Late Planted Crop Research Articles

Progression of Bacterial Blight of Clusterbean (Cyamopsis tetragonoloba) in Relation to Different Sowing Dates, Varieties and Weather Parameters

At CCS Haryana Agricultural University, Hisar, Haryana, a field study was conducted to investigate the impact of varying planting timings, varieties, and weather parameters on the advancement of bacterial blight in clusterbean. The experiment was set up in three replications using a factorial randomized block design. Three types of cluster beans, namely HG 365, HG 563, and HG 2-20, were sowed at three distinct dates i.e., the 1st, 3rd, and 4th week of July. Clusterbean bacterial blight spread faster in late-planted crops (4th week of July) than in timely-planted (2nd week of July) and early-planted (1st week of July). Maximum temperature (Tmax) and maximum relative humidity (RHm) correlated positively, while minimum temperature (Tmin) and minimum relative humidity (RHe) correlated negatively, and disease development was extremely significant and negatively correlated for HG 365 at all sowing dates. Clusterbean HG 365 was shown to be more resistant to bacterial blight than HG 563 and HG 2-20.

Target decomposition using dual-polarization sentinel-1 SAR data: Study on crop growth analysis

Decomposition of synthetic aperture radar data has been carried out using fully polarised microwave bands. Considering the economical point of view, fully polarimetric SAR data is expensive to use for many applications like soil and agriculture, where, it is important to monitor frequently. With the advancement of human civilization, new agricultural techniques and crops are being developed to meet global food demand. With the development of crop growth, crop texture and dielectric properties varies, which is depicted in the backscattering values along with the crop growth. In this study, Sentinel-1 SAR data is used, which is freely available in dual polarimetric mode with a temporal revisit of 12 days with respect to the transmitter polarizations. In this work, we attempt to decompose the targets from dual polarised SAR data using entropy and alpha bands of H-A-α decomposition. The entropy and alpha band clusters are obtained by using K-means unsupervised classification is utilized for target decomposition. The clustering process is repeated 30 times for 100 iterations to obtain the optimum grouping of pixels. The clusters are plotted on the H-α plane to get an H-α plot of dual-polarization SAR data for target decomposition. The obtained H-α plot is used to identify the crop stages and its scattering mechanism at different growth stages. Crops grown in selected crop fields during the considered period include ginger, tobacco, rice, cabbage, and pumpkin. An attempt is made by plotting the time-series trends of early and late-planted crops with peak mature stages in terms of backscattering analysis, and the results were compared to the H-α plot to gain a better understanding of crop growth scattering mechanisms at various growth stages. Although the backscattering values for the VH and VV polarizations of crops are different, the temporal backscattering study showed the same trend for both polarizations with good similarity of VH polarization than VV for analyzing crop growth stages. The crop growth scattering mechanism on the H-α plane produced similar results to the temporal analysis.

Determining Planting Window for Growing Upland Cotton (Gossypium hirsutum L.) during Dry Season in Bandarban, Bangladesh

Farmers in the Chattogram Hill Tracts, Bangladesh have been growing cotton (Gossypium hirsutum L.) in their traditional system of jhum cultivation which is undergoing transformation. Growing rainfed cotton as a monocrop in the uplands is constrained by farmers’ socio-economic conditions and erratic rainfall. Shifting growing season to post-monsoon dry monthscould be an option to sustain cotton production in hilly areas. An exploratory experiment was conducted for two seasons to explore the possibility of growing cotton in valley lands in Bandarban during dry season. Growth and yield potentials of dry season cotton were evaluated in relation to prevailing environmental conditions. Night temperature dropped to 9oC on several occasions in 2018-2019 season; but it remained higher than 11oC throughout the season in 2019-2020. In 2018-2019, day temperatures surged higher past March 15 occasionally exceeding 38oC. Variability in temperatures was more in 2018-19 while average temperatures were higher in 2019-20 season. Rainfall distribution was almost similar in both the growing seasons receiving total rainfall of 757 mm and 579 mm in two seasons, respectively. Higher seed cotton yield (2,047 kg per ha) was recorded for 15 November planted crop compared with 1 December planted crop (1,186 kg per ha). December 1 planted crop was affected more by low temperatures at seedling stage resulting in poor growth and fewer bolls per plant. Late planted crop was more vulnerable to rain damage at boll opening stage. Crops of both the seasons encountered high temperatures (>32oC) during boll development. Changing climate, shorter winter season and rising temperatures may allow cotton production in valley lands shifting growing season from rainy season to post-monsoon dry months. However, the window of dry season cotton growing in Bandarban, Bangladesh seems narrow. Rainfall pattern restricts planting seeds prior to mid-November. Again, high temperatures stress in March and April synchronizing boll development, and rainfall toward late April and May during boll opening may cause yield loss. Development and adoption of short duration, low temperature tolerant upland cotton varieties might be of advantage for adapting to climate change vulnerabilities. Ann. Bangladesh Agric. (2020) 24(2): 1-14

Population dynamics of cabbage aphid, Brevicoryne brassicae L. (Homoptera: Aphididae) in relation to weather factors on major brassica crops in central rift valley of Ethiopia: baseline studies for the management of the pest

Cabbage aphid, Brevicoryne brassicae L. is a major pest of cruciferous crops all over the world. The population dynamics of the pest is highly influenced by weather factors. A field study was carried out in 2018/19 at Debre Zeit Agricultural Research Center (DZARC) to determine the role of weather factors on cabbage aphid population dynamics. Four brassica crops namely Ethiopian Kale, head Cabbage, Cauliflower and Broccoli were planted on two different dates at fifteen days interval. Results revealed that, maximum aphid population of 164.7 ± 2.93 and 70.2 ± 2.64 aphid/ inch2 leaf area were recorded on the date 15/12/2018, on late planted kale and head cabbage crops, respectively. The highest mean infestation for all tested crops (22.77aphids/inch2 leaf area) was observed on late planted crops as compared to 0.82 aphids/inch2 leaf area on early plantings. Accordingly, early planted crops were 96.4% safer than late planted crops for aphid infestations. Correlation analysis showed that, the maximum temperature had a significant influence on aphid population specifically on kale crop (r = 0.676, p = 0.032). Although, the relative humidity, minimum and average temperature, rainfall and wind speed has shown none significant correlation with aphid population growth. There was variation in aphid population, crop preference and infestation peak in relation to weather factors. In general, during the experiment higher aphid population was observed on kale crop when the maximum temperature and relative humidity were < 26.750C and 72%, respectively. This study provided information on time of initial infestation and also the peak activity of the particular insect in relation to temperature. Therefore, the population peak timing reported in this study (45th SMW) is useful as a critical infestation period for scheduling cabbage aphid management practices.

The influence of minisett size and time of planting on the yield of seed yam (Dioscorea Rotundata)

AbstractIn traditional yam (Dioscorea spp.) production systems in West Africa, finding sole seed yam producers is rare and up to 30% of harvested tubers from the ware tuber crop is reserved to plant an equivalent area of the harvested crop during the next season. Many farmers typically must make a trade-off between food and seed in the use of available tubers. A study was carried out using a factorial experiment in a randomised complete block design to investigate the influence of planting different minisett sizes at different planting periods on the yield of seed yam with the aim of improving the availability of this expensive input and saving more ware tubers for food or sale. Results showed that by doubling or tripling the minisett size from 30 to 60 or 90 g, yields of seed yam increased by 61.1 and 103.3%, respectively. The 90 g minisetts had the highest values for all traits studied but had the least sett multiplication ratio. The early planted crop yielded 137% more than the late-planted crop. Significant interactions between minisett size, planting period and season were found. In 2016, although the highest yield of seed tubers was from early planted 90 g minisetts (35.6 t ha−1), the yield of early planted 30 g minisetts (23.8 t ha−1) was similar to those of 60 g planted mid-season (28.7 t ha−1) and 90 g planted late (20.0 t ha−1). To produce a high proportion of seed size tubers with less planting material, early planting of 30 g minisetts is recommended. Such practice will enhance seed tuber availability and food security by saving 1–2 t ha−1 of tubers that would have been used as seed instead of food.

Responses to shade and subsequent recovery of soya bean in maize-soya bean relay strip intercropping

In relay intercropping systems, late-planted crops often grow under the shade of the canopy of early-planted tall crops and then transfer to full sunlight after the harvest of the early-planted crops. In order to know the effects of recovery growth of the late-planted soya bean in maize–soya bean relay intercropping, a field experiment was carried out to observe architectural, morphological, physiological and anatomical traits of soya bean plants related to shade and subsequent removal in intercropping before and after maize harvest, respectively. During shade period, soya bean biomass was severely reduced, and stem elongation was stimulated. Typical features of shade grown leaves were found, such as lower LMA (leaf mass per unit area), thinner thickness, higher chlorophyll content, lower chlorophyll a:b ratio. Whole-plant leaf area analysis found that soya bean increased leaf area ratio by adjusting leaf morphology rather than by dry mass allocation. After maize harvest, leaf area and leaf mass increased rapidly, contributing to compensation growth in intercropped soya bean. Meanwhile, physiological and anatomical traits of leaf went back to similar levels as grown in sole cropping. However, stem morphological traits were irreversible after removal of shade. Finally, no difference on seed weight per plant of soya bean was observed between relay intercropping and sole cropping. Based on these findings, we speculated the recovery growth might be the direct determining factor on pod formation in soya bean, and improvement on the capacity of recovery growth could increase yield of relay intercropped soya bean.

Planting Dates and Varieties Vs. Cabbage Aphid,Brevicoryne Brassicae

A study was carried out in the Entomological Research Farm, SASRD, Nagaland University during rabi, 2010–2011. Results showed that planting dates has significant influence on the aphid population with the peak population from 30 DAP to 75 DAP (days after planting), during December to mid-February. Maximum population (8.10 aphids/leaf) was recorded at 30 DAP and minimum (2.32 aphid/leaf) at 90 DAP on 15th December planting. Out of the five varieties tested, maximum population was recorded on G-8 variety (8.83 aphids/leaf) and least on the cultivar Rare Ball (5.26 aphids/leaf). Overall, late planted crop of 15th December harboured less population and variety Rare Ball planted on 30th November was found most ideal in Nagaland condition.

Effects of Planting Dates and Intra-Row Spacing on Field Infestation and Damage by Hemipteran Sucking Bugs on Soybean in Ibadan, Southwest Nigeria

Effects of Planting Dates and Intra-Row Spacing on Field Infestation and Damage by Hemipteran Sucking Bugs on Soybean in Ibadan, Southwest Nigeria A.A. Omoloye, A.O. Joda, F.O. Tobih Abstract Field experiments were conducted for two years in Ibadan, Southwest Nigeria to determine whether changing planting dates and intra-row spacing in sole soybean crop will reduce field infestation and seed damage by hemiptera sucking bugs. The layout was a split plot arranged in a randomized complete block. The main effects were three planting dates (mid-June, early July and late July), each consisting of four intra-row spacings (15, 20, 25, and 30cm). Results indicated lower (p<0.05) field infestation and seed damage in the early planted crop than in the late planted crop. A significantly higher (p<0.05) yield advantage (935.6 to 974.4 kg/a-1) at the same spacing. However, adoption of these results should be balanced with local pest situation, agronomic and environmental considerations. Full Text: PDF DOI: 10.15640/jaes.v4n1a17

Effect of planting time and nitrogen application on the yield and seed quality of T. Aman rice (Oryza sativa L.)

A field experiment was conducted at the research farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during June 2006 to December 2007 to find out the effect of planting time and nitrogen fertilization on the yield and seed quality of T. Aman rice. BR11 ( Mukta) was transplanted at different dates from 5 July to 19 August at 15 days interval. The rates of N used in the experiment were 80, 100, 120, and 140 kg N/ha,. Plant height, number of tillers/hill, grain yield, and yield components parameters varied significantly due to transplanting of rice at variable dates. The optimum time of planting was found to be 4 August compared to other dates of transplanting. Result indicates that this variety planted in optimum time gave higher yield with high quality of rice seed. In comparison to early and late planting, earlier planting of the variety was better as the late planted crops were severely affected by adverse environmental condition during reproductive phase. The poor grain yield in early or late planting was due to higher percentage of spikelet sterility. The varieties responded positively with increment of N levels upto 120 kg N/ha. The higher number of panicles/m2, lower percentage of unfilled grain, and heavier individual grain contributed to increase grain yield of this verity. It is, therefore, suggested to transplant BR11 rice in the first week of August in Aman season. The application of N of 100 -120 kg/ha with three splits is optimum for achieving higher grain yield and better quality of rice seed. DOI: http://dx.doi.org/10.3329/bjar.v38i4.19660 Bangladesh J. Agril. Res. 38(4): 673-688, December 2013

Comparative assessment of maize, finger millet and sorghum for household food security in the face of increasing climatic risk

Questions as to which crop to grow, where, when and with what management, will be increasingly challenging for farmers in the face of a changing climate. The objective of this study was to evaluate emergence, yield and financial benefits of maize, finger millet and sorghum, planted at different dates and managed with variable soil nutrient inputs in order to develop adaptation options for stabilizing food production and income for smallholder households in the face of climate change and variability. Field experiments with maize, finger millet and sorghum were conducted in farmers’ fields in Makoni and Hwedza districts in eastern Zimbabwe for three seasons: 2009/10, 2010/11 and 2011/12. Three fertilization rates: high (90kgNha−1, 26kgPha−1, 7tha−1 manure), low (35kgNha−1, 14kgPha−1, 3tha−1 manure) and a control (zero fertilization); and three planting dates: early, normal and late, were compared. Crop emergence for the unfertilized finger millet and sorghum was <15% compared with >70% for the fertilized treatments. In contrast, the emergence for maize (a medium-maturity hybrid cultivar, SC635), was >80% regardless of the amount of fertilizer applied. Maize yield was greater than that of finger millet and sorghum, also in the season (2010/11) which had poor rainfall distribution. Maize yielded 5.4tha−1 compared with 3.1tha−1 for finger millet and 3.3tha−1 for sorghum for the early plantings in the 2009/10 rainfall season in Makoni, a site with relatively fertile soils. In the poorer 2010/11 season, early planted maize yielded 2.4tha−1, against 1.6tha−1 for finger millet and 0.4tha−1 for sorghum in Makoni. Similar yield trends were observed on the nutrient-depleted soils in Hwedza, although yields were less than those observed in Makoni. All crops yielded significantly more with increasing rates of fertilization when planting was done early or in what farmers considered the ‘normal window’. Crops planted early or during the normal planting window gave comparable yields that were greater than yields of late-planted crops. Water productivity for each crop planted early or during the normal window increased with increase in the amount of fertilizer applied, but differed between crop type. Maize had the highest water productivity (8.0kgdrymattermm−1ha−1) followed by sorghum (4.9kgmm−1ha−1) and then finger millet (4.6kgmm−1ha−1) when a high fertilizer rate was applied to the early-planted crop. Marginal rates of return for maize production were greater for the high fertilization rate (>50%) than for the low rate (<50%). However, the financial returns for finger millet were more attractive for the low fertilization rate (>100%) than for the high rate (<100%). Although maize yield was greater compared with finger millet, the latter had a higher content of calcium and can be stored for up to five years. The superiority of maize, in terms of yields, over finger millet and sorghum, suggests that the recommendation to substitute maize with small grains may not be a robust option for adaptation to increased temperatures and more frequent droughts likely to be experienced in Zimbabwe and other parts of southern Africa.

Population Dynamics of Cabbage Aphid, Brevicoryne brassicae L. on Major Cole Crops in Meghalaya

Population dynamics of cabbage aphid (Brevicoryne brassicae L.) was studied during 2009-10 at Entomology Farm, ICAR Research Complex for NEH Region, Umiam, Meghalaya. Cabbage, cauliflower, knolkhol and broccoli were planted on two different dates at fifteen days interval to study the incidence pattern of cabbage aphid. Early planted crops were relatively safer than late planted crops in relation to aphid infestation. Mean aphid numbers per square inch leaf area were 1.63, 1.44, 2.79 and 1.14 on first plantings and 3.15, 1.39, 3.68 and 1.68 on second plantings cabbage, cauliflower, knolkhol and broccoli, respectively. Correlation study between weather parameters and aphid population showed negative influence of temperature, relative humidity and rainfall on population growth of aphid.

First Report of Charcoal Rot Caused by Macrophomina phaseolina on Sunflower in Illinois.

In September 2009, sunflower (Helianthus annuus L.) plants (cv. Mycogen 8C451) from a University of Illinois field research trial in Fayette County, Illinois exhibited silvery gray girdling lesions on the lower stems and premature death. When lower stems and roots were split open, the pith tissue was compressed into layers. Black microsclerotia (90 to 180 μm) were present on the outside of the lower stem tissue and in the stem vascular tissue. Five pieces (approximately 1 cm long) of symptomatic stem tissue from five different affected plants (25 pieces total) were soaked in a 0.5% solution of NaOCl for 30 s, rinsed with sterile distilled water, and placed on potato dextrose agar (PDA; Becton, Dickinson, and Company, Franklin Lakes, NJ). Gray hyphae grew from all of the stem pieces, which subsequently turned black and formed black microsclerotia (75 to 175 μm). On the basis of plant symptoms and size and color of the microsclerotia, the disease was diagnosed as charcoal rot caused by Macrophomina phaseolina (Tassi) Goid (2). To confirm that the isolated fungus was M. phaseolina, DNA was extracted from the pure culture, and PCR amplification of a subunit rDNA and internal transcribed spacer (ITS) region with primers EF3RCNL and ITS4 was performed (3). The Keck Biotechnology Center at the University of Illinois, Urbana sequenced the PCR product. The resulting nucleotide sequence shared the highest homology (99%) with sequences of M. phaseolina when compared with the subunit rDNA and ITS sequences in the nucleotide database ( http://www.ncbi.nlm.nih.gov ). A greenhouse experiment was conducted to confirm pathogenicity; the greenhouse temperature was approximately 27°C and sunflower plants (cv. Cargill 270) were grown in pots and watered daily to maintain adequate soil moisture for growth. Sterile toothpicks were infested with M. phaseolina and placed through the stems (10 cm above the soil surface) of five 40-day-old sunflower plants that were approximately at growth stage R4 (1,4). Five sterile, noninfested toothpicks were similarly placed through sunflower plants to act as controls. Parafilm was used to hold the toothpick in the stem and seal the stem injury. Thirty-five days after inoculation, the mean lesion length on stems inoculated with M. phaseolina was 595 mm and no lesions developed on the control plants. M. phaseolina-inoculated plants also began to wilt and die. Cultures identical to the original M. phaseolina isolate were reisolated from stem lesions of the M. phaseolina-inoculated plants. This is the first report of charcoal rot on sunflower in Illinois to our knowledge. Sunflower is currently not a major crop grown in Illinois, but on-going research is focused on evaluating sunflower as a potential late-planted crop to follow winter wheat. If sunflower production increases in Illinois, growers may need to take precautions to manage charcoal rot.

Sweetening responses of potato tubers of different maturity to conventional and non-conventional storage temperature regimes

Low storage temperatures stimulate the accumulation of glucose and fructose (sweetening) in potato ( Solanum tuberosum L.) tubers, resulting in unacceptably dark processed products during frying. Information on how tubers respond to unorthodox storage temperature regimes is lacking, especially for the relatively new frozen-processing cultivars, ‘Umatilla Russet’ and ‘Ranger Russet’. Such knowledge could greatly facilitate the ability to manage immature, over-mature, or otherwise stressed potatoes. This study characterizes the sweetening responses of ‘Russet Burbank’, ‘Ranger Russet’ and ‘Umatilla Russet’ tubers of different maturity, over a range of conditioning and holding storage temperatures. Tubers from early- and late-planted crops were wound-healed (12 °C) for 17 d after harvest (DAH), conditioned for a month (17–48 DAH) at 4.5, 6.7, or 9 °C, and subsequently stored (48–230 DAH) at 4.5, 6.7 or 9 °C (nine temperature regimes) for an additional 182 d before reconditioning at 16 °C for 21 d. Reconditioning hastens catabolism of reducing sugars and restoration of processing quality. On average, tubers from the early planting had lower rates of respiration during wound-healing and emerged from dormancy sooner than those planted later, indicating relative immaturity of the latter. The early-planted crop of ‘Ranger Russet’ was more sensitive to low temperature sweetening than the late-planted crop, reflecting a tendency of tubers to become over-mature and reinforcing the benefit of a ‘green’ harvest for this cultivar. All cultivars sweetened rapidly when conditioned at 4.5 °C. Conditioning at 6.7 and 9 °C, however, decreased the extent of low temperature sweetening during subsequent storage at 4.5 °C through most of the storage season, expanding the options for managing potatoes with lower than normal temperature later in storage. The processing quality of ‘Ranger Russet’ was maintained for 230 d with higher conditioning/holding temperature regimes. Reducing sugar concentrations in cold-sweetened ‘Ranger Russet’ and ‘Russet Burbank’ tubers decreased more than in ‘Umatilla Russet’ tubers in response to reconditioning at 16 °C. Following an interval of wound-healing, the use of combinations of non-conventional conditioning and holding temperatures that do not stimulate excessive sweetening broadens the management options for storing potatoes for the frozen-processing industry.

Nitrogen fertilization to broccoli cultivars at different planting times: Yield and nitrogen use

The effects of three nitrogen (N) fertilizer rates (0, 120, and 240 kg N ha−1) and two planting times (May or late June/July) on yield and N use of the early cultivar ‘Milady’ and the late cultivar ‘Marathon’ of broccoli (Brassica oleracea var. italica) were investigated on three silty loam soils varying in soil mineral N (Nmin) in the southernmost part of Norway during 1999 and 2001. In all crops receiving fertilizer, rapid uptake of N started about three weeks after planting. The relative yield of broccoli heads increased with increasing soil available N (fertilizer N plus Nmin) at planting to 200–250 kg N ha−1 and then levelled off. The two lower fertilizer rates were more restrictive to yields in early-planted than in late-planted crops. A general increase in harvest index with increasing N rate reflected a stronger effect of N on the head yield than on the total above ground biomass production. The apparent recovery of fertilizer N decreased with increasing N rate and was on average 74% in total above ground biomass and 25% in broccoli heads. Despite a higher N uptake, the average soil mineral N level at harvest increased from 12 kg N ha−1 on unfertilized plots to 27 and 78 kg N ha−1 on plots receiving 120 and 240 kg N ha−1, respectively; this increase was stronger in early than in late plantings and stronger in ‘Milady’ than in ‘Marathon’. The yield of broccoli heads was similar in the two cultivars, but ‘Milady’ had a lower total biomass production and thus a higher harvest index, presumably due to earlier head initiation.

Application of a rice growth and water balance model in an irrigated semi-arid subtropical environment

In order to enhance rice productivity in water-limited environments, there is a need to adopt water-saving practices. This study examines the applicability of the ORYZA2000 model in analyzing impact of water-related options on rice yield and water use for enhancing water productivity in irrigated environments of Punjab. Performance of the model was reasonably good as indicated by close matching between simulated harvest-time grain yield, biomass, and soil profile water use with measured data and trends of simulated water balance components for a range of soil and water management scenarios. Using long-term weather data, cumulative probability distribution of simulated grain yield and evapotranspiration (ET) showed that rice yield of late-transplanted (July 1) crop was comparable to that of early-transplanted (May 16) crop, and ET-based water productivity was greater in late-planted crop. Though ET-based water productivity with continuous submergence and 2-day interval regimes were comparable, water-input-based productivity was greater under 2-day interval regime. Increasing puddling intensity from P 1 (puddling once) to P 2 (puddling two times) and P 4 (puddling four times) regimes had little effect on ET-based water productivity, but caused a substantial increase in water-input-based productivity.

Insect Populations on Bacillus thuringiensis Transgenic Sweet Corn

Insect populations and damage in three plantings (early, mid-, and late-season) of Bacillus thuringiensis (Bt) transgenic sweet corn were compared to a non-transgenic isoline at Charleston, SC, during 2000. The transgenic corn was expressing the crylA(b) gene from B. thuringiensis var. kurstaki. No fall armyworms, Spodoptera frugiperda (J. E. Smith), were present in the early-planted crop, and numbers of corn earworms, Heliocoverpa zea (Boddie), were significantly reduced in the Bt-transgenic corn compared to the non-Bt isoline. The non-Bt isoline had 65% H. zea infested ears compared to only 10% ears from the Bt-transgenic line. Damage and numbers of H. zea and S. frugiperda also were significantly higher in the non-Bt sweet corn planted in mid- and late-season plantings. Percent damaged ears by H. zea was 77% in the non-transgenic sweet corn and 21% in the Bt-sweet corn during the mid-season crop. In the late-planted crop, populations of H. zea averaged 15 per 120 ears in the non-BT isoline compared to less than 2 per 120 ears in the Bt-transgenic crop. Whorl damage by fall armyworms significantly reduced plant height in both mid-season and late-season non-transgenic crops but not in Bt-transgenic sweet corn. Numbers of other insects and spiders were low and not significantly different between the two treatments. Bt transformed sweet corn will play a major role in reducing populations of H. zea, S. frugiperda and limiting pesticides in this crop.

Effect of planting time and nitrogen on productioh potential of basmati rice (Oryza sativa) cultivars in Bihar plateau

A field experiment was conducted during rainy season of 1996-97 on clay- loam soil a! Ranchi to study the effect of transplanting time (7 and 22 July) and nitrogen levels (60, 80 and 100 kglha) on production potential and profitability of scented rice (Oryza sativa L.) cultivars (~ugandha, Basmati 370, Pusa Basrnati 1 and BR 10), A split-plot design was followed keeping transplanting time in main plot and combinations of varieties and nitrogen levels in subplot, with 3 replications. Timely tran~planted~(7 July) crop gave 17.2, 18.7, 18.8 and 14.4% higher grain yield, net return, net benefit : cost ratio and monetary productivity than late-planted crop (2,225 kg/ha, Rs 18,3191ha net return, 3.41 net benefit : cost ratio and Rs 136.7lhalday monetary productivity). Rice variety Pusa Basmati 1. gave significantly higher grain yield (2,930 kg/ha) wit! physical productivity (21.7 kg/ha/day), net return (Rs 24,372/ha), net benefit : cost ratio (4.54) and rnonetasy productivity (Rs 180.531h Jday) than the remaining.. Each hcrernental level of nitrogen gave significantly higher grain yield over its preceding levet and maximum grain yield (2,647 kg/ha), physical productivity (1 9.94 kg/ha/q), net return (Rs 24,3721ha), net benefit : costratp (4.54) and rndnetary productivity (Rs 180.53/hdday), net return (Rs 22,5361ha) net benefit : cost ratio (4.07) and rnwetary productivity (Rs 162.13lhdday) were obtained at 100 kg *N/ha. Riee Pusa Basmati 1 and Sugandha ?esponded up to 100 kg .wha, whereas Basinati 370 and BR 10 responded only up to 80 and 60 kg/ha respectively. . . . . , .. . ... . . . . . . ~eywqds . rice, planting iime. ~ibogen . . . . . .Bas* . . : . . .. . . . . . . . . . . . . . - . . . . . . . . .. . liiq Coryza sativa L.), o&amp;.xpying mbte . productiidy of sdented ,ide to e.aqforeign .than90karea,&amp; a domind *@ s&amp;gon exchfuige for,sustainable economic growth . . . cereal -&amp;:e&amp;e&amp;dia. in:~ihar 25% ; of the couptry However, its cultivation is . about of ric-e.arei t5.4 -milliin ha) is under , 9bt as. .gopular. as of coarse rice. A _- . - mediumld fw conseqSetitJy ,information related to ii~u~on;which~~uits~we~1 the cult&amp;atj&amp;&amp;f . .._ . ,free rick. Ihe.refbr8 . . i t is iuit&amp;ility .of. itF..geiiotypes, planting time . .necessitii to inGrease -the. area and and nitrogen nked in.plateau region of . . . . . . . . . - . . .~ . . .~ . . . - . - .. . . . . . . ~ ~ ~. . .. . .. ~ . . ~ .- - - ~ ~. .

Development of economic thresholds and monitoring systems for Helicoverpa armigera (Lepidoptera: Noctuidae) in tomatoes.

Field sampling methods and economic thresholds were developed to provide management recommendations for Helicoverpa armigera (Hübner) on processing tomatoes, based on a commercially acceptable damage level of 5% fruit damage. Population estimates from destructive sampling and a rapid 1-min plant scouting method were related to fruit damage, and a nominal economic threshold of one larva per plant was derived. The economic threshold was confirmed in a designed trial where it resulted in acceptable levels of fruit damage. The 1-min scouting method and economic threshold was validated in 17 commercial crops in the Gisborne, Poverty Bay region of New Zealand. Scouting in these fields was based on 10 plants in each of four quadrants proportionally representing the topography of each field. In unsprayed areas, egg and larval populations were usually below the economic threshold in early-planted crops but often exceeded thresholds in late-planted crops. In commercial demonstration trials where standard calendar spraying practice was compared with no spraying, calendar-based applications maintained fruit damage below 3.4%, but insecticide was applied unnecessarily to more than half the crops. Larval populations were a significant predictor of damage in these commercial crops. In 12 implementation trials, where spraying recommendations were based on the 1-min scouting threshold of one larva per plant, the worst fruit damage observed was 2.3%. The definition of an economic threshold, scouting methods, and establishment of parasitoids have reduced spray applications and contributed to the implementation of an integrated pest management program for processing tomatoes in New Zealand.

Determination of an action threshold for the sugarcane internode borer,Chilo saccchariphagus indicus (Kapur) in Sri Lanka

A damage level-based Action Threshold (AT) level was determined for the sugarcane internode borer (INB)Chilo sacchariphagus indicus (Kapur) in Sri Lanka. Two experiments, one in 1997/ 1998 as early planting crop and the other in 1999/2000 as late planting crop were conducted with the variety Co 775 at Uda Walawe, Sri Lanka. The experiments included maintenance of Chlorpyrifos-sprayed and control plots to measure cane yield at different infestation levels of INB. Cane yield losses were determined at different damage levels. Variation of damage levels and cane yields was tested by ANOVA. Effect of INB on cane yield was studied by correlation and regression analysis and the regression equations were used to estimate net revenue for determining AT. The highest damage level in the early- planted crops selected for chlorpyrifos spraying was 35 percent bored internodes and that for control was 33%. In the late-planted crop, the highest damage levels for the plots selected for chlorpyrifos spraying and control were 40% and 43%, respectively. The cane yield losses of the insecticide-sprayed and unsprayed plots at harvest were 2.6% and 26.8% respectively, in the early planted crop and those for late planted crop were 3.1% and 32.7%. There was a strong negative correlation between cane yield and damage level. The AT for the internode borer was found to be 13 - 15% bored internodes.

Cowpea reactions to Alectra vogelii II: effect on yield and nutrient composition

Field trials were conducted in 1993–1995 wet seasons to evaluate the influence of artificial inoculation of plots with the seeds of Alectra vogelii on the grain yield, yield components and nutrient composition of 16 cowpea varieties. This include 11 resistant varieties: IT81D-985, IT81D-994, IT89KD-245-1, TN93-80, TN121-80, IT90K-76, IT90K-59, IT86D-534, IT86D-843, B301 and IT89KD-245, two tolerant varieties: KANO 1696 and VITA 3 and three susceptible varieties: SAMPEA 7, TVX 3236 and IT82D-849. Alectra inoculation reduced the pod number and weight and grain yield of all the cowpea varieties in the late planted crop. Alectra infestation resulted in higher reduction of grain yield, yield components and grain total soluble carbohydrate (TSC) content in most of the late than early planted cowpea varieties in 1993 and 1994, respectively. In the early planted trial in 1994, the grain yield of the resistant varieties such as IT81D-985, IT81D-994, IT86D-843, IT90K-76, IT90K-59, TN93-80, B301, IT86D-534 and TN121-80 was increased while that of VITA 3, TVX 3236, SAMPEA 7 and IT82D-849 was reduced. Generally, the grain TSC content of the resistant cowpea varieties that had increased grain yield was reduced but that of the susceptible varieties with reduced grain yield was increased in the early-planted trial in 1994. Alectra infestation generally resulted in low percentage increase in the grain protein content of most of the cowpea varieties in the two trials, with greater increase in the late than in the early-planted crop.