Effects of climatic gradient on growth performance, yield components, and chemical composition of lentil legume crop

The main goals of the present study were to characterize, evaluate, compare and determine the suitability of lentil legume crop (Lens culinari Medik., var. Baladi) to different Palestinian agro-ecological locations namely Dora, Al-arroub and Janata. Different morphological traits, yield components and some grain quality parameters were registered. Obtained data were statistically analyzed using MINITAB package system. Results showed highly significant environmental (locations) effects for almost all measured traits. In general, Al-arroub site showed higher morphological and yield values; whereas Janata site presented the lowest values. However, no significant variations were observed for all conducted chemical parameters (dry matter, protein content and ash) among the three examined locations. Drought and the limited water availability are the main factors affecting lentil ontogeny and yield, but not the quality variables. Lentil is not recommended for regions of precipitations lower than 250 mm.


Measured and evaluated parameters
Different agro-morphological parameters including: germination date (when 50% of the total germination occurred), flowering period (the period lasts from the beginning of flowering until all plants were flowered), fruit set period (the period lasts from the beginning of fruit set until all the fruit set of all plants were done), maturation and harvesting period (plants considered mature, when 50% of the maturation occurred and when the moisture contents of the seeds reaches 15%), stem length (from the stem base up-to the stem apex in centimeter), number of branching (using randomly one square meter frame-quadrate per plot), and number of grain per pod were registered [15].
At the maturity stage, plants of each plot were harvested manually, and then sub-dried for a week. Continually, total fresh yield was recorded in kilo-gram (kg). Then, each crop was sun dried and then threshed separately.
The grain weight of each plot was recorded in kg and hay yield of each plot was calculated by subtracting the grain yield from the total yield. In addition, weight of 100 seeds per crop was registered. Finally, obtained data were subsequently converted into kg/dunum (kg/1000m 2 ).
For grain quality parameters, representative seed samples were collected from the three sites. Seeds were ground in a Wiley mill, and then stored in sealed jars [16]. Chemical analysis including: Dry matter was determined using an oven at 65°C for 24 hours [17]. Crude protein was determined by estimating nitrogen content using Kjeldahl procedure; percentage of crude protein obtained by multiplying the nitrogen concentration by 6.25 (NX 6.25); and ash content was determined using igniting in muffle furnace at 550 o C for 8 h [16].

Data analysis
The data were statistically analyzed using the one-way analysis of variance (ANOVA) and means were separated using the Tukey's pairwise comparisons at a significance level of p ≤ 0.05 using the MINITAB package system.

Germination and morphological parameters
As shown in table 1, germination took 10-11 days at Janata and Dora sites; however, it took longer time at Alaroub site by 14 days. Flowering period was almost similar at the three evaluated sites which last from 6-7 days.
Fruit set period lasts 7 days at Janata site, 8 days at Dora site, and 11 days at Al-aroub site. Maturation and consequently harvesting date was earlier at Janata site with 23 days, followed by Dora site 27 days; whereas, maturity stage at Al-arroub site took longer time compared with the other two examined sites.
Significant variation in stem length variable between the three different sites was observed, in which Al-arroub site revealed significantly higher stem length followed by Dora and Janata sites, respectively. In reference to crop branching, Al-arroub and Dora sites revealed higher branching than Janata site. Number of grain per pod showed similar at the three evaluated sites.
Significant variations in the weight of 100 seeds at three different sites were also exhibited. Al-arroub site revealed significantly higher seed weight (7 gram), followed by Dora (6 gram) and Janata (5.56 gram) sites respectively.

Yield parameters
Based on the analysis of variance (Table 2), and comparing with the other two sites, lentil crop at Al-arroub site exhibited significantly the highest yield (grain and hay) by 471.2 kg/dunum (1000m 2 ); however, the lowest yield was presented at Janata site by 288 kg (Table 2). Regarding the total grain production, Al-arroub site presented the highest grain production (43.7 kg), followed significantly by Dora site (18.3 kg), and Janata site with only 4 kilo gram per dunum. Similar trend goes also with the total hay production parameter.

Chemical composition
Dry matter, protein content, and ash variables of lentil crop presented similar results with those of broad bean and chickpea crops, in which the sites have no significant differences among these examined parameters (Table   3) (http://www.feedipedia.org).

Germination
Germination is a critical phase in plant growth that determines plant establishment and final crop yield [18].
Here, our examined crop showed earlier germination date at Janata, followed by Dora and Al-arroub sites respectively. Since the same genotype was repeated at the three sites with the same cultural practices (sowing), and the first rainfall date occur at the same time, therefore the environmental fluctuation among the three sites might explain the differences in the germination period among the three examined sites. In fact, germination period of any crop is depending on the prevailing different agro-climatic condition, in which temperature and rainfall are the most important factors. The high temperature characterized Janata might be the reason for the early germination at this site. Similar results confirmed by [19], who stated that faster germination temperature occurs at high temperature. Furthermore, [20] indicated that the optimal temperature for seed germination of winter legume crops is about 10-15 0 C and high germination temperatures are considered to be 22-35 o C.
Furthermore, germination is directly related to the amount of water absorbed, in which germination rate and the final seed germination decrease with the decrease of the water movement into the seeds during imbibition period [21].

Flowering, fruit set, and maturation periods
Similar trends goes also with flowering, fruit set, and maturation periods, in which lentil crop presented earlier periods at Janata, intermediate at Dora and late flowering, fruit set and maturation periods at Al-arroub sites.
The long flowering, fruit set and maturation periods exhibited at Al-arroub site might be related to the long rainfall and cold season period [22], compared to the drought once at Janata. Accordingly, water stress led to significant decrease in number of days to flowering and maturity stages [23]. This result also in agreement with [24] who found significant differences in days of flowering for some legume cultivars. Furthermore, [25] showed that faba bean legume crop had longer time to flowering when grown under irrigation condition than those grown under rain-fed conditions confirming therefore the significant effects of rainfall period.
Concerning fruit set, it is well documented that there is a significant reduction impact of heat stress on pod-set, filled pods and pod numbers per plant in chickpea legume crop [26].

Stem length
Stem length is genetically and environmentally controlled characteristic. Since same crop genotype is examined at three different locations, therefore the environmental conditions especially water availability probably explained the higher significant values presented at Al-arroub site compared with the other two sites. Consistently, similar results have been confirmed in literature [27] who pointed out that the stem length stage more affected by 19 CC BY 4.0 ) / Islamic University of Gaza IUG Journal of Natural Studies ( drought and water stress, in the event of increase drought lead to reduce the stem length (plant height) of any field crop. Interestingly, plant height is considered an important criterion discriminating among different geographic regions [24]. These results were also in agreement with [25], who found that plant height of broad bean genotypes varied significantly under rain-fed conditions. When we made correlation between stem length and total production, positive relationship was obtained. Similar correlation was found by [28].

Number of branches
No Significant variation was observed in number of branches on the main stem among the three examined sites which imply that this criterion is genetically controlled rather than environmental once. In fact, number of branch per plant and the number of pod per plant were the main constitutes of total plant yield [29].

Number of grain per pod
Environmental factors had little effect on grains per pod of chickpea as a similar legume crop and it is mainly influenced by genotypes [30]. Also, other studies indicated that for any given cultivar of similar faba bean genotype, the average number of seeds per pod is a relatively stable character [31]. Confirming to this assumption, and despite the harsh conditions at Janata site, no significant differences were noticed among the three examined sites for this variable which implying that this variable is more influenced by genetic than environmental factors.
The significant variations in the weight of 100-seeds observed at three different sites (Table 2), might be attributed either to genotype and/or environmental influences. Some researchers stated that, number of seeds per pod and 100 seed weight is relatively stable trait and did not significantly affected by the environment [32].
However, other studies showed that water deficit during the reproductive growth of legume crops is highly influences seed yield components and causes reduced pods per plant and 100-seed weight affecting thereby the total crop productivity [33]. Indeed, water stress has significant effects on all plant characteristics and especially on seed yield. Means that, despite being strongly genetically determined, seed weight also depends on climatic conditions, such as water availability or temperature regime [34]. These explanations confirmed the significant weight of 100-seeds revealed at Al-arroub site (high average rainfall and longer season) compared with Janata site (drought conditions with low average rainfall and short season).
Similar trends go also with the other yield parameters which showed low yield parameters at Janata site and high once at Al-arroub site. Supporting evidences were reported by many researchers [35], who attributed the reduction in grain yields under water deficit to the reduction in number of pods per plant, number of grain per pod and total grain weight.
In addition to water effects, temperature also played an important role in limiting the final legume production in which high temperature reduces total grain yield. Indeed, high temperature during the grain filling period can 20 CC BY 4.0 ) / Islamic University of Gaza IUG Journal of Natural Studies ( reduce the individual seed size at maturity which may lower grain yield per plant [36]. Other studies showed that, average daily temperatures of 20-25°C is required for a proper growth of some legume crops and higher temperatures led to flowers and fruits fall [37], resulting thereby in declining the total yield. Also, in another work, it was reported that heat stress during the reproductive phase in legumes is generally allied with lack of pollination, abscission of flower buds, flowers and pods with substantial yield loss [38]. Hot temperature (> 30 ºC) and dry atmospheric conditions lead to profligate loss of flower buds and open flowers in chickpea [39].
High temperature stress also causes yield losses because of damage to reproductive organs [40], and had reduced total and grain yield during drought [41]. These findings indeed could explain the general trend of low production exhibited at Janata site which characterized by a general harsh conditions in terms of water availability and drought stress.

Chemical composition
Generally, quantity characteristics are influenced mainly by environmental factors, while the quality once is largely genetically determined [42]. In fact, findings on the nature of genetic control are rather controversial, although all scientists agree that this is undoubtedly a complex subject and one that is difficult to study, due to the strong influence of the environment upon its expression [43]. Concerning protein content parameter, it is well documented that protein content is influenced largely by environmental factors [44]. In our study, its values tended to be rather higher at Janata site but not significant compared with the other two tested sites.
Similar results were also registered by [45] who indicated that protein content of legumes such as faba bean tended to increase under water deficit condition. This indeed the case of Janata site (drought conditions) that presented slightly higher protein content. Our finding also confirmed by several researches [46] who reported that water stress can reduce crop yield, but it has no significant effect on seed quality. Furthermore, the protein content of lentil (27.22 to 28.25) found to be within the general international acceptable lentil average (feedipedia) which is ranged between 24.6 to 28% (Table 3). A similar trend goes also with ash contents for all examined sites in which no significant differences observed.

Conclusions:
The present study concluded that drought and the limited water availability are the main factors affecting lentil ontogeny and production, but not the quality parameters (protein content, ash content and dry matter). In addition, lentil could be successfully recommended in the regions with more than 380 mm/year and must exclude in regions of precipitations lower than 285 mm.
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