Intensive Vegetable Cropping Systems Research Articles

How Does Watermelon Grafting Impact Fruit Yield and Quality? A Systematic Review

Globally, there has been an increase in stringent regulations governing the use of chemical soil fumigants for controlling diseases, pests, and weeds. Grafting has been identified as an effective alternative to soil fumigation for managing soilborne diseases and pests in intensive vegetable cropping systems. The majority of watermelon (Citrullus lanatus) grafting research confirms that selected rootstocks play a role in improving plant resistance or tolerance to common soilborne diseases. Currently, there is a lack of evidence-based literature on the effects of grafting on watermelon fruit quality attributes and yield components. Previous reviews report wide variation in the impact of grafting on watermelon production, depending on rootstock–scion combinations and environmental conditions. This review employed evidence-based synthesis methods to comprehensively and methodically summarize research results of the impact of grafting on watermelon, with a focus on fruit quality and yield. In this systematic review, 548 citations (studies published during 2011–21) were screened against strict inclusion criteria, and data were extracted from 47 studies. Meta-analysis of percent differences between the grafted watermelon treatment and the nongrafted or self-grafted watermelon control was performed using extracted data of yield components and a wide range of fruit quality attributes. Meta-analysis of research data with variance measures was also conducted based on a rather limited number of studies. Our findings showed higher levels of total yield, average fruit weight, fruit length and width, fruit lycopene and soluble solids content, rind thickness, flesh firmness, lightness, chroma, and flesh nitrogen (N) content in grafted watermelon treatments compared with the nongrafted or self-grafted control. In particular, total yield, average fruit weight, and flesh firmness exhibited significant increases of a more than 10% difference. In contrast, grafted plants demonstrated decreases in fruit pH, hue angle, and flesh calcium content, although the reduction was not greater than 10% relative to the control. Meta-analysis of research data with variance measures further confirmed significantly greater total yield and flesh N content in grafted watermelon treatments compared with the nongrafted or self-grafted control. In addition, the meta-analysis results confirmed greater benefits of watermelon grafting in the presence of known soilborne disease pressure in contrast to the production scenarios without soilborne disease problems.

Biochar-Induced Mitigation Potential of Greenhouse Gas Emissions Was Enhanced under High Soil Nitrogen Availability in Intensively-Irrigated Vegetable Cropping Systems

Intensive irrigation coupled with excessive nitrogen (N) fertilizer input has resulted in high soil greenhouse gas (GHG) emissions in vegetable cropping systems. Biochar as a soil amendment has been advocated as a desirable option to reduce GHG emissions in agricultural systems, but its interactive effects with soil N availability in vegetable systems have yet to be clarified. We performed a field study to examine how biochar interacts with N fertilizer in driving annual methane (CH4) and nitrous oxide (N2O) emissions from an intensively-irrigated greenhouse vegetable cropping system acting as both sources of atmospheric CH4 and N2O in subtropical China. Biochar amendment significantly increased soil CH4 emissions by 33% and 85%, while it decreased soil N2O emissions by 22% and 12% with and without N fertilizer input, respectively. Fertilizer N combination weakened the positive response of CH4 to biochar while it enhanced the mitigation potential of biochar for N2O. Annual direct emission factors of fertilizer N for N2O were estimated to be 1.35% and 1.94% for the fields with and without biochar amendment, respectively. Annual flux-sustained global warming potential (SGWP) and greenhouse gas intensity (GHGI) were significantly decreased by biochar amendment, and this mitigation effect was enhanced with fertilizer N combination. Altogether, we highlight that biochar can reconcile higher yield and lower climatic impact in intensive vegetable cropping systems in subtropical China, particularly in vegetable soils with high N availability.

Opportunities to improve nitrogen use efficiency in an intensive vegetable system without compromising yield

Intensive vegetable cropping systems rely heavily on nitrogen (N) inputs from multiple synthetic and organic fertilizer applications. The majority of applied N is lost to the environment through numerous pathways, including as nitrous oxide (N2 O). A field trial was conducted to examine the opportunities to reduce N input in an intensive vegetable system without compromising yield. Treatments applied were control (no N), manure (M, 408kg N ha-1 from chicken manure), grower practice (GP, 408kg N ha-1 from chicken manure + 195kg N ha-1 from fertilizer), and 2/3 GP (two-thirds of the total N input in GP), all with and without 3,4-dimethylpyrazole phosphate (DMPP). Nitrogen recovery in the GP treatment was determined using 15 N-labeled fertilizer. Using only manure significantly lowered celery (Apium graveolens L.) yield and apparent N use efficiency (ANUE) compared with GP. Reducing N input by one-third did not affect yield or ANUE. Use of DMPP increased ANUE despite no yield improvement. More than 50% of the applied N in the GP treatment was lost to the environment, with almost 10kg N ha-1 emitted as N2 O over the season, which was 67 times more than from the control. Reducing the N input by one-third or using manure only reduced N2 O emissions by more than 70% relative to GP. This study shows that there is a clear opportunity to reduce N input and N2 O emissions in high-fertilizer-input vegetable systems without compromising vegetable yield.

Rye cover crop improves vegetable crop nitrogen use efficiency and yield in a short season growing region

Cover crops have the potential to immobilize nitrogen (N) that would otherwise be lost before or after the main crop production, leading to improved N management. However, information on how cover crops influence N management in intensive vegetable cropping systems is scarce. This study aimed to determine how an overwintering rye cover crop impacts crop yield and N cycling, for three common prairie vegetable crops. From 2017 to 2019, a broccoli – sweet corn – root crop sequence was tested (in which all crops of rotation were present each year), with each crop type receiving five N fertilizer treatments, ranging from 0 to 300 kg N·ha−1. After harvest each year, sub-plots were established with vs. without a rye cover crop, and the effect on vegetable yield, soil inorganic N, and N use efficiency (NUE) was followed into the subsequent growing season. In most cases, the cover crop increased vegetable crop productivity and N content in the subsequent growing season. The cover crop also lowered soil inorganic N levels at vegetable planting but increased levels at harvest. Vegetable crop NUE indices were frequently improved with vs. without the cover crop. As for the N fertilizer response, increasing N fertilizer rate did not continually increase vegetable crop productivity and N content. Higher N fertilizer rates increased soil inorganic N levels at vegetable planting and harvest, and often lowered vegetable crop NUE indices. These results demonstrate the importance of adjusting soil N levels to better align with crop needs — and that including a rye cover crop in the vegetable rotation is one method of doing so.

Alternative Management Practices Improve Soil Health Indices in Intensive Vegetable Cropping Systems: A Review

An increase in intensive cropping would benefit society by providing food to a growing population, and vegetable production is an excellent example of intensive cropping systems that are indeed on the rise. Vegetable cropping systems are high-input and generally require large quantities of fertilization, frequent irrigation, and repeated tillage operations. Consequently, an increase in global vegetable production may have seriously negative impacts on soil health and ecosystem services. Yet, not only maintaining but improving soil health is critical to enhancing the sustainability of food production systems. Previous agricultural research mainly focused on field crop systems and largely ignored vegetable cropping systems; consequently, this represents a conspicuous research gap, one that must be addressed in order to make progress towards sustainable food production. Here, we review the literature to gain a better understanding of how management has influenced various soil health indices (soil biology, chemistry, and physical dynamics) and to evaluate the implications for soil ecosystem services in vegetable cropping systems. We found that alternative modifications to conventional vegetable production systems, which resemble methods used in organic or conservation agriculture, tended to improve aspects of soil health. For example, soil amendments generally improved soil chemical indices of health – soil carbon levels and nitrogen reserves in particular. Incorporation of cover crops to vegetable crop rotations tended to improve nitrogen recycling via reduced nitrate leaching risks, increased soil carbon levels, and weed suppression. Reduced tillage systems were rare, presenting an important challenge and opportunity for further improving soil health dynamics in vegetable production. Notably, adopting alternative practices generally had no effect on crop yields, which implies little risk of yield penalties when agronomic management is carefully planned. Our results indicate that future sustainable vegetable cropping systems may embody a blend between organic and conventional ideologies to better maintain or improve soil ecosystem functioning.

Nitrification inhibitors mitigated reactive gaseous nitrogen intensity in intensive vegetable soils from China

Nitrification inhibitors, a promising tool for reducing nitrous oxide (N2O) losses and promoting nitrogen use efficiency by slowing nitrification, have gained extensive attention worldwide. However, there have been few attempts to explore the broad responses of multiple reactive gaseous nitrogen emissions of N2O, nitric oxide (NO) and ammonia (NH3) and vegetable yield to nitrification inhibitor applications across intensive vegetable soils in China. A greenhouse pot experiment with five consecutive vegetable crops was performed to assess the efficacies of two nitrification inhibitors, namely, nitrapyrin and dicyandiamide on reactive gaseous nitrogen emissions, vegetable yield and reactive gaseous nitrogen intensity in four typical vegetable soils representing the intensive vegetable cropping systems across mainland China: an Acrisol from Hunan Province, an Anthrosol from Shanxi Province, a Cambisol from Shandong Province and a Phaeozem from Heilongjiang Province. The results showed soil type had significant influences on reactive gaseous nitrogen intensity, with reactive gaseous nitrogen emissions and yield mainly driven by soil factors: pH, nitrate, C:N ratio, cation exchange capacity and microbial biomass carbon. The highest reactive gaseous nitrogen emissions and reactive gaseous nitrogen intensity were in Acrisol while the highest vegetable yield occurred in Phaeozem. Nitrification inhibitor applications decreased N2O and NO emissions by 1.8–61.0% and 0.8–79.5%, respectively, but promoted NH3 volatilization by 3.2–44.6% across all soils. Furthermore, significant positive correlations were observed between inhibited N2O+NO and stimulated NH3 emissions with nitrification inhibitor additions across all soils, indicating that reduced nitrification posed the threat of NH3 losses. Additionally, reactive gaseous nitrogen intensity was significantly reduced in the Anthrosol and Cambisol due to the reduced reactive gaseous nitrogen emissions and increased yield, respectively. Our findings highlight the benefits of nitrification inhibitors for integrating environment and agronomy in intensive vegetable ecosystems in China.

Biochar reduces yield-scaled emissions of reactive nitrogen gases from vegetable soils across China

Abstract. Biochar amendment to soil has been proposed as a strategy for sequestering carbon, mitigating climate change and enhancing crop productivity. However, few studies have compared the general effect of different feedstock-derived biochars on the various gaseous reactive nitrogen emissions (GNrEs) of N2O, NO and NH3 simultaneously across the typical vegetable soils in China. A greenhouse pot experiment with five consecutive vegetable crops was conducted to investigate the effects of two contrasting biochars, namely wheat straw biochar (Bw) and swine manure biochar (Bm) on GNrEs, vegetable yield and gaseous reactive nitrogen intensity (GNrI) in four typical soils which are representative of the intensive vegetable cropping systems across mainland China: an Acrisol from Hunan Province, an Anthrosol from Shanxi Province, a Cambisol from Shandong Province and a Phaeozem from Heilongjiang Province. Results showed that remarkable GNrE mitigation induced by biochar occurred in Anthrosol and Phaeozem, whereas enhancement of yield occurred in Cambisol and Phaeozem. Additionally, both biochars decreased GNrI through reducing N2O and NO emissions by 36.4–59.1 and 37.0–49.5 % for Bw (except for Cambisol), respectively, and by improving yield by 13.5–30.5 % for Bm (except for Acrisol and Anthrosol). Biochar amendments generally stimulated the NH3 emissions with greater enhancement from Bm than Bw. We can infer that the biochar's effects on the GNrEs and vegetable yield strongly depend on the attributes of the soil and biochar. Therefore, in order to achieve the maximum benefits under intensive greenhouse vegetable agriculture, both soil type and biochar characteristics should be seriously considered before conducting large-scale biochar applications.

Quantitative Relationship Between Nitrous Oxide Emissions and Nitrogen Application Rate for a Typical Intensive Vegetable Cropping System in Southeastern China

To explore the mechanism underlying the relationship between nitrous oxide (N2O) emissions and different nitrogen (N) application rates, we conducted a 2‐year‐round field experiment comprising seven vegetable crop seasons by using static chamber‐gas chromatographic techniques in a continuously cultivated vegetable cropping system in Southeastern China. The results showed that N application significantly affected the N2O emissions. The cumulative N2O emissions amounted to 16.9 ± 1.9, 25.2 ± 2.2, 30.0 ± 1.9, 36.7 ± 1.5, and 48.1 ± 2.2 kg N ha−1 y−1 for the five N application rates at 0, 370, 740, 1110, 1480 kg N ha−1 y−1, respectively. Both linear and exponential relationship was observed between cumulative N2O emissions and N application rates. The emission factors ranged from 1.8 ± 0.1 to 2.3 ± 0.6% and averaged 2.0 ± 0.3%. The treatment receiving 2/3 of the conventional N fertilizer amount led to the lowest yield‐scaled N2O emissions. Therefore, according to this study the recommended N application rate should be reduced by one‐third for N2O mitigation while enhancing vegetable production in Southeastern China.

Global Warming Potential in an Intensive Vegetable Cropping System as Affected by Crop Rotation and Nitrogen Rate

Greenhouse gas emissions from vegetable production systems contribute to climate change, but the impact of nitrogen (N) rates and crop rotation on global warming potential (GWP) is not well documented. A field experiment was conducted to estimate the sum of GWP (mGWP) and yield‐scaled GWP in an intensive vegetable cropping system. The study included the traditional rotation of celery‐tomato‐lettuce (Rt) and the modified rotation of bur clover‐tomato‐lettuce (Rm), and each with four fertilizer N options (control, manure‐N, optimum, and conventional N). The nitrous oxide emission rates were 6.87 and 10.24 kg N ha−1, and the mGWP values were 27.9 and 31.8 MgCO2‐eq ha−1 per year from the optimum and conventional N plots under the traditional rotation, respectively. The change from the traditional to modified rotation reduced N input by 25%, N2O emissions by 24%, and mGWP by 14% but increased the net economic benefit by 33% under the optimized N application rate in the intensive vegetable cropping system. The trends of yield‐scaled GWP from different N rates and vegetable crop rotations were similar to the mGWP. This study proved that optimizing vegetable crop rotation by including legumes and adjusting N application rates simultaneously can reduce global warming potential while maintaining agricultural economic benefit.

Decreasing input–output balance by reducing chemical fertilizer input without yield loss in intensive cropping system in the Coastal Area of southeast Lake Dianchi, Yunnan Province, China

Overuse of chemical fertilizer and/or manure in agriculture is a principal factor in water eutrophication in China. Our previous study indicated that reducing chemical fertilizer input effectively decreased the soil nitrogen, phosphorus, and potassium in an intensive vegetable cropping system in the coastal area of southeast Lake Dianchi, China. This study aimed to decrease the input–output balance, namely the nutrient balance between input of fertilizer and output through vegetable harvesting, by reducing chemical fertilizer application without yield loss. A pot experiment was performed using chemical fertilizer with different amounts of N, P, and K on soils from six vegetable fields’ representative of the study area. High nitrate concentration in soils 2, 3, and 6 resulted in high N absorption from soil, and low N absorption from chemical fertilizer. Moreover, the responses of dry matter production to N absorbed from chemical fertilizer were less sensitive in soils 2, 3, and 6 than those in the other soils. Accordingly, reducing N input of chemical fertilizer did not decrease total N absorption or dry matter production, which should be the reason why reducing N input of chemical fertilizer did not reduce dry matter production in soils 2, 3, and 6. In the cases of soils 1, 4, and 5, reducing N input of chemical fertilizer reduced dry matter production, owing to lower levels of soil nitrate. This study should be helpful for reducing nutrient surplus from chemical fertilizer in the coastal area of southeast Lake Dianchi and other eutrophic agricultural areas in China.

Soil quality is positively affected by reduced tillage and compost in an intensive vegetable cropping system

Soil quality in vegetable cropping systems is seriously threatened by intensive tillage and fertilization practices and by limited crop rotations. Inclusion of cover crops, compost application and reduced tillage may help to sustain soil quality. A three-year field trial was set up on horticultural land to explore the combined effects of compost amendment at three rates (0, 15 and 45Mgha−1year−1) and tillage practices (reduced tillage versus conventional ploughing) on soil quality. Cover crop was not a factor in the experiment, but cover crops were included in the rotation for reasons of good agricultural practice. The highest compost dose supported the initial level of total organic carbon in the arable layer. The decrease in pH in the arable layer was considerably limited by compost application, irrespective of the dose applied. Reduced tillage resulted in a favorable stratification for different soil quality indicators both by placement of organic inputs near the soil surface and by a reduction of leaching of base cations and organic carbon compounds. Differences between tillage practices and compost doses were most striking in the 0–10cm soil layer. Compost application at the highest rate enhanced organic C content by 16% compared to the content in the non-amended soil. Reduced tillage induced a 13% higher organic C content in the 0–10cm soil layer than that in the underlying 10–30cm layer. Combining reduced tillage and recurrent compost application resulted in a different soil microbial community structure in the 0–10cm surface layer, as revealed by phospholipid fatty acids analysis. Total microbial biomass was 44% higher under reduced compared to conventional tillage and increased by 27% due to compost application at a rate of 45Mgha−1year−1. Fungal biomass doubled in the surface layer by reduced tillage. Actinomycetes and arbuscular mycorrhizal fungi were favored by both reduced tillage and compost application. Conversion to reduced tillage allowed for sustaining crop production in this intensive vegetable cropping system. Compost application and reduced tillage counteracted soil degradation.

Impact of Farm Design on Plant-pollinator Interaction in Brinjal (Solanum Melongena)

Pollinators are crucial in agricultural crop production as a large variety of crops including horticultural and vegetable crops depend essentially on insect pollination. Unfortunately over the past decades, the pollinator population in the agricultural system has declined across the globe due to over use of synthetic chemical pesticides. Disruption of ecosystem service provided by pollinators due to pollinator decline in chemical intensive cropping systems has assumed a global dimension. This paper addresses how farming practices and designs affect the diversity of pollinators. In this study the relationship between pollinator density and brinjal (Solanum melongena, Fam. Solanacae) productivity was evaluated in a chemical intensive vegetable cropping system in North 24 Parganas, West Bengal, India (hot sub-humid to humid eco-region; Lat 22°22’ 26, N Lon 88°21’ 26 E). By comparing pollinator density and fruit set between ecological farm and chemical intensive farm, it was investigated whether pesticide application affects pollinator visitation and in such a scenario what was the impact on brinjal production. Visitation rate of pollinators (butterflies and bees) was significantly higher in ecological farm as compared to the conventional farm (Mann Whitney U test, p < 0.001).

Traditional and New Approaches to Irrigation Scheduling in Vegetable Crops

Intensive vegetable cropping systems use large amounts of water and nutrients. Excess application of water and nutrients results in economic losses (higher fertilizers and pumping costs) and contributes to nutrient leaching and environmental degradation. Increasing nutrient use efficiency (NUE) and water use efficiency (WUE) should be a priority for sustainable horticulture. This increased NUE, WUE, or both depend on the utilization of efficient irrigation technology, including appropriate methods for irrigation scheduling (IS).Various methods are available for IS based on determination of crop water balance (weather-based method), soil/substrate moisture level, or plant water relations. Rather than discussing the physical and biological basis of irrigation management, this article focuses on currently available irrigation control devices for open-field and greenhouse production systems, with particular emphasis on soil moisture sensors (SMSs). SMS regulates the frequency of irrigation and, possibly, the water dose by continuously monitoring volumetric water content (θ) or matrix potential (ψm) of the growing media. A new generation of dielectric SMS has been developed to measure both θ and the electrical conductivity (EC) of pore water in soil and artificial media. This provides the possibility of controlled fertigation based on measured EC. Despite the development in IS, in most regions worldwide, especially in less developed countries, many growers still rely on personal experience for determining crop water requirements and the timing of irrigation. Therefore, the main constraints to the improvement of irrigation efficiency are related to the overall cost of these technologies and to the policies adopted for their dissemination and transfer to professional growers.

Growth and yield responses of crops and macronutrient balance influenced by commercial organic manure used as a partial substitute for chemical fertilizers in an intensive vegetable cropping system

A long-term field experiment was conducted with an annual rotation of tomato–radish–pakchoi to assess the effects of a commercial organic manure (COM) used as a partial substitute for chemical fertilizers on crop yield and nutrient balance in an intensive vegetable cropping system. Four treatments as chemical fertilizers (T1), chemical fertilizers + lower rate of COM (T2), chemical fertilizers + medium rate of COM (T3), and chemical fertilizers + high rate of COM (T4) were designed in the present experiment. The supplied doses of N, P, and K were equal for all treatments. Results showed that there were no significant differences in shoot biomass and market yields of tomato, radish and pakchoi among treatments ( P > 0.05). It was found that positive P and K balance existed in the tomato–radish–pakchoi cropping system of all treatments. Compared with no manure treatment (T1), application of medium rate of COM (T3) decreased N, P runoff losses, increased N, P, K contents in crop tissues except N, P in pakchoi shoot, and lessened P, K accumulation in soils, accordingly, improved the efficiency of macronutrient. It was concluded that appropriate COM used as a partial substitute for chemical fertilizers could not only meet the crops’ nutrient requirement, but also improved the efficiency of macronutrient and remained positive balance of P and K in the intensive tomato–radish–pakchoi cropping system, which can be regarded as an effective measure for a contribution towards sustainable agriculture and a control pathway for reducing the potential risk of castoff to water environment.

ENERGY BALANCE OF INTENSIVE VEGETABLE CROPPING SYSTEMS IN CENTRAL ITALY

ISHS VIII International Symposium on Protected Cultivation in Mild Winter Climates: Advances in Soil and Soilless Cultivation under Protected Environment ENERGY BALANCE OF INTENSIVE VEGETABLE CROPPING SYSTEMS IN CENTRAL ITALY

RECENT ISSUES ON VEGETABLE GRAFTING

RECENT ISSUES ON VEGETABLE GRAFTING

Low-input technology proves viable for limited-resource farmers in Salinas Valley

Low-input farming techniques offered energy-saving, cost-effective alternatives for resource-poor farmers of Mexican origin in the Salinas Valley. Most of these farmers currently manage small acreages using intensive vegetable cropping systems and high-input technologies.