Summer Crops Research Articles

Climate change challenges and opportunities for seaweed aquaculture in California, the United States

AbstractSeaweed aquaculture in California, the United States, is at an early stage of development. The coastal climate and growing season contrast with the cold‐temperate, where most seaweed cultivation in the US occurs. Climate change is warming coastal waters on average and increasing the frequency of marine heatwaves (MHWs). In California, those changes co‐occur with predicted seasonal changes in upwelling. Warm, low nutrient events cause diebacks of wild Macrocystis pyrifera, and other wild‐harvested species. Aquaculture can replace wild‐harvested seaweeds and expand supplies of California‐grown seaweeds, if cultivation is developed with climate‐change resilience. We consider wild‐harvested species for traits expected to increase climate resilient productivity. Golden kombu, Laminaria farlowii, was selected for test cultivation. Early life stages were successfully grown. Sporophyte growth rates were higher in summer than winter, confirming Golden kombu as a summer crop in California. Based on projections of change in upwelling intensity and season in California, we suggest a physiological screening approach for resilience to conditions expected in different regions of coastal California by mid‐to‐late 21st century.

Seed Germination Ecology of South Eastern Australian Rigid Ryegrass (Lolium rigidum) Populations

Abstract Herbicide resistance is an increasing issue in many weed species, including rigid ryegrass (Lolium rigidum Gaudin); a major weed of winter cropping systems in southern Australia. Recently, this weed has also been found in summer crops in the south eastern region of Australia. Effective control of this herbicide resistant weed across south eastern Australia requires alternative management strategies. These strategies can be informed from analyses on the interaction of germinable seeds with their regional environment and by identifying the differences between populations of varying herbicide resistance levels. In this study, we explore how various environmental factors differentially affect the seed germination and seedling emergence of three L. rigidum populations, including one glyphosate-resistant population (GR), one glyphosate-susceptible population (GS) and one population of unknown resistance status (CC04). Germination was greater than 90% for all populations at each temperature regime except 15/5 C. Populations germinated at a lower rate under 15/5 C, ranging from 74 to 87%. Salt stress had a similar effect on the germination of all populations, with 0% germination occurring at 250 mM salt stress. Population GS had greater tolerance to osmotic stress with 65% germination at −0.4 MPa compared to 47% and 43% germination for CC04 and GR, respectively; however, germination was inhibited at −0.8 and −1.6 MPa for all populations. All populations had lower germination when placed in complete darkness as opposed to alternating light/dark. Germination in darkness was lower for CC04 (69%) than GR (83%) and GS (83%). Seedling emergence declined with increasing burial depth but retained 37% emergence at 8 cm when averaged over the populations. These results indicate that L. rigidum Gaud. can survive under a range of environmental variables and the extent of survival differs based on population, however, there was no difference based on herbicide resistance status.

Management Influence on the Quality of an Agricultural Soil Destined for Forage Production and Evaluated by Physico-Chemical and Biological Indicators

The European Common Agricultural Policy promotes the sustainable use of soils through the principle of cross-compliance that links direct payments to good farming practices. Thus, it is necessary to find sustainable alternatives to the conventional management for forage production in the Atlantic Arc dairy farms. Two alternative managements (faba bean in monoculture—FB—and faba bean–Italian ryegrass intercrop—FBIR) were cultivated with organic fertilization during two consecutive years, and compared to the conventional management (Italian ryegrass in monoculture—IR—under chemical fertilization) as winter crops. Maize was used as the summer crop to complete the rotations using organic and chemical fertilization, respectively. The forage yield of winter fodder was quantified. Soil samples and summer harvests were performed to analyse the physico-chemical and biological parameters. The best forage yield corresponded to FBIR with 9.2 t dry matter (DM) ha−1 vs. 7.2 and 5.7 t DM ha−1 for FB and IR, respectively. The soil organic matter did not show significant differences among treatments, suggesting that it may be a poor indicator of the management influence on edaphic quality in the short term. Biological indicators were more sensitive and faster to differentiate among managements than chemical indicators. Earthworm abundance was higher in FB and FBIR than IR (p < 0.001), and consequently, soil infiltration was improved with the alternative management (13.90 vs. 2.08 and 0.90 min for IR, FB and FBIR, respectively, p < 0.01). As a result, the soil health diagnosis of the agroecosystem was better for alternative management.

Screening of Okra Varieties for Resistance to Okra Yellow Vein Mosaic Disease under Field Conditions

Okra (Abelmoschus esculentus L.) can contract okra yellow vein mosaic disease (OYVMD) caused by Bhendi yellow vein mosaic virus (genus: Begomovirus and family: Geminiviridae), vectored by whitefly (Bemisia tabaci). This study was carried out to screen okra varieties for resistance to OYVMD and to determine the correlation of vector population with the severity of the disease. Six varieties namely, Tulsi, Durgah, Sabz Pari, Sarahariya, Ramaan Kirshna and Pooja were grown under field conditions at localities of Shahpur, Tando Adam and Peer Kathi during rabi (winter cropping) and kharif (summer cropping) seasons during 2016 and 2017, respectively. The first incidence percent of the disease was recorded in the 8th week during rabi and the 6th week during kharif growing season. The Tulsi variety remained disease-free during both growing seasons. A significantly lower disease incidence % was recorded in Sabz Pari (29.32%) and Sarahariya (30.09%) varieties than Durgah, Ramaan Kirshna and Pooja during the rabi growing season. Both varieties were disease-free during the kharif season. There was remarkable variation in disease severity recorded in okra varieties at different trials during rabi and kharif seasons using a 0-6 rating scale (i.e., 0 = The disease-free plants, 1 = 1-10 % vein clearing, 2 = 11-25 % vein yellowing of small leaves , 3 = 26-50 % yellow network on some leaves, 4 = 51-60 % yellow network on all leaves, 5 = 60-70 % complete leaves turn yellow or cream color and 6 = 70 % plant stunted, deformed and small fruit and whole plants becomes colorless). Whitefly appeared in the 5th week during the rabi and 4th week during the kharif growing seasons. Vector population during the rabi growing season was significantly higher than in the kharif season. There was a nonsignificant relationship between disease severity and whitefly population in Ramaan Kirshna, Sarahariya, and Sabz Pari varieties. The disease severity in the Pooja variety showed a significant relationship with vector population, but only in the Tando Adam trial (R2= 0.7455, P= 0.0084), whereas the Durgah variety showed a significant relationship between disease severity and vector population in Shahpur (R2= 0.6615, P= 0.0267) and Tando Adam trials (R2= 0.8235, P= 0.0018). The same variety showed a nonsignificant relationship between disease severity and vector population in the Peer Kathi trial. It is concluded that Sabz Pari and Tulsi varieties are resistant to the disease

Floricane yield and berry quality of seven primocane red raspberry (Rubus idaeus L.) cultivars

Primocane raspberry (Rubus idaeus L.) may produce crop on the lower part of the cane during the second year of its’ growth cycle, if the canes are retained over winter. We aimed to evaluate the floricane cropping potential and berry quality in seven primocane raspberry cultivars, which are too late for fall cropping in the Northern growing conditions. Long cane plants of these cultivars were produced, overwintered, and grown like floricane cultivars in a high tunnel. Harvesting floricane crop started in mid-June, and the length of the summer cropping season was between eight to 10 weeks. 'Joan J' and 'Imara' were the earliest cultivars, and 'Autumn Bliss' was the latest. Total floricane yield in most cultivars was between 1.7 to 2.0 kg/cane. ‘Autumn Treasure’ yielded significantly less, and ‘Autumn Bliss’ produced 2.5 kg berries /cane. The average berry size was 5 g, except in ‘Autumn Bliss’ and ‘Autumn Treasure’, which had smaller berries. The highest sugar content was observed in 'Kwanza' berries and the lowest in 'Polka'. High throughput phenotyping proved an effective tool for determining berry shape and color. ‘Kwanza’ berry color was the reddest, yellowest and lightest of all cultivars. Based on our results, growing primocane raspberry cultivars as long cane plants for production of summer crop is more reliable than growing them as fall cropping in short growing season conditions. The cultivars ‘Imara’ and ‘Kweli’ were the most promising in our experiment; they had a high yield potential and excellent berry quality.

Climate and Socioeconomic Factors Drive Irrigated Agriculture Dynamics in the Lower Colorado River Basin

The Colorado River Basin (CRB) includes seven states and provides municipal and industrial water to millions of people across all major southwestern cities both inside and outside the basin. Agriculture is the largest part of the CRB economy and crop production depends on irrigation, which accounts for about 74% of the total water demand cross the region. A better understanding of irrigation water demands is critically needed as temperatures continue to rise and drought intensifies, potentially leading to water shortages across the region. Yet, past research on irrigation dynamics has generally utilized relatively low spatiotemporal resolution datasets and has often overlooked the relationship between climate and management decisions such as land fallowing, i.e., the practice of leaving cultivated land idle for a growing season. Here, we produced annual estimates of fallow and active cropland extent at high spatial resolution (30 m) from 2001 to 2017 by applying the fallow-land algorithm based on neighborhood and temporal anomalies (FANTA). We specifically focused on diverse CRB agricultural regions: the lower Colorado River planning (LCRP) area and the Pinal and Phoenix active management areas (PPAMA). Utilizing ground observations collected in 2014 and 2017, we found an overall classification accuracy of 88.9% and 87.2% for LCRP and PPAMA, respectively. We then quantified how factors such as climate, district water rights, and market value influenced: (1) annual fallow and active cropland extent and (2) annual cropland productivity, approximated by integrated growing season NDVI (iNDVI). We found that for the LCRP, a region of winter cropping and senior (i.e., preferential) water rights, active cropland productivity was positively correlated with cool-season average vapor pressure deficit (R = 0.72; p < 0.01). By contrast, for the PPAMA, a region of summer cropping and junior water rights, annual fallow and active cropland extent was positively correlated with cool-season aridity (precipitation/potential evapotranspiration) (R = 0.46; p < 0.05), and active cropland productivity was positively correlated with warm-season aridity (precipitation/potential evapotranspiration) (R = 0.42; p < 0.01). We also found that PPAMA cropland productivity was more sensitive to aridity when crop prices were low, potentially due to the influence of market value on management decisions. Our analysis highlights how biophysical (e.g., temperature and precipitation) and socioeconomic (e.g., water rights and crop market value) factors interact to explain seasonal patterns of cropland extent, water use and productivity. These findings indicate that increasing aridity across the region may result in reduced cropland productivity and increased land fallowing for some regions, particularly those with junior water rights.

A case study of insect visitors and pollen vectors in sponge gourd (Luffa cylindrica (Linn.)) during summer and rainy seasons in India

Insect crop visitations do not necessarily always translate to transfer or carriage of pollen. To determine the potential of the various insects visiting summer and rainy seasons sponge gourd (Luffa cylindrica (Linn.)) flowers to facilitate the pollen transfer, the present study examines the diversity of visiting insects to sponge gourd seed crops in relation to the time of day and season, diversity and abundance to its flowers, fruits and seed yield. These visiting insects taxonomically belonged to 8 different insect orders viz. Coleoptera, Diptera, Hymenoptera, Hemiptera, Neuroptera, Lepidoptera, Odonata and Orthoptera/Dictyoptera. Rainy season sponge gourd crops had higher numbers of insect visitors and higher diversity (0.80 of Simpson’s Diversity Index and 1.71 of Shannon–Weaver Index of diversity as compared to summer season crop (0.72 and 1.51, respectively). The summer crop had the highest number of visiting insects belonged to the order Coleoptera followed by Hemiptera and Hymenoptera and their reciprocal form of Berger Parker’s dominance indices were 2.21, 5.05 and 6.17, respectively. In summer crop, honeybees were the main pollinators comprising 57.69% of total pollinators in sponge gourds. All the four honeybee species viz., Apis cerana indica, A. dorsata, A. florea and A. mellifera were found to visit in sponge gourd. However, the dominant species was A. florea with 39% of total honeybee share. In rainy season crop, in contrary, honeybees comprised only 16.32% share on total visiting pollinators in sponge gourd. Rice skipper, Pelopidas mathias (46.84% share) was found almost thorough out the day with higher visitation during evening hours. Other pollinators were stingless bees (11.58% share), butterflies and moths. Consequently, we suggest optimizing pollinators’ management including honeybees and thereby improving the attraction of sponge gourd lines to these pollinators to improve pollination rates for sponge gourd seed crops.

The first comprehensive archaeobotanical analysis of prehistoric agriculture in Kyrgyzstan

We present here the first comprehensive archaeobotanical investigation from the prehistoric farming settlement of Chap I (1065–825 cal bce), located in a high altitude valley in the central Tien Shan mountains, Kyrgyzstan. A total of 40,651 plant remains (seeds, chaff and other plant parts) have been identified, making this archaeobotanical study the first of its kind from Kyrgyzstan to enable a wider discussion on cultivated crop taxa including diversity of varieties and morphotypes within the same crop species, along with crop cultivation and processing practices. Additionally, the analysis of wild plant taxa permits a significant interpretation of crop weeds and the surrounding landscape ecology at the site. The crop assemblage at the site is dominated by Hordeum vulgare (naked and hulled barley) varieties, consisting of thousands of individual grains and chaff fragments recovered from all analysed contexts. The other crops consist of Triticum (free-threshing and possibly glume wheats), Panicum miliaceum (broomcorn millet), Setaria italica (foxtail millet) and Pisum sativum (pea). The wild plant spectrum suggests an open landscape created by humans, dominated by water and nitrogen demanding plants that were growing in a well-watered, possibly irrigated landscape at an altitude of 2,000 m a.s.l. The weed taxa also suggest that possibly both summer and winter crops were cultivated. Finally, we provide illustrations of recovered plant remains and list crop identification criteria, aiming to facilitate future archaeobotanical research in Central Asia.

Water productivity in maize, at different levels of deficit irrigation in humid climate

En regiones de clima templado y húmedo como Uruguay el riego estabiliza y aumenta los rendimientos de los cultivos estivales, suplementando las precipitaciones. El riego a demanda tiene mayor consumo de agua, afectando la sostenibilidad del sistema de producción por el uso ineficiente de los recursos, y es ambientalmente negativo (uso excesivo de agua dulce y energía para su extracción). Es necesario evaluar alternativas de riego deficitario que aumenten la productividad del agua riego. Para ello se evaluaron tres láminas máximas de reposición: (T2) 3 mm día-1, (T3) 6 mm día-1, (T4) 9 mm día-1, y (T1) testigo sin riego, (solo agua de lluvia), sobre la producción de maíz, para definir estrategias de riego más eficientes. Los resultados indican que existe respuesta a diferentes niveles de riego deficitario. Cuando las precipitaciones fueron superiores al promedio, su mala distribución durante el ciclo del cultivo generó déficit hídrico en momentos puntuales, afectando el rendimiento. El T1 y T2 no cubrieron la etc durante el Periodo Crítico y llenado de grano, causando menores rendimientos. El T3 y T4 dieron rendimientos mayores y en el promedio de tres años fueron diferentes significativamente. El T3 no siempre cubrió la etc, pero la reserva del suelo y las precipitaciones contribuyeron para cubrirlo, ahorrando casi 20 % de agua de riego respecto a T4. Sin embargo, los indicadores de productividad del agua (eua, euar) muestran que T4 es mejor estrategia de riego, aunque realice menor aprovechamiento de las precipitaciones y del agua del suelo.

Field-scale assessment of Belgian winter cover crops biomass based on Sentinel-2 data

Winter cover crops, used as green manure, can supply up to 45 units of nitrogen per hectare to the following summer crops. In order to contribute to the establishment of the nitrogen balance sheet for fertilisation recommendation of subsequent main crop at field scale, this supply is currently derived from the biomass production, classically estimated visually using 3 classes: 0–1, 1–3, 3+ tons of dry matter per hectare (Mg DM ha−1). The capabilities of Sentinel-2 satellite data to retrieve an operator-independent winter cover crop biomass have been assessed. Biomass samples were collected in 1 m quadrats for various types of winter cover fields classically used in Belgium (mustard, phacelia, oat and a range of mixed cover), in 2016 and 2017 (yield between 0.1 to 5 tons of dry matter per hectare). Empirical relationships between the winter cover crop biomass and a wide range of vegetation indices (VIs) derived from Sentinel-2 have been defined, and the most performant VI identified. For pure stands of winter cover crops, the cross-validation RMSE (CVRMSE) of the best model is 0.36 Mg DM ha−1 for mustard and 0.3 Mg DM ha−1 for phacelia. The CVRMSE observed for mixed stands, around 0.61 Mg DM ha−1, is roughly two times higher than the CVRMSE observed for pure stands. The added-value of objective satellite-based estimation of winter cover biomass was also assessed by comparing respective estimations with regards to an independent reference dataset made of sample measurements on the ground. Models based on Earth observation showed better results than farmer visual assessment for mustard crops, and were as good as farmers for phacelia crops.

Emergence patterns of winter and summer annual weeds in Ethiopian mustard (Brassica carinata) cropping system

Abstract Ethiopian mustard (Brassica carinata A. Braun) is a biofuel crop recently introduced in the southeastern United States. For this crop to be successful, integrated weed management strategies that complement its rotation with summer cash crops must be developed. The objectives of this research were to evaluate the effect of previous season summer crops on winter weed emergence patterns during Ethiopian mustard growing season and to assess the impact of planting Ethiopian mustard on the emergence patterns of summer weed species. Gompertz models were fit to winter and summer weed emergence patterns. All models represented more than 80% of the variation, with root mean-square error values less than 0.20. The emergence pattern for winter weed species was best described using growing degree-day accumulation, and this model can be utilized for implementing weed control strategies at the critical Ethiopian mustard growth stages. The results also showed that summer weeds can emerge during the winter in northern Florida but do not survive frost damage, which might create off-season seedbank reductions before the summer crop growing season.

Assessing climate risk to cassava (Manihot esculenta) yield based on rainfed

Sowing of cassava is frequently encountered with lack of irrigation water due to the occurrence of meteorological drought, resulting in the decline of yields or even complete crop failure. This research was examined during 2000 to 2019 based on the Crop Wat model to predict cassava yield in the cultivation regions of Tanh Linh district in the context of climate change (CCC). The performance of applied model was valued based on the climate data, soil and crop management during the studied period. The valued results stated that error indices (RMSE = 0.26 ÷ 0.34, R2 = 0.83 ÷ 0.912 and d = 0.78 ÷ 0.88) proved the Crop Wat model's efficiency for simulating cassava yield across the study area. The simulation showed that the optimal cultivation entrance (OCE) varied from 5th to 22nd April, when the cassava yield achieved up to 46.4 ton per ha for spring crop and 42.3 ton per ha for summer crop from 17th to 24th of April. The results indicated that precipitation strongly influenced the cultivation processes as well as cassava yield in the study area. Based on the finding, it can be stated that cultivation seasonal of main cassava crops is not suitable to the weather conditions. In general, farmers need to alter in the cultivation seasonal to minimize the adverse effects of precipitation factor as well as contribute to improve crop yield.

Increase in Importance of Aphelinus nigritus (Howard) on Winter Crops in Oklahoma Coincides with Invasion of Sugarcane Aphid on Sorghum in Oklahoma

Aphid parasitoids on the Southern Great Plains provide important pest suppression services in summer and winter crops. The primary parasitoids Lysiphlebus testaceipes (Cresson), Aphelinus nigritus (Howard), and Diaretiella rapae (McIntosh) use multiple aphid host species on multiple crops in agricultural landscapes and historically, L. testaceipes has been the most abundant and arguably most important. However, after the sugarcane aphid, Melanaphis sacchari (Zehntner), infested sorghum (Sorghum bicolor (L.) Moench) on the Southern Plains, A. nigritus increased in abundance and impact on this summer crop. We hypothesized that A. nigritus also would be more abundant in fields of winter wheat (Triticum aestivum L.) and winter canola (Brassica napus L.) in the region following the sugarcane aphid. From 2016-2019, we documented aphid parasitoid abundance and percentage of parasitism in Oklahoma winter crops during late fall and early spring using a standardized sentinel aphid deployment retrieval and rearing approach. Unexpectedly, A. nigritus was relatively abundant during Fall 2016, parasitizing as many as 5.4% of sentinel aphids in winter wheat fields which was more than the typically dominant parasitoid L. testaceipes. However, percentage of parasitism by A. nigritus decreased during the study. Our results suggested that abundance of A. nigritus mirrored those of sugarcane aphids in the region, and the temporary presence of the parasitoid in winter crops reflected dynamics at a landscape level.

Spatial variability of evapotranspiration and pressure on groundwater resources: remote sensing monitoring by crop type in the Bekaa plain, Lebanon

The lack of data on water consumption by agriculture in the context of climate change led the authors to estimate the water balance of the Bekaa Valley. Plots were mapped according to the normalized difference vegetation index profiles of spring and summer crop with the Sentinels-2 images. Surface energy balance model python (PYSEBAL) estimated the seasonal evapotranspiration (ETseason) and net irrigation requirements (NIRseason). Spring and summer crop maps were accurate: 90% and 93%. The results of PYSEBAL were validated by the comparison between averaged daily ET of PYSEBAL and FAO-56 method (root mean square error from 0.38 to 1.93 and the mean average error from 0.33 to 1.64 mm / day). The water balance was negative: 0.16 km3 of groundwater was extracted against 0.10 km3 of rainfall available for aquifer recharge in 2017. This is explained by ET/ha/season (alfalfa: 1094 mm / ha / season, orchards 881, corn 719, tobacco 606, cucumber 558, late potatoes 487, summer vegetables 483, early potatoes 467, vineyard 390, spring vegetables 237, and wheat 313). ETseason varies according to temperature (strong correlation between daily ET and temperature, Pearson: 0.74), relative humidity (Pearson: −0.65), surface radiation (Pearson: 0.75), and percentage of sand in the soil and its depth (strong negative Pearson: −0.62 and −0.57).

N2O Emissions From Residues of Oat and Grass Pea Cover Crops Cultivated in the US Southern Great Plains

Grass pea (Lathyrus sphaericus) and oat (Avena sativa) are potential cover crops for spring periods of summer crop systems in the US Southern Great Plains (SGP). The main objective of this study was to compare nitrous oxide (N2O) emissions from residues of grass pea and oat grown as green nitrogen (N) crops. The comparisons included responses from plots cultivated with oat, grass pea, and control (spring-fallowed) plots. Two management options were applied to grass pea: residues retained and aboveground biomass removed for forage. Crabgrass (Digitaria sanguinalis) was cultivated as a main summer crop immediately after termination of the cover crops. Fluxes of N2O were measured by closed chamber connected to a portable gas analyzer on 23 dates during a 3 month growing period for crabgrass. At termination, oat produced more aboveground biomass than grass pea (2.17 vs. 3.56 Mg ha−1), but total N in biomass was similar (102–104 kg ha−1) due to greater N concentrations in grass pea than oat (4.80% vs. 2.86% of dry mass). Three month cumulative emissions of N2O from grass pea-incorporated plots (0.76 ± 0.11 kg N2O-N ha−1; mean ± standard error, n = 3) were significantly lower than from oat-incorporated plots (1.26 ± 0.14 kg N2O-N ha−1). Emissions from grass pea plots with harvested biomass (0.48 ± 0.04 kg N2O-N ha−1) were significantly lower than those from grass pea-incorporated plots. Cumulative N2O emissions from control plots were significantly greater than those from grass pea-harvested plots but were similar to the emissions from grass pea-incorporated plots. Yields produced by crabgrass were similar from all cover crop treatments (8.65–10.46 Mg ha−1), but yield responses to the control (18.53 Mg ha−1) were significantly larger. Nitrogen concentrations in crabgrass were greater in response to oat- and grass pea-incorporated plots (2.86–2.87%) than in grass pea-harvested (1.93%) and control (1.44%) plots. In conclusion, the results indicated that (i) post-incorporation emissions of N2O can be greater from a non-legume green N crop than a legume green N crop due to greater biomass productivity of the cereal, and (ii) emissions of N2O could be mitigated by removing biomass of the green N crop for use as forage.

Transforming Malta Orchard into Agroforestry System with Different Crops for Improving Productivity, Profitability and Land Uses

Sustainable agricultural practices like agroforestry systems are being advocated to overcome various problems of farming. A young malta (Citrus sinensis) orchard (3 years old) was transformed into a fruit tree-based agroforestry system in which the performances of summer (okra and Indian spinach) and autumn (mungbean and kangkong) crops and year-round spices (ginger and turmeric) were evaluated following randomized complete block design (RCBD) with three replication each and eventually compared between agroforestry systems and respective sole cropping (control) from March 2018 to February 2019 at BSMRAU field. The experimental results revealed that the yields of the associated crops deprived when grown at the closest row position from the bed of malta tree and spices. Yields of okra, Indian spinach, mungbean, kangkong, turmeric and ginger were reduced by 7.57, 6.52, 14.86, 13.26, 9.70 and 16.23%, respectively under agroforestry system as compared to control. However, malta yield was increased by 5.35% in agroforestry system than control trees. The findings also indicated that the crops in agroforestry system was less hindered by the shade effect of malta trees due to less dense canopy of young malta trees. In comparison to sole cropping system, the higher benefit-cost ratio (BCR) (2.93) and land equivalent ratio (LER) (2.83) were obtained in the studied agroforestry system that explicated higher system productivity and land uses. Notable improvement of total nitrogen and organic matter were obtained in the soil under agroforestry system. Therefore, malta-based agroforestry system can be a promising alternative to provide higher economic benefits, boosting food and nutritional security, improving soil nutrient status and utilization of land.
 Ann. Bangladesh Agric. (2020) 24(1) : 113-125

Effect of emergence time on growth and fecundity of redroot pigweed (Amaranthus retroflexus) and slender amaranth (Amaranthus viridis): emerging problem weeds in Australian summer crops

AbstractRedroot pigweed (Amaranthus retroflexus L.) and slender amaranth (Amaranthus viridis L.) are considered emerging problematic weeds in summer crops in Australia. An outdoor pot experiment was conducted to examine the effects of planting time on two populations of A. retroflexus and A. viridis at the research farm of the University of Queensland, Australia. Both species were planted every month from October to January (2017 to 2018 and 2018 to 2019), and their growth and seed production were recorded. Although both weeds matured at a similar number of growing degree days (GDD), they required a different number of days to complete their life cycles depending on planting date. The growth period was reduced and flowering occurred sooner as both species experienced cooler temperatures and shorter daylight hours. Both species exhibited increased height, biomass, and seed production for the October-sown plants compared with other planting times, and these parameters were reduced by delaying the planting time. The shoot and root biomass of A. retroflexus and A. viridis (averaged over both populations) was reduced by more than 70% and 65%, respectively, when planted in January, in comparison to planting in October. When planted in October, A. retroflexus and A. viridis produced 11,350 and 5,780 seeds plant−1, but these were reduced to 770 and 365 seeds plant−1 for the January planting date, respectively. Although the growth and fecundity of these species were dependent on planting time, these weeds could emerge throughout the late spring to summer growing season (October to March) in southeast Australia and could produce a significant number of seeds. The results showed that when these species emerged in the late spring (October), they grew vigorously and produced more biomass in comparison with the other planting dates. Therefore, any early weed management practice for these species could be beneficial for minimizing the subsequent cost and energy inputs toward their control.

Rice, beans and pulses at Vadnagar: An early historical site with a Buddhist monastery in Gujarat, western India

We present the plant macroremains from the site of Vadnagar, an important centre of Buddhist learning in western India spanned between first century BCE and fourth century CE. The cultural relics and AMS dates of the recovered carbonized seeds from the cultural horizon also confirm the archaeological context. The study indicate that the likely staples were cereals (Oryza sativa, Hordeum vulgare, Triticum aestivum), leguminous crops (Vigna unguiculata, Vigna radiata, Vigna mungo, and Macrotyloma uniflorum), and oil and fibre-yielding (Linum usitatissimum and Gossypium sp.) crops. In addition, there is an evidence that fruits such as Tamarindus indica and Ziziphus sp. may have been consumed by the settlers. Few weeds and wild taxa (Paspalum scrobiculatum, Vicia sp., and Ipomoea sp.), which turned up as an admixture with the above economically important seeds/grains have also been encountered. Abundance of Oryza sativa (rice) grains and spikelet bases indicate crop-processing at the site and played significant role in the subsistence economy. Moreover, the overall assemblage of summer and winter crops suggests the prevalence of multi-cropping system attributed to conducive environmental conditions during ~100BCE–400CE.

Use of Pheromone Traps to Monitor Population Fluctuations of Cotton Leafworm Moth and Their Transmission in Winter and Summer Crop Fields

These experiments were carried out in Lakana and Sharnub villages, El-Beheira Governorate, during the 2017, 2018, and 2019 seasons to study the crop type, regional and seasonal effects on male adults of S. littoralis caught by YWPT. The average numbers of moth, for sugarbeet, clovers and wheat were 7.57, 9.00, and 5.64 respectively, at Lakana village, and were 11.19, 10.70, and 8.77 respectively, at Sharnub village in winter crop fields during the 2017/2018 season. While during the 2018/2019 winter season, the average numbers of moth, were 13.95, 10.65, and 8.05 respectively, at Lakana village, and were 15.33, 10.38, and 13.18 respectively, at Sharnub village. Comparing moth numbers catches significant differences were noticed between the crops, where the average moth for sugarbeet higher than clovers and wheat. The average numbers of moths, for soybean, maize and cotton were 61.00, 15.27, and 70.50 respectively, at Lakana village, where it was 74.23, 23.80, and 87.80 respectively, at Sharnub village in the 2018 summer season. During the 2019 summer season, the average numbers of moths, were 63.05, 24.40, and 75.10 respectively, at Lakana village, and were 71.29, 28.13, and 103.40 respectively, at Sharnub village. However, moth numbers catch significant differences were noticed between the crops, where the average moth for cotton and soybean higher than maize. Also, all treatments were showed significant differences between both locations and between the winter and summer crops.

Soil nutrient status and crop productivity after 6 years of conservation tillage in a subtropical dryland

Conservation tillage is considered one of the most indispensable management practices for crop productivity and soil health in rainfed areas world over. The present study aimed to assess performance of conservation tillage in contrast with conventional tillage for different crop sequences on soil quality and yield productivity under the subtropical dryland conditions of Pothwar, Pakistan. Present study was carried out in the plots of an existing long-term field trial initiated in 2011 where four tillage systems viz. conventional tillage (CT, moldboard), minimum tillage (MT), reduced tillage (RT), and zero tillage (ZT) were compared. In 2015, for current study, each tillage plot was divided into three subplots for crop sequences viz. fallow-wheat (Triticum aestivum) (F-W), mungbean green manure (Vigna radiata)-wheat (M-W), and sorghum fodder (Sorghum bicolor)-wheat (S-W). Soil fertility in terms of NO3-N, P, and K was significantly enhanced by long-term application of RT and ZT tillage systems. Among crop sequences, F-W and M-W had higher soil fertility than S-W sequence. Biomass yield of summer crops was the highest under RT tillage that was 37.31 t ha−1 and 42.01 t ha−1 for sorghum and 19.49 t ha−1 and 26.47 t ha−1 for mungbean in 2015 and 2016, respectively. The lowest biomass of both crops was produced by ZT, mainly due to poor germination and lesser plant height. Grain yield of winter wheat was also statistically highest under RT tillage especially in F-W and M-W sequences. Wheat yields were 2.89 t ha−1 and 2.84 t ha−1 in 2016 and 2.63 t ha−1 and 2.61 t ha−1 in 2017, respectively. Reduced tillage system should be promoted for the improvement of soil fertility and crop productivity in Pothwar and other subtropical dryland areas.