Evaluation Of Maize Research Articles

Evaluation of maize (Zea mays) genotypes under different nitrogen levels in a Trans-Gangetic Plains region

An experiment was conducted during rainy (kharif) seasons of 2021 and 2022 at the research farm of ICARIndian Agricultural Research Institute, New Delhi to study the effects of different genotypes and nitrogen levels on growth and yield of maize (Zea mays L.). Six maize genotypes (‘AH 4271’, ‘DKC 9164’, ‘PJMH 1’, ‘PMH 13’, ‘PC 4’ and Pusa Vivek QPM 9’ Improved (PV QPM 9-I) and 7 levels of nitrogen (0, 40, 80, 120, 160, 200 and 240 kg N/ ha) were evaluated using factorial randomized complete block design with two replications. Results showed that among the genotypes the ‘DKC 9164’ produced the highest kernel yield and resulted in maximum net returns (` 78.0 and 82.8 × 103 /ha) as compared to other genotypes. The growth parameters and yield increased with the increasing level of nitrogen from 0 to 240 kg/ha. Application of nitrogen @240 kg N/ha produced the maximum plant height, total number of leaves, leaf area index and stover as well as biological yield, whereas the maximum kernel yield and net returns (` 91.1 & 97.2 × 103 /ha) were obtained with 200 kg N/ha which was at par with 160 kg N/ha

Evaluation of Maize (Zea mays L.) Germination Traits by Hydro-and Microwave Priming

To study the effects of hydropriming and seed priming with microwaves (MW) on the germination traits of maize (Zea mays L.), a laboratory pot experiment was carried out in 2023. The selected seed treatments were hydropriming with distilled water (0, 6, and 12 h) and microwave priming (0, 10, and 20 s) of the maize seeds. Studied traits were final germination percentage (FPG%), mean germination time (MGT), germination rate index (GRI), coefficient of velocity of germination (CVG), mean daily germination (MDG), peak value (PV), and Germination value (GV). According to the variance analysis of this study, the results indicated that both the priming treatments, hydro and MW, significantly affected all studied traits. The best values for FGP (88.88, 78.99%), MGT (4.07, 4.72 day), GRI (25.08, 21.46 % day-1), CVG (25.79, 23.86), MDG (7.4, 6.66 seed day-1), PV (1.9, 1.64), and GV (14.6, 12.19) were observed in priming with 10 s MW and 12 h hydro, respectively. The combination of hydro and MW priming also showed a significant effect for all traits, except FGP and MDG. Among the combination treatments, MW for 10 s and hydropriming for 12 h were the most effective in improving MGT (3.17 days), GRI (33.27 % day-1), CVG (31.62), PV (2.55), and GV (21.23). In contrast, the interaction between priming treatments had no significant effect on FGP or MDG. However, the MW for 10 s and hydropriming for 12 h resulted in a higher FGP (100%) and MDG (8.33 days). Overall, the findings suggest that hydropriming and seed priming with microwaves is a promising technique for improving maize germination.

Evaluation of Maize and Pulses Intercropping System under Rainfed Condition in Western Zone of Tamil Nadu, India

A field experiment was conducted in rabi seasons (2022) at Karunya Institute of Technology and Sciences, Coimbatore to study the maize-based intercropping with different legumes under rainfed condition as there are less research work regarding intercropping of maize in this area. Greengram (Vigna radiata), cowpea (Vigna unguiculata) and horsegram (Macrotyloma uniflorum) were selected as intercrops in 4:1 and 6:1 row ratio. The result of the study indicated that intercropping of greengram and cowpea with maize (Zea mays L.) in 4:1 gave higher total grain yield and stover yield compared to the sole cropping of maize under rainfed condition. Other intercropping indices like grain equivalent yield, land equivalent ratio, relative crowding coefficient, competition index and income equivalent ratio were calculated. Intercropping system of maize + greengram (4:1) recorded the higher net return and B: C ratio followed by it maize+ cowpea (4:1). Therefore, under rainfed conditions of western zone of Tamil Nadu, maize + greengram 4:1 intercropping system may be suggested to get greater net return and B: C ratio.

Evaluation of Maize (Zea mays) Genotypes forTolerance to Drought using Yield Based Tolerance Indices

A pot trial was conducted at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman University of Agriculture, Gazipur from November 2021 to March 2022 to identify relatively tolerant maize genotypes based on growth, yield, yield stability and stress tolerance. indexes. Twenty maize genotypes, including CML-580, CML-563, CML-591, CML-579, CML-588, CML-593, CML-564, BD-814, BD-821, BD-824, BD-10242, BD-811, BD-826, BD-837, BD-808, BD-10237, and BD-10240, were grown under control conditions (80% of field capacity, FC) and drought conditions (40% of FC) following completely randomized design with three replications. Plant and cob height, days to maturity, cob length, cob girth, number of rows/cob, and kernel yield/plant were recorded. Drought stress reduced plant height, cob height, cob length, cob girth, number of rows/cob, and finally maize yield, but increased the days to maturity. Among the maize genotypes, CML-593, CML-564, BD-814, and BD-821 had the lowest decrease in kernel yield, while BD-808 and BD-813 had the highest decrease. Genotypes CML-593, CML-564, BD-814, and BD-821, on the other hand, demonstrated a higher yield stability index and stress tolerance index. Based on their yield and stress tolerance index, genotypes CML-593, CML-564, BD-814, and BD-821 appear to be drought tolerant, whereas BD-808 and BD-813 appear to be drought sensitive. How to Cite: Md. Abdul Mannan, Ferdousi Begum, Md. Abdullah Al Mamun, Md. Ahsan Habib, 2023. "Evaluation of Maize (Zea mays) Genotypes forTolerance to Drought using Yield Based Tolerance Indices." Journal of Agriculture and Crops, vol. 9, pp. 329-337.

Evaluation of maize (Zea mays L.) varieties for agronomic and yield performance in two locations of Northern Guinea Savanna agro-ecology of Nigeria

Maize (Zea mays L.) is the third most important cereal in the world and the second in Nigeria after rice in terms of cultivation and utilization. Five varieties (TZESR-W, SUWAN-1-SR, DMR-ESR-W, Mega maize and Local cultivar) were evaluated during the 2018 cropping season with the aim of assessing the agronomic and yield potentials in two locations (Jalingo and Yola) of the northern guinea savanna agro-ecology of the country. The experiment was laid out in a Randomized Complete Block Design (RCBD) with four replications. Seeds were sown on a plot size of 5 m x 5 m at a spacing of 75 cm x25 cm. Data collected on vegetative and yield parameters were analyzed using GENSTAT software and means were separated using Duncan’s Multiple Range Test at a 5% level of probability. Results from the study showed high variability among the varieties across locations in most traits studied. However, SUWAN-1-SR and DMR-ESR-W performed better in both locations with an average number of grains per cob of 443 and 483 in Jalingo and Yola, respectively and are recommended for cultivation by farmers. Mega maize was the lowest in most traits suggesting that it is not suitable for Jalingo and Yola locations. The local variety, used as a check performed better than mega maize and TZESR-W, comparing well to SUWAN-1-SR and DMR-ESR-W, the leading varieties in most parameters. The significant differences among the varieties can be harnessed for selective breeding.

Determination of Maize (Zea mays L.) Hybrids under Agro-climatic Conditions of Prayagraj, Uttar Pradesh, India

Worldwide Maize (Zea mays L.) is referred to as the “Miracle Crop” due to its high genetic yield potential compared to other Gramineae family members. Hybridization plays a vital role in boosting the production and productivity of maize, which is crucial for mitigating food insecurity in developing countries. To find out the best hybrid among the maize hybrids, a field experiment was conducted during the kharif season of 2021 at the experimental field of the Crop Research Farm, Department of Agronomy, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India. The study was conducted for “Evaluation of Maize (Zea mays L.) hybrids under agro-climatic conditions of Prayagraj, Uttar Pradesh”. The experiment was done on 10 maize Hybrids. It was carried out in Randomized Block Design (RBD) with three replications. The report of the study indicates that among different maize Hybrids, UM-12 produced significantly higher plant height (217.05 cm), number of leaves per plant (12.80), dry weight per plant (151.25 g), cob length (16.62 cm), number of rows per cob (14.80), number of grains per row (31.73), seed yield (8.27 t/ha) and stover yield (20.50 t/ha). Hence, it can be concluded that the Maize hybrid UM-12 was found to be the most suitable, productive and economical for the agroclimatic conditions of Prayagraj, Uttar Pradesh.

Evaluation of maize based legume intercropping systems

Evaluation of maize based legume intercropping systems

Synthesis and Evaluation of Maize (Zea mays L.) Accessions under Naturally Flooded Tidal-swamp Area

Background: Synthesis and introduction of adaptive open-pollinated-maize accessions may help farmers at tidal-swamp to increase income, since farmers can produce the seeds directly from their plantation. Methods: This research utilized fields and farmers of such area located at South Sumatera, Indonesia. Evaluated plants consisted of Unsri-J1 to J8-accessions, generated from recurrent-selections of double-crossing populations between Indonesian varieties and introduced-accessions of high-quality protein maize (HQPSSS) from Purdue University and acid-soil tolerant accession maize (SA3) from CIMMYT. Evaluation was designed as Randomized Complete Block. Measurements were taken on five observation-plots consisted of 25 plants/plot. Statistical analysis was performed by using Analysis of Variance, followed by Fisher’s protected-LSD-test. Result: Research indicated that most accessions showed good performance. The plant-height ranged 200 to 228 cm and anthesis-period at 44 to 46 days after-planting. The half-sib seeds production ranged from 2.20 to 2.93 t/ha and the real-yield, at farmer level, ranged 5.5 to 7.7 t/ha and the potential-yield reached 7.6 to 9.6 t/ha with protein-content ranged from 8.57 to 9.48%. This research suggested that accessions of Unsri-J6, followed by Unsri-J7, J2, J5 and J1 were promising for further development.

Effectiveness of different alpha lattice designs in the evaluation of maize (Zea mays L.) genotypes in a rainforest agro-ecology

Plant breeding experiments require the use of appropriate experimental designs that will efficiently block variation due to wide heterogeneity nature of tropical soils. The primary objective of this study was to assess the effectiveness of eight different alpha-lattice designs relative to randomized complete block design for evaluating 108 genotypes of maize under rainforest agro-ecology. The maize genotypes were field-tested using three replications at two locations. Data were collected on grain yield and other agronomic traits. Data collected were subjected to analysis of variance (ANOVA) assuming randomized complete block design (RCBD) and eight alpha-lattice designs. Pearson's correlation and stepwise multiple regression analyses were used to analyze relationship among different designs and efficiency of the lattice designs over RCBD was computed. Result showed that all the alpha lattice designs except 27 × 4 were effective in evaluating the genotypes for plant height. There was significant difference (p < 0.001) among genotypes for grain yield only when data were analyzed based on 9 × 12 alpha lattice design. In addition, results showed that the proportion of variation due to blocking and R-square values of the model increased with increase in the number of blocks for grain yield. In contrast, coefficient of variation decreased with increase in the number of blocks. The result showed an increase in efficiency of the alpha lattice designs as the number of blocks increased. It could then be concluded that the more the number of blocks within replicate, the proportion of total variation due to blocking increased, the coefficient of variation (CV) reduced, coefficient of determination (R-square) increased and thus, effectiveness increased. Appropriateness of designs was trait dependent. The 9 × 12 alpha lattice design was identified to be the best in the evaluation of grain yield for the maize genotypes.

Evaluation of Maize (Zea mays L.) Varieties for Moisture Stress Areas in Humbo District, Wolaita Zone, Southern Ethiopia

Maize is a priority crop to farmers because it is a staple food in many rural communities of the southern region. It is widely grown in the various parts of the southern region, from lowland to mid-highlands. On the other hand, moisture stress is one of the most critical production constraints of maize in low to intermediate agroecology. Thus, developing maize varieties tolerant to moisture is of paramount importance to sustain maize production in moisture areas. In this context, field experiments were conducted during 201617 croppings at Kindo Koyisha and Humbo to select adaptable maize varieties for moisture stress areas with reasonable grain yield. Treatments used in this study were eight maize varieties (BH546, BH547, Gibe II, MH130, Melkasa IV, MH140, Melkasa II, and Melkasa 6Q) and three local cultivars (Local red, Local mixed, and Local white) of the total of eleven maize genotypes were evaluated at two moisture-prone areas in southern Ethiopia. Treatments were laid out in a randomized complete block design (RCBD) with three replications. Maize varieties exhibited different performances at two tested locations. The varieties had the relatively superior performance of Kindo Koyisha as compared to Humbo. The Humbo varieties MH140, MH130, BH546, and Melkasa IV, have yielded relatively higher grain than the rest of the areas. At the same time, the Kindo Koyisha maize varieties expressed relatively better performance concerning grain yield. It has been recorded that the varieties with superior performance with sounding grain yield were BH546, MH140, BH547, and MH130 in these locations. Based on this result, BH546, MH140, and MH130 could be used at both locations. Moreover, BH547 at Bale and Melkasa IV at Humbo also be used in respective locations for production.

Evaluation of maize (Zea mays) cultivars under organic production system in north-western Indo-Gangetic Plains of India

Increased awareness of environmental degradation and growing concern of human health has attracted worldwide attention towards organic farming. A field experiment was carried out during kharif of 2013–2014 to identify suitable maize (Zea mays L.) cultivars having high yield potential under organic production system. Twelve released cultivars of maize varied in duration and nitrogen requirement were evaluated. Results revealed that late maturing cultivars PMH-1 and PMH-3 being at par to each other recorded the significantly higher values of growth parameters like plant height, dry matter accumulation and leaf area index; and yield attributes in terms of cobs plant, cob length, cob girth, grain rows/cob, grains/row and test weight, whereas the extra early cultivars like Vivek QPM-9 being at par with Vivek Hybrid-9 registered the lowest values of growth and yield attributes. The late maturing cultivars like PMH-1, PMH-3, Seed tech-2324 and Bio-9681 produced significantly higher grain yield (&gt;5.0 t/ha) and biological yield (&gt;12.5 t/ha). Cultivars PMH-4 among medium maturity group produced comparable yield with late cultivars. Grain yield across the varied duration cultivars had a significant positive correlation with cob length, grains/row and N uptake. As per their maturity class, the extra early and early cultivars commence silking (&lt;50 days) and physiological maturity (&lt;82 days) significantly earlier than medium and late cultivars. Moreover, extra early cultivars (Vivek Hybrid-9 and Vivek QPM-9) recorded significantly higher protein content in grain amongst the cultivars tested. The late cultivars PMH-1 and PMH-3 being at par with each other recorded the highest N, P and K uptake in plants while lowest nutrient uptake was observed in the extra early Vivek QPM-9 and Vivek Hybrid-9. Late cultivar PMH-3 followed by PMH-1 recorded the highest net returns (` 66,759) and B:C ratio (1.79) of organic maize cultivation. Soil fertility status in terms of organic carbon, available P and K could not be influenced significantly, however the available N content was significantly higher under extra early cultivars Vivek QPM-9 (172.1 kg/ha) and Vivek Hybrid-9 (170.3 kg/ha). Thus, it can be concluded that PMH-1 and PMH-3 cultivars of maize are most suitable for growing in north-western plains region of Uttar Pradesh under organic production system.

Evaluation of Maize (Zea mays L.) Half Sib Recurrent Families for Expected Response and Percent Gain Per Cycle

Recurrent Selection (RS) or reselection generation after generation is a vital selection scheme for improving the physio-morphic traits and grain yield in maize populations. The objective of the present research was to determine the response of recurrent selection in CIMMYT maize population CZP-132011 for physio-morphic traits and to estimate selection differential, heritability, expected response and percent gain cycle-1 among the half sib recurrent families for morphological traits and grain yield. Sixty four half sib recurrent families were evaluated in 8×8 lattice square design with two replications at Cereal Crops Research Institute (CCRI), Pirsabak during 2017. Results showed highly significant differences among the half sib families for all the studied traits. Selection differential values were negative for days to tasseling (-3.00), anthesis (-3.08), silking (-3.10), anthesis silking interval (-1.14), plant height (-5.07) and ear height (-7.73). High heritability values (h2 ˃ 0.60) were recorded for all traits except plant height (0.55) which exhibited moderate heritability. Based on broad sense heritability and selection differential, expected response were observed negative for days to tasseling (-2.39), anthesis (-2.56), silking (-2.64), anthesis silking interval (-0.79), plant height (-2.81) and ear height (-5.22). After one cycle of recurrent selection using half sib families, the gain cycle-1 values were negative for (-0.39), anthesis (-0.47), silking (-1.44), anthesis silking interval (-3.17), plant height (-2.34) and ear height (-4.90). Based on the findings of current research it could be concluded that recurrent selection method was found effective in improving the CIMMYT maize source population CZP-132011 for physio-morphic traits.

Evaluation of maize (Zea mays) hybrids for leaf thermo-stability, photosynthetic rate, stem reserves and productivity under rain-dependent conditions

Evaluation of maize (Zea mays) hybrids for leaf thermo-stability, photosynthetic rate, stem reserves and productivity under rain-dependent conditions

Evaluation of maize (Zea mays) based intercropping for productivity, resource-use efficiency and competition indices in the rainfed foothills of northwest Himalayas

A three-year (2009-2011) field experiment was conducted to study competitive behaviour of maize (Zea mays L.)+ legume/oilseed based additive series paired-row intercropping at the Punjab Agricultural University's Regional Research Station for Kandi Area, Ballowal Saunkhri. The experiment comprised 10 treatments viz. 4 sole plantings of maize, blackgram [Vigna mungo (L.) Wilczek], greengram (Vigna radiata L.) and sesame (Sesamum indicum L.) each, and six intercropping treatments. Among two planting patterns, 100 maize:33 intercrop mix proportion proved superior for maize yield than 100:67 for all the intercrops. The productivity (3.07 tonnes/ha) and sustainability yield index (0.69) were highest when 1 row of greengram was intercropped with maize (2 M:1 G). Inclusion of legumes in intercropping improved both production and rain water use efficiencies with definite yield and economic advantage. The higher land equivalent ratio (1.27) and relative crowing coefficient (20.4) values for 2 M:1 G planting pattern indicated more efficient benefits and maximum maize yield advantage. As per values of aggressivity, greengram (2 rows) proved most competitive (±0.0005) while sesame (2 rows) least competitive (±0.0046) to maize. Among intercrops, the competitive ratio was highest (1.42) for greengram followed by blackgram in both the planting patterns. 2 M:1 G provided 9.8% (actual yield loss=+0.098) yield gain as compared to sole cropping. In the maize+greengram planting patterns, area time equivalent ratio values indicated yield advantages in the range of 19% for 2 M: 1G and 17% for 2 M:2 G. Thus, inclusion of legumes (especially greengram) in maize culture system can achieve a sustainable and economic yield advantage along with shorter system duration compared to their monocultures.

Evaluation of maize (Zea mays)-legumes intercropping system under red and lateritic tract of West Bengal

A field experiment was carried out during kharif season of 2010 and 2011 at Sriniketan Research Farm, Visva-Bharati, West Bengal, India. The yield attributes and growth parameters were significantly higher in case of sole maize and intercropping treatments with legumes. The maximum total chlorophyll (chlorophyll a + chlorophyll b) was observed on sole maize, which was statistically at par with maize crop under intercropping system. In the middle canopy, highest light interception (%) was observed in maize + groundnut (2:4). The grain yield (2.48 t ha-1) and stover yield (5.07 t ha-1) of maize were significantly higher in sole maize than either of its intercropping systems with legumes. The legume yield was highest in maize + groundnut (1:2) followed by sole groundnut. The maize equivalent yield (7.06 t ha-1) was highest in maize + groundnut (2:4) followed by maize + groundnut (1:2). The highest benefit cost ratio maize + groundnut (1:2) closely followed by maize + soybean (1:2). The total N uptake by sole maize was significantly higher and under intercropping systems, the highest N concentrations in grain and straw, and protein content in grains were obtained in maize + soybean (1:2) and maize + groundnut (2:4) treatment. DOI: http://dx.doi.org/10.3329/sja.v12i1.21118 SAARC J. Agri., 12(1): 117-126 (2014)

Evaluation of maize (Zea mays) inbred lines for tolerance to low temperature stress under field conditions

In northern India, cold spell is experienced at early vegetative stage. Tolerance to cold in inbred lines is important to ensure seed production in rabi season. Sixty-six inbred lines of Indian maize program were evaluated for their tolerance to low temperature stress under field conditions. Maize (Zea mays L.) inbred lines of Bajaura Centre (BJIM 2780, BJIM 08-100, BJIM 10-1 and BJIM 10-35) and Almora Centre (V 366, V 384, V 351, V 382 and V 378) performed better with minimum leaf yellowing and good plant growth under the cold stress. Inbreds lines BJIM 10- 35, BJIM 10-43, BJIM 10-37, V 364, V 404, V 390, LM 14 and BML 6 exhibited high reduction in yellowing of leaves coupled with fast growth recovery. Expression of yellowing of leaves and plant growth showed significant negative correlation. Yellowing of leaves and recovery of plant growth due to cold spell were important parameters for cold tolerance at early vegetative stage in maize.

Evaluation of Maize “Turda” Germplasm as Sources of Earliness in Breeding Programs

Evaluation of the early maize ( Zea mays L.) germplasm is important for the development of new inbred lines and commercial hybrids adapted to cooler regions. Choice of populations to use in improving elite maize hybrids is a critical decision in maize breeding programs. Our objectives were: I) to examine the variation for earliness in a set of 256 local populations, 56 synthetic populations and 504 inbred lines; II) to determine the performance and heterosis of this germplasm; III) to identify the genotypes (local populations, inbred lines) for the initiation of the primary cycle for directional selection for the studied characters. Seven synthetic populations and six inbred lines formed the base material of this genetic study. The seven synthetic populations and their topcrosses to four inbred lines: two flint inbred lines (TD 233 and CO 255) and two dent inbred lines (TC 184 and TC 209) and also a diallel type p(p-1) system with 30 single-cross hybrids and the six parental forms were evaluated at four environments in: two years 2009 and 2010 and two locations Turda and Targu- Mures. The highest values of additive effects for grain dry matter content were recorded at: Tu Syn Mara (ĝ n = +1.80), Tu SRR 5D (2I) (1) (ĝn = +0.62) and Tu Syn 1 (ĝn = +0.45). Therefore, Tu Syn Mara, Tu SRR 5D (2I)(1) and Tu Syn 1 produced hybrids with the most early maturity. The highest general combining ability (GCA) for dry matter accumulation in grains has registered the inbred lines TC209 (ĝ = +1.36) and TC208 (ĝ = +0.71).

Genetic evaluation of maize (Zea mays L.) genotypes at seedling stage under moisture stress

The present study pertaining to the estimation of genetic parameters and characters association in forty maize genotypes was conducted at the glasshouse of Chaudhary Agriculture farms Kasur, Pakistan, during the crop season 2010-2011. The highest genotypic coefficient of variance was found for fresh root length, the highest value of heritability was found for chlorophyll contents and path coefficient analysis showed that fresh root length had maximum direct effect on fresh shoot length followed by dry root weight, root density, leaf temperature and dry shoot weight at three moisture levels. The root length, root dry weight, root density, leaf temperature and shoot dry weight were the characters which supposed to have contribution to shoot length of maize seedlings. Selection can be made on the basis of these characters. It is suggested that the selection under the discussed traits might be useful for better yield under drought stress.

Evaluation of maize (Zea mays L.) genotypes as a component of integrated stem borer ( Chilo partellus Swinhoe) management in coastal region of Kenya

A study was conducted at six sites of Kenya Coastal region to evaluate candidate maize genotypes for inclusion in stem borer IPM package for the area. Stem borer infestation/damage during the trial period were rather low but nonetheless, significant differences were observed between the insecticide (Carbofuran) and/orBacillus thuriengiensis (Bt) treated plots and the control. Yield loss due perhaps to levels of tolerance of the genotypes varied from 7 to 23%. Generally, varietal crosses were higher yielding than the open pollinated populations with grain yield itself being primarily influenced by number of ears harvested per plot. Therefore, tendency towards prolificacy also determined the choice of ICZ5, IC92M2 and IC92M5 as possible candidates. Keyword: Maize, stem borer control.

Evaluation of maize as a refuge for management of resistance to Bt cotton by Helicoverpa armigera (Hübner) in the Yellow River cotton-farming region of China

Bt cotton has been planted to the exclusion of non-Bt cotton in the Yellow River cotton-farming region of China since 2000. Alternative non-Bt hosts, such as maize, soybean, peanut, wheat, and other host plants of Helicoverpa armigera (Hübner) may be acting as refuges for Bt-susceptible larvae of this pest, thereby delaying evolution of resistance to Bt cotton. Egg, larval, and adult densities of H. armigera were measured on Bt cotton, and on maize that was planted on dates that reflected local farming practices, in order to assess the role of maize as a refuge during 2001–2002 in Xinxiang County, Henan Province and Anci County, Hebei Province. The results indicated that the average egg densities for the second–fourth generation of the pest on Bt cotton in Xinxiang and the second generation in Anci County were significantly higher than those in maize fields. However, maize typically had much higher larval densities in the third and fourth generation of H. armigera than on Bt cotton. These data indicate that maize is probably serving as an effective refuge for third and fourth generation H. armigera, but is of less value for the second generation. The densities of moths produced by Bt cotton and by maize in a cage experiment confirmed the importance of maize as a refuge in the third and fourth generation.