华北平原滴灌灌溉频率对萝卜生长的影响

研究了华北平原秋萝卜滴灌条件下 ,不同滴灌频率处理对萝卜叶面积系数、叶绿素含量、萝卜周径膨大、萝卜干重积累、根长密度、根干重密度等萝卜生长参数的影响并比较了各处理间萝卜产量的差异 ,发现在华北平原下半年降雨较多的情况下种植秋萝卜 ;1滴灌频率无论是 1 d1次还是 8d1次 ,对萝卜生长发育都没有明显影响 ;2滴灌条件下萝卜的平均重量和产量大大高于地面灌溉     

Irrigation studies on watermelon (Citrullus lanatus (Thunb) Matsum et Nakai)

Summary Field experiments carried out on watermelon at the Indian Institute of Horticultural Research, Bangalore, during 1984 and 1985 indicate that frequen irrigations with 100% evaporation replenishment result in highest fruit yield, dry matter production, total soluble solids, sugars, NO₃-N, N, P, K, Ca, Mg uptake and higher water use efficiency. However, yield differences were only statistically significant during 1985. Drip irrigation with 1 emitter per 2 plants produced the highest yield and water use efficiency as compared to other irrigation treatments. Dry matter, total soluble solids, sugars, NO₃-N, N, P, K, Ca, Mg uptake and WUE under drip irrigation were higher than under furrow irrigation treatments.Contribution No. 159/88 from Indian Institute of Horticultural Research, Bangalore, India     

Yield and quality of two tomato (Solanum lycopersicum L.) cultivars as influenced by drip and furrow irrigation using waters having high residual sodium carbonate

Performance of tomato when irrigated with sodic waters particularly under drip irrigation is not well known. A field experiment was conducted for 3 years to study the response of tomato crop to sodic water irrigation on a sandy loam soil. Irrigation waters having 0, 5 and 10 mmol_c L⁻¹ residual sodium carbonate (RSC) were applied through drip and furrow irrigation to two tomato cultivars, Edkawi (a salt tolerant cultivar) and Punjab Chhuhara (PC). High RSC of irrigation water significantly increased soil pH, ECe and exchangeable sodium percentage progressively; the increases were higher in furrow compared to drip irrigation. Effect of high RSC on increasing bulk density and decreasing infiltration rate of soil was also pronounced in furrow-irrigated plots. Higher soil moisture and lower salinity near the plant was maintained under drip irrigation than under furrow irrigation. Performance of the two cultivars was significantly different; pooled over 2002–03 and 2003–04 seasons, PC yielded 38.8 and 30.0 Mg ha⁻¹ and Edkawi yielded 31.8 and 22.9 Mg ha⁻¹ under drip and furrow irrigation, respectively. At RSC10, cultivar PC produced 38 and 46% higher fruit yield than cultivar Edkawi under drip and furrow irrigation, respectively. Reduction in fruit yield at higher RSC was due to lower fruit weight under drip irrigation and due to reduced fruit number as well as fruit weight under furrow irrigation. Decrease in fruit weight was more pronounced in cultivar Edkawi than in cultivar PC. Increase in RSC lowered quality of the fruits except the ascorbic acid content. High RSC under drip irrigation, in general, had lesser deteriorating effect on the fruit quality particularly for cultivar PC than under furrow irrigation. For obtaining high tomato yield and better-quality fruits using high RSC sodic waters, drip irrigation should be preferred over furrow irrigation. Better performance of local cultivar PC compared to Edkawi at medium and high RSC suggests that cultivars categorized as tolerant to salinity should be evaluated in the sodic environment particularly when irrigated with high RSC sodic waters.     

The effect of irrigation and nitrogen fertilizer on rapeseed (Brassica napes) production in South-Eastern Australia

Summary A field trial was conducted to determine the response of rapeseed (Brassica napus cv. Marnoo) to two irrigation treatments and six nitrogen fertilizer treatments. Dry matter accumulation, leaf area development and seed yield were measured. The dry matter and seed yield response to applied nitrogen was greater under irrigated compared to rainfed conditions. Maximum seed yield (approx. 3.8 t ha^–1) was obtained from the irrigated treatment receiving 100 kg N ha^–1 applied at sowing. This high rate of N application at sowing led to more rapid leaf area development and higher maximum LAI compared to treatments supplied with split application of the same amount of N at sowing and rosette stages. Greater partitioning of dry matter into the leaf component and higher specific leaf areas under the higher N regime were largely responsible for this increase. Higher maximum LAI's were associated with greater numbers of pods per plant, which combined with longer leaf area duration led to higher final seed yields.     

不同灌水方式下基于水面蒸发量的夏玉米灌溉试验研究

为了探索依据水面蒸发量确定灌溉定额的可行性,在防雨棚下测坑中进行了夏玉米灌溉试验。结果表明,从总耗水量看,畦灌略高于沟灌,而沟灌又略高于滴灌,但差别不是很大。畦灌条件下植株发育快,滴灌次之,沟灌最慢。畦灌和滴灌下产量均以中等灌溉定额处理最高,而沟灌下产量以最大灌溉定额处理最高。总体上,滴灌条件下水分利用效率高于其他2种灌溉方式。干旱条件下,畦灌下以E601蒸发皿蒸发量(PE)作为夏玉米灌溉定额,每次灌水60mm;滴灌下以2/3PE作为灌溉定额为宜,灌水定额为20mm。     

保护地栽培条件下灌水方法对土壤温度的影响

对塑料大棚内渗灌、滴灌和沟灌条件下土壤温度的变化规律进行研究,结果表明,在早春和秋冬低温期,保护地内采用渗灌、滴灌可以比沟灌更能保持较高的土温,灌水方法对上层土壤温度的影响大于对深层土壤温度的影响。不同灌水方法对0~30 cm土层平均温度的影响差异极显著,其中渗灌比沟灌高1.79℃,滴灌比沟灌高2.70℃。灌水后1 d内保护地0~20 cm土层温度的日变化规律是:10:00~18:00各层土壤温度为渗灌和滴灌高于沟灌,而06:00~08:00和18:00~22:00沟灌高于滴灌和渗灌;这种变化趋势以5~15 cm土层最明显,该层土壤温度日较差以渗灌为最大,其次是滴灌,而以沟灌最小,且温度最大值出现时间依次延后2 h左右。20 cm及其以下层次3种灌水方式土壤温度的日变化平缓,而且不同处理之间温度差异也逐渐减小。     

Effect of irrigation methods,management and salinity of irrigation water on tomato yield,soil moisture and salinity distribution

The increasing demand for irrigation water to secure food for growing populations with limited water supply suggests re-thinking the use of non-conventional water resources. The latter includes saline drainage water, brackish groundwater and treated waste water. The effects of using saline drainage water (electrical conductivity of 4.2–4.8 dS m⁻¹) to irrigate field-grown tomato (Lycopersicon esculentum Mill cv Floradade) using drip and furrow irrigation systems were evaluated, together with the distribution of soil moisture and salt. The saline water was either diluted to different salinity levels using fresh water (blended) or used cyclically with fresh water. The results of two seasons of study (2001 and 2002) showed that increasing salinity resulted in decreased leaf area index, plant dry weight, fruit total yield and individual fruit weight. In all cases, the growth parameters and yield as well as the water use efficiency were greater for drip irrigated tomato plants than furrow-irrigated plants. However, furrow irrigation produced higher individual fruit weight. The electrical conductivity of the soil solution (extracted 48 h after irrigation) showed greater fluctuations when cyclic water management was used compared to those plots irrigated with blended water. In both drip and furrow irrigation, measurements of soil moisture one day after irrigation, showed that soil moisture was higher at the top 20 cm layer and at the location of the irrigation water source; soil moisture was at a minimum in the root zone (20–40 cm layer), but showed a gradual increase at 40–60 and 60–90 cm and was stable at 90–120 cm depth. Soil water content decreased gradually as the distance from the irrigation water source increased. In addition, a few days after irrigation, the soil moisture content decreased, but the deficit was most pronounced in the surface layer. Soil salinity at the irrigation source was lower at a depth of 15 cm (surface layer) than that at 30 and 60 cm, and was minimal in deeper layers (i.e. 90 cm). Salinity increased as the distance from the irrigation source increased particularly in the surface layer. The results indicated that the salinity followed the water front. We concluded that the careful and efficient management of irrigation with saline water can leave the groundwater salinity levels unaffected and recommended the use of drip irrigation as the fruit yield per unit of water used was on average one-third higher than when using furrow irrigation.     

Effect of small irrigation amounts on the yield of wheat

Yields of dryland crops are governed by the moisture in the soil profile at seeding and by rainfall during the growing season. Occasionally limited amounts of water may also be available for irrigation. Field experiments were conducted over a period of 4 years on loamy sand and 3 years on sandy loam to study the effects of pre-seeding, post-seeding and split application of limited amounts of water on root growth, water use, dry matter accumulation and grain yield of wheat. This article reports the treatment effects on dry matter accumulation and grain yield.Early season water stress decreased the rate of dry matter accumulation. Grain yield responded significantly to irrigation 30 days after seeding irrespective of the amount of water, year and soil type. Yield with post-seeding irrigation averaged 3518 kg ha^?1 against 2317 kg ha^?1 for unirrigated control in loamy sand and 4440 kg ha^?1 against 3391 kg ha^?1 in sandy loam. The increase in yield was manifested by a significant increase in the number of effective tillers per m row length, number of grains per ear and thousand grain weight.     

水肥调控模式对滨海盐碱地水肥盐迁移及春玉米水肥利用率的影响

为了探明滨海盐碱地不同灌溉方式及氮肥施用量对水肥盐迁移过程及作物生长的影响,基于大田试验,研究不同灌溉方式及灌水量(F:漫灌,360 mm;D1:滴灌,360 mm;D2:滴灌,288 mm;D3:滴灌,216 mm)、氮肥处理(N1:280 kg/hm²;N2:196 kg/hm²;N3:112 kg/hm²)对盐碱地土壤水肥盐分布含量及对春玉米各生长指标的影响.结果表明,在滴灌模式下,同一灌水量,N1的剖面平均含水量最低,D1,D2出现洗盐点,存在适合作物生长的浅盐区;灌水后D1N1的硝态氮含量增加最显著且含量最高,滴灌处理对应的低氮处理无明显硝态氮积累点,相同灌水量下,漫灌的有效氮含量均高于滴灌,但其有效氮利用率低于滴灌处理;不同施氮对春玉米干物质的差异随灌水量增加而增加.各处理水分利用效率与肥料偏生产力之间产生明显差异,高水低氮肥料偏生产力明显提高,但其水分利用效率低下,D1N1产量最高;在考虑作物产量及水肥利用效率时,采用滴灌方式,则灌水量288~360 mm、施氮量196 kg/hm²为推荐水肥措施.     

Seed yield and water use efficiency of canola (Brassica napus L.) as affected by high temperature stress and supplemental irrigation

The effects of high temperature stress and supplemental irrigation on seed yield and water use efficiency (WUE) of canola (Brassica napus L.) were studied in a field experiment conducted for 2 years. The experiment was a randomized complete block design arranged in split plot, conducted at Agricultural Research Station of Gonbad, Iran. It was arranged in two conditions, i.e. supplemental irrigation and rainfed. Two cultivars of canola (Hyola401 and RGS003) as subplots were grown at five sowing dates as main plots. The sowing dates were 9 November, 6 December, 5 January, 4 February and 6 March in 2005-2006 and 6 November, 6 December, 5 January, 4 February and 6 March in 2006-2007, to have a wide range of environmental conditions around flowering and seed filling periods, and to coincide reproductive stages of the crop with high temperature stress. Seed yield was improved due to field management practices, such as supplemental irrigation and optimum sowing date. Supplemental irrigation was an efficient practice to mitigate water stress, and to increase aboveground dry matter and seed yield. There was a strongly negative relationship between seed yield and air temperature during reproductive stages. Delay in sowing led to more rapid developmental of canola, decreased aboveground dry matter, leaf area index (LAI), harvest index (HI), WUE, and seed yield. Achieving a high aboveground dry matter was an essential prerequisite for high reproductive growth and a high seed yield. Greater seed yield and WUE at first sowing date were associated with greater LAI and aboveground dry matter, and lower temperatures during reproductive stages. The results support the view that WUE can be used as an indirect selection criterion for seed yield in genotypic selection.     

苜蓿田间地下滴灌效应试验研究

根据苜蓿地下滴灌土壤水分变化，并以常规沟灌为对照，对苜蓿田间地下滴灌的适宜埋深和灌水量进行了研究。结果表明，地下滴灌比常规沟灌的苜蓿，鲜草出草率高；滴灌带埋深35cm比埋深10cm的苜蓿长势好，鲜草产量高，并初步拟定了苜蓿地下滴灌的灌溉制度。因此，苜蓿田实施地下滴灌是可行的，在新疆具有推广应用价值和发展潜力。     

不同灌溉和施肥方式对杂交稻生长和根际环境的影响

对杂交稻中优218不同灌溉方式和氮肥管理下水稻生长和根际环境的变化进行研究,结果表明,水稻好气灌溉条件下各施肥处理产量均高于传统灌溉处理,产量比淹水灌溉增产10.5%~11.3%,主要表现在每穗粒数增加而提高产量。好气灌溉与淹水灌溉比较各生育期地上部干物重和叶面积指数均增加,土壤氧化还原电位提高,放线菌数量显著增加。增加有机肥降低土壤氧化还原电位和提高放线菌数量,在好气灌溉条件下施相同氮素有机肥放线菌数多于化肥。     

灌溉方式和灌水下限对温室青茄生长、耗水特性及产量的影响

【目的】探明插入式地下滴灌和地表滴灌条件下,不同灌水下限对温室新乡糙青茄(Solanum melongena L.)的生长、耗水特性及产量的影响。【方法】试验设置2种灌溉方式:插入式地下滴灌(SDI-R)、地表滴灌(DI)。灌水下限设置4个水平:开花坐果期60%θF、成熟采摘期60%θF(F60M60);开花坐果期60%θF、成熟采摘期70%θF(F60M70);开花坐果期70%θF、成熟采摘期60%θF(F70M60);开花坐果期70%θF、成熟采摘期70%θF(F70M70),处理简称为T1(DI,F60M60)、T2(SDI-R,F60M60)、T3(DI,F60M70)、T4(SDI-R,F60M70)、T5(DI,F70M60)、T6(SDI-R,F70M60)、T7(DI,F70M70)、T8(SDI-R,F70M70)。研究了不同处理对温室青茄的株高、根干物质、产量、耗水特性及水分利用效率的影响。【结果】SDI-R处理的青茄株高和总根干质量均高于DI处理的;SDI-R处理的总耗水量和各生育阶段的耗水量均小于DI处理的,2种灌水方式中T7处理和T8处理总耗水量最大,分别为338.09 mm和331.25mm,4种灌水下限下,DI处理较SDI-R处理分别高2.06%～16.67%;SDI-R灌水方式中的T4处理的产量和水分利用效率最大,分别为56 046.30 kg/hm~2和20.43 kg/m3,DI条件下T7处理的产量和水分利用效率最高,分别为51 546.30kg/hm~2和15.24 kg/m3,T4处理显著高于T7处理(P<0.05)。【结论】插入式地下滴灌相对于地表滴灌能达到增产节水的目的,且插入式地下滴灌开花坐果期和成熟采摘期的灌水下限宜分别设为田间持水率的60%和70%。     

锦州市不同播期对玉米生长发育的影响

为确定锦州地区玉米最适宜播期，探讨锦州地区不同气候条件下玉米叶面积指数（LAI）与干物质的关系，选用2个不同玉米品种农华101和丹玉39于8个不同播期开展分期播种试验，观测玉米不同生育期时间、LAI、干物质积累和生长率。试验结果表明，玉米过早播种并不一定使发育期提前；在整个发育期中，农华101的播期越晚LAI越高，第7期干物质积累效果较好，生长率最大；丹玉39早播和晚播玉米LAI、干物质积累和生长率均较低，第4～6期玉米LAI较高，干物质积累效果最好，生长率最大。      

不同灌溉模式对黄淮海平原区夏玉米生产性状及水分利用率的影响

为了探明黄淮海平原区不同灌溉模式对夏玉米生产性状和水分利用效率的影响,2018-2019连续2年设置覆膜浅埋滴灌(T4)、浅埋滴灌(T3)、覆膜滴灌(T2)、地表滴灌(T1)和传统畦灌(CK)等5种灌溉方式实施大田对比试验,测定了玉米株高、叶面积指数(LAI)、地上部干物质累积量、产量及产量构成因素以及水分利用效率(W...     

Irrigation for crops in a sub-humid environment VII. Evaluation of irrigation strategies for cotton

Summary Empirical functions to predict the nitrogen uptake, increase in LAI and minimum leaf water potential (LWP) of cotton were incorporated into a water balance model for the Namoi Valley, N.S.W. A function was then developed to describe the lint yield of irrigated cotton as a function of water stress days at 4 stages of development, total nitrogen uptake and days of waterlogging. A water stress day was defined as predicted minimum leaf water potential less than -1.8 MPa up to 90 days after sowing and -2.4 MPa there-after; stress reduced yield by up to 40 kg lint ha^–1 d^–1 with greatest sensitivity at 81–140 days after sowing and when N uptake was highest. Nitrogen uptake was reduced by 0.98 kg per ha and yield reduced by 33.2 kg lint ha^–1 for each day of waterlogging. The model was used to evaluate various irrigation strategies by simulating production of cotton from historical rainfall data. With a water supply from off farm storage, net returns ($ M1^–1) were maximized by allocating 7 Ml ha^–1 of crop. The optimum practice was not to irrigate until 60 days from sowing and until the deficit in the root zone reached 50%. When the supply of water was less than 7 Ml ha^–1 there was no advantage in either delaying the start of irrigation or irrigating at a greater deficit; it was economically more rational to reduce the area shown or, if already sown, to irrigate part with 6 Ml ha^–1 and leave the rest as a raingrown crop. Irrigation decisions are compromises between reducing the risk of water stress and increasing the risk of waterlogging. The simulation showed that there is no single set of practices that is always best in every season; in a number of seasons practices other than those which on average are best, give better results.     

Potato evapotranspiration and yield under different drip irrigation regimes

A field experiment comparing different irrigation frequencies and soil matric potential thresholds on potato evapotranspiration (ET), yield (Y) and water-use efficiency (WUE) was carried out in a loam soil. The experiment included five treatments for soil matric potential: F1 (-15 kPa), F2 (-25 kPa), F3 (-35 kPa), F4 (-45 kPa) and F5 (-55 kPa) and six treatments for irrigation frequency: N1 (once every day), N2 (once every 2 days), N3 (once every 3 days), N4 (once every 4 days), N6 (once every 6 days) and N8 (once every 8 days). Results indicate that both soil matric potential and drip irrigation frequency influenced potato ET, Y and WUE. Potato ET increased as irrigation frequency and soil matric potential increased. Comparing soil water potential, the highest ET was 63.4 mm (32.1%) more than the lowest value. Based on irrigation frequency treatments, the highest ET was 36.7 mm (19.2%) more than the lowest value. Potato Y and WUE were also found to increase as irrigation frequency increased. Potato Y increased with an increase in soil water potential then started to decrease. The highest Y and WUE values were achieved with a soil matric potential threshold of -25 kPa and an irrigation frequency of once a day.Communicated by J. Ayars     

Impact of fertilisation practices on nitrogen leaching under irrigation

Field experiments were carried out over a 2-year period on a loamy soil plot under corn in Montpellier (south-east France). The effectiveness of improved irrigation practices in reducing the adverse impact of irrigation on the environment was assessed. Different irrigation and fertiliser treatments were applied to identify the best irrigation and fertilisation strategy for each technique (furrow and sprinkler) to ensure both good yields and lower NO₃^- leaching. No significant differences in corn yield and NO₃^- leaching were found for the climatic scenario of 1999 between sprinkler and furrow irrigation during the irrigation season. Following the rainy events occurring after plant maturity (and the irrigation season), differences in N leaching were observed between the treatments. The study shows that both the fertiliser method, consisting of applying a fertiliser just before ridging the furrows, and the two-dimensional (2D) infiltration process, greatly influence the N distribution in the soil. N distribution seems to have a beneficial impact on both yield and N leaching under heavy irrigation rates during the cropping season. But, under rainy events (particularly those occurring after harvesting), the N, stored in the upper part of the ridge and not previously taken up by plants, can be released into the deeper soil layers in a furrow-irrigated plot. In contrast, the 1D infiltration process occurring during sprinkler irrigation events affects the entire soil surface in the same way. As a result the same irrigation rate would probably increase N leaching under sprinkler irrigation to a greater extent than under furrow-irrigation during an irrigation period. In order to assess the robustness of these interpretations derived from soil N-profile analysis, a modelling approach was used to test the irrigation and fertilisation strategies under heavy irrigation rates such as those occurring at the downstream part of closed-end furrows. The RAIEOPT and STICS models were used to simulate water application depths, crop yield and NO₃^- leaching on three measurement sites located along the central furrow of each treatment. The use of a 2D water- and solute-transport model such as HYDRUS-2D enabled us to strengthen the conclusions derived from the observations made on the N distribution under a cross-section of furrow. This model helped to illustrate the risk of over-estimation of N leaching when using a simplified 1D solute-transport model such as STICS.     

Response of cotton to various levels of nitrogen and water applied to normal and paired sown cotton under drip irrigation in relation to check-basin

Field experiments were conducted for 2 years to investigate the effects of various levels of nitrogen (N) and methods of cotton planting on yield, agronomic efficiency of N (AEN) and water use efficiency (WUE) in cotton irrigated through surface drip irrigation at Bathinda situated in semi-arid region of northwest India. Three levels of N (100, 75 and 50% of recommended N, 75 kg ha⁻¹) were tested under drip irrigation in comparison to 75 kg of N ha⁻¹ in check-basin. The three methods of planting tried were; normal sowing of cotton with row to row spacing of 67.5 cm (NS), normal paired row sowing with row to row spacing of 35 and 100 cm alternately (NP) and dense paired row sowing with row to row spacing of 35 and 55 cm alternately resulting in total number rows and plants to be 1.5 times (DP) than NS and NP. In NS there was one lateral along each row, but in paired sowings there was one lateral between each pair of rows. Consequently the number of laterals and quantity of water applied was 50 and 75% in NP and DP, respectively, as compared with NS in which irrigation water applied was equivalent to check-basin.Drip irrigation under NS resulted in an increase of 258 and 453 kg ha⁻¹ seed cotton yield than check-basin during first and second year, respectively, when same quantity of water and N was applied. Drip irrigation under dense paired sowing (DP) in which the quantity of irrigation water applied was 75% as compared with NS, further increased the yield by 84 and 101 kg ha⁻¹ than NS during first and second year, respectively. Drip irrigation under NP, in which the quantity of water applied and number of laterals used were 50% as compared with drip under NS, resulted in a reduction in seed cotton yield of 257 and 112 kg ha⁻¹ than NS during first and second year, respectively. However, the yield obtained in NP under drip irrigation was equivalent to yield obtained in NS under check-basin during first year but 341 kg ha⁻¹ higher yield was obtained during second year. The decrease in N applied, irrespective of methods of planting, caused a significant decline in seed cotton yield during both the years. Water use efficiency (WUE) under drip irrigation increased from 1.648 to 1.847 and from 0.983 to 1.615 kg ha⁻¹ mm⁻¹ during first and second year, respectively, when the same quantity of N and water was applied. The WUE further increased to 2.125 and 1.788 kg ha⁻¹ mm⁻¹ under DP during first and second year, respectively. The agronomic efficiency of nitrogen was higher in drip than check-basin during both the years when equal N was applied. The WUE decreased with decrease in the rate of N applied under fertigation but reverse was true for AEN. It is evident that DP under drip irrigation resulted in higher seed cotton yield, WUE and AEN than NS and also saved 25% irrigation water as well as cost of laterals.     

Effect of surface and subsurface drip fertigation on sweet corn rooting,uptake, dry matter production and yield

Summary Subsurface (SS) drip fertigation may increase sweet corn ear yield relative to surface (S) fertigation, because immobile nutrients are delivered at the center of the soil-root volume rather than on top of the soil. A container (1 × 1 × 1 m) experiment was conducted on a loessial soil (Haploxeralf) to test this hypothesis. Marketable and total ear yields were higher for tricklers placed 30 cm below the soil surface (3.22 and 4.90 kg m^–2, respectively) than on the surface (2.86 and 4.30 kg m^–2, respectively). Total fresh weight, dry matter production and plant height during the growing season were also greater for subsurface emitters. Deep trickler position significantly increased P and K content at the center of the root zone. The enhanced concentration apparently stimulated plant rooting which, together with the higher nutrient activity in the soil solution, increased P and K uptake rates, which in turn facilitated the higher dry matter production and commercial yield relative to surface trickler placement. The higher root activity in SS than in S fertigation was reconfirmed by soil air CO₂ concentration measurements which showed significant differences between the two treatments during the growth season.On studies in the ARO from The College of Postgraduates of Mexico, Montecillos, Mexico.