[Effects of soil matrix potential regulation at various growth states on cotton growth and soil water and salt distribution]. / 不同生育期土壤基质势调控对棉花生长和土壤水盐分布的影响.

Water shortage and soil salinization are two main limiting factors for cotton production in southern Xinjiang. We examined the effects of soil matrix potential (SMP) regulation at various growth stages on cotton growth, soil water and salt distribution, to provide theoretical basis for water saving, salts control, and efficient production in cotton fields. The mulched drip irrigation experiments were conducted to monitor cotton growth, aboveground biomass, cotton yield, soil water and salt distribution and other indicators. Three SMP thresholds, i.e.,W1(-20 kPa), W2(-30 kPa) and W3(-40 kPa) were set at the seedling stage (A), seedling stage + budding stage (B), and seedling stage + budding stage + flowering stage (C), with SMP of -50 kPa at 20 cm soil depth below the emitter as the CK. The results showed that plant height, leaf area index (LAI) and aboveground biomass followed the order of WC>WB>WA>CK, when SMP were changed at various growth stages. Plant height, LAI and aboveground biomass increased with increasing SMP thresholds, with the values under W1C and W2C being significantly higher than the other treatments. The effective bolls per plant, single boll weight and lint percentage all increased with the increases of SMP thresholds. The yields of W1C and W2C were similar, which were significantly higher than those of other treatments. However, the water use efficiency of W2C was significantly higher than that of W1C. Controlling the SMP threshold at -20 or -30 kPa at different growth stages could improve soil moisture status of the primary cotton root zone. All treatments presented shallow salt accumulation (0-40 cm) at the harvest stage, with the bare land having greater salt accumulation than the inner film. The higher the SMP threshold was, the less salt was accumulated in the primary root zone (0-40 cm) under film. The salt accumulation (0-40 cm) under W1C and W2C were reduced by 24% compared with other treatments. Considering the efficient production of cotton, water saving and salt control, it was recommended to maintain the SMP threshold of -30 kPa during irrigation at various growth stages in cotton fields without leaching salts during the local off-crop period.

[Effects of the frequency and amount of drip irrigation on yield, tuber quality and water use efficiency of potato in sandy soil of Yulin, northern Shaanxi, China]. / 滴灌频率和灌水量对榆林沙土马铃薯产量、品质和水分利用效率的影响.

Reasonable irrigation is still lacking for potato production in the sandy areas of Yulin, northern Shaanxi Province. To solve this problem, field drip fertigation was conducted to examine the growth, yield and quality of potato during the whole growing season. We further analyzed the responses of these indices to different irrigation frequencies and amounts. There were three irrigation frequencies (d), i.e. 4 (D1), 8 (D2) and 10 (D3), and three irrigation amounts, i.e. 60%ETc (W1), 80%ETc(W2) and 100%ETc(W3), where ETc was the crop water requirement, resulting in a total of nine treatments. Under the same irrigation frequency, plant height, leaf area index, dry matter, tuber yield and economic benefits of W3 were higher than those of W1 and W2. W1 had the highest irrigation water use efficiency (IWUE), while water use efficiency was not significantly affected by irrigation amount. The average tuber yield of W3 was 43442 kg·hm-2, which was 23.3% and 11.6% higher than that of W1 and W2, respectively. The net income of W3 was 23492 yuan·hm-2, which was 40.4% and 18.7% higher than that of W1 and W2, respectively. Tubers from W3 had the highest starch and vitamin C contents but the lowest reducing sugar content, which were 14.4%, 18.54 mg·(100 g)-1 FW and 0.7%, respectively. At the same irrigation amount, tuber yield, IWUE, starch and vitamin C contents of D1 were the highest, but the reducing sugar content was the lowest at the low and medium irrigation amounts. At the high irrigation amount, D2 had the highest tuber yield, IWUE, net income, starch and vitamin C contents but the lowest reducing sugar content, which were 46572 kg·hm-2, 23.04 kg·m-3, 26,622 yuan·hm-2,14.6%, 19.53 mg·(100 g)-1 FW and 0.7%, respectively. Based on the interacting effects of drip irrigation frequency and amount, both yield and quality of D2W3 reached the maximum. Results from the principal component analysis showed that D2W3 had the highest score. D2W3(8 d, 100%ETc) had the greatest yield and quality and relatively higher water use efficiency, which was thus considered as the optimal combination of drip irrigation frequency and amount. The results could provide a scientific basis for the drip irrigation scheduling design for high-yield, high-efficiency and high-quality potato production in the sandy areas of Yulin, northern Shaanxi.

[Effects of irrigation amount and various fertigation methods on yield and quality of cucumber in greenhouse].

Taking cucumber as experimental plant, an experiment was conducted to study the effects of irrigation amount and fertigation methods on growth, yield and quality of cucumber in greenhouse. The experiment had designed two irrigation levels, i.e. 100% ET0 (W1) and 75% ET0 (W2), and four fertigation fertilization ratios, i.e. 100%, 66.6%, 33.3% and 0% (Z100, Z66 , Z33, Z0) fertigation of a total amount of (360:180:540 kg · hm(-2)) (N:P2O5:K2O) by 8 times with the corresponding remainders (0%, 33.3%, 66.6% and 100%) were applied to soil as basic fertilization before the planting according to the recommended fertilization rate, and no fertilizer treatment was set up as the control (CK). Results showed that irrigation and fertilization levels had positive correlations with plant height, leaf areas, dry mass, yield and quality of cucumber. Yield at W1Z100 was the highest, reaching 67760 kg · hm(-2). W2 treatment increased the mean water use efficiency (WUE) by 9.4% compared to W1. W2Z100 treatment had the highest WUE, reaching 47.13 kg · m(-3). Yield at W2Z100 was only 3.4% lower than the maximum, but saved 25% of water. Yield and dry matter at Z100 were 15.3% and 16.8% higher than at Z0, respectively, the cucumber fruit vitamin C, soluble protein and soluble sugar contents were increased, and the water use efficiency was increased by 19.1%. W2Z100 treatment was the best treatment which could enable cucumber to obtain both the high-yield and the high-quality.

[Coupling effects of partitioning alternative drip irrigation with plastic mulch and nitrogen fertilization on cotton dry matter accumulation and nitrogen use].

A field experiment with complete combination design was conducted to study the effects of partitioning alternative drip irrigation with plastic mulch and nitrogen fertilization on the dry matter accumulation and nitrogen use efficiency of cotton plant. Three levels of irrigation (260, 200, and 140 mm) and of nitrogen fertilizer (270, 180, and 90 kg.hm-2) were installed. The cotton dry mass was the highest in treatments medium nitrogen/high water and high nitrogen/high water. As compared with that in high nitrogen/high water treatment, the nitrogen use efficiency for dry matter accumulation in medium nitrogen/high water treatment was increased by 34.0% -44.6%, with an average of 34.7% , while the water use efficiency was decreased by 6.4% -10.7%, averagely 10.2%. As for the nitrogen accumulation in cotton plant, the nitrogen use efficiency was the highest in medium nitrogen/high water treatment, and the water use efficiency was the highest in high nitrogen/medium water treatment. Compared with high nitrogen/high water treatment, medium nitrogen/high water treatment increased the nitrogen use efficiency for cotton nitrogen accumulation by 29.0% -41.7%, but decreased the water use efficiency for cotton nitrogen accumulation by 5.5%-14.0%. Among the treatments of coupling water and nitrogen of higher cotton yield, treatment medium nitrogen/high water had the higher cotton nitrogen recovery rate, nitrogen agronomic efficiency, and apparent use efficiency than the treatments high nitrogen/medium water and high nitrogen/high water, but no significant differences were observed in the nitrogen absorption ratio and nitrogen physiological efficiency. Treatment medium nitrogen/high water was most beneficial to the coupling effects of water and nitrogen under partitioning alternate drip irrigation with plastic mulch and nitrogen fertilization.

[Coupling effect of water and nitrogen on spring maize in Wuwei Oasis of Shiyang River Basin, Northwest China].

To explore the optimal supply model of water and nitrogen for spring maize under limited irrigation in arid Northwest China, a field experiment with orthogonal design was conducted in the Wuwei Oasis region margin of Shiyang River Basin to study the effects of irrigation amount at different growth stages and the nitrogen application rate on the group yield and the water and nitrogen utilization of spring maize. With the increase of nitrogen application rate, the grain yield of spring maize increased, and the highest grain yield was obtained when the nitrogen application rate was 300 kg x hm(-2) and the irrigation amount at jointing stage was 136 mm. The grain irrigation water use efficiency (GIWUE) decreased with increasing irrigation amount. When the irrigation amount in whole growth period was 340 mm, the grain yield and GIWUE were improved simultaneously with increasing nitrogen application rate. The GIWUE reached the maximum when the nitrogen application rate was 300 kg x hm(-2) and the irrigation amount at seedling and grain-filling stages was 34 mm, respectively. The effects of nitrogen application and irrigation on the nitrogen accumulation in the whole plant decreased in the order of nitrogen application rate, irrigation at jointing stage, irrigation at seedling stage, irrigation at grain-filling stage, and irrigation at heading stage. The optimal supply model of water and nitrogen for spring maize in Wuwei Oasis was 300 kg x hm(-2) of nitrogen application plus 34, 136, 68 and 102 mm of irrigation at seedling, jointing, heading and grain-filling stages, respectively.

[Effects of controlled alternate partial root-zone drip irrigation on apple seedling morphological characteristics and root hydraulic conductivity].

To investigate the effects of alternate partial root-zone drip irrigation (ADI) on the morphological characteristics and root hydraulic conductivity of apple seedlings, three irrigation modes, i.e., fixed partial root-zone drip irrigation (FDI, fixed watering on one side of the seedling root zone), controlled alternate partial root-zone drip irrigation (ADI, alternate watering on both sides of the seedling root zone), and conventional drip irrigation (CDI, watering cling to the seedling base), and three irrigation quotas, i. e., each irrigation amount of FDI and ADI was 10, 20 and 30 mm, and that of CDI was 20, 30 and 40 mm, respectively, were designed. In treatment ADI, the soil moisture content on the both sides of the root zone appeared a repeated alternation of dry and wet process; while in treatment CDI, the soil moisture content had less difference. At the same irrigation quotas, the soil moisture content at the watering sides had no significant difference under the three drip irrigation modes. At irrigation quota 30 mm, the root-shoot ratio, healthy index of seedlings, and root hydraulic conductivity in treatment ADI increased by 31.6% and 47.1%, 34.2% and 53.6%, and 9.0% and 11.0%, respectively, as compared with those in treatments CDI and FDI. The root dry mass and leaf area had a positive linear correlation with root hydraulic conductivity. It was suggested that controlled alternate partial root-zone drip irrigation had obvious compensatory effects on the root hydraulic conductivity of apple seedlings, improved the soil water use by the roots, benefited the equilibrated dry matter allocation in seedling organs, and markedly enhanced the root-shoot ratio and healthy index of the seedlings.

[Regulation effect of water and nitrogen on cotton biomass and yield under different drip irrigation patterns].

Three levels (low, medium, and high) of irrigation amount and nitrogen application rate were installed in a field experiment to study the regulation effect of water and nitrogen on the cotton biomass and yield under different drip irrigation patterns. Under the irrigation patterns 1 lateral 4 rows, 2 laterals 4 rows, and 2 laterals 6 rows, when the irrigation amount increased from low (90, 140, and 140 mm) to medium level (150, 200, and 200 mm), the aboveground dry biomass was increased by 9.2%, 37.9%, and 23.5%, and the seed yield was increased by 19.1%, 14.1%, and 16.0%, respectively. When the irrigation amount increased from medium to high level (210, 260, and 260 mm), the aboveground dry biomass was increased by 15.8%, 19.1%, and 16.7%, and the seed yield was increased by 7.7%, 11.2%, and 9.5%, respectively. When the nitrogen application rate changed from low (67.6 kg x hm(-2)) to medium level (95.2 kg x hm(-2)) the aboveground dry biomass under irrigation pattern 2 laterals 4 rows was increased by 14.3%, the seed yield under irrigation pattern 1 lateral 4 rows was increased by 22. 2% , while these two parameters under other irrigation patterns had no significant change. When the nitrogen application rate changed from medium to high level (122.8 kg x hm(-2)), the seed yield under the irrigation patterns 1 lateral 4 rows, 2 laterals 4 rows, and 2 laterals 6 rows was increased by 7.4%, 13.9%, and 9.9%, respectively, but the aboveground dry biomass had no significant change. Comparing with that under the irrigation patterns 1 lateral 4 rows and 2 laterals 6 rows, the regulation effect of water and nitrogen on the aboveground dry biomass and seed yield under irrigation pattern 2 laterals 4 rows was more apparent. As for the same water and nitrogen treatments, the aboveground dry biomass and seed yield were higher under the irrigation pattern 2 laterals 4 rows, suggesting that this drip irrigation pattern was most appropriate to the water- and nitrogen management of cotton field.

[Effects of water-fertilizer spatial coupling in root zone on winter wheat growth and yield].

A soil column experiment was conducted to study the winter wheat growth and yield under effects of different soil wetting (overall wetting, upper part wetting, and lower part wetting) and fertilization (overall fertilization, upper part fertilization, and lower part fertilization). The plant height and leaf area at tillering stage decreased significantly under lower part fertilization, compared with those under upper part and overall soil fertilization, but had no significant differences under different soil wetting. At jointing stage, the plant height was higher when the soil wetting and fertilization were at same location than at different location, manifesting a synergistic coupling effect of water and fertilizer. Lower part soil wetting and lower part fertilization decreased the root-, shoot-, and total dry biomass significantly, upper part fertilization benefited the biomass accumulation of winter wheat, and upper part soil wetting combined with upper part fertilization had an obvious coupling effect on the shoot- and total dry biomass. Soil wetting and fertilization at same location induced a higher ratio of root to shoot, compared with soil wetting and fertilization at different location, and lower part soil wetting resulted in the maximum water use efficiency (WUE), compared with upper part and overall soil wetting. A higher WUE was observed in the soil wetting and fertilization at same location than at different location, but a lower WUE was induced by lower part fertilization. The grain number per spike under upper part and overall soil wetting was increased by 41.7% and 61.9%, respectively, compared with that under lower part soil wetting, and this yield component under upper part and overall soil fertilization was also higher, compared with that under lower part fertilization. Upper part soil wetting and fertilization had an obvious coupling effect of water-fertilizer on the yield and yield components (except for 1000-grain mass). Different soil wetting and fertilization affected the yield mainly through affecting the grain number per spike.

[Coupling effect of water and nitrogen for cotton under different furrow irrigation patterns].

A field plot experiment with general rotation design was conducted to study the coupling effect of water amount and nitrogen (N) application rate for cotton under alternative furrow irrigation (AFI), conventional furrow irrigation (CFI), and fixed separate furrow irrigation (FFI). When the water amount was 37.52-160.00 mm and N application rate was 56.2-95.2 kg N x hm(-2), cotton yield had significant positive correlations with them; when the two factors were in the ranges of 160.00-218.48 mm and 95.2-134.2 kg N x hm(-2), respectively, no significant change was observed in the cotton yield. Within the test ranges of water amount and N application rate, cotton yield had no significant difference between AFI and CFI, but was 9.15% higher under CFI than under FFI. The water use efficiency (WUE) of cotton was significantly negatively correlated with the water amount 37.52-160.00 mm and positively correlated with the N application rate 56.2-122.8 kg N x hm(-2), but had no significant change when the water amount was 160.00-218.48 mm and N application rate was 122.8-134.2 kg N x hm(-2). Within the test ranges of water amount and N application rate, the WUE had no significant difference between CFI and AFI, but was 9.01% higher under CFI than under FFI. The nitrogen use efficiency (NUE) of cotton had significant positive correlation with the water amount 37.52-160.00 mm but significant negative correlation with the N application rate 56.2-134.2 kg N x hm(-2), and had no significant difference between AFI and CFI but was 6. 34% was lower under FFI than under CFI. Appropriate measures for high-efficiently using water and nitrogen resources under different furrow irrigation patterns were put forward to optimize cotton yield, WUE and NUE.

[Effects of different root zone irrigation modes on apple seedlings hydraulic resistance].

This paper studied the effects of different root zone irrigation modes (alternate partial drip irrigation, ADI; fixed partial drip irrigation, FDI; and conventional drip irrigation, CDI) and their watering amount on the whole-plant and its components hydraulic resistance and the stomata conductance and leaf area of apple seedlings. The results showed that both the irrigation mode and the watering amount had significant effects on the apple seedlings hydraulic resistance (R). Under the same irrigation modes, the root resistance (Rr) of apple seedlings was increased, but the shoot resistance (Rs) was decreased with decreasing watering amount; and under the same watering amounts, ADI and FDI increased the leaf and petiole resistance (R(1+p)), but decreased the whole-plant resistance (Rt), Rr, Rs, and lateral branch and master rod resistance (R(lb+mr)), compared with CDI. Under the irrigation quota of 20 mm and 30 mm, the R(l+p) of ADI was 1.06% and 0.63% higher than that of CDI, respectively; and with the prerequisite of saving 33% of irrigation water, the average R(l+p) of ADI and FDI was increased by 19.65% and 24.34%, while the average R(lb+mr) was decreased by 4.83% and 14.97%, respectively, compared with those of CDI. ADI and FDI effectively decreased stomata conductance and leaf area and increased R(l+p), and thus, decreased leaf blade luxurious transpiration dehydration while increased plant water use efficiency. By decreasing Rr and R(lb+mr), the ADI and FDI improved apple seedlings water regulation function and drought-resistant capability.

[Effects of water deficit and nitrogen fertilization on winter wheat growth and nitrogen uptake].

Winter wheat plants were cultured in vitro tubes to study their growth and nitrogen uptake under effects of water deficit at different growth stages and nitrogen fertilization. Water deficit at any growth stages could obviously affect the plant height, leaf area, dry matter accumulation, and nitrogen uptake. Jointing stage was the most sensitive stage of winter wheat growth to water deficit, followed by flowering stage, grain-filling stage, and seedling stages. Rewatering after the water deficit at seedling stage had a significant compensation effect on winter wheat growth, and definite compensation effect was observed on the biomass accumulation and nitrogen absorption when rewatering was made after the water deficit at flowering stage. Under the same nitrogen fertilization levels, the nitrogen accumulation in root with water deficit at seedling, jointing, flowering, and grain-filling stages was reduced by 25.82%, 55.68%, 46.14%, and 16.34%, and the nitrogen accumulation in aboveground part was reduced by 33.37%, 51.71%, 27.01%, and 2.60%, respectively, compared with no water deficit. Under the same water deficit stages, the nitrogen content and accumulation of winter wheat decreased with decreasing nitrogen fertilization level, i. e., 0.3 g N x kg(-1) FM > 0.2 g N x kg(-1) FM > 0.1 g N x kg(-1) FM. Nitrogen fertilization had obvious regulation effect on winter wheat plant growth, dry matter accumulation, and nitrogen uptake under water stress.

[Effects of different irrigation patterns on the growth of maize root hair].

With split-root pot experiment and using optical and electrical microscopes, the growth of root hair of maize under different irrigation patterns, i. e. , irrigated on both halves of the pot (conventional irrigation, CI), on one half only (fixed partial root zone irrigation, FPRI), and on both halves alternatively (alternate partial root zone irrigation, APRI), was observed. The observation after 40 days of treatment showed that in non-irrigated root zone of FPRI, the length proportion of root covered by vestigial root hairs was 20.96%, being higher than that in other zones. In addition to some bletting spots, the root system in irrigated zone of FPRI turned yellow, root-branching deteriorated to some extent, and the root hair density on the section with thick root hairs was lower than that in non-irrigated zone. However, both the length proportion of root covered by vestigial root hairs (15.72%) and the deterioration of root hair were lower than those in non-irrigated zone. As for CI, the root appearance and root hair growth were similar to those of the FPRI irrigated zone. As for the early and late irrigated root zones of APRI, the root hair density on the section with thick root hairs was high. The length proportion of root covered by vestigial root hairs was 9.77% and 10.38% for these two root zones, respectively, being lower than that in any root zones of FPRI and CI. It was suggested that alternative partial root zone irrigation was more beneficial to the growth of root hair than fixed partial root zone irrigation and conventional irrigation.