Water deficits promote flowering in Rhododendron via regulation of pre and post initiation development

Flowering is generally considered to be advanced by water deficits in many woody perennial species. A long-standing paradigm being that as a plant senses severe environmental conditions resources are diverted away from vegetative growth and towards reproduction before death. It is demonstrated that in Rhododendron flowering is promoted under water deficit treatments. However, the promotion of flowering is not achieved via an increase in floral initiation, but through separate developmental responses. If regulated deficit irrigation (RDI) is imposed prior to the time of initiation, fewer vegetative nodes are formed before the apical meristems switch to floral initiation, and chronologically, floral initiation occurs earlier. Both RDI and partial rootzone drying (PRD) treatments stimulate the development of more flowers on each inflorescence if the treatments are continued after the plant has undergone floral initiation. However, floral initiation is inhibited by soil water deficits. If the soil water deficit continues beyond the stages of floral development then anthesis can occur prematurely on the fully formed floral buds without a need for a winter chilling treatment. It is hypothesised that inhibition of floral initiation in plants experiencing severe soil water deficits results from the inhibitory action of ABA transportation to the apical meristem from stressed roots. It is demonstrated that ABA applications to well-watered Rhododendron inhibit floral initiation.     

西瓜新品种‘抗王’

 ‘抗王’为中早熟西瓜一代杂交种, 适合早春温室、大棚等多种覆盖及露地栽培, 从开花到成熟约32 d。果实圆形, 果皮绿色, 被伏深绿色粗花纹, 含可溶性固形物11%左右。丰产性好, 一般产量可达60～65 t·hm^-2 。抗病性强, 耐贮运。     

西瓜根系浸提物对不同作物种子萌发的化感效应

以黄瓜、西瓜、南瓜、西葫芦、番茄、萝卜、小麦、胡麻、芝麻、蓖麻、花豆、绿豆为受试作物。研究了西瓜根系水浸提物对各个受试作物的发芽、根质量及苗质量的化感作用。结果表明,西瓜根系浸提物对不同作物的各个器官均有影响,其中对黄瓜和小麦种子的发芽和苗质量的增加均有促进作用,但效应不显著;对花豆种子的发芽和根质量的增加以及对辣椒根质量的增加也表现出促进作用,但效应不显著;对绿豆根质量的增加有显著的促进作用,对萝卜苗质量的增加表现为促进作用,而对其他受试作物均表现出抑制作用。     

Combining cover cropping with deficit irrigation in a Mediterranean low vigor vineyard

The aim of this research was to test the effects of vineyard soil management practices combined with deficit irrigation strategies on the performance of the grapevine (Vitisvinifera L.) red variety Tempranillo. Two soil management practices (soil tillage – ST and permanent resident vegetation – RV) were combined with three deficit irrigation treatments (regulated deficit irrigation – RDI, partial rootzone drying – PRD and conventional sustained deficit irrigation – DI) during two growing cycles. Compared to ST, RV reduced soil water content during spring, inducing a significant reduction in vine vegetative growth, yield and must titratable acidity. The effects of irrigation treatments were not much pronounced. Only in the second season RDI showed a significant reduction on vine vegetative growth, yield and must titratable acidity as compared to PRD and DI whose results were similar to one another.     

Regulated deficit irrigation in ‘Clementina de Nules’ citrus trees. II: Vegetative growth

Summary

An experiment on Regulated Deficit Irrigation (RDI) was performed during 1995 and 1996 in an orchard planted with drip-irrigated ‘Clementina de Nules’/Carrizo Citrange in Moncada (Valencia) Spain. Treatments consisted of a control, irrigated during the whole year at 125% ET_lys and RDI treatments where irrigation was reduced to 25% or to 50% of crop evapotranspiration measured by a weighing lysimeter (ET_lys) during one of the following periods: I) flowering and fruit set (spring); II) initial fruit enlargement phase (summer) and III) final fruit growth and maturation phases (end of summer-autumn). An additional treatment, denominated 50%-Year, was irrigated at 50% ET_lys during the whole year. The effects of RDI treatments in relation to tree water status (pre-dawn Ψ^pd and midday Ψ^md leaf water potential, as well as their integral with time) show a good relation between total shoot emergence in the different growth flushes and the stress intensity reached (Ψ^pd) (r² = 0.80). This correlation was mainly due to the number of floral shoots (r² = 0.86) and not to vegetative ones (r² = 0.22). Similar results were observed between the stress integral at pre-dawn in each period and the former sprouting variables. In all cases, correlation was better with pre-dawn leaf water potential or with pre-dawn stress integral than with those at midday. RDI during spring reduced shoot length of the first growth flush (A1) and increased fruitlet fall after restarting normal irrigation. It also produced “off-season” flowering in the second flush growth (A2) and increased shoot emergence of the third flush growth (A3) with about 10% of them being floral. Summer RDI treatments did not alter vegetative growth, and although they produced off-season flowering (A3) it was much smaller than that of autumn RDI treatments, which in addition reduced vegetative growth with respect to the control. These effects, together with those of yield and fruit quality presented elsewhere, show that summer is the more appropriate period to apply RDI in “Clementina de Nules” mandarin trees.     

大棚西瓜一年两种两收优化施肥高效栽培技术

为了有效缓解大棚西瓜种植造成的土壤连作障碍,降低西瓜种植户租地成本,减少大棚搭建和拆除用工,提高棚架及棚膜的利用率,东台市以果菜茶有机肥替代化肥示范县创建项目为契机,集成"有机肥+配方肥+水肥一体化"优化施肥技术,推广大棚春西瓜-秋西瓜两种两收连作高效栽培模式。采用该栽培模式,每667 m^2两茬产值在22 000元,净收入12 500元,比传统模式下增施有机肥,减施化肥20%,增效3 200元,提高了农民种植西瓜的生态和经济效益。     

Transpiration characteristics of banana leaves (cultivar ‘Williams’) in response to progressive depletion of available soil moisture

Young parent-crop banana plants (cultivar ‘Williams’) were subjected to two soil moisture potential (SMP) regimes, namely, continuous field capacity and progressive depletion of total available soil moisture (TAM). Experiments were conducted in a fibreglass tunnel under mild or enhanced conditions of vapour pressure deficit (VPD), and also in the field during summer. Transpiration rates, stomatal resistance, photosynthetically-active radiation and leaf temperature were measured simultaneously with a steady-state porometer, according to a developed technique which minimised natural sources of error.

Under mild conditions of VPD (± 5 hPa) plants responded slowly to soil drying, and at a SMP of −82 kPa, transpiration was reduced by 27% compared to fully-irrigated plants. Under enhanced VPD (15–20 hPa), plants responded rapidly to soil drying, and at a SMP of −75 kPa transpiration was reduced by 73%.

In the field, reduction of transpiration in response to SMP at high VPD followed a similar pattern to the covered experiment. At a SMP of −46 kPa the reduction in transpiration rate was 41% in the late afternoon at high VPD, but the following morning transpiration rates of the two treatments were similar due to lower VPD and overnight re-establishment of turgor. At −525 kPa SMP, reduction of transpiration was 70% and plants could not regain turgor overnight. Stomatal conductance seemed more sensitive to water stress than transpiration, but leaf temperature only differentiated advanced levels of stress (± 2°C difference between stressed and non-stressed leaves).

These results hold important implications for irrigation scheduling of bananas. Initiation of stress occurred at a SMP of around −20 to −25 kPa which occurred at a 20% depletion of TAM, thus necessitating a summer irrigation frequency of daily or every 2 days.     

Use of a cyclic high-pressure sodium lamp to inhibit flowering of chrysanthemum and velvet sage

Photoperiod is commonly controlled in the commercial production of ornamental crops to induce or prevent flowering. Flower induction in short-day (SD) plants can be prevented or delayed when the natural daylength is short by providing low-intensity lighting during the dark period. A stationary high-pressure sodium (HPS) lamp with an oscillating aluminum parabolic reflector (cyclic HPS) has been developed to provide intermittent lighting to greenhouse crops. We determined the efficacy of a cyclic HPS lamp at preventing flowering in SD plants garden chrysanthemum [Chrysanthemum × grandiflorum (Ramat.) Kitam.] ‘Bianca’, pot chrysanthemum ‘Auburn’, and velvet sage (Salvia leucantha L.) relative to traditional night interruption (NI) lighting strategies. Plants were grown in a glass-glazed greenhouse at a mean daily temperature of 19.5–20.7 °C with natural SD photoperiods. NI lighting was delivered during the middle of the night (2230–0230 h) from a 600 W cyclic HPS lamp mounted at one gable end of the greenhouse or from incandescent (INC) lamps that were illuminated for the entire 4 h (CONT INC) or for 6 min every 30 min for 4 h. Plants under cyclic HPS were grown at lateral distances of 1, 4, 7, 10, or 13 m from under the lamp. Control plants were grown under an uninterrupted 15 h skotoperiod. As the distance from the cyclic HPS lamp increased from 1 to 13 m, the maximum irradiance measured during the NI decreased from 25.4 to 0.3 μmol m⁻² s⁻¹ and time to visible inflorescence (VI) and the number of nodes at VI decreased. All species had a VI within 54 d, but ≤10% of plants flowered when grown at a lateral distance of 1 or 4 m from the cyclic HPS lamp or under CONT INC. Plants grown without NI had a VI 2 to 15 d earlier and flowered 7 to 24 d earlier than plants grown at 10 or 13 m from the cyclic HPS. All garden chrysanthemums flowered under cyclic INC, whereas velvet sage and pot chrysanthemum had 15% and 35% flowering, respectively. These results indicate that a cyclic HPS lamp can be used effectively to delay flower induction and prevent flowering in these species when NI is delivered at ≥2.4 μmol m⁻² s⁻¹.     

西瓜新品种‘武农8号’

‘武农8号’是早熟小果型西瓜杂交一代新品种。植株长势强健,易坐果。果实膨大快,单果质量1.43 ~ 2.06 kg。果实椭圆形,果皮绿色,覆墨绿色齿条,厚度0.54 cm,蜡粉轻;果肉红色,中心糖含量12.5%,边糖含量10%,肉质松脆细嫩,品质佳,耐裂。生育期95 d,果实发育期27 ~ 31 d,适合湖北春播日光温室和塑料大棚早熟覆盖栽培。     

中果型西瓜新品种‘甬蜜6号’的选育

‘甬蜜6号’是以优良自交系‘YX-3’为母本、‘WW69’为父本杂交育成的早熟中果型西瓜品种,生长势中等偏强,抗西瓜枯萎病,春季大棚栽培全生育期93~102 d,果实发育期33~38 d,第1雌花出现在主蔓8~9节,以后每隔5~6节出现雌花,坐果性好,单果质量5~6 kg,果实高圆形,果面底色绿、覆墨绿色齿条带、光滑有蜡粉,果实剖面好,果皮厚度适中,瓤色红,汁液多,瓤质脆,口感好,中心可溶性固形物含量(w,后同)12.2%,边部7.3%。大棚栽培可采收3批左右,第1批西瓜667 m2产量2000 kg左右。该品种适合浙江及周边春季大棚和露地栽培。2019年10月通过非主要农作物品种登记。     

Evapotranspiration of potted geraniums (Pelargonium × Hortorum Bailey ‘Carefree Crimson’) related to growth stage and greenhouse environment

Highly significant differences in evapotranspiration (ET) from well-watered greenhouse geraniums at stages ranging from seedling transplants through early and late vegetative growth and flowering were related to variations in plant weight, leaf area and maturity. Between April 25 and May 23, black atmometer and solar radiation (SR) values were more highly correlated to ET than white atmometer, black minus white atmometer values or wet or dry bulb temps. Correlations of ET and SR were lower when SR was measured the same hour as ET than when SR was measured the previous hour. ET per unit change in environmental parameter and plant growth were lowest for the older growth stages and highest for the younger growth stages because ET was greatest per unit leaf area for the younger stages.     

大棚西瓜间套种辣椒周年生产技术模式

摘要：针对沿淮地区大棚单作西瓜时土地和空间的浪费问题，摸索出了1套大棚西瓜间套种辣椒的 栽培模式，即早春采用西瓜间套种辣椒的“3膜覆盖”技术，提高了设施内土地利用率；夏季高温闷棚 技术解决了重茬连作障碍，大棚环境得到改善；秋季采用“防雨棚＋遮阳网”育苗，中后期“大棚＋小 拱棚”进行辣椒活体保鲜，实现了1年2茬、周年生产。该生产模式通过科学管理，667 m2 产值2.5万元以 上，经济效益显著。     

Chill unit models for blackcurrant (Ribes nigrum L.) cultivars ‘Ben Gairn’, ‘Ben Hope’ and ‘Ben Tirran’

Temperate-zone crops require a period of winter chilling to terminate dormancy and ensure adequate bud break the following spring. The exact chilling requirement of blackcurrant (Ribes nigrum), a commercially important crop in northern Europe, is relatively unknown. Chill unit models have been successfully utilized to determine the optimum chilling temperature of a range of crops, with one chill unit equating to 1 h exposure to the optimum temperature for chill satisfaction. Two-year-old R. nigrum plants of the cultivars ‘Ben Gairn’, ‘Ben Hope’ and ‘Ben Tirran’ were exposed to temperatures of −10.1 °C, −3.4 °C, 0.1 °C, 1.5 °C, 2.1 °C, 3.4 °C or 8.9 °C (±0.7 °C) for durations of 0, 2, 4, 6, 8 or 10 weeks and multiple regression analyses used to determine the optimum temperature for chill satisfaction.     

Vegetable crop responses in improved low-cost plastic greenhouses

SUMMARY

Two new unheated prototype greenhouses were evaluated (a north-south oriented multispan of symmetrical 17° roof slope and east-west oriented singlespan of asymmetrical roof angles, 18° and 8°), as possible alternatives to the conventional flat-roofed greenhouse, using a sequence of three crops (cucumber, indeterminate beans and sweet pepper), in Almeria, Spain. Around the winter solstice, when the vegetables reach their best prices in the market, the higher light transmission in the asymmetrical singlespan significantly increased higher cucumber and pepper yields, relative to the conventional plastic house. The additional light reducing materials of the multispan structure generated lower radiation transmisivity in spring and, subsequently, lower yields in the bean and pepper crops. The asymmetrical greenhouse should be more profitable than the conventional one if its building cost does not exceed 24% (equivalent to 1.45 US dollar m"2) of the building cost of the conventional plastic house.     

水肥精量控制对西瓜嫁接苗生长的影响

为培育西瓜壮苗,减少水肥资源浪费,开展了在嫁接成活期控制不同基质含水量（95%～100%、70%～75%）和育苗期使用不同水溶肥包括磷酸二氢钾和氮磷钾平衡肥（15-15-15+T E）的水肥精量控制试验,比较分析了嫁接苗的成活情况、生长指标和壮苗指数。结果表明：冬春季在玻璃温室内培育西瓜嫁接苗,嫁接后7 d内以基质最大含水量保持在95%～100%,施用磷酸二氢钾肥水溶肥1000倍液4次（在砧木现1片真叶时、嫁接苗接穗现1片真叶时、接穗1叶1心时和接穗2叶1心时分别灌根1次）为宜,可提高嫁接成活率（95%）,降低病苗率（5%）,且壮苗指数（165.59）显著高于其他3个处理,有利于培育西瓜壮苗。     

优质早熟小果型西瓜新品种龙盛2号的选育

龙盛2号西瓜是黑龙江省农业科学院园艺分院育成的适宜保护地栽培的极早熟小型西瓜一代杂种。早熟,全生育期75d,果实发育期25d;果实高球形,果皮翠绿覆深绿色条带,果形端正,果个均匀,外观漂亮,果实膨大速度快;果皮薄,厚0.5cm;瓜瓤黄色,瓤质脆沙细嫩,味甜爽口,口感风味佳,中心可溶性固形物含量12.55%;单果重2.0～2.5kg,果皮韧性好;抗枯萎病、炭疽病;667m2产量架式栽培3200kg左右,爬地栽培2200～2700kg。适宜黑龙江省及气候相似地区春季保护地栽培。     

小果型无籽西瓜新品种满春红的选育

满春红是开封市蔬菜科学研究所以诱变稳定的小果型四倍体4X-62作母本,以小果型二倍体自交系X-21为父本配制而成的小果型无籽西瓜新品种,2007-2009年早春大棚种植对比筛选试验与示范表现良好。果实发育期30d左右,植株长势强,果实高圆形,皮色淡绿底覆墨绿条带,瓤色鲜红,中心糖12.5%~13.5%,品质特佳,汁多味甜,肉质脆爽,白色秕籽少,皮厚0.6cm,皮韧耐运,单瓜质量2.5~3kg,连续坐果能力强。其突出特点是：植株长势稳健,抗病性强,早熟性、丰产性和品质均优于江、浙大面积推广的小玉红无籽,较耐低温、弱光,适宜日光温室及大棚早春设施栽培。     

辣椒新品种胜寒740的选育

胜寒740是以辣椒自交系15-Y24为母本,以辣椒自交系15-Y36为父本配制而成的中早熟辣椒一代杂种。始花节位为第10~11节,植株生长旺盛,连续坐果性强,产量高。青熟果淡绿色,老熟果红色,果实长牛角形,纵径26~30 cm,果肩宽约5.2 cm,单果质量120~170 g,果肉厚0.4 cm左右,耐贮运。抗TMV,中抗CMV。突出特点是耐低温能力强,在我国北方日光温室越冬一大茬生产中,每667 m~2产量可达7 000 kg以上。是适宜日光温室越冬生产的专用品种,同时也适于北方保护地早春茬、秋冬茬种植。     

Effects of NH4:NO3:urea ratio on cut roses yield, leaf nutrients content and proton efflux by roots in closed hydroponic system

The effects of the NH₄:NO₃ ratio in replenishment solution on Rosa L. flower yield and the impact of NH₄ substitution by urea on plant performance and on solution EC and pH have not been studied previously in closed (no leaching) hydroponic systems. A greenhouse experiment with six NH₄:NO₃:urea ratios (0:100:0, 12:88:0, 25:75:0, 50:50:0, 100:0:0 and 0:50:50) and two harvest cycles (winter and spring) was carried out to investigate these relationships. In winter, total and >40 cm cut flower yields were maximal in treatment 25:75:0. At lower NH₄ percentages (12.5:87.5:0 and 0:100:0), growth container solution pH varied between 7.8 and 8.5, reducing P, Ca and Mn concentration in leaves and increasing dry matter allocated to them. At higher NH₄ percentages, Ca uptake was inhibited, solution pH reached 3, and %P in leaves increased. Consequently, reducing sugars concentration in leaves increased and sucrose and starch concentrations decreased. A stepwise regression analysis indicated that the optimal NH₄:NO₃ ratio in feed solution is 40:60, with resulting solution pH of 5.9 in the growth container. In spring the maximum yield was obtained in treatment 0:50:50 and it exceeded the winter yield despite a higher solution EC (4.3 dS m⁻¹ vs. 3.5 dS m⁻¹ at harvest). The beneficial effect of urea (0:50:50 vs. 50:50:0) stemmed from the relatively lower NH₄ concentration in solution, that alleviated the NH₄–Ca uptake competition, and higher pH. The slope of the straight line relating [H⁺ efflux rate] to [NH₄⁺ uptake rate] in treatments 25:75:0, 50:50:0 and 100:0:0 was 0.44 mol H⁺/mol NH₄. In all other treatments the proton efflux was negligible.     

越冬栽培与冬贮‘潍县青’萝卜的品质比较

为供应早春市场,在山东地区比较了利用不加温日光温室冬季生产的与贮藏的‘潍县青’萝卜肉质根品质。结果表明:温室栽培萝卜的含水量、维生素C含量、可溶性蛋白含量及淀粉酶活性显著高于贮藏的萝卜,且其根长大于30cm的‘潍县青’萝卜营养和风味品质较好;利用不加温日光温室冬季生产‘潍县青’萝卜供应早春市场是可行的,其皮色鲜绿、肉质脆嫩、适口性强,商品性较好,经济效益高。