Optimizing the planting density of Bt. cotton varieties for rainfed vertisols of central India

Bt (Bacillus thuringiensis) transgenic cotton (Gossypium hirsutumL.), including the introduced, indigenous Chinese non‐hybrid and hybrid cotton, is spreading very rapidly in China. Agronomic and photosynthetic performance as well as the optimum plant density for planting Bt cotton may vary with genotypes. With three types of commercial Bt cotton varieties, two field experiments were conducted to study yield performance and leaf photosynthetic rate (Pn) during 2000 and 2001, and yield interaction between variety and plant density during 2001 and 2002 in Yellow River region in northern China. The first experiment showed that the indigenous Chinese Bt cotton significantly differed from the introduced Bt cotton (IBtC) in plant growth and yield components. As a result of manipulation of boll numbers, boll weight and lint percentage, there was no significant difference in lint yield between Chinese non‐hybrid Bt cotton (CBtC) and the IBtC, but two Chinese hybrid Bt cotton (HBtC) varieties exhibited significantly higher lint yield than all other varieties in either 2000 or 2001. Hybrid cotton SCRC15 showed a one‐peak curvilinear change in diurnal course of Pn throughout the growing season, while non‐hybrid cotton 33B and SCRC16 exhibited severe mid‐day depression in Pn in squaring, flowering or boll‐setting stage. The second experiment showed that the main effect of plant population on lint yield was not significant, and yield difference among all treatments was derived from varieties and the interaction between plant density and variety. The optimal plant densities in terms of lint yield for the introduced, indigenous CBtC and HBtC genotypes were 6.0, 4.5 and 3.0 plants m−2respectively.

Aims: To determine the optimum irrigation schedule and nitrogen level for Bt cotton in alfisols in Southern Telangana.
 Study Design: Split plot design.
 Place and Duration of Study: ARI, Rajendranagar, Hyderabad during kharif 2014.
 Methodology: The experiment was laid out with three irrigation schedules (I1- 0.8 IW/CPE, I2 - 0.4 IW/CPE and I3 - Rainfed) as main plots and four nitrogen levels (N1- 0 kg ha-1, N2 - 75 kg ha-1, N3 - 150 kg ha-1 and N4 - 225 kg ha-1) as sub plot treatments replicated thrice. Treatments imposed as per the schedule and data recorded on yield, yield attributes, nitrogen uptake by adopting standard procedures
 Results: Irrigation at 0.8 IW/CPE recorded significantly higher plant height (79 cm), drymatter at first picking (195 g plant-1), bolls plant-1 (16), seed cotton yield (1435 kg ha-1), lint yield (541 kg ha-1), stalk yield (2057 kg ha-1) and nitrogen uptake (63 kg ha-1) and was not differed significantly with 0.4 IW/CPE and these were significantly superior to rainfed cotton. Among nitrogen levels, significantly higher plant height (90 cm), drymatter at first picking (214 g plant-1) stage, days to reach boll development (90) stage, bolls plant-1 (15), boll weight (5.3 g), seed index (9.9 g), seed cotton yield (1435 kg ha-1), lint yield (547 kg ha -1) and stalk yield (2214 kg ha -1) were found with application of nitrogen at 225 kg ha-1 was comparable with 150 kg N ha-1 and were significantly superior over lower levels of nitrogen application. The substantial increase in yield and yield attributes might be due to favorable effect on growth attributes like plant height, increased bolls plant-1, drymatter accumulation plant-1 and its subsequent translocation towards sink improved the seed cotton yield.
 Conclusion: It can be concluded that, higher seed cotton yield can be obtained with the irrigation scheduled at 0.4 IW/CPE and application of nitrogen at 150 kg ha-1 in Bt cotton grown in alfisols.

Effects of plant density on cotton yield components and quality

Chemicals may be used to reduce plant size in cotton (Gossypium barbadense L.), which can increase cotton yield by allowing an increased number of plants per unit area. Foliar sprays of growth retardants Cycocel and Alar were applied at concentrations of 250, 500, and 750 ppm 105 days after planting (square and boll setting stage) to Egyptian cotton cultivar Giza 75 planted at three plant densities (166,000, 222,000, and 333,000 plant ha−1). The objectives of this two-year study were to determine if growth retardants may be substituted for plant density, and vice versa, and to investigate their effects on yield and fiber properties. Number of opened bolls plant−1, seed-cotton yield plant−1, and earliness increased as plant density decreased in both years, as did seed-cotton and lint yield ha−1 in the second season. In the first year, the intermediate plant density gave the highest yields. Plant density had no significant effect on lint percentage or fiber properties. Both Cycocel and Alar increased the number of opened bolls plant−1, boll weight, seed and lint indices, seed-cotton yield plant−1, and both seed-cotton and lint yield ha−1, but effects were not always significant and response varied for different traits. Neither Cycocel nor Alar affected lint percentage, yield earliness, or fiber properties at any plant density. The interaction of plant density × growth retardant was significant for the number of opened bolls m−2 and plant−1, seed-cotton yield plant−1 and ha−1, and for lint yield ha−1. The lowest plant densities, combined with application of Cycocel or Alar, gave the highest number of opened bolls m−2 and plant−1, seed-cotton yield plant−1 and ha−1, and lint yield ha−1. This implied that the effect of growth retardants on cotton yield depended essentially on the number of plants per unit area or space available to each plant and that applying growth retardants could enhance the effect of low plant density.

The main objective of the present investigation is to obtain wide genetic variation by using lee it tester analysis involving two seeded testers as male parents, namely, AugUraliall and Karashnelry and four Egyptian cotton culbvars as females (lines) namely Gza80, Giza85, Gza90 and Gia87 (G.barbadense). Eight Ft's, the two tester varieties and the four lone cultivars were grown in a randomized complete block design with three replications in 2006 season to evaluate combining abilities and nature of gene action. Genotypes mean squares were highly significant for all traits except for int percentage (L %), lint index (LI) and uniformity index (U.I). Parents mean squares revealed highly significant differences for all studied traits except for lint percentage (L %) and ant index (U). Higher estimates of dominance (02d) variance than additive valance (02A) were recorded and low narrow sense heritability values (h%n.$) and low magnitude of the ratio Q2gCa/Q25ca (less than unity) were found for first fruaing node (FFN), seed cotton yield (KY), lint yield (LY), lint percentage (1%), seed index (SI), lint index (U), micronalr value (Nie), plessly index (PI) and Upper half mean (U.H.M). On the other hand days of first flower (DFF), boll weight (8W) and uniformity index (U.I) recorded lion estimates of additNe variance (02A) and narrow sense heritability (h%n.$). For the testers, Australian and Karashneky varieties were good combiners for first fruiting node (FFN), days of first flower (OFF), seed cotton yield (SCY), lint yield (LY) and uniformity index (VI). Among female parents the variety Giza85 was the best combiner for days of fist flower (OFF), seed cotton yield (SCY), lint yield (LY), seed index (SI) and uniformity index (MI). Giza87 was the best general combiners for fiber traits. Gza90 was the best general combiner for boa weight (avo, seed index (SI) and uniformity index (U.I). Gza80 was the best combiner for first fruiting node (FIN), days of first flower (OFF), boll weight (BW), seed talon yield (SCY), ant yield (LY), micron* value (Mic) and con* index (F1). It oduld be concluded that (tie hybrid (Australian it Giza85) and (Karashneky it Gza85) may be used for the improvement of seed cotton yield (SCY), lint yield (LT), seed Index (SI) and Upper half mean (URA), while (Australian it Gza80) and (Karashneky x Gza80) hybrids were the best for the Improvement of seed cotton yield (SCY), lint yield (1Y) and pressty Index (PI).

Manipulation of dry matter accumulation and partitioning with plant density in relation to yield stability of cotton under intensive management

Cotton is the most extensively grown non-food crop and its lint serves as a source for textile industries. The diversity in upland cotton (G. hirsutum L.) varieties was low. Hence, genetic diversity and marker trait associations were performed in twenty cotton genotypes. Rasi Magic, Platinum, LHBT 2, LHBT 6 and LHBT 7 recorded highest seed and lint yield. Based on PCA, LHBT 6 and LHBT 7 had higher upper half mean fiber length, uniformity index, fiber strength; Rasi Magic and LHBT 2 had high yield. Seed cotton yield (SCY) showed significantly positive association with number of bolls (NB), number of sympodial branches (NSP), boll weight (BW), ginning out turn (GOT) and plant height (PH). The average polymorphic information content and Shannon’s diversity index value were 0.66 and 1.4 per SSR marker locus respectively. Six clusters and six subpopulation groups were observed; LHBT 16 and LHBT 7 were grouped near checks showing genetic similarity. Association study identified high significant associations in markers, BNL1122 (NB), BNL1227 (NB, BW, Plot yield (PY), SCY, Lint yield (LY)), DPL0852 (BW, PH), JESPR204 (Number of Monopodia), MGHES0012 (Lint index (LI), NB, BW, PY), MGHES0021 (SCY), MGHES0036 (NSP, GOT, LY), MGHES0060 (NSP), MUSS162 (LI) and MUSS193 (LI).

Optimal planting density and sowing date can improve cotton yield by maintaining reproductive organ biomass and enhancing potassium uptake

Foliar sprays of (PGR’s) Cycocel and Alar were applied at concentrations of 250, 500, and 750 ppm after 105 days after plantation (square and boll setting stage) to Egyptian cotton cultivar planted at three plant densities (166.000, 222.000, and 333.000 plant ha−1). Number of opened bolls plant−1, seed-cotton yield plant−1, and earliness increased as plant density decreased in both years, as did seed-cotton and lint yield ha−1 in the second season. In the first year, the intermediate plant density gave highest yields. Plant density had no significant effect on lint percentage or fiber properties. Both Cycocel and Alar increased the number of opened bolls plant−1, boll weight, seed and lint indices, seed-cotton yield plant−1 and both seed-cotton and lint yield ha−1, but effects were not always significant and response varied for different traits. Neither Cycocel nor Alar affected lint percentage, yield earliness or fiber properties at any plant density.

The untapped potential of the beneficial alleles from Gossypium barbadense L. has not been well utilized in G. hirsutum L. (often referred to as Upland cotton) breeding programs. This is primarily due to genomic incompatibility and technical challenges associated with conventional methods of interspecific introgression. In this study, we used a hypoaneuploid-based chromosome substitution line as a means for systematically introgressing G. barbadense doubled-haploid line '3-79' germplasm into a common Upland genetic background, inbred 'Texas marker-1' ('TM-1'). We reported on the chromosomal effects, lint percentage, boll weight, seedcotton yield and lint yield in chromosome substitution CS-B (G. barbadense L.) lines. Using an additive-dominance genetic model, we studied the interaction of alleles located on two alien substituted chromosomes versus one alien substituted chromosome using a partial diallel mating design of selected CS-B lines (CS-B05sh, CS-B06, CS-B09, CS-B10, CS-B12, CS-B17 and CS-B18). Among these parents, CS-B09 and CS-B10 were reported for the first time. The donor parent 3-79, had the lowest additive effect for all of the agronomic traits. All of the CS-B lines had significant additive effects with boll weight and lint percentage. CS-B10 had the highest additive effects for lint percentage, and seedcotton and lint yield among all of the lines showing a transgressive genetic mode of inheritance for these traits. CS-B09 had greater additive genetic effects on lint yield, while CS-B06, CS-B10 and CS-B17 had superior additive genetic effects on both lint and seedcotton yield compared to TM-1 parent. The 3-79 line had the highest dominance effects for boll weight (0.513 g) and CS-B10 had the lowest dominance effect for boll weight (-0.702). Some major antagonistic genetic effects for the agronomic traits were present with most of the substituted chromosomes and chromosome arms, a finding suggested their recalcitrance to conventional breeding efforts. The results revealed that the substituted chromosomes and arms of 3-79 carried some cryptic beneficial alleles with potential to improve agronomic traits including yield, whose effects were masked at the whole genome level in 3-79.

An experiment was executed during Kharif 2021 at Regional Agricultural Research Station, Lam, Guntur in randomized block design (RBD) in two replications for estimation of combining ability of the parents and gene effects and also the extent of heterosis using line × tester fashion design. Statistical data were collected on the biometrical observations viz., days to 50% flowering, plant height (cm), number of monopodia/ plant, number of sympodia/plant, number of bolls per plant, boll weight (g), seed index (g), lint index (g), Ginning Out Turn (GOT %), seed cotton yield (kg/ha) and lint yield (kg/ha). The lines GISV298 and SCS1207; the testers, Lam GPC 501 and Lam GPC 355 exhibited positive General Combining Ability (GCA) effects for the traits Ginning Out Turn (GOT%), Seed Cotton Yield (SCY) and Lint Yield (LY) signifying that these were good general combiners. The cross combinations viz., TCH1837/GP117, GISV298/GP274, and SCS1207 / GP117 expressed significant specific combining ability (SCA) effects for Seed Cotton Yield (SCY) and Lint Yield (LY). The cross combination, SCS1207/ Lam GPC 355 was identified as the best hybrid combination with high GCA and SCA for important traits like GOT, seed cotton yield, and lint yield coupled with significant positive heterosis which can be further tested in multi-location testing at the station and all India level.

Cotton is a very important crop that consists of traits with different associationship due to genetic and environmental factors. In order to determine the degree of association between seed cotton yield and important traits, a study was done using an RBD experiment with 30 hybrids. Seed cotton yield, plant height, GOT, number of sympodial braches, boll weight, bolls per plant, span length, fineness and strength data were collected and analysed. The experiment was done with 30 F1 hybrids have delivered through Line x Tester mating configuration utilizing six lines and five testers were planted in a Randomized Block Design (RBD) with two replications at the Department of Cotton, TNAU, Coimbatore. Seed cotton yield per plant was found to have significant positive genotypic connection with boll weight (0.5810), number of bolls per plant (0.3867), plant height (0.422) and ginning percent (0.2182) however altogether and contrarily related with consistency proportion at genotypic level. The phenotypic relationship esteems likewise uncovered that seed cotton yield per plant had highly huge and positive phenotypic connection with number of bolls per plant (0.3470) and boll weight (0.4763). Path coefficients were processed to assess the commitment of individual characters to yield in cotton. The way investigation demonstrated high certain immediate impact of number of bolls per plant (0.4743) and fiber strength (0.6880) on seed cotton yield. Micronaire value displayed high sure circuitous impact on seed cotton yield through range length (0.3393), the outcome showed that number of bolls per plant had a high sure relationship with seed cotton yield and sympodial per plant recorded low certain connection with seed cotton yield. It was therefore concluded that selection of high yielding cotton hybrids could emphasize more on lint yield, boll weights, plant height and bolls per plant for better-performing lines. Gin outturn and fibre strength could be used indirectly to improve seed cotton yield through other traits.

Two experiments were carried out at Sakha Agriculture Research Station, Cotton Research Institute, Agriculture Research Center, Egypt. The aim of this investigation was to study heterosis and combining ability for the most important traits of cotton (boll weight, seed cotton yield, lint yield, lint percentage, number of bolls per plant and seed index). Eight cotton genotypes 10229 x G.86, G.45, Pima S1, Suven, TNB, CB.58, G. 70 and G. 93 were crossed in half diallel mating design in 2011 season to obtain 28 single crosses. These parents and their respective 28 F1 crosses were evaluated in two planting dates (April and May) in a randomized complete blocks design in 2012 season. The results obtained could be summarized as follows:- 1- Highly significant mean square values were obtained for genotypes, genotypes x dates, parents x dates, crosses x dates for all the studied traits. 2- The best general combiner for most of studied traits was parent (10229 x G. 86). Also the best general combiners for most of studied traits were crosses (10229 x G. 86) x Pima S1, G.45 x G.70, CB.58 x G.70 and CB.58 x G.93 3- The parent (10229 x G. 86) had the best general combining ability for boll weight, seed cotton yield, lint yield and lint percentage under two sowing dates and their combined. 4- The crosses CB.58 x G.93 and G.45 x G.70 showed highly significant desirable specific combining ability for boll weight, seed cotton yield, lint yield and number of bolls per plant at two sowing dates and their combined. 5- Positive heterotic effects relative to the mid-parent were found for most of the traits in the crosses (10229 x G.86) x G.45, G.45 x Suven, G.45 x G.70, TNB x G.70 and C.B 58 x G.93. Also positive heterotic effects relative to the better parent were found for most of the traits in the crosses (10229 x G.86) x TNB, G.45 x Suven and G.45 x G.70 over two planting dates and their combined. 6- Dominance effects were important in the inheritance of boll weight, seed cotton yield and number of bolls per plant traits. The additive gene effects contribute the major portion of gene pool for lint yield, lint percentage and seed index traits. 7- Heritability estimates in narrow sense were low to high for all the studied traits, ranged from 32.17% for seed cotton yield to 91% for boll weight for the combined data. 8- From these results it could be concluded that the crosses CB.58 x G.93 and G.45 x G.70 appeared to be promising for late-planted tolerance therefore could be exploited in breeding program aiming to improve late-planting tolerance.

Nitrogen rate and plant density effects on yield and late-season leaf senescence of cotton raised on a saline field

There have been conflicting results reported about the effect on cotton (Gossypium spp.) lint yield of altering planting and irrigation termination (IT) timing. The objectives of this study were to identify a planting window (PW), on a heat unit (HU) basis, and IT timing, as a function of crop growth stage, for optimum yield potential of Upland (G. hirsutum L.) and American Pima (G. babadense L.) cotton. Two PWs of Upland 'Deltapine 90' (DPL 90), Pima 'S-6', and IT treatments were included in field experiments for 11 site-years. Planting windows were defined as PW1 and PW2 for plantings prior to and following 600 HU accumulated after 1 January, respectively. Two IT treatments were imposed for each planting. Irrigation termination in the desert Southwest generally results in cessation of growth (crop termination). The first IT treatment (IT1), was imposed to ensure full development of bolls set up to cutout, and the second (IT2) was after two additional irrigations. From covariate analysis, there was no evidence of interaction between PW and IT, indicating that these treatments responded the same across the different environments for both cotton species. There were, however, differences in lint yields among treatments. For DPL 90, PW1 IT2 yielded 83 and 97 Ib/acre more than PW1 IT1 and PW2 IT2; and for Pima S-6, PW1 IT2 was 118 and 204 Ib/acre more than PW1 IT1 and PW2 IT2, respectively. Early planting is necessary for optimum yield potential of full-season cotton varieties; with the greatest yield coming from early planting and termination after the development of a second fruiting cycle (PW1 IT2). However, if a reduction in input costs and the avoidance of late-season insect pests are important considerations then cotton should be planted early (300 to 600 HU after 1 Jan) and terminated at the end of the first fruiting cycle (approximately 600 HU past cutout) to maintain the lint yield potential of full-season maturity types of Upland and Pima cotton.