H495 Independent Study Fresh Market Lettuce Production Spring 2005, 2credits Peter Mendicino

Transcription

1 H495 Independent Study Fresh Market Lettuce Prductin Spring 2005, 2credits Peter Mendicin

2 Intrductin: Due t the relatively shrt lifecycle, and quick prductin capabilities, lettuce has pertinence and value as a greenhuse crp. Lettuce mixes and specialty salad greens have becme increasingly ppular at framers markets, all-natural grcery stres, and restaurants, ften by means f direct marketing. A gd example f this is currently demnstrated by the CSU Specialty Crps Prgram. Fresh market salad mix is grwn in the greenhuse, harvested and delivered t the Aspen Grill, all taking place n the CSU campus. A greenhuse lettuce prductin system has been develped, and is in current peratin. This prductin system utilizes several methds and techniques f prductin which have been discvered largely by repetitin, experimentatin, and thrugh the applied knwledge f the SCP staff. In this prject I will be wrking t better quantify and evaluate bth new and existing prductin practices currently in peratin by the Specialty crps Prgram. Thrugh the effrts f this prject: recmmendatins, bservatins and results will be applied t the advancement and prgressin f the existing salad prductin system. In rder t better understand the grwing regime f fresh salad greens and lettuce mixes in the greenhuse envirnment, I will be cnducting research and study invlving media selectin, fertility, seeding densities and their pertinence t the cultivatin f fresh market salad greens. The cultivatin f this lettuce will take place in the Specialty Crp s qunest #1. Prductin systems will cnsist f 5 Hydrpnic NFT trughs and 9 trughs f sil culture. The main variety f lettuce prduced will be All-Star gurmet lettuce mix. Objectives: The main bjective f this experiment is geared twards the advancement f prductin practices that will result in the highest quality f lettuce yield. Develping a general sense f the prductin scheme required t prduce a crp f quality lettuce will becme an inherent part f this prject. Anther bjective is t develp seeding density rates fr All-Star that will ptimize the existing prductin system f rganic salad mix. Anther bjective is t quantify the fertility value f incrprating vermicmpst int the grwing media. Objectives will als

3 cnsist f mnitring plant grwth and crp duratin as well as dcumenting thughts and ideas relevant t future prductin. Hypthesis: T determine hw much f a rle fertility and media selectin play in develpment and grwth f a quick crp like lettuce? Materials: The majrity f the materials necessary fr this prject have been prvided by the Specialty Crps Prgram, and thrugh the use f available resurces at the Plant Envirnmental Research Center. In exchange fr greenhuse space this prject will prvide lettuce t the Specialty Crps Prgram. Aside frm bench space inside the greenhuse the fllwing materials are needed t help facilitate this study: Seeds: All-star Gurmet Lettuce Mix, Butterhead-Burpee & Sweet Red Hydrpnic system: 5 cleaned trughs and return system (1 trugh) ¾ PVC pipe and misc. fittings Pump Drip/emitter tubes 10 galln tank Organic fertilizer Bi-Buzz 1 rckwl cubes 1 asis grw cubes Media: Sunshine carse Organic mix, by Sun Gr Sunshine carse rganic mix, by Sun Gr Sun leaves hrticulture Cir Vermicmpst Harvesting shears Scale Watering system Digital Camera Methds: The design and cnstructin f the prductin system was the initial step in this prject. Recycled NFT hydrpnic trughs were used as the cntainer device. A ttal f 14 trughs will be used in this prductin system, incrprating bth sil and hydrpnic culture. Trugh measurements are 13 in length and apprximately 3 wide by 2.6 deep. These trughs are t be supprted by a grwing bench inside the greenhuse. This bench will supprt 9 trughs f sil culture and five trughs f hydrpnic culture. The sil culture trughs will cnsist f three different sil mixes, each mix will have a set f three replicatins with a different seedling rate

4 (ttal f nine sets f three). Each set within the trugh will share the same media, but will have its wn specific seedling rate. The hydrpnic trughs run n an independent circulating system. Figure 1 displays a map f the prductin design. Fig 1. After the cmpletin f the prductin system, all trays were ready t be filled with their respective media and swn with seed. The media was brken up evenly t a suitable tilth and used t fill the three trughs. The cntrl set cnsisted f Sunshine carse rganic mix by Sun Gr; this mix is relatively free f any micr and macr nutrients. The next sil treatment cntained the same Sun Gr rganic mix, but was cmbined int a 4:1 rati with Jhn Andersn s Vermicmpst wrm castings. The sil and castings were measured and blended tgether with a small cement mixer then filled int the trughs. The third mix cnsisted f Sunleaves hrticultural cir blended with vermipst at the same rate f 4:1. On March 15 th, 2005 the nine trughs f sil culture were planted with their respective densities. T accmplish this planting each set f 3 trughs was gruped by their respective grwth substrate. Frm here, fllwing the system design, each set was divided int equal thirds and swn with its crrect seedling rate. Seed densities were adapted frm pre-existing

5 prductin practices develped by the Specialty Crps Prgram. The fllwing densities were swn: 0.75ml, 1.0ml and 1.5ml. Seed densities were measured in a small incremental ml vial. Seeds were carefully dispersed by a gentle tapping actin applied t the vial while simultaneusly mving dwn the trugh, this was repeated tree times (nce fr each replicatin in the set f 3 trughs). In ther wrds each trugh in its respective seeding density had 1/3 f the ttal seeds fr that treatment. This prcess was cmpleted a ttal f nine times. After each sectin was seeded a tag labeled with the date, sil mix, and variety was inserted int the sil. T prmte seedling germinatin a light cat f vermiculite, apprximately ne piece thick, was cast ver the trughs. Trughs were then carefully and evenly watered in using a Redhead water breaker and mved t the greenhuse bench. Cnsult figure 2. In addressing the irrigatin practices and needs f the prductin system, all attempts t apply irrigatin in a unifrm and cnsistent methd were applied. Sil trugh treatments received water every mrning between the hurs f 8:00 and 9:00 P.M. In the instances f ht days and high temperatures in the greenhuse, additinal applicatins f water in the afternn hurs became warranted. In rder t best evaluate crp grwth, additinal fertilizatin was nt incrprated int the watering schedule. On March 15 th, Fig , the cnstructin f hydrpnic system was cmplete. In this system all five trughs ran ff a circulating system pwered by a pump, return trugh, and a 10- galln sump tank. Water is directed int the trughs via an irrigatin

6 manifld cnnected t the pump. Emitter tubing runs frm the manifld t a small plate secured t the trugh int which the drip line is inserted and stabilized. Frm here water trickles dwn the trugh int the return gutter/return trugh and is pured back int the sump tank. The sump tank was filled with water and Bi-Buzz rganic fertilizer at a rate f 2ml per liter water. On March 16 th the hydrpnic system was planted, cnsult fig. 3. Trugh 1 cnsisted f Oasis rckwl grw cubes, these cubes were planted with All- Star, Burpee Bibb Butterhead and Sweet Red Figure 3 Butterhead lettuce varieties. The remaining 4 trughs used a slightly different grw cube, similar in size t that f the rckwl cube, but much mre dense. This brand was hydrtn. Tw f the fur trughs were planted with All- Star; the remaining tw trughs were planted with Sweet Red and Burpee Bibb butterhead varieties. Befre planting, all grw cubes were placed int the running system fr 24 hurs. This allwed the cube t becme saturated with water prir t planting the seed. One seed was drpped int each grwth cube. In effrt t keep the seed in the cube nce germinatin started, a small amunt f vermiculite was gently packed int the seedling hle. Grwth f the lettuce was terminated at the time a quality, harvestable plant size was btained. Observatins: On Saturday March 19 th, after planting, all seeds in the sil trughs displayed their first signs f germinatin. Small seedlings had emerged and were just beginning t pke trugh the surface f the vermiculite. On this date all seed densities in each trugh displayed an initial emergence t varius degrees. Sme treatments had mre emergence than thers. Althugh each treatment was relatively yung at this pint, the Sun Gr rganic media treatments seemed t shw the mst

7 prminent germinatin. Als n this date a lack f germinatin in the hydrpnic system was visible. During the fllwing week f March 21 st seedlings in all sil sets were shwing signs f early plant develpment. By the end f the week seedlings frm each treatment were starting t elngate slightly and exhibit ctyledns. On Wednesday March 30 th, 15 days after seeding, the ctyledns n these yung lettuce plants began expand and grw in size. On March 30 th the majrity f seeds in the hydrpnic system were just beginning t sprut. By Sunday, April 3 rd, all seedlings in each set f treatments were just beginning t sprut their first set f true leaves. Figure 4 displays the prductin system n Tuesday, April 5 th. At this date the differences in seeding densities were starting t be clearly expressed, bservatins were als easily made. The 1.5ml density displayed a mre visible patch f yung, green grwth than bth the 1.0ml and 0.75ml seedling densities. Plants within each density began t exhibit slightly darker and lighter clrs. The variatin f seeds within the All-Star mix was becming evident. In terms f the healthiest and best lking trughs, the treatments within the Figure 4.

8 4:1 Sun Gr / vermipst set appeared larger and mre attractive than the thers. On this same date the 4:1 Cir/vermipst set lked slightly larger and a little healthier than the cntrl set. The seeds in the hydrpnic system have all emerged frm their grw cubes. Sme seeds are standing up while thers have flpped ver. On the fllwing Mnday, April 10 th, the lettuce plants in the sil sets began t exhibit a significant amunt f new grwth in terms f plant height and width. The media set cmpsed f the 4:1 Sun gr/vermipst mixture was unanimusly utperfrming bth the cntrl and cir sets. This bservatin was bvius. At this pint the cir set exhibited mre lush grwth than that f the cntrl. During this week it als came t my attentin that the cir trughs were much mre prne t drying ut than thse cntaining the Sun Gr mix. On ht days the drying ut f the sil was bserved in all trughs; hwever the drying was especially evident in the cir treatments. T cmbat drying f the trughs additinal irrigatin was applied in the afternn. Measurements in the frm f ph and E.C. were als taken n April 10 th, see the fllwing table. Treatment ph EC ppm Greenhuse water Cir/vermipst 4: Sunshine/vermipst 4: Cntrl (just Sunshine) On April 10 th, the hydrpnic trughs started t becme slightly cvered in algae. This grwth was cntained n the inside f the trughs and n the surface f the grw cubes. The presence f fungus gnats and several shre flies was bserved. On this date the water in the sump tank was changed. The trughs were als cleaned and any grw cube that did nt sprut was dispsed f. Cvers were als placed ver the trughs t prevent algae and evapratin. The grw cubes were inserted int the hles n the trugh cvers. It seems as if the tank needs t be re-filled n a semi regular basis, abut every hurs. The evapratin f water frm the

9 tank and entire system seems greatly dependent n the weather cnditins and temperatures. Overall, the grwth f seedlings had yet t significantly prgress. By April 15 th the hydrpnic system had yet t respnd t the changes made t the system. In the sil culture, plant respnse was clearly displayed between the three different sets. Once again the 4:1 Sunshine/vermipst set was the mst prlific set f the three. Plants within this set had the fullest size, and mst grwth. These plants were 30 days ld and had nice, thick, glssy leaves. This set appeared t be harvestable. Ranked secnd was the cir set; this set had exhibited little grwth and lked slightly stunted when cmpared t the sunshine/vermipst set. A lack f nutritin was bserved by the slightly chlrtic plants within the cir set. The cntrl appeared t be shwing sme new grwth, the lettuce leaves were slightly smaller than thse f the cir but had a much healthier lking appearance. On April 19 th the Sunshine/vermipst set clearly demnstrated advanced grwth, larger leaves and thicker lking plants. The cntrl set lked healthier than thse in the cir set, they were relatively the same size. Figure 5, cntains a pht f the system taken n April 19 th Figure 5.

10 Once again the grwth f the 4:1 Sunshine/vermipst was unanimus. Figure 5, displays a side by side cmparisn f the cir set n the left side, and the Sunshine/vermipst set n the right side. Figure 6 is a similar image but cmpares the Sunshine/vermipst n the left t the Sunshine cntrl n the right. These images reveal a nice cmparisn between the media sets. Nutritinal deficiencies are als present in these images. Figure 5. On the fllwing day f April 20 th all three densities f the 4:1 Sunshine/vermipst set were harvested. Each seeding density exhibited nice clr, but when cmpared t the cntrl, was less intense. The 1.5mL density seemed t be in high cmpetitin, the mst dense, and displayed the largest size and f the three densities. The individual plants in this set were the largest. The 0.10mL density appeared t have the best spacing between plants, being slightly less dense than the 1.5mL. The presence f aphids n this density was nt bserved. The 0.75mL treatment had similar plant spacing t the 1.0mL but individual plant size was several cm smaller. Als n this date the hydrpnic system was terminated due t an insufficient amunt f time t finish the crp.

11 On April 26 th the Sunshine cntrl set was ready t be harvested and delivered t market. All trughs in this set displayed attractive plant clrs and hues, nt bserved in the ther sets. Hwever, the quality f this lettuce seemed less than that f the first harvest. The 1.5mL treatment displayed gd rbust plant size and nice green clr, these plants were abut 3-3 ½ inches tall. This treatment had a small presence f aphids. The plants in the 1.0mL treatment displayed the highest ppulatin f aphids in the prject thus far. These plants were slightly smaller than the 1.5mL plants, rughly 1-2 cm shrter. This treatment had a very unifrm canpy and nice spacing amngst the plants. The last f the tree treatments, the 0.75mL plants were cnsiderable smaller than thse f the ther densities, the plants in these densities were apprximately half the size f the plants in the 1.5mL densities. Aphids were detected in sparse ppulatins. Btrytis cinerea was als detected n the sil surface in 2 spts. Observatins were als recrded fr the cir set n April 26 th. Grwth f the plants within the cir set were less than half the size f their cunterparts in the cntrl set. Clratin f the lettuce was als much less prnunced than in the cntrl. Plants almst seemed t be stunted and displayed signs f nutritinal deficiencies. In this set the 1.5mL densities displayed the best health and fullest, mst rbust grwth. On May 3rd the remaining three 4:1 cir/vermipst trughs were ready t be harvested. Due t slw grwth and market demand, this set was fertilized with Old Age Organics Grwing Mix, a ttal f tw times. All densities within the set had reached the height f rughly 2-1/2 t 3 inches in height. The plants seemed t respnd nicely t fertilizer applicatin. The 1.5,L densities displayed nice thick grwth, these were the mst prminent treatments in the set. The 1.0mL was smaller than the 1.5, hwever it retained a nice spacing and canpy cver. The 0.75mL treatment was sparse and quite small. Results and Discussin: Thrugh the duratin f the prject many bservatins and discveries were made, gaining insight in the prductin f fresh market salad greens. In terms f the general design and implementatin f the prductin system all aspects went quite smth, especially the sil

12 culture. One discrepancy I ran int when planting the seeds was measuring each seeding density. A small vlumetric 50 ml vial was used t measure seeds. This vial had been marked with three lines each crrespnding t a different seed density. When measuring the seeds it was ften difficult t get the exact amunt, especially n a cnsistent basis frm ne density t the next. Regardless all attempts were made at unifrmity. Aside frm minr difficulties in measuring the seed the planting f the trughs was a relatively easy and quick prcess. The main challenge was mving the trughs int Qunset 1 frm the prp huse. The germinatin and grwth f the seed seemed t be successful. The vermiculite really seemed t help maintain misture levels fr the seedlings. The grwth and develpment f the lettuce went very well. It was quite interesting t watch its varius grwth stages and respnse t the media set. In the first tw weeks the lettuce plants within the three sets were relatively the same size, making it difficult t bserve many differences in character. Once the plants really began t grw, abut halfway thrugh the secnd week f the prject, it became very bvius which media sets and seedling densities were utperfrming the thers. The additin f the vermicmpst t the media prved t be a huge factr in the success f specific plantings. Overall the mst prlific set f trughs were thse cntaining the 4:1 sunshine/vermipst blend. Plants in this set exhibited the mst lush, thick grwth while als grwing faster than any f the ther cmparisn sets. Every time bservatins were recrded this set was hands dwn the largest in size and in new grwth, usually tw times that f the ther sets. Interestingly the Sunshine cntrl set seemed t utperfrm the 4:1 cir/vermpst in the lng run. The cntrl set had the nicest leaf clr thrughut the entire experiment (see figure 6), and was als ready t harvest ne week befre the cir/vermipst set. The cir set was very prne t drying ut. Bth Sunshine sets appeared t maintain gd sil misture levels. Hwever when the sil was drught stressed it tended t get a little dry, and cnstricted quite a bit. In terms f seed densities the 0.75mL seemed t be a little lw in quantity. This was bserved by a cnsistent lack in size and relatively lw plant density cmpared t the ther treatments. The 1.0mL density prvided a nice canpy and gd plant size. This density

13 seemed t maintain a much mre unifrm grwth habit than that f the 1.5mL treatment, while als maintaining a lw incidence f aphids. The 1.5mL density prvided the fullest and mst dense grwth. Trughs planted with this density seemed t be in high cmpetin with ne anther, the plants als grew at a much quicker pace than the thers. This density seemed t fster the highest ppulatins f aphids, pssibly due t the clseness f the lettuce leaves. The duratin f the lettuce crp als seemed t be an integral factr in the appearance and grwth f the plants. It was bserved that the plants in the higher densities, especially the 1.5mL, were grwing much faster than the thers. This fast grwth seemed t result in a slight variatin in plant size. Sme plants were large while thers were quite small. The 1.5mL density wuld be gd fr a fast and quickly prduced crp. Overall I think the 1.0mL density prvided the mst unifrm and predictable grwth. The fllwing is a table illustrating harvest dates and yields. The hydrpnic culture was mre difficult and time cnsuming than that f the lettuce. The planting f the hydrpnic grw cubes tk a cnsiderably lnger amunt f time than thse in the sil treatments. Minr difficulties were encuntered in drpping nly ne seed int each grw cube. Applying the vermiculite t each seedling hle was als a very time cnsuming prcess. Maintaining an adequate water level in the sump tank was als difficult, primarily due t high temperatures and surface evapratin. The sump tank was tpped ff rughly every hurs, a 20 galln sump wuld have been better suited. Due t the relatively slw grwth f the lettuce in the gr cubes the hydrpnic system was cut shrt. This was due in part t many variables. The first being a cnsiderable delay in the grwth f the lettuce, and the slw prgressin f the varius species planted. The high input f resurces such as refilling the water tank every day, the cst f sufficient fertilizer, cnstantly mnitring the ph and E.C levels, and the high time requirements, warranted its terminatin.

14 Cnclusin: The system f trugh prductin seemed a little inefficient at times; in the future I wuld use a different cntainer system. A shallw harvesting tray r large flat wuld be a mre efficient cntainer t grw in. Frm this experiment the best means by which t culture the lettuce seemed t be rganic sil ver rganic hydrpnics. The culture f hydrpnic lettuce seemed slwer and mre demanding than the sil prductin. Incrpratin f the vermipst prved t be quite beneficial. In terms f sustainable practices reusing the sil might prve t save mney and time. The relatively shrt time frame f the lettuce crp has frmulated the basis f my cnclusins. Althugh there are many factrs ne culd manipulate in this experiment I think keeping things simple is the best apprach in this kind f greenhuse peratin. In cnclusin and in rder t prduce a quality and quick crp f lettuce f fresh salad greens I wuld utilize the fllwing practices; Plant all seeds at a density f 1.0mL int pre-mistened 4:1 sunshine/vermpst mix, prvide ne r t treatments f supplemental fertilizatin during week three f grwth and harvest when the plants are days ld. Figure 6 cmparisn f cir (left side) t cntrl