Crop yield response to water - Cra
Crop yield response to water - Cra Crop yield response to water - Cra
several others since that time have found that Stage II is not sensitive to water deficits interms of negatively impacting yield. It has been shown (Girona et al., 2003) that significantwater deficits applied during Stage II may induce some dehydration of the fruit, but thatsubsequent recovery of fruit growth is usually complete after the water stress is relieved atthe onset of Stage III, and that Stage II water deficits have no impact on final yield.Even though there has been an initial report showing (Chalmers et al., 1981) increased fruitsize, relative to fully irrigated controls, when applying RDI in Stage II, no other publishedpapers reported such results, with one exception (Girona et al., 2003) for a single season in athree-year study, where low temperatures at blooming time damaged many fruit and the finalfruit load was very low. A comprehensive analysis of the effect of fruit load on the response toRDI at Stage II (Girona et al., 2004), detected larger fruit in the RDI treatment compared withan unstressed control only with low fruit loads, and as the fruit load increased, no effects weredetected and in some cases, even a reduction in fruit size was observed. Presumably the RDI inStage II enhances fruit growth relative to unstressed controls by directing more carbohydratesto fruit growth, but this phenomenon apparently occurs only with low fruit loads (Girona etal., 2004). There have been reports of less fruit drop before harvest under RDI (Girona et al.,2003), and this could explain the few observations where water deficits during Stage II hadpositive effects on yield, relative to fully-irrigated treatments.Vigorous fruit expansion takes place during Stage III when the rate of fruit expansion ishighest and most sensitive to water deficits. Fruit water content is more sensitive to waterdeficits than fruit dry weight during this period. A reduction of 25 percent in fruit watercontent occurred with Stage III water deficits in a medium peach cultivar (Girona et al., 2004).Water deficits that affect fruit dry matter accumulation must be quite severe because, notonly must they decrease photosynthesis but they must also counterbalance the tendencyof many fruit trees, including peach, where assimilate allocation to fruit has higher priorityrelative to its distribution to other tree parts (DeJong et al., 1987). Leaf photosynthesis andtree transpiration in peach are not affected by water deficits until more than 50 percent ofthe available water in the root zone is depleted (Girona et al., 2002). When water deficitsoccur under these conditions, the peak of daily Tr moves from a plateau between noon and14:00 hours towards the morning hours, and by the time Tr was reduced by 70 percent, themaximum Tr rate occurred at 9:00 am hours (Girona et al., 2002).Indicators of peach tree water status are used to quantify the water stress levels. A comparativestudy among different indicators (Goldhamer et al., 1999) found that indices derived frommicrometric measurements of trunk diameter fluctuations were the most sensitive forwater stress detection, followed by stem-water potential. Other indicators such as stomatalconductance, leaf photosynthesis, and leaf temperature were less sensitive (Goldhamer et al.,1999).Water deficits may have a negative impact on fruit appearance in the next season. Anincreased frequency of fruit doubles and deep sutures have been observed in water-stressedpeach trees (Johnson and Phene, 2008). These problems have been overcome by relievingthe water stress shortly before and during carpel differentiation (Johnson et al., 1992). Withearly-season cultivars, this stress-sensitive period is in August and September and suggestsavoidance of water deficits during these months (Johnson and Phene, 2008). For a midseasoncultivar, the increase in occurrence of double and deep suture fruit is highly correlated with398crop yield response to water
the midday stem-water potential in August of the previous year, i.e. during the initial stagesof flower bud development (Naor et al., 2005). The occurrence of double fruit was observedto increase sharply as the midday stem-water potentials fell below -2.0 MPa, suggesting thata midday stem-water potential of -2.0 MPa could serve as threshold for postharvest irrigationscheduling (Naor et al., 2005).Fruit set can also be influenced by postharvest stress. Both early season (Johnson and Phene,2008) and midseason (Goodwin and Bruce, 2011) cultivars found that fruit set was moderatelysensitive to the degree of water stress during the previous season’s postharvest period. In lateseason-cultivars, fruit set was highly affected by the level of water stress during postharvest,as shown by the strong correlation between the average leaf water potential during thepostharvest period and the fruit set (Girona et al., 2004) (Figure 4). The negative impact ofwater deficits on fruit set in the next year may not be important as thinning is a commonpractice in peach, but severe impacts on fruit set cannot be corrected by thinning (Goodwinand Bruce, 2011).Moderate water deficits applied during Stage II improved fruit quality (firmness, colour,improved TSS) without affecting yield (Gelly et al., 2003 and Gelly et al., 2004). Moderatewater stress in Stage III also improves fruit quality, but a negative impact on fruit size and yieldis very likely. The trade-offs between quality and size must be resolved bearing in mind themarket where the produce will be sold.Figure 4Relationship between fruit set 2 months after full bloom in 1996 and seasonal average middayleaf water potential experienced under several irrigation treatments during the previous yearat postharvest (Girona et al., 2004).ControlRDI -SIIRDI -P RDI -SII -P3025R 2 = 0.83Fruit set (%)2015105- 1.20 - 1.70 - 2.20 - 2.70 - 3.20Leaf water potential at midday during postharvest (MPa)peach 399
- Page 355 and 356: Figure 10Response of marketable fru
- Page 357: Failla, O., Zocchi, Z., Treccani, C
- Page 360 and 361: Figure 1 Production trends for plum
- Page 362 and 363: soil water. In young orchards, post
- Page 364 and 365: Figure 3 Relationships between rela
- Page 366: ReferencesAllen, R.G., Pereira, L.S
- Page 369 and 370: Figure 1 Production trends for almo
- Page 371 and 372: FIGURE 2The three stages of almond
- Page 373 and 374: Figure 3Differences in the cultivar
- Page 375 and 376: Indicators of tree water statusTo p
- Page 377 and 378: nuts are rapidly expanding and late
- Page 379 and 380: ReferencesAyars, J.E., Johnson, R.
- Page 381 and 382: Table 2 (Continued)Year TreatmentWa
- Page 383: Table 3 (continued)Potential900 mmA
- Page 386 and 387: Figure 1 Production trends for pear
- Page 388 and 389: (Elkins et al., 2007). The appearan
- Page 390 and 391: out in Spain under more common grow
- Page 392 and 393: Figure 4Relationships between the p
- Page 394 and 395: Data in Figure 5 suggest that there
- Page 396 and 397: e saved, but this causes a reductio
- Page 398: pear 389
- Page 401 and 402: Figure 1 Production trends for peac
- Page 403 and 404: Figure 2bEvolution of vegetative (s
- Page 405: The postharvest period is important
- Page 409 and 410: PHOTOPeach leaf appearance under th
- Page 411 and 412: FIGURE 5Relation between the crop c
- Page 413 and 414: In applying RDI strategies an impor
- Page 415: peach 407
- Page 418 and 419: Figure 1 Production trends of walnu
- Page 420: 1 100 mm, a team in California appl
- Page 423 and 424: Figure 1 Production trends for pist
- Page 425 and 426: There are two types of shoot growth
- Page 427 and 428: FIGURE 3Time course development of
- Page 429 and 430: Stage III was the most stress sensi
- Page 431: (see Chapter 4), as in other specie
- Page 434 and 435: Table 2 Suggested RDI strategies fo
- Page 437 and 438: Lead AuthorSCristos Xiloyannis(Univ
- Page 439 and 440: is completed within 20 days; therea
- Page 441 and 442: or peach. However, because fruit is
- Page 443 and 444: to a midday value varying between -
- Page 446 and 447: Lead AuthorRaúl Ferreyraand Gabrie
- Page 448 and 449: The most critical developmental per
- Page 450 and 451: Figure 4Effects of the level of app
- Page 453 and 454: Lead AuthorJordi Marsal(IRTA, Lleid
- Page 455 and 456: water stress should not be imposed
the midday stem-<strong>water</strong> potential in August of the previous year, i.e. during the initial stagesof flower bud development (Naor et al., 2005). The occurrence of double fruit was observed<strong>to</strong> increase sharply as the midday stem-<strong>water</strong> potentials fell below -2.0 MPa, suggesting thata midday stem-<strong>water</strong> potential of -2.0 MPa could serve as threshold for postharvest irrigationscheduling (Naor et al., 2005).Fruit set can also be influenced by postharvest stress. Both early season (Johnson and Phene,2008) and midseason (Goodwin and Bruce, 2011) cultivars found that fruit set was moderatelysensitive <strong>to</strong> the degree of <strong>water</strong> stress during the previous season’s postharvest period. In lateseason-cultivars, fruit set was highly affected by the level of <strong>water</strong> stress during postharvest,as shown by the strong correlation between the average leaf <strong>water</strong> potential during thepostharvest period and the fruit set (Girona et al., 2004) (Figure 4). The negative impact of<strong>water</strong> deficits on fruit set in the next year may not be important as thinning is a commonpractice in peach, but severe impacts on fruit set cannot be corrected by thinning (Goodwinand Bruce, 2011).Moderate <strong>water</strong> deficits applied during Stage II improved fruit quality (firmness, colour,improved TSS) without affecting <strong>yield</strong> (Gelly et al., 2003 and Gelly et al., 2004). Moderate<strong>water</strong> stress in Stage III also improves fruit quality, but a negative impact on fruit size and <strong>yield</strong>is very likely. The trade-offs between quality and size must be resolved bearing in mind themarket where the produce will be sold.Figure 4Relationship between fruit set 2 months after full bloom in 1996 and seasonal average middayleaf <strong>water</strong> potential experienced under several irrigation treatments during the previous yearat postharvest (Girona et al., 2004).ControlRDI -SIIRDI -P RDI -SII -P3025R 2 = 0.83Fruit set (%)2015105- 1.20 - 1.70 - 2.20 - 2.70 - 3.20Leaf <strong>water</strong> potential at midday during postharvest (MPa)peach 399