branches, respectively. Shading also reduced sucrose and starch contents of leaves at each fruiting position. Shading decreased the number and mass of cotton bolls, the fiber strength and micronaire, while the fiber length increased at both fruiting positions. Our results suggested that shading resulted in the reduction of the cotton yield and fiber quality, which are mainly associated with the changes in boll number and alteration of photosynthesis and carbohydrate concentrations during the boll development.     

Effect of mepiquat chloride and nitrogen levels on yield, growth characteristics, and elemental composition of cotton

A 3-year study was conducted to determine the effects of mepiquat chloride and N levels on yield and quality of cotton (Gossypium hirsutum L.). Mepiquat chloride (MC) treatments did not significantlyaffect yields; however, cotton lint yields (1980) were 688, 949, 1,011, and 1,045 kg/ha for N rates of 0, 45, 90, and 135 kg/ha, respectively. Nitrogen by MC interactions on yield were not significant for any of the 3 years. MC treatments reduced plant height for all N levels. Plant height averages over all N levels were reduced 15–33% by the addition of MC. The MC treatments significantly increased the percent of Ca and Mg in the cotton leaves on a dry-weight basis. Nitrogen concentrations of the leaves were not affected by MC treatments. Leaf N levels were not significantly affected by N fertilization in 1979, but leaf N levels in 1980 were significantly increased at the 90 kg N/ha rate when compared with the check treatment.     

Pre-sowing gamma irradiation of cotton seeds from a point source of Cs137 and its effect on emergence,growth and yield

Summary The effect of pre-sowing -irradiation of cotton seeds from a point source of Cs¹³⁷ on emergence, growth, flowering, and yield was studied. High radiation doses caused reduction of emergence, inhibition of growth retardation of flowering, and reduction in number of flowers and bolls produced by the plant. The yield was greatly reduced under high dosages and approached that of the control plants under low dosages. -rays caused a marked degree of sterility.No significant stimulating effect on growth and development was detected when the dry cotton seeds were subjected to -irradiation doses of 1.17 to 26.92 kr.     

Impact of drought on assimilates partitioning associated fruiting physiognomies and yield quality attributes of desert grown cotton

Deficit irrigation has great significance for sustainable cultivation of cotton in water scarce arid regions, but this technique creates drought situation that induces stress adaptive changes in cotton plants due to indeterminate growth habit. In the present experiment, the impact of drought stress on assimilates partitioning associated vegetative and reproductive development, and yield quality attributes of cotton were examined under desert conditions. Four levels of drip irrigation including 100, 80, 60, and 40% replenishment of depleted water from field capacity were applied to develop drought stress regimes during two growing seasons (2015 and 2016). Results revealed that under limited water supplies, plant’s preference for allocation of photo-assimilates was roots?>?leaves?>?fruits that substantially increased root–shoot ratio and hampered reproductive growth. Consequently, boll density (m^?2), fresh boll weight and lint yield (kg ha^?1) were significantly reduced. An obvious change in partitioning of assimilates inside stressed bolls was observed that indicated relatively more accumulation in seeds than fiber, thus reducing the fiber quality. In addition, decreased starch, oil, and protein contents in seeds of stressed plants markedly reduced 100 seeds weight and also the vigor. Later, seed quality confirmatory tests of subsequent years (2016 and 2017) showed significant reduction in emergence counts (m^?2) and seedling biomasses of seeds harvested from deficit drip irrigated cotton. These results suggest that deficit irrigation could necessarily be an appropriate yield optimization and water saving technique for cotton in desert environment but, for the best quality fiber and cottonseeds, full irrigation should be preferred.     

胚轴切断法诱导棉株对棉铃虫生长发育的影响

通过室内饲喂棉铃虫的方法,测定了诱导棉株对棉铃虫幼虫发育历期、幼虫体重和肾重的影响。结果表明,不加菌处理和加菌处理的诱导抗性棉株可分别使棉铃虫幼虫发育历期延长０．５和３ｄ,幼虫体重（５龄）降低１１．４５％和１９．６０％,蛹重降低６．５４％和１０．８１％。用诱导棉株叶片饲养８日龄棉铃虫幼虫３天后,菌诱导和无菌诱导分别使棉铃虫的相对生长率降低２２．９％和１７．２％,相对取食量降低２６．１％和２１．４％     

Evolution characteristics related to photosynthesis,growth and yield in some old and new cotton cultivars

Changes in photosynthetic attributes related to genetic improvement of cotton yield were studied in seven Chinese cotton cultivars widely grown in Xinjiang during the past 30 years. Our results showed that a chlorophyll (Chl) content and net photosynthetic rate (P _N) of the 1980s cultivar was the highest among all after 60 days from planting (DAP). However, after 75 DAP, the Chl content, P _N, and actual photochemical efficiency of PSII of the old cultivars declined gradually, whereas those of the new cultivars remained relatively high. Compared to the old cultivars, leaves of the new cultivars endured a longer period and their senescence was slower, shoot and boll dry mass was higher, but the root to shoot ratio was lower. The lint yield of the 2000s cultivars was 14.7 and 21.4% higher than that of 1990s and 1980s cultivars, respectively. The high yield of the new cultivars was attributed to a greater number of bolls per unit of area with high lint percentage. We suggested that the improved photosynthetic capacity and the increased ability to deliver photosynthates to reproductive sites during the peak boll-setting stage to boll-opening stage were the key physiological basis in the evolution process of cotton cultivars from 1980s to 2000s for the cotton yield improvement within a short growing period.     

苗期遮荫对棉花产量与品质形成的影响

为揭示棉麦两熟共生期遮荫对棉花产量与品质形成的影响。在棉花苗期利用模拟棉麦两熟共生期遮荫的方法进行了研究。结果表明,遮荫对棉铃形成的影响因果枝,果节部位而异,遮荫有利于棉株下（1-3果枝）,中（4-6果枝）,上（7-9果枝）部果枝内围（1-2果节）铃的形成,对外围（≥3果节）尤其顶部果枝（≥10果枝）外围铃形成不利,从而决定铃重也随果枝,果节部位相应地变化,但遮荫对单株平均铃重的影响畔 小,变遮荫棉花籽棉产量而论,下,中部果枝的内围铃籽棉产量高于常规棉,在上,顶部果枝则相反,各部位果枝外围铃的籽棉产量均低于常规棉,遮荫棉花内,外围铃分布为1：0.36(常规棉为1：0.58),产量分布为1：0.42(常规棉为1：0.72)。苗期遮荫对棉纤维,棉籽品质性状的影响也主要在顶部果枝和上部果枝外围铃,综合分析遮荫棉花产量与品质的形成,棉花苗期耐遮荫性品种间存在差异。在本研究中以中9418耐遮荫性最强,中棉所19和春矮早次之。     

Treatment of cotton seeds for germination

Summary Effects of H₂SO₄, H₂O₂, C₂H₅OH and of acetone on germination of cotton seeds and on the growth of seedling root were studied under laboratory conditions. H₂SO₄ or H₂O₂ hastened germination but decreased the ultimate number of seeds germinated. Higher temperature (27°C) hastened germination and increased the number of seeds germinated. Root length remained unaffected by treatments at room temperature while H₂SO₄ or H₂SO₄/H₂O₂ substantially decreased it at 27°C.     

Studies on aspergilli XVII. Effect of nitrogen sources on growth and fruiting

Summary The effect of ammonium, nitrate, and organic nitrogen on growth and sporulation of 18 Aspergilli was examined in a chemically defined medium in surface culture under controlled conditions. All three forms of nitrogen were metabolized by all the Aspergilli tested. Ammonium nitrogen was not good both for growth and fruiting. This was due to the sharp fall in the pH level which resulted due to the rapid utilization of anions of the ammonium nitrogen than cations. The effect of adding succinic acid in the medium containing ammonium nitrogen has been discussed.Good growth of Aspergilli in media containing nitrate nitrogen with the accompanying rise in the pH of the medium showed that these species are capable of reducing nitrate nitrogen to the level of ammonia. The role of succinic acid in the utilization of nitrate nitrogen was investigated. All fungi accomplished good growth on a medium containing asparagine.     

Effect of sulphate waters on soil salinity,growth and yield of tomatoes

Summary Tomato (Lycopersicon esculentum var. VF 145) plants were grown with three soils in a greenhouse irrigated with water high in sulphates to determine their effects on soil salinity, growth and yield. Fruit fresh weights decreased by 53 and 40% when irrigated with water having 32 and 16 meq SO₄/l respectively, and no leaching was allowed, relative to irrigating with a half strength modified Hoagland solution. When a 0.3 leaching fraction was allowed the respective decrease in fruit fresh weights were 32 and 12% for the two levels of sulphate. Tops were less affected than were fruits. The electrical conductivity of solutions extracted from the soils during the growing period was highly correlated with the soil solution SAR (sodium adsorption ratio) and with Na and Cl concentrations. Leaching, although effective in controlling soil salinity caused by highly soluble salts, was ineffective in controlling salinity derived from SO₄.     

Effect of various sterilization procedures on the in vitro germination of cotton seeds

In vitro manipulations of cotton often require high-quality sterile seedlings as a source of hypocotyl and cotyledon explants for initiation of embryogenic cultures or embryo apexes for shoot production. Unfortunately, in vitro seed germination is often hindered if cotton seeds were collected from the open field and stored under improper conditions. In our case a limited supply of field-grown cotton seeds was received, which necessitated the development of a more effective surface sterilization protocol. Seeds from two accessions, designated as I and II, with very high contamination levels and lowered germination rate were used in this study. These seeds were treated with the most commonly used sterilizing agents, which included commercial bleach, chlorine gas and hydrogen peroxide. Additional steps such as soap-water washes (SW), 70 % ethanol (ETH) and plant preservative mixture rinses were also included in the sterilization procedures to improve the efficiency of tested protocols. Surface sterilized seeds were germinated on Linsmaier and Skoog medium and the percentage of contamination free and well-germinated seeds were recorded for each treatment. Seeds treated with hydrogen peroxide showed significant improvement in germination rate and level of contamination when compared to identical seeds treated with chlorine gas and commercial bleach. The most effective sterilization protocol for all genotypes tested consisted of SW wash followed by ETH rinse and H₂O₂ sterilization for 7 h. This protocol was successfully used to sterilize seeds of 55 cotton lines.     

Effect of the time of inoculation of the cotton vein mosaic virus by Aphis gossypii Glover (Hemiptera: Aphididae) on growth and yield of cotton plants

Aphis gossypii Glover is the vector of the Cotton Vein Mosaic Virus (CVMV), which causes serious damages to cotton. This work was carried out in a greenhouse at UNESP - Universidade Estadual Paulista, in Jaboticabal, S?o Paulo State, Brazil, to evaluate the effect of inoculation date of the CVMV on growth and yield of cotton plants. Cotton plants of cultivar CNPA ITA 90 at 20, 27, 34, 41, 48 and 55 days after the emergency (DAE) received one wingless viruliferous adult of A. gossypii, which remained confined in the plants for 48h. The percentage of plants with the symptoms of the disease and its influence in the phenological aspects of cotton plant were evaluated. The age of the plants did not influence the transmission efficiency of CVMV by A. gossypii. Percentages of plants showing disease symptoms varied from 40% to 65% when inoculated at 20 and 48 DAE, respectively. Plant height was reduced in 54.5% when they were infected 20 DAE and 1.3% when infection occurred at 55 DAE, as compared to the control. The number and diameter of the bolls were also influenced by the age the plants were infected. Plants inoculated 20 DAE did not produce cotton. Plants inoculated 55 DAE produced 20.7 g of cotton/plant, significantly less than control plants (35.9 g/plant). The severity of the symptoms was directly associated to the age the plants were infected with CVMV.     

Effect of kinetin concentration and methods of application on seed germination, yield components, yield and fiber properties of the Egyptian cotton (Gossypium barbadense)

Two field experiments in 1993 and 1994 as well as a laboratory germination experiment were conducted on the Egyptian cotton cultivar Giza 75 (Gossypium barbadense) to determine the effect of six concentrations of kinetin (6-furfurylaminopurine) ranging from 0 to 10.0 mg l(-1) and three different methods of application: (A) seeds were soaked for 24 h before germination (laboratory experiment) or sowing (field experiment) in solutions of different kinetin concentration, (B) cotton plants were sprayed twice with different kinetin concentrations at 60 and 75 days after sowing (DAS) during the square initiation and the beginning of bolling stages, at volume solution of 480 l ha(-1). (C) Seeds were soaked in kinetin solutions before sowing as method A. In addition cotton plants were sprayed twice as method B with the same kinetin concentrations. Kinetin application improved seed viability and seedling vigour as shown by lengths of the hypocotyl, radicle and the entire seedling, as well as seedling fresh weight. Moreover, significant increases were recorded in the number of open bolls/plant, boll weight, lint and seed indices, seed cotton yield/plant, and seed cotton and lint yields/plot. The highest means were obtained at 5 mg kinetin l(-1) concentration and under method C of application. Treatments generally, had no significant effects on lint percentage, yield earliness and fiber properties. These results show that, the use of kinetin at 5 mg l(-1) for pre-soaking seeds before planting and spraying cotton plants at 60 and 75 DAS with the same concentration could improve cotton germination, seed cotton and lint yields.