Effect of saline irrigation and water deficit on tuber quality

Summary The effect of salinity and water dificit on the quality of tubers for processing was investigated. Total tuber yield was not affected by the treatments, while the percentage of non-marketable tubers was significantly reduced by high salinity (EC_i=6dS m⁻¹) and by water reduction. Accumulation of dry matter in the tubers was increased by all the treatments, that of proline by salinity only and the content of reducing sugars was increased only by water deficit. The colour of the french fries was similar in tubers from the various treatments.     

Response of soil properties and vegetation to reclamation period using drip irrigation in coastal saline soils of the Bohai Gulf

Paddy and Water Environment - Soil salinization is a major soil degradation threat worldwide. Sparse vegetation and soil desertification are widespread phenomena in coastal saline land due to high...     

Yield response,water productivity,and seasonal water production functions for maize under deficit irrigation water management in southern Taiwan

As the challenges toward increasing water for irrigation become more prevalent, knowledge of crop yield response to water can facilitate the development of irrigation strategies for improving agricultural productivity. Experiments were conducted to quantify maize yield response to soil moisture deficits, and assess the effects of deficit irrigation (DI) on water productivity (water and irrigation water use efficiency, WUE and IWUE). Five irrigation treatments were investigated: a full irrigation (I₁) with a water application of 60 mm and four deficit treatments with application depths of 50 (I₂), 40 (I₃), 30 (I₄), and 20 mm (I₅). On average, the highest grain yield observed was 1008.41 g m^?2 in I₁, and water deficits resulted in significant (p < .05) reduction within range of 6 and 33%. This reduction was significantly correlated with a decline in grain number per ear, 1000-grain weight, ear number per plant, and number of grain per row. The highest correlation was found between grain yield and grain number per ear. The WUE and IWUE were within range of 1.52–2.25 kg m^?3 and 1.64–4.53 kg m^?3, respectively. High water productivity without significant reduction in yield (<13%) for I₂ and I₃ compared to the yield in I₁ indicates that these water depths are viable practices to promote sustainable water development. Also, for assessing the benefits of irrigation practices in the region crop water production functions were established. Maize yield response to water stress was estimated as .92, suggesting the environmental conditions are conducive for implementing DI strategies.     

Critical water content and water stress coefficient of soybean (Glycine max [L.] Merr.) under deficit irrigation

The objective of this research was to investigate the critical water content (θ _c) and water stress coefficient (K _s) of soybean plant under deficit irrigation. This research was conducted in a plastic house at the University of Lampung, Sumatra in Indonesia from June to September 2000. The water deficit levels were 0–20%, 20–40%, 40–60%, 60–80%, and 80–100% of available water (AW) deficit, arranged in Randomized Completely Block (RCB) design with four replications. The results showed that the soybean plant started to experience stress from week IV within 40–60% of AW deficit. The fraction of total available water (TAW) that the crop can extract from the root zone without suffering water stress (p) was 0.5 and θ_c was 0.305 m³ m⁻³. The values of K _s at p=0.5 were 0.78, 0.86, 0.78, and 0.71 from week IV to week VII, respectively. The optimum yield of soybean plant with the highest yield efficiency was reached at 40–60% of AW deficit with an average K _s value of 0.78; this level of deficit irrigation could conserve about 10% of the irrigation. The optimum yield of soybean plant was 7.9 g/pot and crop water requirement was 372 mm.     

Lesquerella growth and selenium uptake affected by saline irrigation water composition

A greenhouse study was conducted to determine the effects of waters differing in salt composition on growth and selenium (Se) accumulation by lesquerella (Lesquerella fendleri Gray S. Wats.). Plants were established by direct seeding into sand cultures and irrigated with solutions containing either (a) Cl⁻ as the dominant anion or (b) a mixture of salts of SO₄²⁻ and Cl⁻. Four treatments of each salinity type were imposed. Electrical conductivities of the irrigation waters were 1.7, 4, 8, and 13 dS m⁻¹. Two months after salinization, Se (l mg l⁻¹, 12.7 μM) was added to all solutions as Na₂SeO₄. Shoot growth was significantly reduced by increasing Cl-salinity. Regardless of salinity type, concentrations of Ca²⁺, Mg²⁺, Cl⁻, total-S, and Se were higher in the leaves than the stems, whereas K⁺ and Na⁺ were higher in the stem. Leaf-Se concentrations were not significantly affected by Cl-based irrigation waters, averaging 503 mg Se kg⁻¹ dry wt across salinity levels, whereas leaf-Se decreased consistently and significantly from 218 to 13 mg kg⁻¹ as mixed salt salinity increased. The dramatic reduction in Se was attributed to SO₄²⁻:SeO₄²⁻ competition during plant uptake. The strong Se-accumulating ability of lesquerella suggests that the crop should be further evaluated as a potentially valuable phytoremediator of Se-contaminated soils and waters of low to moderate salinity in areas where the dominant anion in the substrate is Cl⁻.     

Application of infrared thermography to assess cassava physiology under water deficit condition

ABSTRACT

Water deficit stress is a major factor that inhibits the overall growth and development in cassava (Manihot esculenta), leading to decreased storage root yield. We conducted a study to investigate whether thermal sensing could be used to indicate water deficit stress and the health and yield of cassava crops in field. The objective of the study was to use thermal imaging to determine relationship between crop water stress index (CWSI) and physiological changes, and to identify the critical CWSI point in fields of cassava cv. Rayong 9 under well-irrigated and water-deficit conditions. At the time of storage root initiation (85 DAP [day after planting]), thermal imagery was collected and the physiological changes and growth characters were measured prior to storage root harvesting (162 DAP). Thermal infrared imager was used to measure the canopy temperature and CWSI of cassava plants. Net photosynthetic rate (P_n), stomatal conductance (g_s) and transpiration rates (T_r) of cassava plants under water deficit conditions for 29 d (114 DAP) were significantly decreased, leading to delayed plant growth as compared to those under well-irrigated conditions. In contrast, air vapor pressure deficit (VPD_air) and CWSI in drought-stressed plants were higher than well irrigated plants. High correlations between T_r/g_s/P_n and CWSI were observed. The study concludes that CWSI is a sensitive indicator of water deficit stress caused due to stomatal function.

Abbreviations: CWSI: crop water stress index; DAP: day after planting; Pn: net photosynthetic rate; gs: stomatal conductance; Tr: transpiration rate; VPDair: air vapor pressure; RMSE: root mean square error     

不同有机质含量的菜园土保水效果研究

2002～2004年,在东安采用田间小区试验,研究了不同有机质含量的黄泥菜园土种植辣椒时对其土壤含水量、保水能力、产量和水分利用效率的影响.结果表明,有机质含量高的菜园土保水能力强,土壤含水量和产量也相应较高,水分利用效率更高,并且土壤含水量随土层加深呈上升趋势.     

Sweet sorghum productivity for biofuels under increased soil salinity and reduced irrigation

Sweet sorghum (Sorghum bicolor (L.) Moench.) is a drought-tolerant crop with high resistance to saline-alkaline soils, and sweet sorghum may serve as an alternative summer crop for biofuel production in areas where irrigation water is limited. A two-year study was conducted in Northern Greece to assess the productivity (biomass, juice, total sugar and theoretical ethanol yields) of four sweet sorghum cultivars (Sugar graze, M-81E, Urja and Topper-76-6), one grain sorghum cultivar (KN-300) and one grass sorghum cultivar (Susu) grown in intermediate (3.2 dS m⁻¹) or in high (6.9 dS m⁻¹) soil salinity with either low (120 mm) or intermediate (210 mm) irrigation water supply (supplemented with 142–261 mm of rainfall during growth). The soil salinity and irrigation water supply effects on the sorghum chlorophyll content index, photosystem II quantum yield, stomatal conductance and leaf K/Na ratio were also determined. The sorghum emergence averaged 75,083 plants ha⁻¹ and 59,917 plants ha⁻¹ in a soil salinity of 3.2 dS m⁻¹ and 6.9 dS m⁻¹, respectively. The most affected cultivar, as averaged across the two soil salinity levels, was the Susu grass sorghum emerging at 53,250 plants ha⁻¹, followed by the Topper-76-6 sweet sorghum emerging at 61,250 plants ha⁻¹. The leaf K/Na ratio decreased with decreasing irrigation water supply, in most cases, but it was not significantly affected by soil salinity. The dry biomass, juice and total sugar yields of sorghum that received 210 mm of irrigation water was 49–88% greater than the yields of sorghum that received the 120 mm of irrigation water. Sorghum plants grown in a soil salinity of 3.2 dS m⁻¹ produced 42–58% greater dry biomass, juice and total sugar yields than the yields of sorghum plants grown in a soil salinity of 6.9 dS m⁻¹. The greatest theoretical ethanol yield was produced by sweet sorghum plants grown in a soil salinity of 3.2 dS m⁻¹ with 210 mm of irrigation water (6130 L ha⁻¹, as averaged across cultivar), and the Urja and Sugar graze cultivars produced the most ethanol (7620 L ha⁻¹ and 6528 L ha⁻¹, respectively). Conclusively, sweet sorghum provided sufficient juice, total sugar and ethanol yields in fields with a soil salinity of 3.2 dS m⁻¹, even if the plants received 50–75% of the irrigation water typically applied to sorghum.     

Rice genotype and fertilizer management for improving rice productivity under saline soil conditions

Paddy and Water Environment - Soil salinity is a threat to crop production in the Senegal River Delta where salt intrusion increases soil electrical conductivity and most of farmers had abandoned...     

Variations in responses of potato germplasm to deficit irrigation as affected by soil texture

The response to irrigation of three parental potato cultivars was studied on loam and sandy soils by use of the line source sprinkler technique, which provided a continuous irrigation variable from 0 to 100% or more replacement of estimated evapotranspiration (Et). Solid-set sprinkler irrigation from planting until near full ground cover provided optimal early plant growth and a soil profile filled with water when the irrigation variable was started in July. On the loam soil this residual soil water provided most of the water needs of the three cultivars over a 10–12 week period until harvest. On this soil, irrigation levels providing replacement above 20 to 40% Et had little beneficial effect. In fact, higher irrigation levels had serious deleterious effects, especially on grade and solids of Nooksack. On the loam soil, Nooksack performed best in every regard at deficit irrigation levels below 50% Et. In contrast, on this loam soil, differing irrigation levels had very little effect on the productivity of Lemhi. The response of all cultivars on sandy soil was much different than on loam soil. On sand, total and U.S. No. 1 yield of all cultivars increased greatly as irrigation levels increased, up to 70 to 80% Et. Levels above this had minimal effect. Nooksack again performed better than the other two cultivars under deficit irrigation. The results of these and other studies show there is potential for identifying or developing potato cultivars which are more efficient users of irrigation water.     

Effects of saline irrigation water and heat waves on potato production in an arid environment

Production of spring potato (Solanum tuberosum L. cv. Désirée) on a deep sandy soil in the central highland of the Negev desert of Israel under drip irrigation with saline water (up to 6.2 dS m⁻¹) was studied in the years 1992–1997. The objective of the study was to determine the effects of saline water irrigation on potato production in an arid environment with special focus on the interactions with weather conditions. Although yields were often high, salinity effects were evident in some years. Thus 1992 and 1996 yields were 6–7 kg m⁻² and showed no significant effect of salinity, while a pronounced drop in yield with increasing salinity was observed in 1993 and 1994. Analysis of weather data for 1993–1994 suggests that the decline in yield was due to interactions between saline irrigation and prolonged heat wave events occurring during crop development. Further experimental work (1997) revealed that tuber yield was most sensitive to combined salt and heat stress when heat waves occurred at 40–60 days after emergence. The combined stress apparently leads to the collapse of mechanisms for avoiding salt accumulation in young expanding leaves, resulting in failure of vegetative growth recovery and a consequent reduction in the leaf area index and canopy functioning. The relationship between tuber sink demand and available photoassimilate supply at certain stages of plant development is discussed with reference to the ability of the potato plant to recover from the combined stress.     

Crop water stress index for potato under furrow and drip irrigation systems

Summary This study was conducted to determine the crop water stress index (CWSI) for potato (Solanum tuberosum L.) grown under furrow and drip irrigation methods and subjected to three different irrigation levels (100, 50 and 0% replenishment of soil water depleted). The lower (non-stressed) and upper (stressed) baselines were determined empirically from measurements of canopy temperatures, ambient air temperatures and vapor pressure deficit values. Tuber yield decreased when mean CWSI prior to irrigation exceeded 0.68 in furrow and 0.81 in drip irrigation. The tuber yield was directly correlated with the seasonal CWSI values and the linear equations for furrow and drip irrigation methods, Y = −45.82 CWSI + 50.69 and Y = −52.65 CWSI + 58.44, respectively, can be used for yield prediction.     

Water deficit effects on potato leaf growth and transpiration: Utilizing fraction extractable soil water for comparison with other crops

Numerous studies have demonstrated that physiological responses of many crops to the fraction of extractable soil water conforms to a generalizable pattern. This suggests that differences among crops in their drought tolerance are largely due to differences in the total amount of transpirable water the crop can extract. Potato is frequently assumed to be more drought sensitive than other agronomic crops due, at least in part, to a shallow root system. In the research reported here, potato leaf growth and transpiration response to water deficits were determined as a function of fraction transpirable soil water (FTSW). Transpiration was unaffected by water stress until a critical FTSW was achieved when 64% to 80% of the extractable soil water was depleted depending on the cultivar. This was similar to the response reported for 8 other agronomic crops. In terms of transpiration, potato hypersensitivity to drought stress appears to be due to less effective soil water extraction. Leaf growth, however, showed a unique response to soil water deficits. Leaf growth began to decline when 40% of the extractable soil water was depleted. The associated critical FTSW was higher than any previously reported for all other crops. These data indicate that in addition to extracting less soil water, an additional physiological process related to leaf expansion must be contributing to the potato’s hypersensitivity to drought.     

Experimental evaluation of irrigation methods for soil desalinization

Paddy and Water Environment - Soil salinization has provided a serious threat for global agriculture throughout human history. It is becoming ever more prevalent as human land use intensifies in...     

Binding forms and availability of Cd and Cr in paddy soil under non-flooding controlled irrigation

To quantify the change in the binding forms and the availability of heavy metals Cd and Cr in paddy soil under non-flooding controlled irrigation (NFI), field experiments were conducted with flooding irrigation (FI) as control. The multi-wetting–drying condition in NFI fields enhanced the transformation of Cd and Cr in surface soil from oxidizable (B3) to acid-soluble (B1) form, and inhibited the transformation of Cd and Cr from reducible (B2) to B1 form. The B1 form Cd in NFI soil was lower, but B1 form Cr was higher than in FI soil. Thus, B3 form may play a more important role in determining the solubility of Cr than B2 in paddy soil, but it is just reverse for the metal of Cd. As a result, NFI led to higher crop uptake of Cd and Cr, but lower Cd and Cr content in the 0–20-cm surface soil and less accumulation of Cd and Cr in 40–60-cm deep soil compared with FI. It indicates that NFI results in higher bioavailability and crop uptakes, and may led to high risks in food safety in short period. But in long term, NFI will result in lower accumulation of Cd and Cr in soils, and should eventually lower the crop uptakes of Cd and Cr.     

Physiology and productivity of sugarcane with early and mid-season water deficit

An analysis of the physiological consequences of water deficit during the first half of the season on sugarcane productivity, can aid the evaluation of yield expectations under rainfed systems and the opportunities for saving irrigation water early in the season. Four field experiments were conducted at Ayr in the semi-arid tropics of Australia. Irrigation was withheld at different stages of crop development to investigate timing and severity of water deficit on crop development, biomass accumulation and partitioning of biomass to millable stalk and sucrose, both during the season and at final harvest. Deficits imposed during the tillering phase, while having large impacts on leaf area, tillering and biomass accumulation, had little impact on final yield. This was primarily due to the length of time required to impose significant water deficit when the canopy is small, the comparatively small amount of biomass accumulation lost through water deficit, and the ability of the crop to produce leaves and tillers at a rapid rate during subsequent well-watered conditions. On the other hand, water deficit imposed when the canopy was well-established (leaf area index >2) had a more deleterious impact on final yield of total biomass, stalk biomass, and stalk sucrose. Reductions in millable stalk biomass, could be solely explained by reductions in total biomass. Similarly, >97% of the variation in final cane or sucrose yield could be explained by variation in stalk biomass. While there were transient effects of water deficit on stalk sucrose and dry matter concentration, significant impacts at final harvest did not occur until stalk biomass levels fell to ca. 50% of that of the well-watered control.     

Quality characteristics of Burley tobacco irrigated with saline water

The effect of irrigation with saline water on quality of Burley tobacco (cv. C 104) was investigated in Southern Italy over four consecutive years. A rainfed control (RC) was compared with treatments irrigated with volumes equal to crop evapotranspiration of saline waters at 0.5 (NW), 2.5 (SW₁), 5 (SW₂) and 10 (SW₃) dS m⁻¹ electrical conductivity (EC_w). In 2000 and 2001 an additional salinity treatment (15 dS m⁻¹ EC_w) was included (SW₄). The amounts of Cl⁻ added to the soil by irrigation ranged from 36.3 kg ha⁻¹ (good quality water in 1999) to 16.2 Mg ha⁻¹ (saline water at 15 dS m⁻¹ EC_w in 2000). Saline irrigation did not affect yield and yield components of cured leaves. In 1998 and 1999 the filling power of Burley tobacco did not change significantly with increasing salinity of the irrigation water. In 2000 and 2001 the filling power of SW₂, SW₃ and SW₄ treatments was significantly less than that of NW. The Cl⁻ content of tobacco grown with SW₂ was significantly greater than that grown with NW and there were no differences between SW₁ through SW₄ treatments. The filling power and the leaf Cl⁻ content were inversely related to the amount of Cl⁻ applied in the range between 40.3 kg ha⁻¹ and 5.1 Mg ha⁻¹. The filling power decreased and Cl⁻ increased up to the SW₂ treatment; beyond that level neither Cl⁻ nor filling power changed in response to increasing amounts of Cl⁻ applied. The leaf alkaloid content was unaffected by salinity. Total N was unaffected by either the growing season or the saline treatments. Cigarettes obtained from saline treatments did not burn during the smoking test in 1998. In 1999 cigarettes made from SW₁ and SW₂ did burn, but those from SW₃ did not. In 2000 and 2001 the smoking test was performed only on commercial blends containing 10 or 30% of cut tobacco from saline treatments and both blends burned similarly to cigarettes made entirely from tobacco grown under non-saline conditions. In conclusion, quality of Burley tobacco was unaffected by irrigation with saline water at 2.5 dS m⁻¹ and the inhibitory effect of salinity on burning properties could be overcome by appropriate mixture in commercial blends.     

Simulation of salt and water movement and estimation of water productivity of rice crop irrigated with saline water

The HYDRUS-ID model was experimentally tested for water balance and salt build up in soil under rice crop irrigated with different salinity water (ECiw) of 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ in micro-lysimeters filled with sandy loam soil. Differences of means between measured (M) and HYDRUS-1D predicted (P) values of bottom flux (Q _o) and leachate EC as tested by paired t test were not found significant at P = 0.05 and a close agreement between RMSE values showed the applicability of the HYDRUS-1D to simulate percolation and salt concentration in the micro-lysimeters under rice crop. Potential ET values of rice as obtained from CROPWAT matched well with model predicted and measured one at all ECiw treatments. The model predicted root water uptake varied from 66.1 to 652.7 mm and the maximum daily salt concentration in the root zone was 0.46, 2.3, 4.5, 6.7, 8.4 and 10.2 me cm⁻³ in 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ ECiw treatments, respectively. The grain production per unit evapotranspiration ( \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} ) value of 2.56 in ECiw of 0.4 dS m⁻¹ treatment declined to 1.31 with ECiw of 2 dS m⁻¹. The \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} reduced to one-fifth when percolation was included in the productivity determination. Similarly, the water productivity in respect of total dry matter production (TDM) was also reduced in different treatments. Therefore, the model predicted values of water balance can be effectively utilized to calculate the water productivity of rice crop.     

Growth and yield of wheat lines with differing osmoregulative capacity at high soil water deficit in seasons of varying evaporative demand

Wheat lines with differing capacities for osmoregulation were grown on a full profile of soil water at sowing in seasons of contrasting evaporative demand. Watered experiments were also included. Across seasons the relative increase in dry weight and yield associated with high osmoregulation was positively correlated with cumulative pan evaporation during the period of most rapid growth before anthesis. In experiments showing the most extreme responses to osmoregulative capacity there was no association with the overall soil water deficit at anthesis or harvest suggesting a direct effect of evaporative demand. This was further confirmed by correlations between vapour pressure deficit and leaf water potential and differences in turgor pressure. Significant differences in turgor were, in turn, associated with significant differences in dry weight. It was therefore concluded that osmoregulative effects on growth were mediated through leaf or shoot responses to leaf water stress rather than through root responses to soil water deficit, and that it was necessary to screen lines specifically for osmoregulation rather than for growth responses to soil water deficit.